Review ArticleA Review of In Vitro Drug Release Test Methods forNano-Sized Dosage Forms

Susan DrsquoSouza

Sunovion Pharmaceuticals Inc Marlborough MA 01752 USA

Correspondence should be addressed to Susan DrsquoSouza dr ssdsouzayahoocom

Received 16 June 2014 Revised 15 August 2014 Accepted 15 August 2014 Published 20 November 2014

Academic Editor Cornelia M Keck

Copyright copy 2014 Susan DrsquoSouzaThis is an open access article distributed under theCreativeCommonsAttributionLicensewhichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

This review summarizes the methods used to study real-time (37∘C) drug release from nanoparticulate drug delivery systems andestablish an IVIVC Since no compendial standards exist drug release is currently assessed using a variety of methods includingsample and separate (SS) continuous flow (CF) dialysis membrane (DM) methods and a combination thereof as well as noveltechniques like voltametry and turbidimetry This review describes the principle of each method along with their advantages anddisadvantages including challenges with set-up and sampling The SS method allows direct measurement of drug release withsimple set-up requirements but sampling is cumbersome With the CF method sampling is straightforward but the set-up is timeconsuming Set-up as well as sampling is easier with the DM but it may not be suitable for drugs that bind to the membraneNovel methods offer the possibility of real-time drug release measurement but may be restricted to certain types of drugs Of thesemethods Level A IVIVCs have been obtained with dialysis alone or in combination with the sample and separate technique Futureefforts should focus on developing mathematical models that describe drug release mechanisms as well as facilitate formulationdevelopment of nano-sized dosage forms

1 Introduction

Ever since reports documenting the utility of polycyanoacry-late and poly-120576-caprolactone nanocapsules for ocular admin-istration were published over two decades ago severalpublications have highlighted the benefits of using nano-sized dosage forms for medical and imaging purposes [1ndash3] Indeed advantages such as improved drug solubility andstability enhanced performance as well as increased efficacyhave been well established with nanoparticulate preparations[4] The increasing interest in nanotechnology based drugdelivery systems has been a key factor in the design anddevelopment of numerous novel dosage forms and com-plex delivery therapies such as liposomes nanoemulsionsnanocrystals polymeric nanoparticles solid lipid nanoparti-cles nanofibers and dendrimers to treat a variety of diseasestates [5ndash7] As an example researchers have investigatednanoparticles of Fenofibrate for the treatment of hypercholes-terolemia and Cyclosporine nanoparticles against cancer [89] Unsurprisingly several nanoparticulate preparations are

currently undergoing clinical investigation for the deliveryof a wide range of therapeutics like antibiotics antigenscytostatics and so forth via the intramuscular subcutaneousoral and intravenous route [10 11] A few examples ofcurrently marketed nanotechnology based dosage forms arelisted in Table 1

By the ISO definition the size for these formulationscan range between 1 and 100 nm Since sizes below 10 nmhave a greater propensity for renal clearance and tissueextravasations and larger sizes are quickly opsonized viathe macrophages of the reticuloendothelial system the 10ndash100 nm size range is considered optimal for nanoparticulatepreparations [12] Hence for medical and therapeutic pur-poses a range of less than 10ndash100 nm (in at least one dimen-sion) for nanoparticulates appears to be generally acceptedwith a few exceptions where sizes greater than 100 nmmay beapplicable [4 13] Due to their small size nano-sized dosageforms possess an unusually large surface-to-volume ratiothat alters the chemical physical and biological propertiesof the dosage form allowing them to cross cell and tissue

Hindawi Publishing CorporationAdvances in PharmaceuticsVolume 2014 Article ID 304757 12 pageshttpdxdoiorg1011552014304757

2 Advances in Pharmaceutics

Table 1 List of a few currently marketed nanoparticulate products

Brand Name API IndicationDaunoXome Daunorubicin Kaposirsquos sarcomaDepocyt Cytarabine Lymphomatous meningitisMyocet Doxorubicin Breast cancer

Oncaspar PEG-asparaginase

Acute LymphoblasticLeukemia

Restasis Cyclosporine Chronic dry eye diseaseTriglide Fenofibrate Hypercholesterolemia

Emend Aprepitant Chemotherapy inducednausea and vomiting

barriers thereby altering the pharmacokinetics and pharma-codynamics of the therapeutic agent This unique aspect ofnanoparticulate preparations has been exploited to delivertherapeutics to specific cells organs and other challengingin vivo targets Another consequence of enhanced delivery tothe target site is an increase in potency of the drug includingthe potential for elevated toxicity due to the carrier materialpossibly leading to reduced safety Therefore determinationof product quality and performance becomes a crucial aspectduring nanoparticulate dosage form development

As with most dosage forms product quality and per-formance may be verified through several in vivo andorin vitro experiments [14] Of these drug release kineticsprovides critical information about dosage form behaviorand is a key parameter used to assess product safety andefficacy Due to the expense time labor and need for humansubjectsanimals when performing in vitro measurementsof drug release kinetics in vitro release is gaining greaterattention as a surrogate test for product performance Indeedin vitro release testing is commonly used as a predictor ofin vivo behavior historically with traditional dosage formslike capsules and tablets (ie dissolution) and more recentlywith novel dosage forms like injectable biodegradable micro-spheres and implants [15ndash17] Generally in vitro releasestudies are performed at 37∘C (physiological temperature)though in some instances testing at elevated temperatures hasbeen explored to characterize drug release from a variety ofdosage forms [18 19] Some of the key objectives of in vitrorelease testing are one or more of the following

(a) assessing the effect of formulation factors and manu-facturing methods on the drug product

(b) routine assessment of quality control to support batchrelease

(c) substantiating product label claims

(d) establishing an in vitro in vivo correlationrelation-ship (IVIVCR)

(e) assuring product sameness under the SUPAC guide-lines

(f) as a compendial requirement [20 21]

Without exception in vitro release testing is an importantanalytical tool that is used to investigate and establish productbehavior during the various stages of drug product devel-opment as well as life cycle management When designedappropriately an in vitro release profile can reveal funda-mental information on the dosage form and its behavioras well as provide details on the release mechanism andkinetics enabling a rational and scientific approach to drugproduct development Understandably for complex dosageforms like nanoparticulates in vitro release testing assumesgreater significance

Despite the great strides in design and development ofnano-sized dosage forms no compendial or regulatory stan-dards exist for in vitro release testing Although there havebeen attempts to use the existing USP apparatus for in vitrodrug assessment of nanoparticles the set-ups were designedprimarily for oral and transdermal products and as such posemany challenges during a release study Hence several invitro release methods both compendial and noncompendialhave been utilized and reported Certainly the area of in vitrotesting for nanoparticulates lags behind the advances realizedin drug product development

Given the urgent need for improved product safety whilemaintaining quality of novel dosage forms like nanoparticlesthe past decade witnessed a series of international in vitrorelease workshops co-sponsored by the AAPS (AmericanAssociation of Pharmaceutical Scientists) US FDA (Foodand Drug Administration) FIP (Federation InternationalPharmaceutique) and several other scientific groups andagencies [22ndash25] The outcomes of these workshops werepublished as position papers with the general consensusthat dissolution or in vitro release testing was an importanttool in pharmaceutical development and quality control fora plethora of dosage forms both traditional and novelFurther the attendees highlighted the fact when compared totraditional formulations the characteristics of novelspecialdosage forms including site and mode of administrationwas vastly different and hence appropriate considerationshould be taken during selection of the apparatus releasemedium agitation (flow rate) and temperature In summarythe workshops concluded that along with a few other noveldosage forms nanoparticulate preparations were categorizedas those ldquodosage forms requiring more work before a (disso-lution) method can be recommendedrdquo [22 23]

In a separate endeavor the Nanotechnology Risk Assess-ment Working Group in the Center for Drug Evaluation andResearch (CDER) within the US FDA published a regulatorynote outlining the risk assessment and management processon a hypothetical nanomaterial drug to be administeredorally [4] In this example the Working Group identifiedldquodissolutionrelease raterdquo as a risk factor that may impactthe evaluation of quality safety and efficacy of the drugproduct containing nano-sized drug that is during ingestionand in vitro releasedissolution Hence the utility of in vitrorelease testing from a drug product development as well asregulatory standpoint cannot be ignored

Thus the purpose of this review is to provide the readerwith a summary of existing in vitro release methods fornano-sized dosage forms along with their strengths and

Advances in Pharmaceutics 3

shortcomings It is hoped that this review will serve as aguideline for developing suitable techniques for assessmentof exploratory formulations clinical and commercial dosageforms and establishment of an in vitro in vivo correlation(IVIVC)

2 In Vitro Release Methods

Much attention has been devoted to the development of suit-able apparatus to assess in vitro release fromnanoparticulatesHowever additional considerations like release media selec-tion agitation and so forth cannot be overlooked In contrastto oral dosage forms where release media typically mimicspH of the gastrointestinal tract selection of release media fornano-sized dosage forms will vary depending on the site ofadministration as well as the site of action of the formulationand thus simulation of in vivo conditions may be difficultIn general selection of release media for nanoparticulatepreparation is generally based on drug solubility and stabilityassay sensitivity and the method used Though maintenanceof sink conditions is preferable nonsink conditions havebeen employed Agitation frequently utilized to preventaggregation of dosage forms during an in vitro release studywill depend on the apparatus used Similarly sampling andbuffer replacement (total or partial) techniques are also basedon the type of in vitromethod used

As such drug release from nano-sized dosage formscan be assessed using one of the following three categoriesnamely sample and separate (SS) continuous flow (CF) anddialysis membrane (DM) methods More recently apparatusthat combine the principles of either the SS andDMorCF andDMhave also been reported Lastly a few novel methods thatuse voltametry turbidimetry and so forth are discussed Foreach of these methods a brief description is provided alongwith adaptations additional considerations advantages anddisadvantages

21 Sample and Separate In the SS method the nanopartic-ulate dosage form is introduced into the release media thatis maintained at a constant temperature after which drugrelease is assessed by sampling of the releasemedia (filtrate orsupernatant) or the nanoparticles From literature there areseveral adaptations to the SS method with differences notedin set-up container size mode of agitation and samplingtechniques

Commonly reported set-ups include USP I (basket) USPII (paddle) or vials and generally depend on the volume ofrelease media used in the in vitro release study [7 38ndash40] Forinstance vials were used when the volume of release mediawas small (1ndash15mL) and in vitro release vesselswere employedwith larger volumes (600ndash900mL) [5 7 38 40 41]

In addition to determining the type of set-up containersize also influences the mode of agitation used in an in vitrorelease study with the SS method With small sized dosageforms like nanoparticles agitation of the release media iscritical to the in vitro release process as it reduces the potential

for aggregation and enhances wetting thereby reducing theimpact of these factors on the in vitro release rate [38] Whileagitation of the release media is easily accomplished via theUSP I or USP II apparatus media contents in vials have beenagitated using alternate techniques For example Danhieret al and Li et al used magnetic stirrers with Paclitaxel andBSA nanoparticles respectively while Prabha et al reportedthe use of orbital shakers with DNA nanoparticles [42ndash44]

Drug release is monitored by physically separating thenanoparticles from the release media followed by analysis ofthe former or the latter [7 41] While several authors havedocumented the use of syringe filters to achieve physicalseparation between the release media and nanoparticlesthe small size of nanoparticles has necessitated the useof high energy separation techniques like centrifugationultracentrifugation and ultrafiltration [40 42 45ndash47] Forfiltration syringe filters with pore size as large as 045 120583mhave been used for withdrawing supernatant to monitordrug release of small molecules such as Celecoxib [40] Incomparison high energy separation techniques have beenreported with larger biomolecules like Insulin BSA (BovineSerum Albumin) and DNA [43 44 48] Once separateddrug release is generally monitored by sampling a part ofthe supernatant or decanting the entire supernatant contentat periodic intervals [7 49] In other instances separationwas followed by analysis of the nanoparticles (destructivetechnique) [41] After sampling an equal amount of freshrelease media or buffer is added to the set-up so that sinkconditions are maintained for the duration of the in vitrorelease study

In general the SS method provides a direct approach tomonitor drug release With this method most sample set-ups agitationmodes and sampling techniques are reasonablystraightforward and simple However due to the small sizeof nanoparticulate dosage forms several practical challengeshave been noted For instance aggregation of nanoparticlesduring in vitro release appears to be a key concern Addi-tionally while sampling techniques like filtration seem fairlyreasonable in principle clogging of filters during samplingadsorption of drug to the filter and so forth have beenreported [50] Indeed difficulty in physical separation evenwith high energy techniques continued drug release duringthe high energy separation process and so forth are someof the challenges often observed during sampling [38 45]Although sink conditions are recommended with the SSmethod nonsink conditions have been reported to be morediscriminatory with poorly soluble drugs [51] Neverthelessas with microparticulate dosage forms the SS method offersresearchers a simple and straightforward approach to moni-tor in vitro release from nano-sized dosage forms

22 Continuous Flow In the CF method drug release fromthe nanoparticulate dosage form is monitored using theUSP IV apparatus or a modification thereof Drug releaseoccurs as a result of buffer or media constantly circulatingthrough a column containing the immobilized dosage formand is monitored by collecting the eluent at periodic intervals(Figure 1)

4 Advances in Pharmaceutics

Flow through cell

Filter

Nanosuspension distributed in

glass beads

Release media

Pump

Detector

Figure 1 Continuous flow set-up in closed loop configuration

Unlike the widely used SS method only a few examplesof the CF method have been reported for nano-sized dosageforms [38 52] For example the release profiles of amor-phous nanoparticles and an unprocessed crystalline form ofCefuroxime Axetil a BCS II cephalosporin antibiotic wereevaluated using the CF method as well as other methodsdescribed below [38]

(a) USP I (basket) 900mL buffer at 100 rpm(b) USP II (paddle) 900mL buffer at 100 rpm(c) USP IV (flow through cell) 900mL buffer at a flow

rate of 16mLmin (peristaltic pump closed loop)through a cell (internal diameter = 25mm) and02 120583mmembrane disc filter

(d) dialysis bag (MWCO 12 kDa inner volume = 7mL)placed into a USP II (paddle) in vitro release tester(outer volume = 900mL paddle rpm = 100)

The results revealed that complete drug release wasachieved only with the USP II paddle and USP IV apparatusrelease profiles with the USP IVmethod being well separated

Immobilization of the nanoparticles was thought to bea factor contributing to the discriminatory results obtainedwith the USP IV apparatus

Similarly in an experiment on nano- and micro-particleloaded strip films of another BCS II drug Griseofulvin invitro release was performed using two methods [52]

(a) USP I (basket) 500 and 900mLmedia at 50 100 and150 rpm

(b) USP IV (flow through cell) 100mL media at flowrates of 4 8 and 16mLmin (peristaltic pump closedloop) through a cell (internal diameter = 226mm)and 02120583m membrane disc filter with the strip filmloaded in 6 different configurations

While complete release was observed only with USP Iand configuration B (strip film positioned in the cell on topof round glass beads) of the USP IV method results withconfigurations A (strip film positioned in the cone section

Sampling from outer compartment

Dialyzer cap

Inner compartment containing nanosuspension

Dialysis membrane

Outer compartment containing release media

Stir bar

Figure 2 ldquoRegular dialysisrdquo set-up (adapted from [21])

of the cell without round glass beads) and C (strip filmsandwiched between round glass beads) of USP IV at thehighest flow rate were more discriminatory than all the otherrelease profiles obtained in the in vitro study

In comparison to nanoparticulate dosage forms whereliterature on the use of USP IV methodology is sparseseveral salient aspects of the CF method can be inferredfrom its use in microparticulate dosage forms [21] As anexample flow rates used in the CF method depend on thetype of pump (peristaltic versus syringe) as well as the filtersused (membrane versus ultrafilters) Low flow rates havebeen known to be a key factor causing slow or incompleterelease from dosage forms [21] In general the availabilityof automated equipment has simplified routine samplingand media replacement with the the CF method in closed(recirculating media) and open (nonrecirculating media)loop systems However the CF methods suffer from severaldisadvantages that include instrument costs difficulty in set-up filter clogging adsorption to the filter and glass beads anddifficulty in maintaining a constant flow rate leading to widevariability in results

23 Dialysis Method Of all the methods used to assess drugrelease from nano-sized dosage forms the dialysis method(DM) is the most versatile and popular In this methodphysical separation of the dosage forms is achieved by usageof a dialysis membrane which allows for ease of samplingat periodic intervals As with the other methods severaladaptations of the DM have been reported in literaturewith key differences in set-up container size and molecularweight cut-off (MWCO)

Of the variety of DM set-ups used the most commonlycited is the dialysis bag (regular dialysis) other adaptationsbeing the reverse dialysis and side-by-side dialysis set-up[26 53 54] (Figures 2ndash4)With the regular dialysis technique

Advances in Pharmaceutics 5

Sampling from inner compartment

Dialyzer cap

Inner compartment containing release media

Dialysis membrane

Outer compartment containing nanosuspension

Stir bar

Figure 3 ldquoReverse dialysisrdquo set-up

Receiver compartment

Dialysis membrane

Stir bar

Sampling

Nanoemulsion in donor compartment

Figure 4 ldquoSide-by-side dialysisrdquo set-up (adapted from [26])

the nanoparticles are introduced into a dialysis bag contain-ing release media (inner mediacompartment) that is subse-quently sealed and placed in a larger vessel containing releasemedia (outer mediacompartment) agitated to minimizeunstirred water layer effects [32 55] In general the volumeenclosed in a dialysis bag (inner media) is significantlysmaller than the outer media For instance inner mediavolumes reported in literature range from 1 to 10mL whereasthe outermedia volume ismuch greater typically around 40ndash90mL [32 53 55] Thus container size will depend on thetotal volume of release media required for the in vitro releasestudy In the regular dialysis technique drug released fromthe nanoparticles diffuses through the dialysis membraneto the outer compartment from where it is sampled foranalysis (Figure 2) In contrast with the reverse dialysis set-up the nanoparticles are placed in the outer compartment(agitated to minimize the unstirred water layer) and theinner compartment is sampled for drug release (Figure 3)[54 56 57] Other adaptations of the DM include the side-by-side dialysis set-up where donor and receiver cells bothcontaining equal volumes of media agitated with a magneticstirrer are separated by a dialysis membrane and samplingoccurs from the receiver cell (Figure 4) and a vertical Franzdiffusion cell [26 58 59]

As with other methods drug solubility in the releasemedia is essential to its transport across the dialysis mem-brane Apart from release media the importance of selectingan appropriate molecular weight cut-off (MWCO) for thedialysis membrane cannot be overlooked Indeed the basicpremise of the DM is that drug that is released from thedosage form will diffuse rapidly from one compartmentthrough the membrane and enter the second compartmentfrom where it is sampled for analysis Thus membranes witha sufficiently high membrane MWCO are often selected forin vitro release studies so that drug transport is not a limitingfactor As an example in a study with 3 dosage forms ofIndomethacin (eg nanoparticles and nanocapsules usingpoly-120576-caprolactone and a submicron emulsion) Calvo et alnoted that nearly 85 of drug was released within 2 hoursand complete release was achieved in 4 hours when a 12 kDamembranewas used [54] However the rationale for selectinga MWCO is rather subjective For instance a MWCO ashigh as 10ndash14 kDa was used to study drug release of smallmolecules like Risperidone and Indomethacin and aMWCOas low as 1 kDa though suitable for assessing in vitro releaseof a large molecule pDNA proved to be limiting for thediffusion of Cefuroxime Axetil a cephalosporin antibiotic[32 38 55 60] In general the MWCO should be sufficientlylarge to permit drug transport

The ease of set-up and sampling with the DM make ita very simple and straightforward technique to study drugrelease from a wide variety of nano-sized dosage forms likenanospheres liposomes emulsions nanosuspensions andso forth [53ndash55] However issues have been reported withthe regular dialysis method If incorrectly sealed leakage ofmedia and dosage form may occur from both ends of thedialysis bag set-up Incomplete release data may be observedif nonsink conditions exist or equilibration times are high[38] On the other hand the difference in equilibration timescan be exploited as a discriminatory tool to distinguish releasebehavior between fast and slow releasing dosage forms [50]Another factor to be considered is that the DM cannotbe used with drugs that bind to the dialyzing membraneAs stated in a review paper on microparticulate dosageforms it is recommended that the suitability of the dialyzingmembrane be assessed prior to use [21 61]

24 CombinationMethods A fewpublications havemodifiedthe set-ups used in the SS CF and DM methods to evaluatedrug release from nano-sized dosage forms In most of thesereports the set-up of the SS method is combined with adialyzer to allow ease of sampling In other publications theDM and the CF set-up is used to assess in vitro release fromnanoparticulates

As an example Mottaleb et al compared release profilesof Ibuprofen from liposomes and lipid nanocapsules andnanoparticles using the regular dialysis method (dialysis bag)and modified USP I (basket) set-up where the shaft wasaffixed with a glass basket having a dialysis membrane atthe bottom that is glass basket dialysis (GBD) and placedin a larger vessel (Figure 5) [27] Sampling was performedfrom the outer vessel Unlike the dialysis bag that had a large

6 Advances in Pharmaceutics

Glass basket

Dialysis membrane

Figure 5 Comparison ofUSP I (left) and glass basket dialysis (right)set-ups (adapted from [27])

membrane surface area the GBD was able to discriminatedifferences between release profiles from different formu-lations (lipid nanocapsules nanoparticles liposomes) Inanother study Lobenberg et al compared drug release fromRifampicin and Moxifloxacin hydrochloride nanoparticleswith the regular dialysis method (dialysis bag) as well as anadaptation of USP I (basket) where a cylinder containing adialysis membrane at the bottom was attached to the basketshaft [62] Results from this study showed that modifiedUSP I set-up was more discriminatory in nature and couldbe attributed to the reduced surface area of the dialysismembrane In yet another modification of the USP I (basket)set-up a dialysis bag containing nanostructured lipid carriersof Artemether was placed inside the basket and drug releasemonitored over time [63] Though most studies have utilizedthe USP I set-up others have used the USP II (paddle) set-upin combination with the DM For example Cao et al affixeddialysis bags containing Silybin meglumine nanoparticlesonto a USP II (paddle) apparatus and assessed drug releasein five different release media [33 35]

A combination of aDM previously reported byKostanskiet al and CF method was utilized to assess drug releasefrom 5-Fluorouracil loaded BSA nanoparticles [28 64] Thesetup comprised a glass tube (with a dialysis membrane atthe bottom) that was placed into a larger vessel containingbuffer (Figure 6) Sampling as well as buffer replacement wasperformed from the larger vessel with the aid of two pumpshaving the same flow rate The combined DM-CF set-up wasable to demonstrate sustained levels of 5-Fluorouracil andthe absence of burst release from the BSA nanoparticles Analternate dialysis-CFmethod utilized a dialysis adaptor insidethe CF set-up (Figure 7) [29]

25 New Methods Apart from the commonly reported SSCF and DM methods a few alternate approaches have beenutilized tomonitor drug release Amajority of these appear tobe targeted towards electroactive drugsWhile the techniquesmay differ in principle or application they possess a fewcommon elements in that physical separation of the dosageform from the release media is not required Additionallythese techniques offer the possibility of measurement underreal-time conditions

Detector

Waste

Dialysis membrane

Nanosuspension

Stir bar

Pump 2Pump 1

Release media

Figure 6 Continuous flow dialysis set-up with two pumps (adaptedfrom [28])

Flow through cell

Releasemedia

Pump

Detector

Filter

Glass beads

Dialyzer containingnanosuspension

Figure 7 Dialysis adapter inside a continuous flow set-up (adaptedfrom [29])

As such electrochemical methods offer the possibility ofrapid in situ measurements while avoiding the interferencecaused by the presence of undissolved dosage form in therelease media In one such approach a potentiometric drugselective electrode was used to monitor real-time release ofProcaine hydrochloride from pH-responsive nanogels [65]In another report by Mora et al a highly sensitive repetitivesquare-wave voltammetric technique was utilized to measurethe redox reaction of Doxorubicin hydrochloride (Figure 8)[30] Similarly differential pulse polarography was used toassess continuous drug release from Piroxicam Chloram-phenicol and Diazepam [66 67] Apart from the fact thatonly electroactive drugs can be measured by the abovemethods these methods suffer from additional drawbacksFor example the sensitivity as well as responsiveness ofeach technique varies greatly Also the sensors used may bespecific to a particular drug

Nonelectrochemical methods like calorimetry turbidim-etry and laser diffraction have also been evaluated as invitro release methods Solution calorimetry was employedby Kayaert et al during in vitro release measurement ofNaproxen Cinnarizine and Compound A (investigational

Advances in Pharmaceutics 7

Working electrode

Reference electrode

Counter electrode

Release media

Redox reactionAox Ared

A Liposome containing drug ldquoArdquo

Figure 8 Electrochemical cell set-up for real-time measurement ofdrug release (adapted from [30])

Pump control

Syringe Analyte

NanosuspensionMicrodialysis probe

pump

Figure 9 Microdialysis set-up (adapted from [31])

API) from nanocrystals [68] The principle of this tech-nique is based on detection of the net proportion of heatchange during in vitro release Challenges with calorimetricmeasurements include long equilibration times Further theheat produced by all the processes needs to be consideredTurbidimetric and laser diffraction approaches utilizing thechange light scattering properties of nanoparticles dispersedin release media have also been utilized [69 70] Concernswith these methods include the long equilibration timeslimited range of particle size and initial concentration ofsamples that can be used

Helle et al designed a novel online system for evaluatingthe drug release from Indomethacin and Beclomethasonedipropionate nanoparticles In thismethod nanoparticles arepacked into small column which is connected to multiportmodulation valve attached to an HPLC system allowingfor rapid analysis [71] Other new methods reported inliterature include a vertical diffusion Franz cell and an invitro lipolysis model [37 72] Microdialysis another set-up utilized to measure drug release from nanoparticules isbased on passive diffusion of drug through a concentrationgradient across a semipermeable membrane (Figure 9) [3147] Drug release can be measured in real-time conditionsusing analytical methods like HPLC However care shouldbe taken when surfactants are used in the release media asrecovery may be affected

3 Modeling Drug Release

Very few publications have attempted to describe drug releaseprofiles from nanoparticulate dosage forms using mathe-matical models This is not surprising given that nano-sizeddosage forms are complex and drug release evaluations arenot straightforward However a few authors have discussedthe importance of mathematical models and endeavored tocharacterize drug release For instance Barzegar-Jalali et alsuggested the use of reciprocal powered time (RPT) as generalmodel to analyze the complex nature of drug release fromnanoparticles with alternate approaches being the Weibulland log-probabilitymodels [73] In another report Zeng et aldeveloped a three-parameter model that considers reversibledrug-carrier interaction as well as diffusional drug releasefrom liposomes [74 75]

Use of mathematical models to describe drug releaseprofiles offers several advantages It permits the elucidationof drug release mechanisms and can be used to guide for-mulation development efforts Furthermodel parameters canserve to represent as well as compare in vitro release profilesHowever caution must be used when applying mathematicalmodels to complex drug release mechanisms

4 IVIVC

The US FDA defines IVIVC as ldquoA predictive mathematicalmodel describing the relationship between an in vitro prop-erty of an extended release dosage form (usually the rate orextent of drug in vitro release or release) and a relevant invivo response for example plasma drug concentration oramount of drug absorbedrdquo [76] Thus establishment of anIVIVC described as a correlation between in vitro release andin vivo behavior enhances the utility of an in vitro study Fromthe 1997 FDA guidance document an IVIVC will reduce theregulatory burden by paring the number of in vivo studiesneeded for product approval Additionally it promotes thesetting of clinically relevant in vitro release specifications [76]

The FDA guidance also categorizes IVIVCs into threelevels Level A represents a linear or nonlinear point-to-point relationship between the in vitro and in vivo releaseprofiles If the relationship is nonlinear suitable modelingor scaling is required Of the three IVIVC levels Level Adescribes the highest correlation and is most commonly usedto obtain a biowaiver On the other hand a Level B correlationis a comparison of summary parameters such as the meanin vitro dissolution time with mean in vivo dissolution timeor mean residence time (MRT) Since several in vivo curveswill produce a similarMRT value ormean in vitro dissolutiontime Level B correlations are not as discriminatory as LevelA but acceptable for an IVIVC A Level C correlationdescribes a relationship between an in vitro release parameter(eg dissolved at a particular time) and a pharmacokineticparameter (eg 119862max) However a Level C correlation is notdescriptive of the complete shape of the in vivo release profileand though acceptable seldom used

As such the FDA guidance is intended for oral extendedrelease products However principles of the FDA guidance

8 Advances in Pharmaceutics

Table 2 Examples of IVIVC with nano-sized dosage forms in animal models

Drug and dosage form In vitro release set-up In vivo studies IVIVC type Reference

Indomethacin gelatin nanoparticles Dialysis bags Wistar Albinorats Level A [32]

Silybin meglumine hollow-spheremesoporous silica nanoparticles Combination (USP Imdashdialysis bag) Beagle dogs Level A [33]

Silybin 72-hour SLB andPSNs (porous silica nanoparticles) Combination (USP Imdashdialysis bag) Beagle dogs Level A [35]

Simvastatin nanostructured lipidcarriers and nanoparticles Dialysis bag BalbC mice Level A [34]

Fenofibrate nanosuspension USP I apparatus SpragueDawley rats Level A [36]

Fenofibrate lipid matrix particles In vitro lipolysis model SpragueDawley rats Rank order [37]

Table 3 Level A IVIVC with two Silybin preparations (data from reference [35])

Formulation absorbed equals 1198772

72-hour SLB 11379 times dissolved + 88688 09831Silybin PSNs (porous silica nanoparticles) 08915 times dissolved minus 10152 09831

have been used to demonstrate an IVIVC from severalnonoral dosage forms including nano-sized preparationsMost published literature on IVIVC compares the in vitrorelease behavior with the in vivo absorption profile thelatter calculated by the FDA recommended Wagner-Nelsonmethod [76 77] Once the fraction absorbed is computeda correlation is obtained by comparing it with the in vitrorelease profile and the type of IVIVC (Level A level B etc) isdetermined

Over the last decade a few reports on IVIVC from nano-sized dosage forms have been published (Table 2) In someinstances a rank order correlation was observed while inothers a Level A IVIVC was established with some or allof the formulations evaluated in the study As an example arank order correlation was observed with three preparationsof Fenofibrate with drug release and absorption from 100 nmlipid matrix particles gt microparticles gt control (crystallinesuspension) [37] In another study on Fenofibrate nanosus-pensions Xu et al attempted to elucidate the absorptionmechanism using in situ gut perfusion model [36] Dataanalysis between in vitro dissolution (119875) in situ intestinalabsorption (119865) and in vivo absorption (119865

119886) demonstrated

a Level A correlation (1198772 gt 095) As a result the authorsconcluded that the in situ intestinal perfusion model couldbe a predictor of in vivo pharmacokinetic behavior for thenanosuspension

In a recent report Kumar et al investigated the relation-ship between in vitro and in vivo release from Indomethacingelatin nanoparticles administered orally to Wistar albinorats [32] Study results indicated that a good correlation wasobtained by plotting the fraction absorbed in vivo (Wagner-Nelson method) against the fraction released the latter per-formed using regular dialysis (dialysis bags) (Figure 10) TheWagner-Nelsonmethod was also used in another publication

0

20

40

60

80

100

120

0 20 40 60 80 100

In v

ivo

abso

rptio

n (

)

In vitro release ()

R2 = 0981

y = 1121x

Figure 10 Level A IVIVC from Indomethacin gelatin nanoparticlesusing regular dialysis (redrawn from [32])

where the in vivo absorption fromSilybinmeglumine hollow-sphere mesoporous silica nanoparticles dosed orally to bea-gle dogs was compared with in vitro results obtained using acombination USP I (paddle) dialysis bag set-up [33] Of thefive different releasemedia used in the study a Level A IVIVC(1198772 gt 097) was obtained with 006M Na

2CO3and 008M

Na2CO3solutions (Figure 11) In another study with Silybin

an IVIVC was achieved with a 72-hour release formulationof Silybin (72-hour SLB) that consisted of a solid dispersiongel matrix and porous silica nanoparticles (PSNs) (Table 3)[35] Similar to the earlier study the authors compared invivo release from beagle dogs with in vitro release assessedusing a combination USP I (paddle) dialysis bag set-upIn another paper Tiwari et al demonstrated a Level A

Advances in Pharmaceutics 9

0

20

40

60

80

100

0 20 40 60 80 100

Abso

rbed

()

Abso

rbed

()

0 20 40 60 80 1000

20

40

60

80

100

In vitro release ()

In vitro release ()

y = 23417x minus 78256

R2 = 09741

y = 16114x minus 56752

R2 = 09931

006M Na2CO3

008M Na2CO3

Figure 11 Level A IVIVC from Silybin meglumine hollow-typemesoporous silica nanoparticles using a combined USP II-dialysisbag set-up (redrawn from [33])

correlation between in vitro release (dialysis bag) and percentdrug absorbed (Wagner Nelson method) for Simvastatinnanostructured lipid carriers as well as nanoparticles (1198772 gt094) (Figure 12) [34]

5 Conclusions

For novel dosage forms like nanoparticles where no regu-latory or compendial standards exist in vitro drug releaseassessment assumes greater significance in serving as anindicator of product quality and performance A plethoraof methods have been used each with their advantages anddrawbacks with respect to ease of set-up sampling and rapidbuffer replacement Ideally an in vitro release method shouldsimulate in vivo conditions release mechanisms and enablethe establishment of an IVIVC Future research should focuson developing relevant mathematical models to predict drugrelease behavior as well as release mechanisms applicable to awide range of nano-sized dosage forms

Conflict of Interests

The author declares that there is no conflict of interestsregarding the publication of this paper

0

20

40

60

80

100

120

Dru

g ab

sorb

ed (

)

0

20

40

60

80

100

120

Dru

g ab

sorb

ed (

)

Simvastatin loaded nanostructured lipid carriers

Simvastatin loaded solid lipid nanoparticles

0 20 40 60 80 100In vitro release ()

0 20 40 60 80 100In vitro release ()

R2 = 09404

R2 = 0941

Figure 12 Level A correlation of Simvastatin from two nano-sizeddosage forms (redrawn from [34])

References

[1] N Al Khouri Fallouh L Roblot-Treupel and H Fessi ldquoDevel-opment of a new process for the manufacture of polyisobutyl-cyanoacrylate nanocapsulesrdquo International Journal of Pharma-ceutics vol 28 no 2-3 pp 125ndash132 1986

[2] C Losa P Calvo E Castro J L Vila-Jato and M J AlonsoldquoImprovement of ocular penetration of amikacin sulphate byassociation to poly(butylcyanoacrylate) nanoparticlesrdquo Journalof Pharmacy and Pharmacology vol 43 no 8 pp 548ndash552 1991

[3] C Losa L Marchal-Heussler F Orallo J L Vila Jato andM J Alonso ldquoDesign of new formulations for topical ocularadministration polymeric nanocapsules containing metipra-nololrdquo Pharmaceutical Research vol 10 no 1 pp 80ndash87 1993

[4] C N Cruz K M Tyner L Velazquez et al ldquoCDER riskassessment exercise to evaluate potential risks from the use ofnanomaterials in drug productsrdquo AAPS Journal vol 15 no 3pp 623ndash628 2013

[5] G Verreck I Chun J Rosenblatt et al ldquoIncorporation of drugsin an amorphous state into electrospun nanofibers composedof a water-insoluble nonbiodegradable polymerrdquo Journal ofControlled Release vol 92 no 3 pp 349ndash360 2003

[6] H Heiati R Tawashi R R Shivers and N C PhillipsldquoSolid lipid nanoparticles as drug carriers I incorporation andretention of the lipophilic prodrug 31015840-azido-31015840-deoxythymidinepalmitaterdquo International Journal of Pharmaceutics vol 146 no1 pp 123ndash131 1997

10 Advances in Pharmaceutics

[7] M Cetin A Atila and Y Kadioglu ldquoFormulation and in vitrocharacterization of Eudragit L100 and Eudragit L100-PLGAnanoparticles containing diclofenac sodiumrdquo AAPS Pharm-SciTech vol 11 pp 1250ndash1256 2010

[8] A Hanafy H Spahn-Langguth G Vergnault et al ldquoPharma-cokinetic evaluation of oral fenofibrate nanosuspensions andSLN in comparison to conventional suspensions of micronizeddrugrdquo Advanced Drug Delivery Reviews vol 59 no 6 pp 419ndash426 2007

[9] T M Allen W W K Cheng J I Hare and K M LaginhaldquoPharmacokinetics and pharmacodynamics of lipidic nano-particles in cancerrdquoAnti-Cancer Agents in Medicinal Chemistryvol 6 no 6 pp 513ndash523 2006

[10] J Kreuter ldquoNanoparticle-based drug delivery systemsrdquo Journalof Controlled Release vol 16 no 1-2 pp 169ndash176 1991

[11] M L Etheridge S A Campbell A G Erdman C L Haynes SMWolf and JMcCullough ldquoThe big picture on nanomedicinethe state of investigational and approved nanomedicine prod-uctsrdquo Nanomedicine Nanotechnology Biology and Medicinevol 9 no 1 pp 1ndash14 2013

[12] S Nie ldquoUnderstanding and overcoming major barriers incancer nanomedicinerdquoNanomedicine vol 5 no 4 pp 523ndash5282010

[13] W H de Jong and P J A Borm ldquoDrug delivery andnanoparticles applications and hazardsrdquo International Journalof Nanomedicine vol 3 no 2 pp 133ndash149 2008

[14] S DrsquoSouza J A Faraj R Dorati and P P DeLuca ldquoA short termquality control tool for biodegradable microspheresrdquo AAPSPharmSciTech vol 15 no 3 pp 530ndash541 2014

[15] P Buch P Holm J Q Thomassen et al ldquoIVIVC for fenofibrateimmediate release tablets using solubility and permeability as invitro predictors for pharmacokineticsrdquo Journal of Pharmaceuti-cal Sciences vol 99 no 10 pp 4427ndash4436 2010

[16] S DrsquoSouza J A Faraj S Giovagnoli and P P DeLuca ldquoIVIVCfrom long acting olanzapine microspheresrdquo International Jour-nal of Biomaterials vol 2014 Article ID 407065 11 pages 2014

[17] L C Amann M J Gandal R Lin Y Liang and S J SiegelldquoIn vitro-in vivo correlations of scalable PLGA-Risperidoneimplants for the treatment of schizophreniardquo PharmaceuticalResearch vol 27 no 8 pp 1730ndash1737 2010

[18] G Zackrisson G Ostling B Skagerberg and T Anfalt ldquoACcel-erated Dissolution Rate Analysis (ACDRA) for controlledrelease drugs Application to Roxiamrdquo Journal of Pharmaceu-tical and Biomedical Analysis vol 13 no 4-5 pp 377ndash383 1995

[19] S S DSouza J A Faraj and P P DeLuca ldquoA model-dependentapproach to correlate accelerated with real-time release frombiodegradable microspheresrdquo AAPS PharmSciTech vol 6 arti-cle 70 no 4 2005

[20] D J Burgess A S Hussain T S Ingallinera and M ChenldquoAssuring quality and performance of sustained and controlledrelease parenterals workshop reportrdquo AAPS PharmSci vol 4article E7 2002

[21] S S DrsquoSouza and P P DeLuca ldquoMethods to assess in vitrodrug release from injectable polymeric particulate systemsrdquoPharmaceutical Research vol 23 no 3 pp 460ndash474 2006

[22] M Siewert J Dressman C K Brown and V P ShahldquoFIPAAPS guidelines to dissolutionin vitro release testing ofnovelspecial dosage formsrdquo AAPS PharmSciTech vol 4 article7 2003

[23] C K Brown H D Friedel A R Barker et al ldquoFIPAAPSjoint workshop report dissolutionin vitro release testing of

novelspecial dosage formsrdquo AAPS PharmSciTech vol 12 no2 pp 782ndash794 2011

[24] MMartinezM Rathbone D Burgess andMHuynh ldquoIn vitroand in vivo considerations associated with parenteral sustainedrelease products a review based upon information presentedand points expressed at the 2007 Controlled Release SocietyAnnual Meetingrdquo Journal of Controlled Release vol 129 no 2pp 79ndash87 2008

[25] M N Martinez M J Rathbone D Burgess and M HuynhldquoBreakout session summary from AAPSCRS joint workshopon critical variables in the in vitro and in vivo performanceof parenteral sustained release productsrdquo Journal of ControlledRelease vol 142 no 1 pp 2ndash7 2010

[26] N Chidambaram and D J Burgess ldquoA novel in vitro releasemethod for submicron-sized dispersed systemsrdquo AAPS Pharm-Sci vol 1 no 3 pp 32ndash40 1999

[27] M M A Abdel-Mottaleb and A Lamprecht ldquoStandardized invitro drug release test for colloidal drug carriers using modifiedUSP dissolution apparatus Irdquo Drug Development and IndustrialPharmacy vol 37 no 2 pp 178ndash184 2011

[28] A Maghsoudi S A Shojaosadati and E Vasheghani Farahanildquo5-Fluorouracil-loaded BSA nanoparticles formulation opti-mization and in vitro release studyrdquo AAPS PharmSciTech vol9 no 4 pp 1092ndash1096 2008

[29] U Bhardwaj and D J Burgess ldquoA novel USP apparatus 4 basedrelease testing method for dispersed systemsrdquo InternationalJournal of Pharmaceutics vol 388 no 1-2 pp 287ndash294 2010

[30] L Mora K Y Chumbimuni-Torres C Clawson L HernandezL Zhang and J Wang ldquoReal-time electrochemical monitoringof drug release from therapeutic nanoparticlesrdquo Journal ofControlled Release vol 140 no 1 pp 69ndash73 2009

[31] C B Michalowski S S Guterres and T Dalla CostaldquoMicrodialysis for evaluating the entrapment and release of alipophilic drug from nanoparticlesrdquo Journal of Pharmaceuticaland Biomedical Analysis vol 35 no 5 pp 1093ndash1100 2004

[32] R Kumar R C Nagarwal M Dhanawat and J K PanditldquoIn-vitro and in-vivo study of indomethacin loaded gelatinnanoparticlesrdquo Journal of Biomedical Nanotechnology vol 7 no3 pp 325ndash333 2011

[33] X Cao W W Deng M Fu et al ldquoIn vitro release and in vitro-in vivo correlation for silybin meglumine incorporated intoHollow-type mesoporous silica nanoparticlesrdquo InternationalJournal of Nanomedicine vol 7 pp 753ndash762 2012

[34] R Tiwari and K Pathak ldquoNanostructured lipid carrier versussolid lipid nanoparticles of simvastatin comparative analysis ofcharacteristics pharmacokinetics and tissue uptakerdquo Interna-tional Journal of Pharmaceutics vol 415 no 1-2 pp 232ndash2432011

[35] X Cao W Deng M Fu et al ldquoSeventy-two-hour releaseformulation of the poorly soluble drug silybin based on poroussilica nanoparticles in vitro release kinetics and in vitroin vivocorrelations in beagle dogsrdquo European Journal of Pharmaceuti-cal Sciences vol 48 no 1-2 pp 64ndash71 2013

[36] Y Xu Y Wang X M Li et al ldquoStudy on the release offenofibrate nanosuspension in vitro and its correlation with insitu intestinal and in vivo absorption kinetics in ratsrdquo DrugDevelopment and Industrial Pharmacy vol 40 no 7 pp 972ndash979 2014

[37] N Borkar D Xia R Holm et al ldquoInvestigating the correlationbetween in vivo absorption and in vitro release of fenofibratefrom lipid matrix particles in biorelevant mediumrdquo EuropeanJournal of Pharmaceutical Sciences vol 51 pp 204ndash210 2014

Advances in Pharmaceutics 11

[38] D Heng D J Cutler H K Chan J Yun and J A RaperldquoWhat is a suitable dissolutionmethod for drug nanoparticlesrdquoPharmaceutical Research vol 25 no 7 pp 1696ndash1701 2008

[39] A C Kilic Y Capan I Vural et al ldquoPreparation and characteri-zation of PLGA nanospheres for the targeted delivery of NR2B-specific antisense oligonucleotides to the NMDA receptors inthe brainrdquo Journal of Microencapsulation vol 22 no 6 pp 633ndash641 2005

[40] Y Zhang H Wang C Li et al ldquoA novel three-dimensionallarge-pore mesoporous carbon matrix as a potential nanove-hicle for the fast release of the poorly water-soluble drugcelecoxibrdquoPharmaceutical Research vol 31 pp 1059ndash1070 2014

[41] V Sanna A M Roggio S Siliani et al ldquoDevelopment of novelcationic chitosan-and anionic alginate-coated poly(DL-lactide-co-glycolide) nanoparticles for controlled release and light pro-tection of resveratrolrdquo International Journal of Nanomedicinevol 7 pp 5501ndash5516 2012

[42] F Danhier N Lecouturier B Vroman et al ldquoPaclitaxel-loadedPEGylated PLGA-based nanoparticles In vitro and in vivoevaluationrdquo Journal of Controlled Release vol 133 no 1 pp 11ndash17 2009

[43] Y Li Y Pei X Zhang et al ldquoPEGylated PLGA nanoparticlesas protein carriers synthesis preparation and biodistributionin ratsrdquo Journal of Controlled Release vol 71 no 2 pp 203ndash2112001

[44] S Prabha W-Z Zhou J Panyam and V Labhasetwar ldquoSize-dependency of nanoparticle-mediated gene transfection stud-ies with fractionated nanoparticlesrdquo International Journal ofPharmaceutics vol 244 no 1-2 pp 105ndash115 2002

[45] S J Wallace J Li R L Nation and B J Boyd ldquoDrug releasefrom nanomedicines selection of appropriate encapsulationand release methodologyrdquo Drug Delivery and TranslationalResearch vol 2 no 4 pp 284ndash292 2012

[46] D Juenemann E Jantratid C Wagner C Reppas M Vertzoniand J B Dressman ldquoBiorelevant in vitro dissolution testingof products containing micronized or nanosized fenofibratewith a view to predicting plasma profilesrdquo European Journal ofPharmaceutics and Biopharmaceutics vol 77 no 2 pp 257ndash2642011

[47] P F Yue X Y Lu Z Z Zhang et al ldquoThe study on theentrapment efficiency and in vitro release of puerarin submi-cron emulsionrdquoAAPS PharmSciTech vol 10 no 2 pp 376ndash3832009

[48] M Mahkam F Hosseinzadeh and M Galehassadi ldquoPrepara-tion of ionic liquid functionalized silica nanoparticles for oraldrug deliveryrdquo Journal of Biomaterials amp Nanobiotechnologyvol 3 pp 391ndash395 2012

[49] A S Ham M R Cost A B Sassi C S Dezzutti andL C Rohan ldquoTargeted delivery of PSC-RANTES for HIV-1prevention using biodegradable nanoparticlesrdquo PharmaceuticalResearch vol 26 no 3 pp 502ndash511 2009

[50] Y I Kim L Fluckiger M Hoffman I Lartaud-IdjouadieneJ Atkinson and P Maincent ldquoThe antihypertensive effect oforally administered nifedipine-loaded nanoparticles in sponta-neously hypertensive ratsrdquoThe British Journal of Pharmacologyvol 120 no 3 pp 399ndash404 1997

[51] P Liu O de Wulf J Laru et al ldquoDissolution studies of poorlysoluble drug nanosuspensions in non-sink conditionsrdquo AAPSPharmSciTech vol 14 no 2 pp 748ndash756 2013

[52] L Sievens-Figueroa N Pandya A Bhakay et al ldquoUsing USPI and USP IV for discriminating dissolution rates of nano-

and microparticle-loaded pharmaceutical strip-filmsrdquo AAPSPharmSciTech vol 13 no 4 pp 1473ndash1482 2013

[53] G P Yan R F Zong L Li T Fu F Liu and X H YuldquoAnticancer drug-loaded nanospheres based on biodegradableamphiphilic 120576-caprolactone and carbonate copolymersrdquo Phar-maceutical Research vol 27 no 12 pp 2743ndash2752 2010

[54] P Calvo J L Vila-Jato and M J Alonso ldquoComparative invitro evaluation of several colloidal systems nanoparticlesnanocapsules and nanoemulsions as ocular drug carriersrdquoJournal of Pharmaceutical Sciences vol 85 no 5 pp 530ndash5361996

[55] M SMuthu and S Singh ldquoPoly (D L-lactide) nanosuspensionsof risperidone for parenteral delivery formulation and in-vitroevaluationrdquoCurrent DrugDelivery vol 6 no 1 pp 62ndash68 2009

[56] MY Levy and S Benita ldquoDrug release from submicronized owemulsion a new in vitro kinetic evaluationmodelrdquo InternationalJournal of Pharmaceutics vol 66 no 1ndash3 pp 29ndash37 1990

[57] X Xu M A Khan and D J Burgess ldquoA two-stage reversedialysis in vitro dissolution testing method for passive targetedliposomesrdquo International Journal of Pharmaceutics vol 426 no1-2 pp 211ndash218 2012

[58] B E Kilfoyle L Sheihet Z Zhang M Laohoo J Kohn and BBMichniak-Kohn ldquoDevelopment of paclitaxel-TyroSpheres fortopical skin treatmentrdquo Journal of Controlled Release vol 163no 1 pp 18ndash24 2012

[59] S Uprit R K Sahu A Roy and A Pare ldquoPreparation and char-acterization of minoxidil loaded nanostructured lipid carriergel for effective treatment of alopeciardquo Saudi PharmaceuticalJournal vol 21 pp 379ndash385 2013

[60] B Qiu M Ji X Song et al ldquoCo-delivery of docetaxel andendostatin by a biodegradable nanoparticle for the synergistictreatment of cervical cancerrdquo Nanoscale Research Letters vol 7article 666 2012

[61] S S DrsquoSouza and P P DeLuca ldquoDevelopment of a dialysis invitro release method for biodegradable microspheresrdquo AAPSPharmSciTech vol 6 no 2 article 42 2005

[62] Y Gao J Zuo N Bou-Chacra et al ldquoIn vitro release kineticsof antituberculosis drugs from nanoparticles assessed usinga modified dissolution apparatusrdquo BioMed Research Interna-tional vol 2013 Article ID 136590 9 pages 2013

[63] M Joshi S Pathak S Sharma and V Patravale ldquoDesignand in vivo pharmacodynamic evaluation of nanostructuredlipid carriers for parenteral delivery of artemether nanojectrdquoInternational Journal of Pharmaceutics vol 364 no 1 pp 119ndash126 2008

[64] J W Kostanski and P P DeLuca ldquoA novel in vitro releasetechnique for peptide-containing biodegradable microspheresrdquoAAPS PharmSciTech vol 1 article 4 2000

[65] J P K Tan C H Goh and K C Tam ldquoComparative drugrelease studies of two cationic drugs from pH-responsivenanogelsrdquo European Journal of Pharmaceutical Sciences vol 32no 4-5 pp 340ndash348 2007

[66] K M Rosenblatt D Douroumis and H Bunjes ldquoDrug releasefrom differently structured monooleinpoloxamer nanodisper-sions studied with differential pulse polarography and ultrafil-tration at low pressurerdquo Journal of Pharmaceutical Sciences vol96 no 6 pp 1564ndash1575 2007

[67] N Charalampopoulos K Avgoustakis and C G KontoyannisldquoDifferential pulse polarography a suitable technique for mon-itoring drug release from polymeric nanoparticle dispersionsrdquoAnalytica Chimica Acta vol 491 no 1 pp 57ndash62 2003

12 Advances in Pharmaceutics

[68] P Kayaert B Li I Jimidar P Rombaut F Ahssini and G Vanden Mooter ldquoSolution calorimetry as an alternative approachfor dissolution testing of nanosuspensionsrdquo European Journal ofPharmaceutics and Biopharmaceutics vol 76 no 3 pp 507ndash5132010

[69] M T Crisp C J Tucker T L Rogers R O Williams III andK P Johnston ldquoTurbidimetric measurement and prediction ofdissolution rates of poorly soluble drug nanocrystalsrdquo Journalof Controlled Release vol 117 no 3 pp 351ndash359 2007

[70] M V Chaubal and C Popescu ldquoConversion of nanosus-pensions into dry powders by spray drying a case studyrdquoPharmaceutical Research vol 25 no 10 pp 2302ndash2308 2008

[71] A Helle S Hirsjarvi L Peltonen J Hirvonen S K Wied-mer and T Hyotylainen ldquoNovel dynamic on-line analyticalseparation system for dissolution of drugs from poly(lacticacid) nanoparticlesrdquo Journal of Pharmaceutical and BiomedicalAnalysis vol 51 no 1 pp 125ndash130 2010

[72] V Domınguez-Villegas B Clares-Naveros M L Garcıa-Lopez et al ldquoDevelopment and characterization of two nano-structured systems for topical application of flavanones isolatedfrom Eysenhardtia platycarpardquo Colloids and Surfaces B Bioint-erfaces vol 116 pp 183ndash192 2014

[73] M Barzegar-Jalali K AdibkiaHValizadeh et al ldquoKinetic anal-ysis of drug release from nanoparticlesrdquo Journal of Pharmacyand Pharmaceutical Sciences vol 11 no 1 pp 167ndash177 2008

[74] L Zeng L An and X Wu ldquoModeling drug-carrier interactionin the drug release from nanocarriersrdquo Journal of Drug Deliveryvol 2011 Article ID 370308 15 pages 2011

[75] L Zeng andXWu ldquoModeling the sustained release of lipophilicdrugs from liposomesrdquo Applied Physics Letters vol 97 no 7Article ID 073701 2010

[76] FDA Guidance for Industry Extended Release Oral DosageForms Development Evaluation and Application of In VitroInVivo Correlations 1997

[77] J G Wagner and E Nelson ldquoPer cent absorbed time plotsderived fromblood level andor urinary excretion datardquo Journalof Pharmaceutical Sciences vol 52 pp 610ndash611 1963

Submit your manuscripts athttpwwwhindawicom

PainResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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StrokeResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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Pharmaceutics

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MEDIATORSINFLAMMATION

of

2 Advances in Pharmaceutics

Table 1 List of a few currently marketed nanoparticulate products

Brand Name API IndicationDaunoXome Daunorubicin Kaposirsquos sarcomaDepocyt Cytarabine Lymphomatous meningitisMyocet Doxorubicin Breast cancer

Oncaspar PEG-asparaginase

Acute LymphoblasticLeukemia

Restasis Cyclosporine Chronic dry eye diseaseTriglide Fenofibrate Hypercholesterolemia

Emend Aprepitant Chemotherapy inducednausea and vomiting

barriers thereby altering the pharmacokinetics and pharma-codynamics of the therapeutic agent This unique aspect ofnanoparticulate preparations has been exploited to delivertherapeutics to specific cells organs and other challengingin vivo targets Another consequence of enhanced delivery tothe target site is an increase in potency of the drug includingthe potential for elevated toxicity due to the carrier materialpossibly leading to reduced safety Therefore determinationof product quality and performance becomes a crucial aspectduring nanoparticulate dosage form development

As with most dosage forms product quality and per-formance may be verified through several in vivo andorin vitro experiments [14] Of these drug release kineticsprovides critical information about dosage form behaviorand is a key parameter used to assess product safety andefficacy Due to the expense time labor and need for humansubjectsanimals when performing in vitro measurementsof drug release kinetics in vitro release is gaining greaterattention as a surrogate test for product performance Indeedin vitro release testing is commonly used as a predictor ofin vivo behavior historically with traditional dosage formslike capsules and tablets (ie dissolution) and more recentlywith novel dosage forms like injectable biodegradable micro-spheres and implants [15ndash17] Generally in vitro releasestudies are performed at 37∘C (physiological temperature)though in some instances testing at elevated temperatures hasbeen explored to characterize drug release from a variety ofdosage forms [18 19] Some of the key objectives of in vitrorelease testing are one or more of the following

(a) assessing the effect of formulation factors and manu-facturing methods on the drug product

(b) routine assessment of quality control to support batchrelease

(c) substantiating product label claims

(d) establishing an in vitro in vivo correlationrelation-ship (IVIVCR)

(e) assuring product sameness under the SUPAC guide-lines

(f) as a compendial requirement [20 21]

Without exception in vitro release testing is an importantanalytical tool that is used to investigate and establish productbehavior during the various stages of drug product devel-opment as well as life cycle management When designedappropriately an in vitro release profile can reveal funda-mental information on the dosage form and its behavioras well as provide details on the release mechanism andkinetics enabling a rational and scientific approach to drugproduct development Understandably for complex dosageforms like nanoparticulates in vitro release testing assumesgreater significance

Despite the great strides in design and development ofnano-sized dosage forms no compendial or regulatory stan-dards exist for in vitro release testing Although there havebeen attempts to use the existing USP apparatus for in vitrodrug assessment of nanoparticles the set-ups were designedprimarily for oral and transdermal products and as such posemany challenges during a release study Hence several invitro release methods both compendial and noncompendialhave been utilized and reported Certainly the area of in vitrotesting for nanoparticulates lags behind the advances realizedin drug product development

Given the urgent need for improved product safety whilemaintaining quality of novel dosage forms like nanoparticlesthe past decade witnessed a series of international in vitrorelease workshops co-sponsored by the AAPS (AmericanAssociation of Pharmaceutical Scientists) US FDA (Foodand Drug Administration) FIP (Federation InternationalPharmaceutique) and several other scientific groups andagencies [22ndash25] The outcomes of these workshops werepublished as position papers with the general consensusthat dissolution or in vitro release testing was an importanttool in pharmaceutical development and quality control fora plethora of dosage forms both traditional and novelFurther the attendees highlighted the fact when compared totraditional formulations the characteristics of novelspecialdosage forms including site and mode of administrationwas vastly different and hence appropriate considerationshould be taken during selection of the apparatus releasemedium agitation (flow rate) and temperature In summarythe workshops concluded that along with a few other noveldosage forms nanoparticulate preparations were categorizedas those ldquodosage forms requiring more work before a (disso-lution) method can be recommendedrdquo [22 23]

In a separate endeavor the Nanotechnology Risk Assess-ment Working Group in the Center for Drug Evaluation andResearch (CDER) within the US FDA published a regulatorynote outlining the risk assessment and management processon a hypothetical nanomaterial drug to be administeredorally [4] In this example the Working Group identifiedldquodissolutionrelease raterdquo as a risk factor that may impactthe evaluation of quality safety and efficacy of the drugproduct containing nano-sized drug that is during ingestionand in vitro releasedissolution Hence the utility of in vitrorelease testing from a drug product development as well asregulatory standpoint cannot be ignored

Thus the purpose of this review is to provide the readerwith a summary of existing in vitro release methods fornano-sized dosage forms along with their strengths and

Advances in Pharmaceutics 3

shortcomings It is hoped that this review will serve as aguideline for developing suitable techniques for assessmentof exploratory formulations clinical and commercial dosageforms and establishment of an in vitro in vivo correlation(IVIVC)

2 In Vitro Release Methods

Much attention has been devoted to the development of suit-able apparatus to assess in vitro release fromnanoparticulatesHowever additional considerations like release media selec-tion agitation and so forth cannot be overlooked In contrastto oral dosage forms where release media typically mimicspH of the gastrointestinal tract selection of release media fornano-sized dosage forms will vary depending on the site ofadministration as well as the site of action of the formulationand thus simulation of in vivo conditions may be difficultIn general selection of release media for nanoparticulatepreparation is generally based on drug solubility and stabilityassay sensitivity and the method used Though maintenanceof sink conditions is preferable nonsink conditions havebeen employed Agitation frequently utilized to preventaggregation of dosage forms during an in vitro release studywill depend on the apparatus used Similarly sampling andbuffer replacement (total or partial) techniques are also basedon the type of in vitromethod used

As such drug release from nano-sized dosage formscan be assessed using one of the following three categoriesnamely sample and separate (SS) continuous flow (CF) anddialysis membrane (DM) methods More recently apparatusthat combine the principles of either the SS andDMorCF andDMhave also been reported Lastly a few novel methods thatuse voltametry turbidimetry and so forth are discussed Foreach of these methods a brief description is provided alongwith adaptations additional considerations advantages anddisadvantages

21 Sample and Separate In the SS method the nanopartic-ulate dosage form is introduced into the release media thatis maintained at a constant temperature after which drugrelease is assessed by sampling of the releasemedia (filtrate orsupernatant) or the nanoparticles From literature there areseveral adaptations to the SS method with differences notedin set-up container size mode of agitation and samplingtechniques

Commonly reported set-ups include USP I (basket) USPII (paddle) or vials and generally depend on the volume ofrelease media used in the in vitro release study [7 38ndash40] Forinstance vials were used when the volume of release mediawas small (1ndash15mL) and in vitro release vesselswere employedwith larger volumes (600ndash900mL) [5 7 38 40 41]

In addition to determining the type of set-up containersize also influences the mode of agitation used in an in vitrorelease study with the SS method With small sized dosageforms like nanoparticles agitation of the release media iscritical to the in vitro release process as it reduces the potential

for aggregation and enhances wetting thereby reducing theimpact of these factors on the in vitro release rate [38] Whileagitation of the release media is easily accomplished via theUSP I or USP II apparatus media contents in vials have beenagitated using alternate techniques For example Danhieret al and Li et al used magnetic stirrers with Paclitaxel andBSA nanoparticles respectively while Prabha et al reportedthe use of orbital shakers with DNA nanoparticles [42ndash44]

Drug release is monitored by physically separating thenanoparticles from the release media followed by analysis ofthe former or the latter [7 41] While several authors havedocumented the use of syringe filters to achieve physicalseparation between the release media and nanoparticlesthe small size of nanoparticles has necessitated the useof high energy separation techniques like centrifugationultracentrifugation and ultrafiltration [40 42 45ndash47] Forfiltration syringe filters with pore size as large as 045 120583mhave been used for withdrawing supernatant to monitordrug release of small molecules such as Celecoxib [40] Incomparison high energy separation techniques have beenreported with larger biomolecules like Insulin BSA (BovineSerum Albumin) and DNA [43 44 48] Once separateddrug release is generally monitored by sampling a part ofthe supernatant or decanting the entire supernatant contentat periodic intervals [7 49] In other instances separationwas followed by analysis of the nanoparticles (destructivetechnique) [41] After sampling an equal amount of freshrelease media or buffer is added to the set-up so that sinkconditions are maintained for the duration of the in vitrorelease study

In general the SS method provides a direct approach tomonitor drug release With this method most sample set-ups agitationmodes and sampling techniques are reasonablystraightforward and simple However due to the small sizeof nanoparticulate dosage forms several practical challengeshave been noted For instance aggregation of nanoparticlesduring in vitro release appears to be a key concern Addi-tionally while sampling techniques like filtration seem fairlyreasonable in principle clogging of filters during samplingadsorption of drug to the filter and so forth have beenreported [50] Indeed difficulty in physical separation evenwith high energy techniques continued drug release duringthe high energy separation process and so forth are someof the challenges often observed during sampling [38 45]Although sink conditions are recommended with the SSmethod nonsink conditions have been reported to be morediscriminatory with poorly soluble drugs [51] Neverthelessas with microparticulate dosage forms the SS method offersresearchers a simple and straightforward approach to moni-tor in vitro release from nano-sized dosage forms

22 Continuous Flow In the CF method drug release fromthe nanoparticulate dosage form is monitored using theUSP IV apparatus or a modification thereof Drug releaseoccurs as a result of buffer or media constantly circulatingthrough a column containing the immobilized dosage formand is monitored by collecting the eluent at periodic intervals(Figure 1)

4 Advances in Pharmaceutics

Flow through cell

Filter

Nanosuspension distributed in

glass beads

Release media

Pump

Detector

Figure 1 Continuous flow set-up in closed loop configuration

Unlike the widely used SS method only a few examplesof the CF method have been reported for nano-sized dosageforms [38 52] For example the release profiles of amor-phous nanoparticles and an unprocessed crystalline form ofCefuroxime Axetil a BCS II cephalosporin antibiotic wereevaluated using the CF method as well as other methodsdescribed below [38]

(a) USP I (basket) 900mL buffer at 100 rpm(b) USP II (paddle) 900mL buffer at 100 rpm(c) USP IV (flow through cell) 900mL buffer at a flow

rate of 16mLmin (peristaltic pump closed loop)through a cell (internal diameter = 25mm) and02 120583mmembrane disc filter

(d) dialysis bag (MWCO 12 kDa inner volume = 7mL)placed into a USP II (paddle) in vitro release tester(outer volume = 900mL paddle rpm = 100)

The results revealed that complete drug release wasachieved only with the USP II paddle and USP IV apparatusrelease profiles with the USP IVmethod being well separated

Immobilization of the nanoparticles was thought to bea factor contributing to the discriminatory results obtainedwith the USP IV apparatus

Similarly in an experiment on nano- and micro-particleloaded strip films of another BCS II drug Griseofulvin invitro release was performed using two methods [52]

(a) USP I (basket) 500 and 900mLmedia at 50 100 and150 rpm

(b) USP IV (flow through cell) 100mL media at flowrates of 4 8 and 16mLmin (peristaltic pump closedloop) through a cell (internal diameter = 226mm)and 02120583m membrane disc filter with the strip filmloaded in 6 different configurations

While complete release was observed only with USP Iand configuration B (strip film positioned in the cell on topof round glass beads) of the USP IV method results withconfigurations A (strip film positioned in the cone section

Sampling from outer compartment

Dialyzer cap

Inner compartment containing nanosuspension

Dialysis membrane

Outer compartment containing release media

Stir bar

Figure 2 ldquoRegular dialysisrdquo set-up (adapted from [21])

of the cell without round glass beads) and C (strip filmsandwiched between round glass beads) of USP IV at thehighest flow rate were more discriminatory than all the otherrelease profiles obtained in the in vitro study

In comparison to nanoparticulate dosage forms whereliterature on the use of USP IV methodology is sparseseveral salient aspects of the CF method can be inferredfrom its use in microparticulate dosage forms [21] As anexample flow rates used in the CF method depend on thetype of pump (peristaltic versus syringe) as well as the filtersused (membrane versus ultrafilters) Low flow rates havebeen known to be a key factor causing slow or incompleterelease from dosage forms [21] In general the availabilityof automated equipment has simplified routine samplingand media replacement with the the CF method in closed(recirculating media) and open (nonrecirculating media)loop systems However the CF methods suffer from severaldisadvantages that include instrument costs difficulty in set-up filter clogging adsorption to the filter and glass beads anddifficulty in maintaining a constant flow rate leading to widevariability in results

23 Dialysis Method Of all the methods used to assess drugrelease from nano-sized dosage forms the dialysis method(DM) is the most versatile and popular In this methodphysical separation of the dosage forms is achieved by usageof a dialysis membrane which allows for ease of samplingat periodic intervals As with the other methods severaladaptations of the DM have been reported in literaturewith key differences in set-up container size and molecularweight cut-off (MWCO)

Of the variety of DM set-ups used the most commonlycited is the dialysis bag (regular dialysis) other adaptationsbeing the reverse dialysis and side-by-side dialysis set-up[26 53 54] (Figures 2ndash4)With the regular dialysis technique

Advances in Pharmaceutics 5

Sampling from inner compartment

Dialyzer cap

Inner compartment containing release media

Dialysis membrane

Outer compartment containing nanosuspension

Stir bar

Figure 3 ldquoReverse dialysisrdquo set-up

Receiver compartment

Dialysis membrane

Stir bar

Sampling

Nanoemulsion in donor compartment

Figure 4 ldquoSide-by-side dialysisrdquo set-up (adapted from [26])

the nanoparticles are introduced into a dialysis bag contain-ing release media (inner mediacompartment) that is subse-quently sealed and placed in a larger vessel containing releasemedia (outer mediacompartment) agitated to minimizeunstirred water layer effects [32 55] In general the volumeenclosed in a dialysis bag (inner media) is significantlysmaller than the outer media For instance inner mediavolumes reported in literature range from 1 to 10mL whereasthe outermedia volume ismuch greater typically around 40ndash90mL [32 53 55] Thus container size will depend on thetotal volume of release media required for the in vitro releasestudy In the regular dialysis technique drug released fromthe nanoparticles diffuses through the dialysis membraneto the outer compartment from where it is sampled foranalysis (Figure 2) In contrast with the reverse dialysis set-up the nanoparticles are placed in the outer compartment(agitated to minimize the unstirred water layer) and theinner compartment is sampled for drug release (Figure 3)[54 56 57] Other adaptations of the DM include the side-by-side dialysis set-up where donor and receiver cells bothcontaining equal volumes of media agitated with a magneticstirrer are separated by a dialysis membrane and samplingoccurs from the receiver cell (Figure 4) and a vertical Franzdiffusion cell [26 58 59]

As with other methods drug solubility in the releasemedia is essential to its transport across the dialysis mem-brane Apart from release media the importance of selectingan appropriate molecular weight cut-off (MWCO) for thedialysis membrane cannot be overlooked Indeed the basicpremise of the DM is that drug that is released from thedosage form will diffuse rapidly from one compartmentthrough the membrane and enter the second compartmentfrom where it is sampled for analysis Thus membranes witha sufficiently high membrane MWCO are often selected forin vitro release studies so that drug transport is not a limitingfactor As an example in a study with 3 dosage forms ofIndomethacin (eg nanoparticles and nanocapsules usingpoly-120576-caprolactone and a submicron emulsion) Calvo et alnoted that nearly 85 of drug was released within 2 hoursand complete release was achieved in 4 hours when a 12 kDamembranewas used [54] However the rationale for selectinga MWCO is rather subjective For instance a MWCO ashigh as 10ndash14 kDa was used to study drug release of smallmolecules like Risperidone and Indomethacin and aMWCOas low as 1 kDa though suitable for assessing in vitro releaseof a large molecule pDNA proved to be limiting for thediffusion of Cefuroxime Axetil a cephalosporin antibiotic[32 38 55 60] In general the MWCO should be sufficientlylarge to permit drug transport

The ease of set-up and sampling with the DM make ita very simple and straightforward technique to study drugrelease from a wide variety of nano-sized dosage forms likenanospheres liposomes emulsions nanosuspensions andso forth [53ndash55] However issues have been reported withthe regular dialysis method If incorrectly sealed leakage ofmedia and dosage form may occur from both ends of thedialysis bag set-up Incomplete release data may be observedif nonsink conditions exist or equilibration times are high[38] On the other hand the difference in equilibration timescan be exploited as a discriminatory tool to distinguish releasebehavior between fast and slow releasing dosage forms [50]Another factor to be considered is that the DM cannotbe used with drugs that bind to the dialyzing membraneAs stated in a review paper on microparticulate dosageforms it is recommended that the suitability of the dialyzingmembrane be assessed prior to use [21 61]

24 CombinationMethods A fewpublications havemodifiedthe set-ups used in the SS CF and DM methods to evaluatedrug release from nano-sized dosage forms In most of thesereports the set-up of the SS method is combined with adialyzer to allow ease of sampling In other publications theDM and the CF set-up is used to assess in vitro release fromnanoparticulates

As an example Mottaleb et al compared release profilesof Ibuprofen from liposomes and lipid nanocapsules andnanoparticles using the regular dialysis method (dialysis bag)and modified USP I (basket) set-up where the shaft wasaffixed with a glass basket having a dialysis membrane atthe bottom that is glass basket dialysis (GBD) and placedin a larger vessel (Figure 5) [27] Sampling was performedfrom the outer vessel Unlike the dialysis bag that had a large

6 Advances in Pharmaceutics

Glass basket

Dialysis membrane

Figure 5 Comparison ofUSP I (left) and glass basket dialysis (right)set-ups (adapted from [27])

membrane surface area the GBD was able to discriminatedifferences between release profiles from different formu-lations (lipid nanocapsules nanoparticles liposomes) Inanother study Lobenberg et al compared drug release fromRifampicin and Moxifloxacin hydrochloride nanoparticleswith the regular dialysis method (dialysis bag) as well as anadaptation of USP I (basket) where a cylinder containing adialysis membrane at the bottom was attached to the basketshaft [62] Results from this study showed that modifiedUSP I set-up was more discriminatory in nature and couldbe attributed to the reduced surface area of the dialysismembrane In yet another modification of the USP I (basket)set-up a dialysis bag containing nanostructured lipid carriersof Artemether was placed inside the basket and drug releasemonitored over time [63] Though most studies have utilizedthe USP I set-up others have used the USP II (paddle) set-upin combination with the DM For example Cao et al affixeddialysis bags containing Silybin meglumine nanoparticlesonto a USP II (paddle) apparatus and assessed drug releasein five different release media [33 35]

A combination of aDM previously reported byKostanskiet al and CF method was utilized to assess drug releasefrom 5-Fluorouracil loaded BSA nanoparticles [28 64] Thesetup comprised a glass tube (with a dialysis membrane atthe bottom) that was placed into a larger vessel containingbuffer (Figure 6) Sampling as well as buffer replacement wasperformed from the larger vessel with the aid of two pumpshaving the same flow rate The combined DM-CF set-up wasable to demonstrate sustained levels of 5-Fluorouracil andthe absence of burst release from the BSA nanoparticles Analternate dialysis-CFmethod utilized a dialysis adaptor insidethe CF set-up (Figure 7) [29]

25 New Methods Apart from the commonly reported SSCF and DM methods a few alternate approaches have beenutilized tomonitor drug release Amajority of these appear tobe targeted towards electroactive drugsWhile the techniquesmay differ in principle or application they possess a fewcommon elements in that physical separation of the dosageform from the release media is not required Additionallythese techniques offer the possibility of measurement underreal-time conditions

Detector

Waste

Dialysis membrane

Nanosuspension

Stir bar

Pump 2Pump 1

Release media

Figure 6 Continuous flow dialysis set-up with two pumps (adaptedfrom [28])

Flow through cell

Releasemedia

Pump

Detector

Filter

Glass beads

Dialyzer containingnanosuspension

Figure 7 Dialysis adapter inside a continuous flow set-up (adaptedfrom [29])

As such electrochemical methods offer the possibility ofrapid in situ measurements while avoiding the interferencecaused by the presence of undissolved dosage form in therelease media In one such approach a potentiometric drugselective electrode was used to monitor real-time release ofProcaine hydrochloride from pH-responsive nanogels [65]In another report by Mora et al a highly sensitive repetitivesquare-wave voltammetric technique was utilized to measurethe redox reaction of Doxorubicin hydrochloride (Figure 8)[30] Similarly differential pulse polarography was used toassess continuous drug release from Piroxicam Chloram-phenicol and Diazepam [66 67] Apart from the fact thatonly electroactive drugs can be measured by the abovemethods these methods suffer from additional drawbacksFor example the sensitivity as well as responsiveness ofeach technique varies greatly Also the sensors used may bespecific to a particular drug

Nonelectrochemical methods like calorimetry turbidim-etry and laser diffraction have also been evaluated as invitro release methods Solution calorimetry was employedby Kayaert et al during in vitro release measurement ofNaproxen Cinnarizine and Compound A (investigational

Advances in Pharmaceutics 7

Working electrode

Reference electrode

Counter electrode

Release media

Redox reactionAox Ared

A Liposome containing drug ldquoArdquo

Figure 8 Electrochemical cell set-up for real-time measurement ofdrug release (adapted from [30])

Pump control

Syringe Analyte

NanosuspensionMicrodialysis probe

pump

Figure 9 Microdialysis set-up (adapted from [31])

API) from nanocrystals [68] The principle of this tech-nique is based on detection of the net proportion of heatchange during in vitro release Challenges with calorimetricmeasurements include long equilibration times Further theheat produced by all the processes needs to be consideredTurbidimetric and laser diffraction approaches utilizing thechange light scattering properties of nanoparticles dispersedin release media have also been utilized [69 70] Concernswith these methods include the long equilibration timeslimited range of particle size and initial concentration ofsamples that can be used

Helle et al designed a novel online system for evaluatingthe drug release from Indomethacin and Beclomethasonedipropionate nanoparticles In thismethod nanoparticles arepacked into small column which is connected to multiportmodulation valve attached to an HPLC system allowingfor rapid analysis [71] Other new methods reported inliterature include a vertical diffusion Franz cell and an invitro lipolysis model [37 72] Microdialysis another set-up utilized to measure drug release from nanoparticules isbased on passive diffusion of drug through a concentrationgradient across a semipermeable membrane (Figure 9) [3147] Drug release can be measured in real-time conditionsusing analytical methods like HPLC However care shouldbe taken when surfactants are used in the release media asrecovery may be affected

3 Modeling Drug Release

Very few publications have attempted to describe drug releaseprofiles from nanoparticulate dosage forms using mathe-matical models This is not surprising given that nano-sizeddosage forms are complex and drug release evaluations arenot straightforward However a few authors have discussedthe importance of mathematical models and endeavored tocharacterize drug release For instance Barzegar-Jalali et alsuggested the use of reciprocal powered time (RPT) as generalmodel to analyze the complex nature of drug release fromnanoparticles with alternate approaches being the Weibulland log-probabilitymodels [73] In another report Zeng et aldeveloped a three-parameter model that considers reversibledrug-carrier interaction as well as diffusional drug releasefrom liposomes [74 75]

Use of mathematical models to describe drug releaseprofiles offers several advantages It permits the elucidationof drug release mechanisms and can be used to guide for-mulation development efforts Furthermodel parameters canserve to represent as well as compare in vitro release profilesHowever caution must be used when applying mathematicalmodels to complex drug release mechanisms

4 IVIVC

The US FDA defines IVIVC as ldquoA predictive mathematicalmodel describing the relationship between an in vitro prop-erty of an extended release dosage form (usually the rate orextent of drug in vitro release or release) and a relevant invivo response for example plasma drug concentration oramount of drug absorbedrdquo [76] Thus establishment of anIVIVC described as a correlation between in vitro release andin vivo behavior enhances the utility of an in vitro study Fromthe 1997 FDA guidance document an IVIVC will reduce theregulatory burden by paring the number of in vivo studiesneeded for product approval Additionally it promotes thesetting of clinically relevant in vitro release specifications [76]

The FDA guidance also categorizes IVIVCs into threelevels Level A represents a linear or nonlinear point-to-point relationship between the in vitro and in vivo releaseprofiles If the relationship is nonlinear suitable modelingor scaling is required Of the three IVIVC levels Level Adescribes the highest correlation and is most commonly usedto obtain a biowaiver On the other hand a Level B correlationis a comparison of summary parameters such as the meanin vitro dissolution time with mean in vivo dissolution timeor mean residence time (MRT) Since several in vivo curveswill produce a similarMRT value ormean in vitro dissolutiontime Level B correlations are not as discriminatory as LevelA but acceptable for an IVIVC A Level C correlationdescribes a relationship between an in vitro release parameter(eg dissolved at a particular time) and a pharmacokineticparameter (eg 119862max) However a Level C correlation is notdescriptive of the complete shape of the in vivo release profileand though acceptable seldom used

As such the FDA guidance is intended for oral extendedrelease products However principles of the FDA guidance

8 Advances in Pharmaceutics

Table 2 Examples of IVIVC with nano-sized dosage forms in animal models

Drug and dosage form In vitro release set-up In vivo studies IVIVC type Reference

Indomethacin gelatin nanoparticles Dialysis bags Wistar Albinorats Level A [32]

Silybin meglumine hollow-spheremesoporous silica nanoparticles Combination (USP Imdashdialysis bag) Beagle dogs Level A [33]

Silybin 72-hour SLB andPSNs (porous silica nanoparticles) Combination (USP Imdashdialysis bag) Beagle dogs Level A [35]

Simvastatin nanostructured lipidcarriers and nanoparticles Dialysis bag BalbC mice Level A [34]

Fenofibrate nanosuspension USP I apparatus SpragueDawley rats Level A [36]

Fenofibrate lipid matrix particles In vitro lipolysis model SpragueDawley rats Rank order [37]

Table 3 Level A IVIVC with two Silybin preparations (data from reference [35])

Formulation absorbed equals 1198772

72-hour SLB 11379 times dissolved + 88688 09831Silybin PSNs (porous silica nanoparticles) 08915 times dissolved minus 10152 09831

have been used to demonstrate an IVIVC from severalnonoral dosage forms including nano-sized preparationsMost published literature on IVIVC compares the in vitrorelease behavior with the in vivo absorption profile thelatter calculated by the FDA recommended Wagner-Nelsonmethod [76 77] Once the fraction absorbed is computeda correlation is obtained by comparing it with the in vitrorelease profile and the type of IVIVC (Level A level B etc) isdetermined

Over the last decade a few reports on IVIVC from nano-sized dosage forms have been published (Table 2) In someinstances a rank order correlation was observed while inothers a Level A IVIVC was established with some or allof the formulations evaluated in the study As an example arank order correlation was observed with three preparationsof Fenofibrate with drug release and absorption from 100 nmlipid matrix particles gt microparticles gt control (crystallinesuspension) [37] In another study on Fenofibrate nanosus-pensions Xu et al attempted to elucidate the absorptionmechanism using in situ gut perfusion model [36] Dataanalysis between in vitro dissolution (119875) in situ intestinalabsorption (119865) and in vivo absorption (119865

119886) demonstrated

a Level A correlation (1198772 gt 095) As a result the authorsconcluded that the in situ intestinal perfusion model couldbe a predictor of in vivo pharmacokinetic behavior for thenanosuspension

In a recent report Kumar et al investigated the relation-ship between in vitro and in vivo release from Indomethacingelatin nanoparticles administered orally to Wistar albinorats [32] Study results indicated that a good correlation wasobtained by plotting the fraction absorbed in vivo (Wagner-Nelson method) against the fraction released the latter per-formed using regular dialysis (dialysis bags) (Figure 10) TheWagner-Nelsonmethod was also used in another publication

0

20

40

60

80

100

120

0 20 40 60 80 100

In v

ivo

abso

rptio

n (

)

In vitro release ()

R2 = 0981

y = 1121x

Figure 10 Level A IVIVC from Indomethacin gelatin nanoparticlesusing regular dialysis (redrawn from [32])

where the in vivo absorption fromSilybinmeglumine hollow-sphere mesoporous silica nanoparticles dosed orally to bea-gle dogs was compared with in vitro results obtained using acombination USP I (paddle) dialysis bag set-up [33] Of thefive different releasemedia used in the study a Level A IVIVC(1198772 gt 097) was obtained with 006M Na

2CO3and 008M

Na2CO3solutions (Figure 11) In another study with Silybin

an IVIVC was achieved with a 72-hour release formulationof Silybin (72-hour SLB) that consisted of a solid dispersiongel matrix and porous silica nanoparticles (PSNs) (Table 3)[35] Similar to the earlier study the authors compared invivo release from beagle dogs with in vitro release assessedusing a combination USP I (paddle) dialysis bag set-upIn another paper Tiwari et al demonstrated a Level A

Advances in Pharmaceutics 9

0

20

40

60

80

100

0 20 40 60 80 100

Abso

rbed

()

Abso

rbed

()

0 20 40 60 80 1000

20

40

60

80

100

In vitro release ()

In vitro release ()

y = 23417x minus 78256

R2 = 09741

y = 16114x minus 56752

R2 = 09931

006M Na2CO3

008M Na2CO3

Figure 11 Level A IVIVC from Silybin meglumine hollow-typemesoporous silica nanoparticles using a combined USP II-dialysisbag set-up (redrawn from [33])

correlation between in vitro release (dialysis bag) and percentdrug absorbed (Wagner Nelson method) for Simvastatinnanostructured lipid carriers as well as nanoparticles (1198772 gt094) (Figure 12) [34]

5 Conclusions

For novel dosage forms like nanoparticles where no regu-latory or compendial standards exist in vitro drug releaseassessment assumes greater significance in serving as anindicator of product quality and performance A plethoraof methods have been used each with their advantages anddrawbacks with respect to ease of set-up sampling and rapidbuffer replacement Ideally an in vitro release method shouldsimulate in vivo conditions release mechanisms and enablethe establishment of an IVIVC Future research should focuson developing relevant mathematical models to predict drugrelease behavior as well as release mechanisms applicable to awide range of nano-sized dosage forms

Conflict of Interests

The author declares that there is no conflict of interestsregarding the publication of this paper

0

20

40

60

80

100

120

Dru

g ab

sorb

ed (

)

0

20

40

60

80

100

120

Dru

g ab

sorb

ed (

)

Simvastatin loaded nanostructured lipid carriers

Simvastatin loaded solid lipid nanoparticles

0 20 40 60 80 100In vitro release ()

0 20 40 60 80 100In vitro release ()

R2 = 09404

R2 = 0941

Figure 12 Level A correlation of Simvastatin from two nano-sizeddosage forms (redrawn from [34])

References

[1] N Al Khouri Fallouh L Roblot-Treupel and H Fessi ldquoDevel-opment of a new process for the manufacture of polyisobutyl-cyanoacrylate nanocapsulesrdquo International Journal of Pharma-ceutics vol 28 no 2-3 pp 125ndash132 1986

[2] C Losa P Calvo E Castro J L Vila-Jato and M J AlonsoldquoImprovement of ocular penetration of amikacin sulphate byassociation to poly(butylcyanoacrylate) nanoparticlesrdquo Journalof Pharmacy and Pharmacology vol 43 no 8 pp 548ndash552 1991

[3] C Losa L Marchal-Heussler F Orallo J L Vila Jato andM J Alonso ldquoDesign of new formulations for topical ocularadministration polymeric nanocapsules containing metipra-nololrdquo Pharmaceutical Research vol 10 no 1 pp 80ndash87 1993

[4] C N Cruz K M Tyner L Velazquez et al ldquoCDER riskassessment exercise to evaluate potential risks from the use ofnanomaterials in drug productsrdquo AAPS Journal vol 15 no 3pp 623ndash628 2013

[5] G Verreck I Chun J Rosenblatt et al ldquoIncorporation of drugsin an amorphous state into electrospun nanofibers composedof a water-insoluble nonbiodegradable polymerrdquo Journal ofControlled Release vol 92 no 3 pp 349ndash360 2003

[6] H Heiati R Tawashi R R Shivers and N C PhillipsldquoSolid lipid nanoparticles as drug carriers I incorporation andretention of the lipophilic prodrug 31015840-azido-31015840-deoxythymidinepalmitaterdquo International Journal of Pharmaceutics vol 146 no1 pp 123ndash131 1997

10 Advances in Pharmaceutics

[7] M Cetin A Atila and Y Kadioglu ldquoFormulation and in vitrocharacterization of Eudragit L100 and Eudragit L100-PLGAnanoparticles containing diclofenac sodiumrdquo AAPS Pharm-SciTech vol 11 pp 1250ndash1256 2010

[8] A Hanafy H Spahn-Langguth G Vergnault et al ldquoPharma-cokinetic evaluation of oral fenofibrate nanosuspensions andSLN in comparison to conventional suspensions of micronizeddrugrdquo Advanced Drug Delivery Reviews vol 59 no 6 pp 419ndash426 2007

[9] T M Allen W W K Cheng J I Hare and K M LaginhaldquoPharmacokinetics and pharmacodynamics of lipidic nano-particles in cancerrdquoAnti-Cancer Agents in Medicinal Chemistryvol 6 no 6 pp 513ndash523 2006

[10] J Kreuter ldquoNanoparticle-based drug delivery systemsrdquo Journalof Controlled Release vol 16 no 1-2 pp 169ndash176 1991

[11] M L Etheridge S A Campbell A G Erdman C L Haynes SMWolf and JMcCullough ldquoThe big picture on nanomedicinethe state of investigational and approved nanomedicine prod-uctsrdquo Nanomedicine Nanotechnology Biology and Medicinevol 9 no 1 pp 1ndash14 2013

[12] S Nie ldquoUnderstanding and overcoming major barriers incancer nanomedicinerdquoNanomedicine vol 5 no 4 pp 523ndash5282010

[13] W H de Jong and P J A Borm ldquoDrug delivery andnanoparticles applications and hazardsrdquo International Journalof Nanomedicine vol 3 no 2 pp 133ndash149 2008

[14] S DrsquoSouza J A Faraj R Dorati and P P DeLuca ldquoA short termquality control tool for biodegradable microspheresrdquo AAPSPharmSciTech vol 15 no 3 pp 530ndash541 2014

[15] P Buch P Holm J Q Thomassen et al ldquoIVIVC for fenofibrateimmediate release tablets using solubility and permeability as invitro predictors for pharmacokineticsrdquo Journal of Pharmaceuti-cal Sciences vol 99 no 10 pp 4427ndash4436 2010

[16] S DrsquoSouza J A Faraj S Giovagnoli and P P DeLuca ldquoIVIVCfrom long acting olanzapine microspheresrdquo International Jour-nal of Biomaterials vol 2014 Article ID 407065 11 pages 2014

[17] L C Amann M J Gandal R Lin Y Liang and S J SiegelldquoIn vitro-in vivo correlations of scalable PLGA-Risperidoneimplants for the treatment of schizophreniardquo PharmaceuticalResearch vol 27 no 8 pp 1730ndash1737 2010

[18] G Zackrisson G Ostling B Skagerberg and T Anfalt ldquoACcel-erated Dissolution Rate Analysis (ACDRA) for controlledrelease drugs Application to Roxiamrdquo Journal of Pharmaceu-tical and Biomedical Analysis vol 13 no 4-5 pp 377ndash383 1995

[19] S S DSouza J A Faraj and P P DeLuca ldquoA model-dependentapproach to correlate accelerated with real-time release frombiodegradable microspheresrdquo AAPS PharmSciTech vol 6 arti-cle 70 no 4 2005

[20] D J Burgess A S Hussain T S Ingallinera and M ChenldquoAssuring quality and performance of sustained and controlledrelease parenterals workshop reportrdquo AAPS PharmSci vol 4article E7 2002

[21] S S DrsquoSouza and P P DeLuca ldquoMethods to assess in vitrodrug release from injectable polymeric particulate systemsrdquoPharmaceutical Research vol 23 no 3 pp 460ndash474 2006

[22] M Siewert J Dressman C K Brown and V P ShahldquoFIPAAPS guidelines to dissolutionin vitro release testing ofnovelspecial dosage formsrdquo AAPS PharmSciTech vol 4 article7 2003

[23] C K Brown H D Friedel A R Barker et al ldquoFIPAAPSjoint workshop report dissolutionin vitro release testing of

novelspecial dosage formsrdquo AAPS PharmSciTech vol 12 no2 pp 782ndash794 2011

[24] MMartinezM Rathbone D Burgess andMHuynh ldquoIn vitroand in vivo considerations associated with parenteral sustainedrelease products a review based upon information presentedand points expressed at the 2007 Controlled Release SocietyAnnual Meetingrdquo Journal of Controlled Release vol 129 no 2pp 79ndash87 2008

[25] M N Martinez M J Rathbone D Burgess and M HuynhldquoBreakout session summary from AAPSCRS joint workshopon critical variables in the in vitro and in vivo performanceof parenteral sustained release productsrdquo Journal of ControlledRelease vol 142 no 1 pp 2ndash7 2010

[26] N Chidambaram and D J Burgess ldquoA novel in vitro releasemethod for submicron-sized dispersed systemsrdquo AAPS Pharm-Sci vol 1 no 3 pp 32ndash40 1999

[27] M M A Abdel-Mottaleb and A Lamprecht ldquoStandardized invitro drug release test for colloidal drug carriers using modifiedUSP dissolution apparatus Irdquo Drug Development and IndustrialPharmacy vol 37 no 2 pp 178ndash184 2011

[28] A Maghsoudi S A Shojaosadati and E Vasheghani Farahanildquo5-Fluorouracil-loaded BSA nanoparticles formulation opti-mization and in vitro release studyrdquo AAPS PharmSciTech vol9 no 4 pp 1092ndash1096 2008

[29] U Bhardwaj and D J Burgess ldquoA novel USP apparatus 4 basedrelease testing method for dispersed systemsrdquo InternationalJournal of Pharmaceutics vol 388 no 1-2 pp 287ndash294 2010

[30] L Mora K Y Chumbimuni-Torres C Clawson L HernandezL Zhang and J Wang ldquoReal-time electrochemical monitoringof drug release from therapeutic nanoparticlesrdquo Journal ofControlled Release vol 140 no 1 pp 69ndash73 2009

[31] C B Michalowski S S Guterres and T Dalla CostaldquoMicrodialysis for evaluating the entrapment and release of alipophilic drug from nanoparticlesrdquo Journal of Pharmaceuticaland Biomedical Analysis vol 35 no 5 pp 1093ndash1100 2004

[32] R Kumar R C Nagarwal M Dhanawat and J K PanditldquoIn-vitro and in-vivo study of indomethacin loaded gelatinnanoparticlesrdquo Journal of Biomedical Nanotechnology vol 7 no3 pp 325ndash333 2011

[33] X Cao W W Deng M Fu et al ldquoIn vitro release and in vitro-in vivo correlation for silybin meglumine incorporated intoHollow-type mesoporous silica nanoparticlesrdquo InternationalJournal of Nanomedicine vol 7 pp 753ndash762 2012

[34] R Tiwari and K Pathak ldquoNanostructured lipid carrier versussolid lipid nanoparticles of simvastatin comparative analysis ofcharacteristics pharmacokinetics and tissue uptakerdquo Interna-tional Journal of Pharmaceutics vol 415 no 1-2 pp 232ndash2432011

[35] X Cao W Deng M Fu et al ldquoSeventy-two-hour releaseformulation of the poorly soluble drug silybin based on poroussilica nanoparticles in vitro release kinetics and in vitroin vivocorrelations in beagle dogsrdquo European Journal of Pharmaceuti-cal Sciences vol 48 no 1-2 pp 64ndash71 2013

[36] Y Xu Y Wang X M Li et al ldquoStudy on the release offenofibrate nanosuspension in vitro and its correlation with insitu intestinal and in vivo absorption kinetics in ratsrdquo DrugDevelopment and Industrial Pharmacy vol 40 no 7 pp 972ndash979 2014

[37] N Borkar D Xia R Holm et al ldquoInvestigating the correlationbetween in vivo absorption and in vitro release of fenofibratefrom lipid matrix particles in biorelevant mediumrdquo EuropeanJournal of Pharmaceutical Sciences vol 51 pp 204ndash210 2014

Advances in Pharmaceutics 11

[38] D Heng D J Cutler H K Chan J Yun and J A RaperldquoWhat is a suitable dissolutionmethod for drug nanoparticlesrdquoPharmaceutical Research vol 25 no 7 pp 1696ndash1701 2008

[39] A C Kilic Y Capan I Vural et al ldquoPreparation and characteri-zation of PLGA nanospheres for the targeted delivery of NR2B-specific antisense oligonucleotides to the NMDA receptors inthe brainrdquo Journal of Microencapsulation vol 22 no 6 pp 633ndash641 2005

[40] Y Zhang H Wang C Li et al ldquoA novel three-dimensionallarge-pore mesoporous carbon matrix as a potential nanove-hicle for the fast release of the poorly water-soluble drugcelecoxibrdquoPharmaceutical Research vol 31 pp 1059ndash1070 2014

[41] V Sanna A M Roggio S Siliani et al ldquoDevelopment of novelcationic chitosan-and anionic alginate-coated poly(DL-lactide-co-glycolide) nanoparticles for controlled release and light pro-tection of resveratrolrdquo International Journal of Nanomedicinevol 7 pp 5501ndash5516 2012

[42] F Danhier N Lecouturier B Vroman et al ldquoPaclitaxel-loadedPEGylated PLGA-based nanoparticles In vitro and in vivoevaluationrdquo Journal of Controlled Release vol 133 no 1 pp 11ndash17 2009

[43] Y Li Y Pei X Zhang et al ldquoPEGylated PLGA nanoparticlesas protein carriers synthesis preparation and biodistributionin ratsrdquo Journal of Controlled Release vol 71 no 2 pp 203ndash2112001

[44] S Prabha W-Z Zhou J Panyam and V Labhasetwar ldquoSize-dependency of nanoparticle-mediated gene transfection stud-ies with fractionated nanoparticlesrdquo International Journal ofPharmaceutics vol 244 no 1-2 pp 105ndash115 2002

[45] S J Wallace J Li R L Nation and B J Boyd ldquoDrug releasefrom nanomedicines selection of appropriate encapsulationand release methodologyrdquo Drug Delivery and TranslationalResearch vol 2 no 4 pp 284ndash292 2012

[46] D Juenemann E Jantratid C Wagner C Reppas M Vertzoniand J B Dressman ldquoBiorelevant in vitro dissolution testingof products containing micronized or nanosized fenofibratewith a view to predicting plasma profilesrdquo European Journal ofPharmaceutics and Biopharmaceutics vol 77 no 2 pp 257ndash2642011

[47] P F Yue X Y Lu Z Z Zhang et al ldquoThe study on theentrapment efficiency and in vitro release of puerarin submi-cron emulsionrdquoAAPS PharmSciTech vol 10 no 2 pp 376ndash3832009

[48] M Mahkam F Hosseinzadeh and M Galehassadi ldquoPrepara-tion of ionic liquid functionalized silica nanoparticles for oraldrug deliveryrdquo Journal of Biomaterials amp Nanobiotechnologyvol 3 pp 391ndash395 2012

[49] A S Ham M R Cost A B Sassi C S Dezzutti andL C Rohan ldquoTargeted delivery of PSC-RANTES for HIV-1prevention using biodegradable nanoparticlesrdquo PharmaceuticalResearch vol 26 no 3 pp 502ndash511 2009

[50] Y I Kim L Fluckiger M Hoffman I Lartaud-IdjouadieneJ Atkinson and P Maincent ldquoThe antihypertensive effect oforally administered nifedipine-loaded nanoparticles in sponta-neously hypertensive ratsrdquoThe British Journal of Pharmacologyvol 120 no 3 pp 399ndash404 1997

[51] P Liu O de Wulf J Laru et al ldquoDissolution studies of poorlysoluble drug nanosuspensions in non-sink conditionsrdquo AAPSPharmSciTech vol 14 no 2 pp 748ndash756 2013

[52] L Sievens-Figueroa N Pandya A Bhakay et al ldquoUsing USPI and USP IV for discriminating dissolution rates of nano-

and microparticle-loaded pharmaceutical strip-filmsrdquo AAPSPharmSciTech vol 13 no 4 pp 1473ndash1482 2013

[53] G P Yan R F Zong L Li T Fu F Liu and X H YuldquoAnticancer drug-loaded nanospheres based on biodegradableamphiphilic 120576-caprolactone and carbonate copolymersrdquo Phar-maceutical Research vol 27 no 12 pp 2743ndash2752 2010

[54] P Calvo J L Vila-Jato and M J Alonso ldquoComparative invitro evaluation of several colloidal systems nanoparticlesnanocapsules and nanoemulsions as ocular drug carriersrdquoJournal of Pharmaceutical Sciences vol 85 no 5 pp 530ndash5361996

[55] M SMuthu and S Singh ldquoPoly (D L-lactide) nanosuspensionsof risperidone for parenteral delivery formulation and in-vitroevaluationrdquoCurrent DrugDelivery vol 6 no 1 pp 62ndash68 2009

[56] MY Levy and S Benita ldquoDrug release from submicronized owemulsion a new in vitro kinetic evaluationmodelrdquo InternationalJournal of Pharmaceutics vol 66 no 1ndash3 pp 29ndash37 1990

[57] X Xu M A Khan and D J Burgess ldquoA two-stage reversedialysis in vitro dissolution testing method for passive targetedliposomesrdquo International Journal of Pharmaceutics vol 426 no1-2 pp 211ndash218 2012

[58] B E Kilfoyle L Sheihet Z Zhang M Laohoo J Kohn and BBMichniak-Kohn ldquoDevelopment of paclitaxel-TyroSpheres fortopical skin treatmentrdquo Journal of Controlled Release vol 163no 1 pp 18ndash24 2012

[59] S Uprit R K Sahu A Roy and A Pare ldquoPreparation and char-acterization of minoxidil loaded nanostructured lipid carriergel for effective treatment of alopeciardquo Saudi PharmaceuticalJournal vol 21 pp 379ndash385 2013

[60] B Qiu M Ji X Song et al ldquoCo-delivery of docetaxel andendostatin by a biodegradable nanoparticle for the synergistictreatment of cervical cancerrdquo Nanoscale Research Letters vol 7article 666 2012

[61] S S DrsquoSouza and P P DeLuca ldquoDevelopment of a dialysis invitro release method for biodegradable microspheresrdquo AAPSPharmSciTech vol 6 no 2 article 42 2005

[62] Y Gao J Zuo N Bou-Chacra et al ldquoIn vitro release kineticsof antituberculosis drugs from nanoparticles assessed usinga modified dissolution apparatusrdquo BioMed Research Interna-tional vol 2013 Article ID 136590 9 pages 2013

[63] M Joshi S Pathak S Sharma and V Patravale ldquoDesignand in vivo pharmacodynamic evaluation of nanostructuredlipid carriers for parenteral delivery of artemether nanojectrdquoInternational Journal of Pharmaceutics vol 364 no 1 pp 119ndash126 2008

[64] J W Kostanski and P P DeLuca ldquoA novel in vitro releasetechnique for peptide-containing biodegradable microspheresrdquoAAPS PharmSciTech vol 1 article 4 2000

[65] J P K Tan C H Goh and K C Tam ldquoComparative drugrelease studies of two cationic drugs from pH-responsivenanogelsrdquo European Journal of Pharmaceutical Sciences vol 32no 4-5 pp 340ndash348 2007

[66] K M Rosenblatt D Douroumis and H Bunjes ldquoDrug releasefrom differently structured monooleinpoloxamer nanodisper-sions studied with differential pulse polarography and ultrafil-tration at low pressurerdquo Journal of Pharmaceutical Sciences vol96 no 6 pp 1564ndash1575 2007

[67] N Charalampopoulos K Avgoustakis and C G KontoyannisldquoDifferential pulse polarography a suitable technique for mon-itoring drug release from polymeric nanoparticle dispersionsrdquoAnalytica Chimica Acta vol 491 no 1 pp 57ndash62 2003

12 Advances in Pharmaceutics

[68] P Kayaert B Li I Jimidar P Rombaut F Ahssini and G Vanden Mooter ldquoSolution calorimetry as an alternative approachfor dissolution testing of nanosuspensionsrdquo European Journal ofPharmaceutics and Biopharmaceutics vol 76 no 3 pp 507ndash5132010

[69] M T Crisp C J Tucker T L Rogers R O Williams III andK P Johnston ldquoTurbidimetric measurement and prediction ofdissolution rates of poorly soluble drug nanocrystalsrdquo Journalof Controlled Release vol 117 no 3 pp 351ndash359 2007

[70] M V Chaubal and C Popescu ldquoConversion of nanosus-pensions into dry powders by spray drying a case studyrdquoPharmaceutical Research vol 25 no 10 pp 2302ndash2308 2008

[71] A Helle S Hirsjarvi L Peltonen J Hirvonen S K Wied-mer and T Hyotylainen ldquoNovel dynamic on-line analyticalseparation system for dissolution of drugs from poly(lacticacid) nanoparticlesrdquo Journal of Pharmaceutical and BiomedicalAnalysis vol 51 no 1 pp 125ndash130 2010

[72] V Domınguez-Villegas B Clares-Naveros M L Garcıa-Lopez et al ldquoDevelopment and characterization of two nano-structured systems for topical application of flavanones isolatedfrom Eysenhardtia platycarpardquo Colloids and Surfaces B Bioint-erfaces vol 116 pp 183ndash192 2014

[73] M Barzegar-Jalali K AdibkiaHValizadeh et al ldquoKinetic anal-ysis of drug release from nanoparticlesrdquo Journal of Pharmacyand Pharmaceutical Sciences vol 11 no 1 pp 167ndash177 2008

[74] L Zeng L An and X Wu ldquoModeling drug-carrier interactionin the drug release from nanocarriersrdquo Journal of Drug Deliveryvol 2011 Article ID 370308 15 pages 2011

[75] L Zeng andXWu ldquoModeling the sustained release of lipophilicdrugs from liposomesrdquo Applied Physics Letters vol 97 no 7Article ID 073701 2010

[76] FDA Guidance for Industry Extended Release Oral DosageForms Development Evaluation and Application of In VitroInVivo Correlations 1997

[77] J G Wagner and E Nelson ldquoPer cent absorbed time plotsderived fromblood level andor urinary excretion datardquo Journalof Pharmaceutical Sciences vol 52 pp 610ndash611 1963

Submit your manuscripts athttpwwwhindawicom

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StrokeResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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Pharmaceutics

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MEDIATORSINFLAMMATION

of

Advances in Pharmaceutics 3

shortcomings It is hoped that this review will serve as aguideline for developing suitable techniques for assessmentof exploratory formulations clinical and commercial dosageforms and establishment of an in vitro in vivo correlation(IVIVC)

2 In Vitro Release Methods

Much attention has been devoted to the development of suit-able apparatus to assess in vitro release fromnanoparticulatesHowever additional considerations like release media selec-tion agitation and so forth cannot be overlooked In contrastto oral dosage forms where release media typically mimicspH of the gastrointestinal tract selection of release media fornano-sized dosage forms will vary depending on the site ofadministration as well as the site of action of the formulationand thus simulation of in vivo conditions may be difficultIn general selection of release media for nanoparticulatepreparation is generally based on drug solubility and stabilityassay sensitivity and the method used Though maintenanceof sink conditions is preferable nonsink conditions havebeen employed Agitation frequently utilized to preventaggregation of dosage forms during an in vitro release studywill depend on the apparatus used Similarly sampling andbuffer replacement (total or partial) techniques are also basedon the type of in vitromethod used

As such drug release from nano-sized dosage formscan be assessed using one of the following three categoriesnamely sample and separate (SS) continuous flow (CF) anddialysis membrane (DM) methods More recently apparatusthat combine the principles of either the SS andDMorCF andDMhave also been reported Lastly a few novel methods thatuse voltametry turbidimetry and so forth are discussed Foreach of these methods a brief description is provided alongwith adaptations additional considerations advantages anddisadvantages

21 Sample and Separate In the SS method the nanopartic-ulate dosage form is introduced into the release media thatis maintained at a constant temperature after which drugrelease is assessed by sampling of the releasemedia (filtrate orsupernatant) or the nanoparticles From literature there areseveral adaptations to the SS method with differences notedin set-up container size mode of agitation and samplingtechniques

Commonly reported set-ups include USP I (basket) USPII (paddle) or vials and generally depend on the volume ofrelease media used in the in vitro release study [7 38ndash40] Forinstance vials were used when the volume of release mediawas small (1ndash15mL) and in vitro release vesselswere employedwith larger volumes (600ndash900mL) [5 7 38 40 41]

In addition to determining the type of set-up containersize also influences the mode of agitation used in an in vitrorelease study with the SS method With small sized dosageforms like nanoparticles agitation of the release media iscritical to the in vitro release process as it reduces the potential

for aggregation and enhances wetting thereby reducing theimpact of these factors on the in vitro release rate [38] Whileagitation of the release media is easily accomplished via theUSP I or USP II apparatus media contents in vials have beenagitated using alternate techniques For example Danhieret al and Li et al used magnetic stirrers with Paclitaxel andBSA nanoparticles respectively while Prabha et al reportedthe use of orbital shakers with DNA nanoparticles [42ndash44]

Drug release is monitored by physically separating thenanoparticles from the release media followed by analysis ofthe former or the latter [7 41] While several authors havedocumented the use of syringe filters to achieve physicalseparation between the release media and nanoparticlesthe small size of nanoparticles has necessitated the useof high energy separation techniques like centrifugationultracentrifugation and ultrafiltration [40 42 45ndash47] Forfiltration syringe filters with pore size as large as 045 120583mhave been used for withdrawing supernatant to monitordrug release of small molecules such as Celecoxib [40] Incomparison high energy separation techniques have beenreported with larger biomolecules like Insulin BSA (BovineSerum Albumin) and DNA [43 44 48] Once separateddrug release is generally monitored by sampling a part ofthe supernatant or decanting the entire supernatant contentat periodic intervals [7 49] In other instances separationwas followed by analysis of the nanoparticles (destructivetechnique) [41] After sampling an equal amount of freshrelease media or buffer is added to the set-up so that sinkconditions are maintained for the duration of the in vitrorelease study

In general the SS method provides a direct approach tomonitor drug release With this method most sample set-ups agitationmodes and sampling techniques are reasonablystraightforward and simple However due to the small sizeof nanoparticulate dosage forms several practical challengeshave been noted For instance aggregation of nanoparticlesduring in vitro release appears to be a key concern Addi-tionally while sampling techniques like filtration seem fairlyreasonable in principle clogging of filters during samplingadsorption of drug to the filter and so forth have beenreported [50] Indeed difficulty in physical separation evenwith high energy techniques continued drug release duringthe high energy separation process and so forth are someof the challenges often observed during sampling [38 45]Although sink conditions are recommended with the SSmethod nonsink conditions have been reported to be morediscriminatory with poorly soluble drugs [51] Neverthelessas with microparticulate dosage forms the SS method offersresearchers a simple and straightforward approach to moni-tor in vitro release from nano-sized dosage forms

22 Continuous Flow In the CF method drug release fromthe nanoparticulate dosage form is monitored using theUSP IV apparatus or a modification thereof Drug releaseoccurs as a result of buffer or media constantly circulatingthrough a column containing the immobilized dosage formand is monitored by collecting the eluent at periodic intervals(Figure 1)

4 Advances in Pharmaceutics

Flow through cell

Filter

Nanosuspension distributed in

glass beads

Release media

Pump

Detector

Figure 1 Continuous flow set-up in closed loop configuration

Unlike the widely used SS method only a few examplesof the CF method have been reported for nano-sized dosageforms [38 52] For example the release profiles of amor-phous nanoparticles and an unprocessed crystalline form ofCefuroxime Axetil a BCS II cephalosporin antibiotic wereevaluated using the CF method as well as other methodsdescribed below [38]

(a) USP I (basket) 900mL buffer at 100 rpm(b) USP II (paddle) 900mL buffer at 100 rpm(c) USP IV (flow through cell) 900mL buffer at a flow

rate of 16mLmin (peristaltic pump closed loop)through a cell (internal diameter = 25mm) and02 120583mmembrane disc filter

(d) dialysis bag (MWCO 12 kDa inner volume = 7mL)placed into a USP II (paddle) in vitro release tester(outer volume = 900mL paddle rpm = 100)

The results revealed that complete drug release wasachieved only with the USP II paddle and USP IV apparatusrelease profiles with the USP IVmethod being well separated

Immobilization of the nanoparticles was thought to bea factor contributing to the discriminatory results obtainedwith the USP IV apparatus

Similarly in an experiment on nano- and micro-particleloaded strip films of another BCS II drug Griseofulvin invitro release was performed using two methods [52]

(a) USP I (basket) 500 and 900mLmedia at 50 100 and150 rpm

(b) USP IV (flow through cell) 100mL media at flowrates of 4 8 and 16mLmin (peristaltic pump closedloop) through a cell (internal diameter = 226mm)and 02120583m membrane disc filter with the strip filmloaded in 6 different configurations

While complete release was observed only with USP Iand configuration B (strip film positioned in the cell on topof round glass beads) of the USP IV method results withconfigurations A (strip film positioned in the cone section

Sampling from outer compartment

Dialyzer cap

Inner compartment containing nanosuspension

Dialysis membrane

Outer compartment containing release media

Stir bar

Figure 2 ldquoRegular dialysisrdquo set-up (adapted from [21])

of the cell without round glass beads) and C (strip filmsandwiched between round glass beads) of USP IV at thehighest flow rate were more discriminatory than all the otherrelease profiles obtained in the in vitro study

In comparison to nanoparticulate dosage forms whereliterature on the use of USP IV methodology is sparseseveral salient aspects of the CF method can be inferredfrom its use in microparticulate dosage forms [21] As anexample flow rates used in the CF method depend on thetype of pump (peristaltic versus syringe) as well as the filtersused (membrane versus ultrafilters) Low flow rates havebeen known to be a key factor causing slow or incompleterelease from dosage forms [21] In general the availabilityof automated equipment has simplified routine samplingand media replacement with the the CF method in closed(recirculating media) and open (nonrecirculating media)loop systems However the CF methods suffer from severaldisadvantages that include instrument costs difficulty in set-up filter clogging adsorption to the filter and glass beads anddifficulty in maintaining a constant flow rate leading to widevariability in results

23 Dialysis Method Of all the methods used to assess drugrelease from nano-sized dosage forms the dialysis method(DM) is the most versatile and popular In this methodphysical separation of the dosage forms is achieved by usageof a dialysis membrane which allows for ease of samplingat periodic intervals As with the other methods severaladaptations of the DM have been reported in literaturewith key differences in set-up container size and molecularweight cut-off (MWCO)

Of the variety of DM set-ups used the most commonlycited is the dialysis bag (regular dialysis) other adaptationsbeing the reverse dialysis and side-by-side dialysis set-up[26 53 54] (Figures 2ndash4)With the regular dialysis technique

Advances in Pharmaceutics 5

Sampling from inner compartment

Dialyzer cap

Inner compartment containing release media

Dialysis membrane

Outer compartment containing nanosuspension

Stir bar

Figure 3 ldquoReverse dialysisrdquo set-up

Receiver compartment

Dialysis membrane

Stir bar

Sampling

Nanoemulsion in donor compartment

Figure 4 ldquoSide-by-side dialysisrdquo set-up (adapted from [26])

the nanoparticles are introduced into a dialysis bag contain-ing release media (inner mediacompartment) that is subse-quently sealed and placed in a larger vessel containing releasemedia (outer mediacompartment) agitated to minimizeunstirred water layer effects [32 55] In general the volumeenclosed in a dialysis bag (inner media) is significantlysmaller than the outer media For instance inner mediavolumes reported in literature range from 1 to 10mL whereasthe outermedia volume ismuch greater typically around 40ndash90mL [32 53 55] Thus container size will depend on thetotal volume of release media required for the in vitro releasestudy In the regular dialysis technique drug released fromthe nanoparticles diffuses through the dialysis membraneto the outer compartment from where it is sampled foranalysis (Figure 2) In contrast with the reverse dialysis set-up the nanoparticles are placed in the outer compartment(agitated to minimize the unstirred water layer) and theinner compartment is sampled for drug release (Figure 3)[54 56 57] Other adaptations of the DM include the side-by-side dialysis set-up where donor and receiver cells bothcontaining equal volumes of media agitated with a magneticstirrer are separated by a dialysis membrane and samplingoccurs from the receiver cell (Figure 4) and a vertical Franzdiffusion cell [26 58 59]

As with other methods drug solubility in the releasemedia is essential to its transport across the dialysis mem-brane Apart from release media the importance of selectingan appropriate molecular weight cut-off (MWCO) for thedialysis membrane cannot be overlooked Indeed the basicpremise of the DM is that drug that is released from thedosage form will diffuse rapidly from one compartmentthrough the membrane and enter the second compartmentfrom where it is sampled for analysis Thus membranes witha sufficiently high membrane MWCO are often selected forin vitro release studies so that drug transport is not a limitingfactor As an example in a study with 3 dosage forms ofIndomethacin (eg nanoparticles and nanocapsules usingpoly-120576-caprolactone and a submicron emulsion) Calvo et alnoted that nearly 85 of drug was released within 2 hoursand complete release was achieved in 4 hours when a 12 kDamembranewas used [54] However the rationale for selectinga MWCO is rather subjective For instance a MWCO ashigh as 10ndash14 kDa was used to study drug release of smallmolecules like Risperidone and Indomethacin and aMWCOas low as 1 kDa though suitable for assessing in vitro releaseof a large molecule pDNA proved to be limiting for thediffusion of Cefuroxime Axetil a cephalosporin antibiotic[32 38 55 60] In general the MWCO should be sufficientlylarge to permit drug transport

The ease of set-up and sampling with the DM make ita very simple and straightforward technique to study drugrelease from a wide variety of nano-sized dosage forms likenanospheres liposomes emulsions nanosuspensions andso forth [53ndash55] However issues have been reported withthe regular dialysis method If incorrectly sealed leakage ofmedia and dosage form may occur from both ends of thedialysis bag set-up Incomplete release data may be observedif nonsink conditions exist or equilibration times are high[38] On the other hand the difference in equilibration timescan be exploited as a discriminatory tool to distinguish releasebehavior between fast and slow releasing dosage forms [50]Another factor to be considered is that the DM cannotbe used with drugs that bind to the dialyzing membraneAs stated in a review paper on microparticulate dosageforms it is recommended that the suitability of the dialyzingmembrane be assessed prior to use [21 61]

24 CombinationMethods A fewpublications havemodifiedthe set-ups used in the SS CF and DM methods to evaluatedrug release from nano-sized dosage forms In most of thesereports the set-up of the SS method is combined with adialyzer to allow ease of sampling In other publications theDM and the CF set-up is used to assess in vitro release fromnanoparticulates

As an example Mottaleb et al compared release profilesof Ibuprofen from liposomes and lipid nanocapsules andnanoparticles using the regular dialysis method (dialysis bag)and modified USP I (basket) set-up where the shaft wasaffixed with a glass basket having a dialysis membrane atthe bottom that is glass basket dialysis (GBD) and placedin a larger vessel (Figure 5) [27] Sampling was performedfrom the outer vessel Unlike the dialysis bag that had a large

6 Advances in Pharmaceutics

Glass basket

Dialysis membrane

Figure 5 Comparison ofUSP I (left) and glass basket dialysis (right)set-ups (adapted from [27])

membrane surface area the GBD was able to discriminatedifferences between release profiles from different formu-lations (lipid nanocapsules nanoparticles liposomes) Inanother study Lobenberg et al compared drug release fromRifampicin and Moxifloxacin hydrochloride nanoparticleswith the regular dialysis method (dialysis bag) as well as anadaptation of USP I (basket) where a cylinder containing adialysis membrane at the bottom was attached to the basketshaft [62] Results from this study showed that modifiedUSP I set-up was more discriminatory in nature and couldbe attributed to the reduced surface area of the dialysismembrane In yet another modification of the USP I (basket)set-up a dialysis bag containing nanostructured lipid carriersof Artemether was placed inside the basket and drug releasemonitored over time [63] Though most studies have utilizedthe USP I set-up others have used the USP II (paddle) set-upin combination with the DM For example Cao et al affixeddialysis bags containing Silybin meglumine nanoparticlesonto a USP II (paddle) apparatus and assessed drug releasein five different release media [33 35]

A combination of aDM previously reported byKostanskiet al and CF method was utilized to assess drug releasefrom 5-Fluorouracil loaded BSA nanoparticles [28 64] Thesetup comprised a glass tube (with a dialysis membrane atthe bottom) that was placed into a larger vessel containingbuffer (Figure 6) Sampling as well as buffer replacement wasperformed from the larger vessel with the aid of two pumpshaving the same flow rate The combined DM-CF set-up wasable to demonstrate sustained levels of 5-Fluorouracil andthe absence of burst release from the BSA nanoparticles Analternate dialysis-CFmethod utilized a dialysis adaptor insidethe CF set-up (Figure 7) [29]

25 New Methods Apart from the commonly reported SSCF and DM methods a few alternate approaches have beenutilized tomonitor drug release Amajority of these appear tobe targeted towards electroactive drugsWhile the techniquesmay differ in principle or application they possess a fewcommon elements in that physical separation of the dosageform from the release media is not required Additionallythese techniques offer the possibility of measurement underreal-time conditions

Detector

Waste

Dialysis membrane

Nanosuspension

Stir bar

Pump 2Pump 1

Release media

Figure 6 Continuous flow dialysis set-up with two pumps (adaptedfrom [28])

Flow through cell

Releasemedia

Pump

Detector

Filter

Glass beads

Dialyzer containingnanosuspension

Figure 7 Dialysis adapter inside a continuous flow set-up (adaptedfrom [29])

As such electrochemical methods offer the possibility ofrapid in situ measurements while avoiding the interferencecaused by the presence of undissolved dosage form in therelease media In one such approach a potentiometric drugselective electrode was used to monitor real-time release ofProcaine hydrochloride from pH-responsive nanogels [65]In another report by Mora et al a highly sensitive repetitivesquare-wave voltammetric technique was utilized to measurethe redox reaction of Doxorubicin hydrochloride (Figure 8)[30] Similarly differential pulse polarography was used toassess continuous drug release from Piroxicam Chloram-phenicol and Diazepam [66 67] Apart from the fact thatonly electroactive drugs can be measured by the abovemethods these methods suffer from additional drawbacksFor example the sensitivity as well as responsiveness ofeach technique varies greatly Also the sensors used may bespecific to a particular drug

Nonelectrochemical methods like calorimetry turbidim-etry and laser diffraction have also been evaluated as invitro release methods Solution calorimetry was employedby Kayaert et al during in vitro release measurement ofNaproxen Cinnarizine and Compound A (investigational

Advances in Pharmaceutics 7

Working electrode

Reference electrode

Counter electrode

Release media

Redox reactionAox Ared

A Liposome containing drug ldquoArdquo

Figure 8 Electrochemical cell set-up for real-time measurement ofdrug release (adapted from [30])

Pump control

Syringe Analyte

NanosuspensionMicrodialysis probe

pump

Figure 9 Microdialysis set-up (adapted from [31])

API) from nanocrystals [68] The principle of this tech-nique is based on detection of the net proportion of heatchange during in vitro release Challenges with calorimetricmeasurements include long equilibration times Further theheat produced by all the processes needs to be consideredTurbidimetric and laser diffraction approaches utilizing thechange light scattering properties of nanoparticles dispersedin release media have also been utilized [69 70] Concernswith these methods include the long equilibration timeslimited range of particle size and initial concentration ofsamples that can be used

Helle et al designed a novel online system for evaluatingthe drug release from Indomethacin and Beclomethasonedipropionate nanoparticles In thismethod nanoparticles arepacked into small column which is connected to multiportmodulation valve attached to an HPLC system allowingfor rapid analysis [71] Other new methods reported inliterature include a vertical diffusion Franz cell and an invitro lipolysis model [37 72] Microdialysis another set-up utilized to measure drug release from nanoparticules isbased on passive diffusion of drug through a concentrationgradient across a semipermeable membrane (Figure 9) [3147] Drug release can be measured in real-time conditionsusing analytical methods like HPLC However care shouldbe taken when surfactants are used in the release media asrecovery may be affected

3 Modeling Drug Release

Very few publications have attempted to describe drug releaseprofiles from nanoparticulate dosage forms using mathe-matical models This is not surprising given that nano-sizeddosage forms are complex and drug release evaluations arenot straightforward However a few authors have discussedthe importance of mathematical models and endeavored tocharacterize drug release For instance Barzegar-Jalali et alsuggested the use of reciprocal powered time (RPT) as generalmodel to analyze the complex nature of drug release fromnanoparticles with alternate approaches being the Weibulland log-probabilitymodels [73] In another report Zeng et aldeveloped a three-parameter model that considers reversibledrug-carrier interaction as well as diffusional drug releasefrom liposomes [74 75]

Use of mathematical models to describe drug releaseprofiles offers several advantages It permits the elucidationof drug release mechanisms and can be used to guide for-mulation development efforts Furthermodel parameters canserve to represent as well as compare in vitro release profilesHowever caution must be used when applying mathematicalmodels to complex drug release mechanisms

4 IVIVC

The US FDA defines IVIVC as ldquoA predictive mathematicalmodel describing the relationship between an in vitro prop-erty of an extended release dosage form (usually the rate orextent of drug in vitro release or release) and a relevant invivo response for example plasma drug concentration oramount of drug absorbedrdquo [76] Thus establishment of anIVIVC described as a correlation between in vitro release andin vivo behavior enhances the utility of an in vitro study Fromthe 1997 FDA guidance document an IVIVC will reduce theregulatory burden by paring the number of in vivo studiesneeded for product approval Additionally it promotes thesetting of clinically relevant in vitro release specifications [76]

The FDA guidance also categorizes IVIVCs into threelevels Level A represents a linear or nonlinear point-to-point relationship between the in vitro and in vivo releaseprofiles If the relationship is nonlinear suitable modelingor scaling is required Of the three IVIVC levels Level Adescribes the highest correlation and is most commonly usedto obtain a biowaiver On the other hand a Level B correlationis a comparison of summary parameters such as the meanin vitro dissolution time with mean in vivo dissolution timeor mean residence time (MRT) Since several in vivo curveswill produce a similarMRT value ormean in vitro dissolutiontime Level B correlations are not as discriminatory as LevelA but acceptable for an IVIVC A Level C correlationdescribes a relationship between an in vitro release parameter(eg dissolved at a particular time) and a pharmacokineticparameter (eg 119862max) However a Level C correlation is notdescriptive of the complete shape of the in vivo release profileand though acceptable seldom used

As such the FDA guidance is intended for oral extendedrelease products However principles of the FDA guidance

8 Advances in Pharmaceutics

Table 2 Examples of IVIVC with nano-sized dosage forms in animal models

Drug and dosage form In vitro release set-up In vivo studies IVIVC type Reference

Indomethacin gelatin nanoparticles Dialysis bags Wistar Albinorats Level A [32]

Silybin meglumine hollow-spheremesoporous silica nanoparticles Combination (USP Imdashdialysis bag) Beagle dogs Level A [33]

Silybin 72-hour SLB andPSNs (porous silica nanoparticles) Combination (USP Imdashdialysis bag) Beagle dogs Level A [35]

Simvastatin nanostructured lipidcarriers and nanoparticles Dialysis bag BalbC mice Level A [34]

Fenofibrate nanosuspension USP I apparatus SpragueDawley rats Level A [36]

Fenofibrate lipid matrix particles In vitro lipolysis model SpragueDawley rats Rank order [37]

Table 3 Level A IVIVC with two Silybin preparations (data from reference [35])

Formulation absorbed equals 1198772

72-hour SLB 11379 times dissolved + 88688 09831Silybin PSNs (porous silica nanoparticles) 08915 times dissolved minus 10152 09831

have been used to demonstrate an IVIVC from severalnonoral dosage forms including nano-sized preparationsMost published literature on IVIVC compares the in vitrorelease behavior with the in vivo absorption profile thelatter calculated by the FDA recommended Wagner-Nelsonmethod [76 77] Once the fraction absorbed is computeda correlation is obtained by comparing it with the in vitrorelease profile and the type of IVIVC (Level A level B etc) isdetermined

Over the last decade a few reports on IVIVC from nano-sized dosage forms have been published (Table 2) In someinstances a rank order correlation was observed while inothers a Level A IVIVC was established with some or allof the formulations evaluated in the study As an example arank order correlation was observed with three preparationsof Fenofibrate with drug release and absorption from 100 nmlipid matrix particles gt microparticles gt control (crystallinesuspension) [37] In another study on Fenofibrate nanosus-pensions Xu et al attempted to elucidate the absorptionmechanism using in situ gut perfusion model [36] Dataanalysis between in vitro dissolution (119875) in situ intestinalabsorption (119865) and in vivo absorption (119865

119886) demonstrated

a Level A correlation (1198772 gt 095) As a result the authorsconcluded that the in situ intestinal perfusion model couldbe a predictor of in vivo pharmacokinetic behavior for thenanosuspension

In a recent report Kumar et al investigated the relation-ship between in vitro and in vivo release from Indomethacingelatin nanoparticles administered orally to Wistar albinorats [32] Study results indicated that a good correlation wasobtained by plotting the fraction absorbed in vivo (Wagner-Nelson method) against the fraction released the latter per-formed using regular dialysis (dialysis bags) (Figure 10) TheWagner-Nelsonmethod was also used in another publication

0

20

40

60

80

100

120

0 20 40 60 80 100

In v

ivo

abso

rptio

n (

)

In vitro release ()

R2 = 0981

y = 1121x

Figure 10 Level A IVIVC from Indomethacin gelatin nanoparticlesusing regular dialysis (redrawn from [32])

where the in vivo absorption fromSilybinmeglumine hollow-sphere mesoporous silica nanoparticles dosed orally to bea-gle dogs was compared with in vitro results obtained using acombination USP I (paddle) dialysis bag set-up [33] Of thefive different releasemedia used in the study a Level A IVIVC(1198772 gt 097) was obtained with 006M Na

2CO3and 008M

Na2CO3solutions (Figure 11) In another study with Silybin

an IVIVC was achieved with a 72-hour release formulationof Silybin (72-hour SLB) that consisted of a solid dispersiongel matrix and porous silica nanoparticles (PSNs) (Table 3)[35] Similar to the earlier study the authors compared invivo release from beagle dogs with in vitro release assessedusing a combination USP I (paddle) dialysis bag set-upIn another paper Tiwari et al demonstrated a Level A

Advances in Pharmaceutics 9

0

20

40

60

80

100

0 20 40 60 80 100

Abso

rbed

()

Abso

rbed

()

0 20 40 60 80 1000

20

40

60

80

100

In vitro release ()

In vitro release ()

y = 23417x minus 78256

R2 = 09741

y = 16114x minus 56752

R2 = 09931

006M Na2CO3

008M Na2CO3

Figure 11 Level A IVIVC from Silybin meglumine hollow-typemesoporous silica nanoparticles using a combined USP II-dialysisbag set-up (redrawn from [33])

correlation between in vitro release (dialysis bag) and percentdrug absorbed (Wagner Nelson method) for Simvastatinnanostructured lipid carriers as well as nanoparticles (1198772 gt094) (Figure 12) [34]

5 Conclusions

For novel dosage forms like nanoparticles where no regu-latory or compendial standards exist in vitro drug releaseassessment assumes greater significance in serving as anindicator of product quality and performance A plethoraof methods have been used each with their advantages anddrawbacks with respect to ease of set-up sampling and rapidbuffer replacement Ideally an in vitro release method shouldsimulate in vivo conditions release mechanisms and enablethe establishment of an IVIVC Future research should focuson developing relevant mathematical models to predict drugrelease behavior as well as release mechanisms applicable to awide range of nano-sized dosage forms

Conflict of Interests

The author declares that there is no conflict of interestsregarding the publication of this paper

0

20

40

60

80

100

120

Dru

g ab

sorb

ed (

)

0

20

40

60

80

100

120

Dru

g ab

sorb

ed (

)

Simvastatin loaded nanostructured lipid carriers

Simvastatin loaded solid lipid nanoparticles

0 20 40 60 80 100In vitro release ()

0 20 40 60 80 100In vitro release ()

R2 = 09404

R2 = 0941

Figure 12 Level A correlation of Simvastatin from two nano-sizeddosage forms (redrawn from [34])

References

[1] N Al Khouri Fallouh L Roblot-Treupel and H Fessi ldquoDevel-opment of a new process for the manufacture of polyisobutyl-cyanoacrylate nanocapsulesrdquo International Journal of Pharma-ceutics vol 28 no 2-3 pp 125ndash132 1986

[2] C Losa P Calvo E Castro J L Vila-Jato and M J AlonsoldquoImprovement of ocular penetration of amikacin sulphate byassociation to poly(butylcyanoacrylate) nanoparticlesrdquo Journalof Pharmacy and Pharmacology vol 43 no 8 pp 548ndash552 1991

[3] C Losa L Marchal-Heussler F Orallo J L Vila Jato andM J Alonso ldquoDesign of new formulations for topical ocularadministration polymeric nanocapsules containing metipra-nololrdquo Pharmaceutical Research vol 10 no 1 pp 80ndash87 1993

[4] C N Cruz K M Tyner L Velazquez et al ldquoCDER riskassessment exercise to evaluate potential risks from the use ofnanomaterials in drug productsrdquo AAPS Journal vol 15 no 3pp 623ndash628 2013

[5] G Verreck I Chun J Rosenblatt et al ldquoIncorporation of drugsin an amorphous state into electrospun nanofibers composedof a water-insoluble nonbiodegradable polymerrdquo Journal ofControlled Release vol 92 no 3 pp 349ndash360 2003

[6] H Heiati R Tawashi R R Shivers and N C PhillipsldquoSolid lipid nanoparticles as drug carriers I incorporation andretention of the lipophilic prodrug 31015840-azido-31015840-deoxythymidinepalmitaterdquo International Journal of Pharmaceutics vol 146 no1 pp 123ndash131 1997

10 Advances in Pharmaceutics

[7] M Cetin A Atila and Y Kadioglu ldquoFormulation and in vitrocharacterization of Eudragit L100 and Eudragit L100-PLGAnanoparticles containing diclofenac sodiumrdquo AAPS Pharm-SciTech vol 11 pp 1250ndash1256 2010

[8] A Hanafy H Spahn-Langguth G Vergnault et al ldquoPharma-cokinetic evaluation of oral fenofibrate nanosuspensions andSLN in comparison to conventional suspensions of micronizeddrugrdquo Advanced Drug Delivery Reviews vol 59 no 6 pp 419ndash426 2007

[9] T M Allen W W K Cheng J I Hare and K M LaginhaldquoPharmacokinetics and pharmacodynamics of lipidic nano-particles in cancerrdquoAnti-Cancer Agents in Medicinal Chemistryvol 6 no 6 pp 513ndash523 2006

[10] J Kreuter ldquoNanoparticle-based drug delivery systemsrdquo Journalof Controlled Release vol 16 no 1-2 pp 169ndash176 1991

[11] M L Etheridge S A Campbell A G Erdman C L Haynes SMWolf and JMcCullough ldquoThe big picture on nanomedicinethe state of investigational and approved nanomedicine prod-uctsrdquo Nanomedicine Nanotechnology Biology and Medicinevol 9 no 1 pp 1ndash14 2013

[12] S Nie ldquoUnderstanding and overcoming major barriers incancer nanomedicinerdquoNanomedicine vol 5 no 4 pp 523ndash5282010

[13] W H de Jong and P J A Borm ldquoDrug delivery andnanoparticles applications and hazardsrdquo International Journalof Nanomedicine vol 3 no 2 pp 133ndash149 2008

[14] S DrsquoSouza J A Faraj R Dorati and P P DeLuca ldquoA short termquality control tool for biodegradable microspheresrdquo AAPSPharmSciTech vol 15 no 3 pp 530ndash541 2014

[15] P Buch P Holm J Q Thomassen et al ldquoIVIVC for fenofibrateimmediate release tablets using solubility and permeability as invitro predictors for pharmacokineticsrdquo Journal of Pharmaceuti-cal Sciences vol 99 no 10 pp 4427ndash4436 2010

[16] S DrsquoSouza J A Faraj S Giovagnoli and P P DeLuca ldquoIVIVCfrom long acting olanzapine microspheresrdquo International Jour-nal of Biomaterials vol 2014 Article ID 407065 11 pages 2014

[17] L C Amann M J Gandal R Lin Y Liang and S J SiegelldquoIn vitro-in vivo correlations of scalable PLGA-Risperidoneimplants for the treatment of schizophreniardquo PharmaceuticalResearch vol 27 no 8 pp 1730ndash1737 2010

[18] G Zackrisson G Ostling B Skagerberg and T Anfalt ldquoACcel-erated Dissolution Rate Analysis (ACDRA) for controlledrelease drugs Application to Roxiamrdquo Journal of Pharmaceu-tical and Biomedical Analysis vol 13 no 4-5 pp 377ndash383 1995

[19] S S DSouza J A Faraj and P P DeLuca ldquoA model-dependentapproach to correlate accelerated with real-time release frombiodegradable microspheresrdquo AAPS PharmSciTech vol 6 arti-cle 70 no 4 2005

[20] D J Burgess A S Hussain T S Ingallinera and M ChenldquoAssuring quality and performance of sustained and controlledrelease parenterals workshop reportrdquo AAPS PharmSci vol 4article E7 2002

[21] S S DrsquoSouza and P P DeLuca ldquoMethods to assess in vitrodrug release from injectable polymeric particulate systemsrdquoPharmaceutical Research vol 23 no 3 pp 460ndash474 2006

[22] M Siewert J Dressman C K Brown and V P ShahldquoFIPAAPS guidelines to dissolutionin vitro release testing ofnovelspecial dosage formsrdquo AAPS PharmSciTech vol 4 article7 2003

[23] C K Brown H D Friedel A R Barker et al ldquoFIPAAPSjoint workshop report dissolutionin vitro release testing of

novelspecial dosage formsrdquo AAPS PharmSciTech vol 12 no2 pp 782ndash794 2011

[24] MMartinezM Rathbone D Burgess andMHuynh ldquoIn vitroand in vivo considerations associated with parenteral sustainedrelease products a review based upon information presentedand points expressed at the 2007 Controlled Release SocietyAnnual Meetingrdquo Journal of Controlled Release vol 129 no 2pp 79ndash87 2008

[25] M N Martinez M J Rathbone D Burgess and M HuynhldquoBreakout session summary from AAPSCRS joint workshopon critical variables in the in vitro and in vivo performanceof parenteral sustained release productsrdquo Journal of ControlledRelease vol 142 no 1 pp 2ndash7 2010

[26] N Chidambaram and D J Burgess ldquoA novel in vitro releasemethod for submicron-sized dispersed systemsrdquo AAPS Pharm-Sci vol 1 no 3 pp 32ndash40 1999

[27] M M A Abdel-Mottaleb and A Lamprecht ldquoStandardized invitro drug release test for colloidal drug carriers using modifiedUSP dissolution apparatus Irdquo Drug Development and IndustrialPharmacy vol 37 no 2 pp 178ndash184 2011

[28] A Maghsoudi S A Shojaosadati and E Vasheghani Farahanildquo5-Fluorouracil-loaded BSA nanoparticles formulation opti-mization and in vitro release studyrdquo AAPS PharmSciTech vol9 no 4 pp 1092ndash1096 2008

[29] U Bhardwaj and D J Burgess ldquoA novel USP apparatus 4 basedrelease testing method for dispersed systemsrdquo InternationalJournal of Pharmaceutics vol 388 no 1-2 pp 287ndash294 2010

[30] L Mora K Y Chumbimuni-Torres C Clawson L HernandezL Zhang and J Wang ldquoReal-time electrochemical monitoringof drug release from therapeutic nanoparticlesrdquo Journal ofControlled Release vol 140 no 1 pp 69ndash73 2009

[31] C B Michalowski S S Guterres and T Dalla CostaldquoMicrodialysis for evaluating the entrapment and release of alipophilic drug from nanoparticlesrdquo Journal of Pharmaceuticaland Biomedical Analysis vol 35 no 5 pp 1093ndash1100 2004

[32] R Kumar R C Nagarwal M Dhanawat and J K PanditldquoIn-vitro and in-vivo study of indomethacin loaded gelatinnanoparticlesrdquo Journal of Biomedical Nanotechnology vol 7 no3 pp 325ndash333 2011

[33] X Cao W W Deng M Fu et al ldquoIn vitro release and in vitro-in vivo correlation for silybin meglumine incorporated intoHollow-type mesoporous silica nanoparticlesrdquo InternationalJournal of Nanomedicine vol 7 pp 753ndash762 2012

[34] R Tiwari and K Pathak ldquoNanostructured lipid carrier versussolid lipid nanoparticles of simvastatin comparative analysis ofcharacteristics pharmacokinetics and tissue uptakerdquo Interna-tional Journal of Pharmaceutics vol 415 no 1-2 pp 232ndash2432011

[35] X Cao W Deng M Fu et al ldquoSeventy-two-hour releaseformulation of the poorly soluble drug silybin based on poroussilica nanoparticles in vitro release kinetics and in vitroin vivocorrelations in beagle dogsrdquo European Journal of Pharmaceuti-cal Sciences vol 48 no 1-2 pp 64ndash71 2013

[36] Y Xu Y Wang X M Li et al ldquoStudy on the release offenofibrate nanosuspension in vitro and its correlation with insitu intestinal and in vivo absorption kinetics in ratsrdquo DrugDevelopment and Industrial Pharmacy vol 40 no 7 pp 972ndash979 2014

[37] N Borkar D Xia R Holm et al ldquoInvestigating the correlationbetween in vivo absorption and in vitro release of fenofibratefrom lipid matrix particles in biorelevant mediumrdquo EuropeanJournal of Pharmaceutical Sciences vol 51 pp 204ndash210 2014

Advances in Pharmaceutics 11

[38] D Heng D J Cutler H K Chan J Yun and J A RaperldquoWhat is a suitable dissolutionmethod for drug nanoparticlesrdquoPharmaceutical Research vol 25 no 7 pp 1696ndash1701 2008

[39] A C Kilic Y Capan I Vural et al ldquoPreparation and characteri-zation of PLGA nanospheres for the targeted delivery of NR2B-specific antisense oligonucleotides to the NMDA receptors inthe brainrdquo Journal of Microencapsulation vol 22 no 6 pp 633ndash641 2005

[40] Y Zhang H Wang C Li et al ldquoA novel three-dimensionallarge-pore mesoporous carbon matrix as a potential nanove-hicle for the fast release of the poorly water-soluble drugcelecoxibrdquoPharmaceutical Research vol 31 pp 1059ndash1070 2014

[41] V Sanna A M Roggio S Siliani et al ldquoDevelopment of novelcationic chitosan-and anionic alginate-coated poly(DL-lactide-co-glycolide) nanoparticles for controlled release and light pro-tection of resveratrolrdquo International Journal of Nanomedicinevol 7 pp 5501ndash5516 2012

[42] F Danhier N Lecouturier B Vroman et al ldquoPaclitaxel-loadedPEGylated PLGA-based nanoparticles In vitro and in vivoevaluationrdquo Journal of Controlled Release vol 133 no 1 pp 11ndash17 2009

[43] Y Li Y Pei X Zhang et al ldquoPEGylated PLGA nanoparticlesas protein carriers synthesis preparation and biodistributionin ratsrdquo Journal of Controlled Release vol 71 no 2 pp 203ndash2112001

[44] S Prabha W-Z Zhou J Panyam and V Labhasetwar ldquoSize-dependency of nanoparticle-mediated gene transfection stud-ies with fractionated nanoparticlesrdquo International Journal ofPharmaceutics vol 244 no 1-2 pp 105ndash115 2002

[45] S J Wallace J Li R L Nation and B J Boyd ldquoDrug releasefrom nanomedicines selection of appropriate encapsulationand release methodologyrdquo Drug Delivery and TranslationalResearch vol 2 no 4 pp 284ndash292 2012

[46] D Juenemann E Jantratid C Wagner C Reppas M Vertzoniand J B Dressman ldquoBiorelevant in vitro dissolution testingof products containing micronized or nanosized fenofibratewith a view to predicting plasma profilesrdquo European Journal ofPharmaceutics and Biopharmaceutics vol 77 no 2 pp 257ndash2642011

[47] P F Yue X Y Lu Z Z Zhang et al ldquoThe study on theentrapment efficiency and in vitro release of puerarin submi-cron emulsionrdquoAAPS PharmSciTech vol 10 no 2 pp 376ndash3832009

[48] M Mahkam F Hosseinzadeh and M Galehassadi ldquoPrepara-tion of ionic liquid functionalized silica nanoparticles for oraldrug deliveryrdquo Journal of Biomaterials amp Nanobiotechnologyvol 3 pp 391ndash395 2012

[49] A S Ham M R Cost A B Sassi C S Dezzutti andL C Rohan ldquoTargeted delivery of PSC-RANTES for HIV-1prevention using biodegradable nanoparticlesrdquo PharmaceuticalResearch vol 26 no 3 pp 502ndash511 2009

[50] Y I Kim L Fluckiger M Hoffman I Lartaud-IdjouadieneJ Atkinson and P Maincent ldquoThe antihypertensive effect oforally administered nifedipine-loaded nanoparticles in sponta-neously hypertensive ratsrdquoThe British Journal of Pharmacologyvol 120 no 3 pp 399ndash404 1997

[51] P Liu O de Wulf J Laru et al ldquoDissolution studies of poorlysoluble drug nanosuspensions in non-sink conditionsrdquo AAPSPharmSciTech vol 14 no 2 pp 748ndash756 2013

[52] L Sievens-Figueroa N Pandya A Bhakay et al ldquoUsing USPI and USP IV for discriminating dissolution rates of nano-

and microparticle-loaded pharmaceutical strip-filmsrdquo AAPSPharmSciTech vol 13 no 4 pp 1473ndash1482 2013

[53] G P Yan R F Zong L Li T Fu F Liu and X H YuldquoAnticancer drug-loaded nanospheres based on biodegradableamphiphilic 120576-caprolactone and carbonate copolymersrdquo Phar-maceutical Research vol 27 no 12 pp 2743ndash2752 2010

[54] P Calvo J L Vila-Jato and M J Alonso ldquoComparative invitro evaluation of several colloidal systems nanoparticlesnanocapsules and nanoemulsions as ocular drug carriersrdquoJournal of Pharmaceutical Sciences vol 85 no 5 pp 530ndash5361996

[55] M SMuthu and S Singh ldquoPoly (D L-lactide) nanosuspensionsof risperidone for parenteral delivery formulation and in-vitroevaluationrdquoCurrent DrugDelivery vol 6 no 1 pp 62ndash68 2009

[56] MY Levy and S Benita ldquoDrug release from submicronized owemulsion a new in vitro kinetic evaluationmodelrdquo InternationalJournal of Pharmaceutics vol 66 no 1ndash3 pp 29ndash37 1990

[57] X Xu M A Khan and D J Burgess ldquoA two-stage reversedialysis in vitro dissolution testing method for passive targetedliposomesrdquo International Journal of Pharmaceutics vol 426 no1-2 pp 211ndash218 2012

[58] B E Kilfoyle L Sheihet Z Zhang M Laohoo J Kohn and BBMichniak-Kohn ldquoDevelopment of paclitaxel-TyroSpheres fortopical skin treatmentrdquo Journal of Controlled Release vol 163no 1 pp 18ndash24 2012

[59] S Uprit R K Sahu A Roy and A Pare ldquoPreparation and char-acterization of minoxidil loaded nanostructured lipid carriergel for effective treatment of alopeciardquo Saudi PharmaceuticalJournal vol 21 pp 379ndash385 2013

[60] B Qiu M Ji X Song et al ldquoCo-delivery of docetaxel andendostatin by a biodegradable nanoparticle for the synergistictreatment of cervical cancerrdquo Nanoscale Research Letters vol 7article 666 2012

[61] S S DrsquoSouza and P P DeLuca ldquoDevelopment of a dialysis invitro release method for biodegradable microspheresrdquo AAPSPharmSciTech vol 6 no 2 article 42 2005

[62] Y Gao J Zuo N Bou-Chacra et al ldquoIn vitro release kineticsof antituberculosis drugs from nanoparticles assessed usinga modified dissolution apparatusrdquo BioMed Research Interna-tional vol 2013 Article ID 136590 9 pages 2013

[63] M Joshi S Pathak S Sharma and V Patravale ldquoDesignand in vivo pharmacodynamic evaluation of nanostructuredlipid carriers for parenteral delivery of artemether nanojectrdquoInternational Journal of Pharmaceutics vol 364 no 1 pp 119ndash126 2008

[64] J W Kostanski and P P DeLuca ldquoA novel in vitro releasetechnique for peptide-containing biodegradable microspheresrdquoAAPS PharmSciTech vol 1 article 4 2000

[65] J P K Tan C H Goh and K C Tam ldquoComparative drugrelease studies of two cationic drugs from pH-responsivenanogelsrdquo European Journal of Pharmaceutical Sciences vol 32no 4-5 pp 340ndash348 2007

[66] K M Rosenblatt D Douroumis and H Bunjes ldquoDrug releasefrom differently structured monooleinpoloxamer nanodisper-sions studied with differential pulse polarography and ultrafil-tration at low pressurerdquo Journal of Pharmaceutical Sciences vol96 no 6 pp 1564ndash1575 2007

[67] N Charalampopoulos K Avgoustakis and C G KontoyannisldquoDifferential pulse polarography a suitable technique for mon-itoring drug release from polymeric nanoparticle dispersionsrdquoAnalytica Chimica Acta vol 491 no 1 pp 57ndash62 2003

12 Advances in Pharmaceutics

[68] P Kayaert B Li I Jimidar P Rombaut F Ahssini and G Vanden Mooter ldquoSolution calorimetry as an alternative approachfor dissolution testing of nanosuspensionsrdquo European Journal ofPharmaceutics and Biopharmaceutics vol 76 no 3 pp 507ndash5132010

[69] M T Crisp C J Tucker T L Rogers R O Williams III andK P Johnston ldquoTurbidimetric measurement and prediction ofdissolution rates of poorly soluble drug nanocrystalsrdquo Journalof Controlled Release vol 117 no 3 pp 351ndash359 2007

[70] M V Chaubal and C Popescu ldquoConversion of nanosus-pensions into dry powders by spray drying a case studyrdquoPharmaceutical Research vol 25 no 10 pp 2302ndash2308 2008

[71] A Helle S Hirsjarvi L Peltonen J Hirvonen S K Wied-mer and T Hyotylainen ldquoNovel dynamic on-line analyticalseparation system for dissolution of drugs from poly(lacticacid) nanoparticlesrdquo Journal of Pharmaceutical and BiomedicalAnalysis vol 51 no 1 pp 125ndash130 2010

[72] V Domınguez-Villegas B Clares-Naveros M L Garcıa-Lopez et al ldquoDevelopment and characterization of two nano-structured systems for topical application of flavanones isolatedfrom Eysenhardtia platycarpardquo Colloids and Surfaces B Bioint-erfaces vol 116 pp 183ndash192 2014

[73] M Barzegar-Jalali K AdibkiaHValizadeh et al ldquoKinetic anal-ysis of drug release from nanoparticlesrdquo Journal of Pharmacyand Pharmaceutical Sciences vol 11 no 1 pp 167ndash177 2008

[74] L Zeng L An and X Wu ldquoModeling drug-carrier interactionin the drug release from nanocarriersrdquo Journal of Drug Deliveryvol 2011 Article ID 370308 15 pages 2011

[75] L Zeng andXWu ldquoModeling the sustained release of lipophilicdrugs from liposomesrdquo Applied Physics Letters vol 97 no 7Article ID 073701 2010

[76] FDA Guidance for Industry Extended Release Oral DosageForms Development Evaluation and Application of In VitroInVivo Correlations 1997

[77] J G Wagner and E Nelson ldquoPer cent absorbed time plotsderived fromblood level andor urinary excretion datardquo Journalof Pharmaceutical Sciences vol 52 pp 610ndash611 1963

Submit your manuscripts athttpwwwhindawicom

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Autoimmune Diseases

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Pharmaceutics

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MEDIATORSINFLAMMATION

of

4 Advances in Pharmaceutics

Flow through cell

Filter

Nanosuspension distributed in

glass beads

Release media

Pump

Detector

Figure 1 Continuous flow set-up in closed loop configuration

Unlike the widely used SS method only a few examplesof the CF method have been reported for nano-sized dosageforms [38 52] For example the release profiles of amor-phous nanoparticles and an unprocessed crystalline form ofCefuroxime Axetil a BCS II cephalosporin antibiotic wereevaluated using the CF method as well as other methodsdescribed below [38]

(a) USP I (basket) 900mL buffer at 100 rpm(b) USP II (paddle) 900mL buffer at 100 rpm(c) USP IV (flow through cell) 900mL buffer at a flow

rate of 16mLmin (peristaltic pump closed loop)through a cell (internal diameter = 25mm) and02 120583mmembrane disc filter

(d) dialysis bag (MWCO 12 kDa inner volume = 7mL)placed into a USP II (paddle) in vitro release tester(outer volume = 900mL paddle rpm = 100)

The results revealed that complete drug release wasachieved only with the USP II paddle and USP IV apparatusrelease profiles with the USP IVmethod being well separated

Immobilization of the nanoparticles was thought to bea factor contributing to the discriminatory results obtainedwith the USP IV apparatus

Similarly in an experiment on nano- and micro-particleloaded strip films of another BCS II drug Griseofulvin invitro release was performed using two methods [52]

(a) USP I (basket) 500 and 900mLmedia at 50 100 and150 rpm

(b) USP IV (flow through cell) 100mL media at flowrates of 4 8 and 16mLmin (peristaltic pump closedloop) through a cell (internal diameter = 226mm)and 02120583m membrane disc filter with the strip filmloaded in 6 different configurations

While complete release was observed only with USP Iand configuration B (strip film positioned in the cell on topof round glass beads) of the USP IV method results withconfigurations A (strip film positioned in the cone section

Sampling from outer compartment

Dialyzer cap

Inner compartment containing nanosuspension

Dialysis membrane

Outer compartment containing release media

Stir bar

Figure 2 ldquoRegular dialysisrdquo set-up (adapted from [21])

of the cell without round glass beads) and C (strip filmsandwiched between round glass beads) of USP IV at thehighest flow rate were more discriminatory than all the otherrelease profiles obtained in the in vitro study

In comparison to nanoparticulate dosage forms whereliterature on the use of USP IV methodology is sparseseveral salient aspects of the CF method can be inferredfrom its use in microparticulate dosage forms [21] As anexample flow rates used in the CF method depend on thetype of pump (peristaltic versus syringe) as well as the filtersused (membrane versus ultrafilters) Low flow rates havebeen known to be a key factor causing slow or incompleterelease from dosage forms [21] In general the availabilityof automated equipment has simplified routine samplingand media replacement with the the CF method in closed(recirculating media) and open (nonrecirculating media)loop systems However the CF methods suffer from severaldisadvantages that include instrument costs difficulty in set-up filter clogging adsorption to the filter and glass beads anddifficulty in maintaining a constant flow rate leading to widevariability in results

23 Dialysis Method Of all the methods used to assess drugrelease from nano-sized dosage forms the dialysis method(DM) is the most versatile and popular In this methodphysical separation of the dosage forms is achieved by usageof a dialysis membrane which allows for ease of samplingat periodic intervals As with the other methods severaladaptations of the DM have been reported in literaturewith key differences in set-up container size and molecularweight cut-off (MWCO)

Of the variety of DM set-ups used the most commonlycited is the dialysis bag (regular dialysis) other adaptationsbeing the reverse dialysis and side-by-side dialysis set-up[26 53 54] (Figures 2ndash4)With the regular dialysis technique

Advances in Pharmaceutics 5

Sampling from inner compartment

Dialyzer cap

Inner compartment containing release media

Dialysis membrane

Outer compartment containing nanosuspension

Stir bar

Figure 3 ldquoReverse dialysisrdquo set-up

Receiver compartment

Dialysis membrane

Stir bar

Sampling

Nanoemulsion in donor compartment

Figure 4 ldquoSide-by-side dialysisrdquo set-up (adapted from [26])

the nanoparticles are introduced into a dialysis bag contain-ing release media (inner mediacompartment) that is subse-quently sealed and placed in a larger vessel containing releasemedia (outer mediacompartment) agitated to minimizeunstirred water layer effects [32 55] In general the volumeenclosed in a dialysis bag (inner media) is significantlysmaller than the outer media For instance inner mediavolumes reported in literature range from 1 to 10mL whereasthe outermedia volume ismuch greater typically around 40ndash90mL [32 53 55] Thus container size will depend on thetotal volume of release media required for the in vitro releasestudy In the regular dialysis technique drug released fromthe nanoparticles diffuses through the dialysis membraneto the outer compartment from where it is sampled foranalysis (Figure 2) In contrast with the reverse dialysis set-up the nanoparticles are placed in the outer compartment(agitated to minimize the unstirred water layer) and theinner compartment is sampled for drug release (Figure 3)[54 56 57] Other adaptations of the DM include the side-by-side dialysis set-up where donor and receiver cells bothcontaining equal volumes of media agitated with a magneticstirrer are separated by a dialysis membrane and samplingoccurs from the receiver cell (Figure 4) and a vertical Franzdiffusion cell [26 58 59]

As with other methods drug solubility in the releasemedia is essential to its transport across the dialysis mem-brane Apart from release media the importance of selectingan appropriate molecular weight cut-off (MWCO) for thedialysis membrane cannot be overlooked Indeed the basicpremise of the DM is that drug that is released from thedosage form will diffuse rapidly from one compartmentthrough the membrane and enter the second compartmentfrom where it is sampled for analysis Thus membranes witha sufficiently high membrane MWCO are often selected forin vitro release studies so that drug transport is not a limitingfactor As an example in a study with 3 dosage forms ofIndomethacin (eg nanoparticles and nanocapsules usingpoly-120576-caprolactone and a submicron emulsion) Calvo et alnoted that nearly 85 of drug was released within 2 hoursand complete release was achieved in 4 hours when a 12 kDamembranewas used [54] However the rationale for selectinga MWCO is rather subjective For instance a MWCO ashigh as 10ndash14 kDa was used to study drug release of smallmolecules like Risperidone and Indomethacin and aMWCOas low as 1 kDa though suitable for assessing in vitro releaseof a large molecule pDNA proved to be limiting for thediffusion of Cefuroxime Axetil a cephalosporin antibiotic[32 38 55 60] In general the MWCO should be sufficientlylarge to permit drug transport

The ease of set-up and sampling with the DM make ita very simple and straightforward technique to study drugrelease from a wide variety of nano-sized dosage forms likenanospheres liposomes emulsions nanosuspensions andso forth [53ndash55] However issues have been reported withthe regular dialysis method If incorrectly sealed leakage ofmedia and dosage form may occur from both ends of thedialysis bag set-up Incomplete release data may be observedif nonsink conditions exist or equilibration times are high[38] On the other hand the difference in equilibration timescan be exploited as a discriminatory tool to distinguish releasebehavior between fast and slow releasing dosage forms [50]Another factor to be considered is that the DM cannotbe used with drugs that bind to the dialyzing membraneAs stated in a review paper on microparticulate dosageforms it is recommended that the suitability of the dialyzingmembrane be assessed prior to use [21 61]

24 CombinationMethods A fewpublications havemodifiedthe set-ups used in the SS CF and DM methods to evaluatedrug release from nano-sized dosage forms In most of thesereports the set-up of the SS method is combined with adialyzer to allow ease of sampling In other publications theDM and the CF set-up is used to assess in vitro release fromnanoparticulates

As an example Mottaleb et al compared release profilesof Ibuprofen from liposomes and lipid nanocapsules andnanoparticles using the regular dialysis method (dialysis bag)and modified USP I (basket) set-up where the shaft wasaffixed with a glass basket having a dialysis membrane atthe bottom that is glass basket dialysis (GBD) and placedin a larger vessel (Figure 5) [27] Sampling was performedfrom the outer vessel Unlike the dialysis bag that had a large

6 Advances in Pharmaceutics

Glass basket

Dialysis membrane

Figure 5 Comparison ofUSP I (left) and glass basket dialysis (right)set-ups (adapted from [27])

membrane surface area the GBD was able to discriminatedifferences between release profiles from different formu-lations (lipid nanocapsules nanoparticles liposomes) Inanother study Lobenberg et al compared drug release fromRifampicin and Moxifloxacin hydrochloride nanoparticleswith the regular dialysis method (dialysis bag) as well as anadaptation of USP I (basket) where a cylinder containing adialysis membrane at the bottom was attached to the basketshaft [62] Results from this study showed that modifiedUSP I set-up was more discriminatory in nature and couldbe attributed to the reduced surface area of the dialysismembrane In yet another modification of the USP I (basket)set-up a dialysis bag containing nanostructured lipid carriersof Artemether was placed inside the basket and drug releasemonitored over time [63] Though most studies have utilizedthe USP I set-up others have used the USP II (paddle) set-upin combination with the DM For example Cao et al affixeddialysis bags containing Silybin meglumine nanoparticlesonto a USP II (paddle) apparatus and assessed drug releasein five different release media [33 35]

A combination of aDM previously reported byKostanskiet al and CF method was utilized to assess drug releasefrom 5-Fluorouracil loaded BSA nanoparticles [28 64] Thesetup comprised a glass tube (with a dialysis membrane atthe bottom) that was placed into a larger vessel containingbuffer (Figure 6) Sampling as well as buffer replacement wasperformed from the larger vessel with the aid of two pumpshaving the same flow rate The combined DM-CF set-up wasable to demonstrate sustained levels of 5-Fluorouracil andthe absence of burst release from the BSA nanoparticles Analternate dialysis-CFmethod utilized a dialysis adaptor insidethe CF set-up (Figure 7) [29]

25 New Methods Apart from the commonly reported SSCF and DM methods a few alternate approaches have beenutilized tomonitor drug release Amajority of these appear tobe targeted towards electroactive drugsWhile the techniquesmay differ in principle or application they possess a fewcommon elements in that physical separation of the dosageform from the release media is not required Additionallythese techniques offer the possibility of measurement underreal-time conditions

Detector

Waste

Dialysis membrane

Nanosuspension

Stir bar

Pump 2Pump 1

Release media

Figure 6 Continuous flow dialysis set-up with two pumps (adaptedfrom [28])

Flow through cell

Releasemedia

Pump

Detector

Filter

Glass beads

Dialyzer containingnanosuspension

Figure 7 Dialysis adapter inside a continuous flow set-up (adaptedfrom [29])

As such electrochemical methods offer the possibility ofrapid in situ measurements while avoiding the interferencecaused by the presence of undissolved dosage form in therelease media In one such approach a potentiometric drugselective electrode was used to monitor real-time release ofProcaine hydrochloride from pH-responsive nanogels [65]In another report by Mora et al a highly sensitive repetitivesquare-wave voltammetric technique was utilized to measurethe redox reaction of Doxorubicin hydrochloride (Figure 8)[30] Similarly differential pulse polarography was used toassess continuous drug release from Piroxicam Chloram-phenicol and Diazepam [66 67] Apart from the fact thatonly electroactive drugs can be measured by the abovemethods these methods suffer from additional drawbacksFor example the sensitivity as well as responsiveness ofeach technique varies greatly Also the sensors used may bespecific to a particular drug

Nonelectrochemical methods like calorimetry turbidim-etry and laser diffraction have also been evaluated as invitro release methods Solution calorimetry was employedby Kayaert et al during in vitro release measurement ofNaproxen Cinnarizine and Compound A (investigational

Advances in Pharmaceutics 7

Working electrode

Reference electrode

Counter electrode

Release media

Redox reactionAox Ared

A Liposome containing drug ldquoArdquo

Figure 8 Electrochemical cell set-up for real-time measurement ofdrug release (adapted from [30])

Pump control

Syringe Analyte

NanosuspensionMicrodialysis probe

pump

Figure 9 Microdialysis set-up (adapted from [31])

API) from nanocrystals [68] The principle of this tech-nique is based on detection of the net proportion of heatchange during in vitro release Challenges with calorimetricmeasurements include long equilibration times Further theheat produced by all the processes needs to be consideredTurbidimetric and laser diffraction approaches utilizing thechange light scattering properties of nanoparticles dispersedin release media have also been utilized [69 70] Concernswith these methods include the long equilibration timeslimited range of particle size and initial concentration ofsamples that can be used

Helle et al designed a novel online system for evaluatingthe drug release from Indomethacin and Beclomethasonedipropionate nanoparticles In thismethod nanoparticles arepacked into small column which is connected to multiportmodulation valve attached to an HPLC system allowingfor rapid analysis [71] Other new methods reported inliterature include a vertical diffusion Franz cell and an invitro lipolysis model [37 72] Microdialysis another set-up utilized to measure drug release from nanoparticules isbased on passive diffusion of drug through a concentrationgradient across a semipermeable membrane (Figure 9) [3147] Drug release can be measured in real-time conditionsusing analytical methods like HPLC However care shouldbe taken when surfactants are used in the release media asrecovery may be affected

3 Modeling Drug Release

Very few publications have attempted to describe drug releaseprofiles from nanoparticulate dosage forms using mathe-matical models This is not surprising given that nano-sizeddosage forms are complex and drug release evaluations arenot straightforward However a few authors have discussedthe importance of mathematical models and endeavored tocharacterize drug release For instance Barzegar-Jalali et alsuggested the use of reciprocal powered time (RPT) as generalmodel to analyze the complex nature of drug release fromnanoparticles with alternate approaches being the Weibulland log-probabilitymodels [73] In another report Zeng et aldeveloped a three-parameter model that considers reversibledrug-carrier interaction as well as diffusional drug releasefrom liposomes [74 75]

Use of mathematical models to describe drug releaseprofiles offers several advantages It permits the elucidationof drug release mechanisms and can be used to guide for-mulation development efforts Furthermodel parameters canserve to represent as well as compare in vitro release profilesHowever caution must be used when applying mathematicalmodels to complex drug release mechanisms

4 IVIVC

The US FDA defines IVIVC as ldquoA predictive mathematicalmodel describing the relationship between an in vitro prop-erty of an extended release dosage form (usually the rate orextent of drug in vitro release or release) and a relevant invivo response for example plasma drug concentration oramount of drug absorbedrdquo [76] Thus establishment of anIVIVC described as a correlation between in vitro release andin vivo behavior enhances the utility of an in vitro study Fromthe 1997 FDA guidance document an IVIVC will reduce theregulatory burden by paring the number of in vivo studiesneeded for product approval Additionally it promotes thesetting of clinically relevant in vitro release specifications [76]

The FDA guidance also categorizes IVIVCs into threelevels Level A represents a linear or nonlinear point-to-point relationship between the in vitro and in vivo releaseprofiles If the relationship is nonlinear suitable modelingor scaling is required Of the three IVIVC levels Level Adescribes the highest correlation and is most commonly usedto obtain a biowaiver On the other hand a Level B correlationis a comparison of summary parameters such as the meanin vitro dissolution time with mean in vivo dissolution timeor mean residence time (MRT) Since several in vivo curveswill produce a similarMRT value ormean in vitro dissolutiontime Level B correlations are not as discriminatory as LevelA but acceptable for an IVIVC A Level C correlationdescribes a relationship between an in vitro release parameter(eg dissolved at a particular time) and a pharmacokineticparameter (eg 119862max) However a Level C correlation is notdescriptive of the complete shape of the in vivo release profileand though acceptable seldom used

As such the FDA guidance is intended for oral extendedrelease products However principles of the FDA guidance

8 Advances in Pharmaceutics

Table 2 Examples of IVIVC with nano-sized dosage forms in animal models

Drug and dosage form In vitro release set-up In vivo studies IVIVC type Reference

Indomethacin gelatin nanoparticles Dialysis bags Wistar Albinorats Level A [32]

Silybin meglumine hollow-spheremesoporous silica nanoparticles Combination (USP Imdashdialysis bag) Beagle dogs Level A [33]

Silybin 72-hour SLB andPSNs (porous silica nanoparticles) Combination (USP Imdashdialysis bag) Beagle dogs Level A [35]

Simvastatin nanostructured lipidcarriers and nanoparticles Dialysis bag BalbC mice Level A [34]

Fenofibrate nanosuspension USP I apparatus SpragueDawley rats Level A [36]

Fenofibrate lipid matrix particles In vitro lipolysis model SpragueDawley rats Rank order [37]

Table 3 Level A IVIVC with two Silybin preparations (data from reference [35])

Formulation absorbed equals 1198772

72-hour SLB 11379 times dissolved + 88688 09831Silybin PSNs (porous silica nanoparticles) 08915 times dissolved minus 10152 09831

have been used to demonstrate an IVIVC from severalnonoral dosage forms including nano-sized preparationsMost published literature on IVIVC compares the in vitrorelease behavior with the in vivo absorption profile thelatter calculated by the FDA recommended Wagner-Nelsonmethod [76 77] Once the fraction absorbed is computeda correlation is obtained by comparing it with the in vitrorelease profile and the type of IVIVC (Level A level B etc) isdetermined

Over the last decade a few reports on IVIVC from nano-sized dosage forms have been published (Table 2) In someinstances a rank order correlation was observed while inothers a Level A IVIVC was established with some or allof the formulations evaluated in the study As an example arank order correlation was observed with three preparationsof Fenofibrate with drug release and absorption from 100 nmlipid matrix particles gt microparticles gt control (crystallinesuspension) [37] In another study on Fenofibrate nanosus-pensions Xu et al attempted to elucidate the absorptionmechanism using in situ gut perfusion model [36] Dataanalysis between in vitro dissolution (119875) in situ intestinalabsorption (119865) and in vivo absorption (119865

119886) demonstrated

a Level A correlation (1198772 gt 095) As a result the authorsconcluded that the in situ intestinal perfusion model couldbe a predictor of in vivo pharmacokinetic behavior for thenanosuspension

In a recent report Kumar et al investigated the relation-ship between in vitro and in vivo release from Indomethacingelatin nanoparticles administered orally to Wistar albinorats [32] Study results indicated that a good correlation wasobtained by plotting the fraction absorbed in vivo (Wagner-Nelson method) against the fraction released the latter per-formed using regular dialysis (dialysis bags) (Figure 10) TheWagner-Nelsonmethod was also used in another publication

0

20

40

60

80

100

120

0 20 40 60 80 100

In v

ivo

abso

rptio

n (

)

In vitro release ()

R2 = 0981

y = 1121x

Figure 10 Level A IVIVC from Indomethacin gelatin nanoparticlesusing regular dialysis (redrawn from [32])

where the in vivo absorption fromSilybinmeglumine hollow-sphere mesoporous silica nanoparticles dosed orally to bea-gle dogs was compared with in vitro results obtained using acombination USP I (paddle) dialysis bag set-up [33] Of thefive different releasemedia used in the study a Level A IVIVC(1198772 gt 097) was obtained with 006M Na

2CO3and 008M

Na2CO3solutions (Figure 11) In another study with Silybin

an IVIVC was achieved with a 72-hour release formulationof Silybin (72-hour SLB) that consisted of a solid dispersiongel matrix and porous silica nanoparticles (PSNs) (Table 3)[35] Similar to the earlier study the authors compared invivo release from beagle dogs with in vitro release assessedusing a combination USP I (paddle) dialysis bag set-upIn another paper Tiwari et al demonstrated a Level A

Advances in Pharmaceutics 9

0

20

40

60

80

100

0 20 40 60 80 100

Abso

rbed

()

Abso

rbed

()

0 20 40 60 80 1000

20

40

60

80

100

In vitro release ()

In vitro release ()

y = 23417x minus 78256

R2 = 09741

y = 16114x minus 56752

R2 = 09931

006M Na2CO3

008M Na2CO3

Figure 11 Level A IVIVC from Silybin meglumine hollow-typemesoporous silica nanoparticles using a combined USP II-dialysisbag set-up (redrawn from [33])

correlation between in vitro release (dialysis bag) and percentdrug absorbed (Wagner Nelson method) for Simvastatinnanostructured lipid carriers as well as nanoparticles (1198772 gt094) (Figure 12) [34]

5 Conclusions

For novel dosage forms like nanoparticles where no regu-latory or compendial standards exist in vitro drug releaseassessment assumes greater significance in serving as anindicator of product quality and performance A plethoraof methods have been used each with their advantages anddrawbacks with respect to ease of set-up sampling and rapidbuffer replacement Ideally an in vitro release method shouldsimulate in vivo conditions release mechanisms and enablethe establishment of an IVIVC Future research should focuson developing relevant mathematical models to predict drugrelease behavior as well as release mechanisms applicable to awide range of nano-sized dosage forms

Conflict of Interests

The author declares that there is no conflict of interestsregarding the publication of this paper

0

20

40

60

80

100

120

Dru

g ab

sorb

ed (

)

0

20

40

60

80

100

120

Dru

g ab

sorb

ed (

)

Simvastatin loaded nanostructured lipid carriers

Simvastatin loaded solid lipid nanoparticles

0 20 40 60 80 100In vitro release ()

0 20 40 60 80 100In vitro release ()

R2 = 09404

R2 = 0941

Figure 12 Level A correlation of Simvastatin from two nano-sizeddosage forms (redrawn from [34])

References

[1] N Al Khouri Fallouh L Roblot-Treupel and H Fessi ldquoDevel-opment of a new process for the manufacture of polyisobutyl-cyanoacrylate nanocapsulesrdquo International Journal of Pharma-ceutics vol 28 no 2-3 pp 125ndash132 1986

[2] C Losa P Calvo E Castro J L Vila-Jato and M J AlonsoldquoImprovement of ocular penetration of amikacin sulphate byassociation to poly(butylcyanoacrylate) nanoparticlesrdquo Journalof Pharmacy and Pharmacology vol 43 no 8 pp 548ndash552 1991

[3] C Losa L Marchal-Heussler F Orallo J L Vila Jato andM J Alonso ldquoDesign of new formulations for topical ocularadministration polymeric nanocapsules containing metipra-nololrdquo Pharmaceutical Research vol 10 no 1 pp 80ndash87 1993

[4] C N Cruz K M Tyner L Velazquez et al ldquoCDER riskassessment exercise to evaluate potential risks from the use ofnanomaterials in drug productsrdquo AAPS Journal vol 15 no 3pp 623ndash628 2013

[5] G Verreck I Chun J Rosenblatt et al ldquoIncorporation of drugsin an amorphous state into electrospun nanofibers composedof a water-insoluble nonbiodegradable polymerrdquo Journal ofControlled Release vol 92 no 3 pp 349ndash360 2003

[6] H Heiati R Tawashi R R Shivers and N C PhillipsldquoSolid lipid nanoparticles as drug carriers I incorporation andretention of the lipophilic prodrug 31015840-azido-31015840-deoxythymidinepalmitaterdquo International Journal of Pharmaceutics vol 146 no1 pp 123ndash131 1997

10 Advances in Pharmaceutics

[7] M Cetin A Atila and Y Kadioglu ldquoFormulation and in vitrocharacterization of Eudragit L100 and Eudragit L100-PLGAnanoparticles containing diclofenac sodiumrdquo AAPS Pharm-SciTech vol 11 pp 1250ndash1256 2010

[8] A Hanafy H Spahn-Langguth G Vergnault et al ldquoPharma-cokinetic evaluation of oral fenofibrate nanosuspensions andSLN in comparison to conventional suspensions of micronizeddrugrdquo Advanced Drug Delivery Reviews vol 59 no 6 pp 419ndash426 2007

[9] T M Allen W W K Cheng J I Hare and K M LaginhaldquoPharmacokinetics and pharmacodynamics of lipidic nano-particles in cancerrdquoAnti-Cancer Agents in Medicinal Chemistryvol 6 no 6 pp 513ndash523 2006

[10] J Kreuter ldquoNanoparticle-based drug delivery systemsrdquo Journalof Controlled Release vol 16 no 1-2 pp 169ndash176 1991

[11] M L Etheridge S A Campbell A G Erdman C L Haynes SMWolf and JMcCullough ldquoThe big picture on nanomedicinethe state of investigational and approved nanomedicine prod-uctsrdquo Nanomedicine Nanotechnology Biology and Medicinevol 9 no 1 pp 1ndash14 2013

[12] S Nie ldquoUnderstanding and overcoming major barriers incancer nanomedicinerdquoNanomedicine vol 5 no 4 pp 523ndash5282010

[13] W H de Jong and P J A Borm ldquoDrug delivery andnanoparticles applications and hazardsrdquo International Journalof Nanomedicine vol 3 no 2 pp 133ndash149 2008

[14] S DrsquoSouza J A Faraj R Dorati and P P DeLuca ldquoA short termquality control tool for biodegradable microspheresrdquo AAPSPharmSciTech vol 15 no 3 pp 530ndash541 2014

[15] P Buch P Holm J Q Thomassen et al ldquoIVIVC for fenofibrateimmediate release tablets using solubility and permeability as invitro predictors for pharmacokineticsrdquo Journal of Pharmaceuti-cal Sciences vol 99 no 10 pp 4427ndash4436 2010

[16] S DrsquoSouza J A Faraj S Giovagnoli and P P DeLuca ldquoIVIVCfrom long acting olanzapine microspheresrdquo International Jour-nal of Biomaterials vol 2014 Article ID 407065 11 pages 2014

[17] L C Amann M J Gandal R Lin Y Liang and S J SiegelldquoIn vitro-in vivo correlations of scalable PLGA-Risperidoneimplants for the treatment of schizophreniardquo PharmaceuticalResearch vol 27 no 8 pp 1730ndash1737 2010

[18] G Zackrisson G Ostling B Skagerberg and T Anfalt ldquoACcel-erated Dissolution Rate Analysis (ACDRA) for controlledrelease drugs Application to Roxiamrdquo Journal of Pharmaceu-tical and Biomedical Analysis vol 13 no 4-5 pp 377ndash383 1995

[19] S S DSouza J A Faraj and P P DeLuca ldquoA model-dependentapproach to correlate accelerated with real-time release frombiodegradable microspheresrdquo AAPS PharmSciTech vol 6 arti-cle 70 no 4 2005

[20] D J Burgess A S Hussain T S Ingallinera and M ChenldquoAssuring quality and performance of sustained and controlledrelease parenterals workshop reportrdquo AAPS PharmSci vol 4article E7 2002

[21] S S DrsquoSouza and P P DeLuca ldquoMethods to assess in vitrodrug release from injectable polymeric particulate systemsrdquoPharmaceutical Research vol 23 no 3 pp 460ndash474 2006

[22] M Siewert J Dressman C K Brown and V P ShahldquoFIPAAPS guidelines to dissolutionin vitro release testing ofnovelspecial dosage formsrdquo AAPS PharmSciTech vol 4 article7 2003

[23] C K Brown H D Friedel A R Barker et al ldquoFIPAAPSjoint workshop report dissolutionin vitro release testing of

novelspecial dosage formsrdquo AAPS PharmSciTech vol 12 no2 pp 782ndash794 2011

[24] MMartinezM Rathbone D Burgess andMHuynh ldquoIn vitroand in vivo considerations associated with parenteral sustainedrelease products a review based upon information presentedand points expressed at the 2007 Controlled Release SocietyAnnual Meetingrdquo Journal of Controlled Release vol 129 no 2pp 79ndash87 2008

[25] M N Martinez M J Rathbone D Burgess and M HuynhldquoBreakout session summary from AAPSCRS joint workshopon critical variables in the in vitro and in vivo performanceof parenteral sustained release productsrdquo Journal of ControlledRelease vol 142 no 1 pp 2ndash7 2010

[26] N Chidambaram and D J Burgess ldquoA novel in vitro releasemethod for submicron-sized dispersed systemsrdquo AAPS Pharm-Sci vol 1 no 3 pp 32ndash40 1999

[27] M M A Abdel-Mottaleb and A Lamprecht ldquoStandardized invitro drug release test for colloidal drug carriers using modifiedUSP dissolution apparatus Irdquo Drug Development and IndustrialPharmacy vol 37 no 2 pp 178ndash184 2011

[28] A Maghsoudi S A Shojaosadati and E Vasheghani Farahanildquo5-Fluorouracil-loaded BSA nanoparticles formulation opti-mization and in vitro release studyrdquo AAPS PharmSciTech vol9 no 4 pp 1092ndash1096 2008

[29] U Bhardwaj and D J Burgess ldquoA novel USP apparatus 4 basedrelease testing method for dispersed systemsrdquo InternationalJournal of Pharmaceutics vol 388 no 1-2 pp 287ndash294 2010

[30] L Mora K Y Chumbimuni-Torres C Clawson L HernandezL Zhang and J Wang ldquoReal-time electrochemical monitoringof drug release from therapeutic nanoparticlesrdquo Journal ofControlled Release vol 140 no 1 pp 69ndash73 2009

[31] C B Michalowski S S Guterres and T Dalla CostaldquoMicrodialysis for evaluating the entrapment and release of alipophilic drug from nanoparticlesrdquo Journal of Pharmaceuticaland Biomedical Analysis vol 35 no 5 pp 1093ndash1100 2004

[32] R Kumar R C Nagarwal M Dhanawat and J K PanditldquoIn-vitro and in-vivo study of indomethacin loaded gelatinnanoparticlesrdquo Journal of Biomedical Nanotechnology vol 7 no3 pp 325ndash333 2011

[33] X Cao W W Deng M Fu et al ldquoIn vitro release and in vitro-in vivo correlation for silybin meglumine incorporated intoHollow-type mesoporous silica nanoparticlesrdquo InternationalJournal of Nanomedicine vol 7 pp 753ndash762 2012

[34] R Tiwari and K Pathak ldquoNanostructured lipid carrier versussolid lipid nanoparticles of simvastatin comparative analysis ofcharacteristics pharmacokinetics and tissue uptakerdquo Interna-tional Journal of Pharmaceutics vol 415 no 1-2 pp 232ndash2432011

[35] X Cao W Deng M Fu et al ldquoSeventy-two-hour releaseformulation of the poorly soluble drug silybin based on poroussilica nanoparticles in vitro release kinetics and in vitroin vivocorrelations in beagle dogsrdquo European Journal of Pharmaceuti-cal Sciences vol 48 no 1-2 pp 64ndash71 2013

[36] Y Xu Y Wang X M Li et al ldquoStudy on the release offenofibrate nanosuspension in vitro and its correlation with insitu intestinal and in vivo absorption kinetics in ratsrdquo DrugDevelopment and Industrial Pharmacy vol 40 no 7 pp 972ndash979 2014

[37] N Borkar D Xia R Holm et al ldquoInvestigating the correlationbetween in vivo absorption and in vitro release of fenofibratefrom lipid matrix particles in biorelevant mediumrdquo EuropeanJournal of Pharmaceutical Sciences vol 51 pp 204ndash210 2014

Advances in Pharmaceutics 11

[38] D Heng D J Cutler H K Chan J Yun and J A RaperldquoWhat is a suitable dissolutionmethod for drug nanoparticlesrdquoPharmaceutical Research vol 25 no 7 pp 1696ndash1701 2008

[39] A C Kilic Y Capan I Vural et al ldquoPreparation and characteri-zation of PLGA nanospheres for the targeted delivery of NR2B-specific antisense oligonucleotides to the NMDA receptors inthe brainrdquo Journal of Microencapsulation vol 22 no 6 pp 633ndash641 2005

[40] Y Zhang H Wang C Li et al ldquoA novel three-dimensionallarge-pore mesoporous carbon matrix as a potential nanove-hicle for the fast release of the poorly water-soluble drugcelecoxibrdquoPharmaceutical Research vol 31 pp 1059ndash1070 2014

[41] V Sanna A M Roggio S Siliani et al ldquoDevelopment of novelcationic chitosan-and anionic alginate-coated poly(DL-lactide-co-glycolide) nanoparticles for controlled release and light pro-tection of resveratrolrdquo International Journal of Nanomedicinevol 7 pp 5501ndash5516 2012

[42] F Danhier N Lecouturier B Vroman et al ldquoPaclitaxel-loadedPEGylated PLGA-based nanoparticles In vitro and in vivoevaluationrdquo Journal of Controlled Release vol 133 no 1 pp 11ndash17 2009

[43] Y Li Y Pei X Zhang et al ldquoPEGylated PLGA nanoparticlesas protein carriers synthesis preparation and biodistributionin ratsrdquo Journal of Controlled Release vol 71 no 2 pp 203ndash2112001

[44] S Prabha W-Z Zhou J Panyam and V Labhasetwar ldquoSize-dependency of nanoparticle-mediated gene transfection stud-ies with fractionated nanoparticlesrdquo International Journal ofPharmaceutics vol 244 no 1-2 pp 105ndash115 2002

[45] S J Wallace J Li R L Nation and B J Boyd ldquoDrug releasefrom nanomedicines selection of appropriate encapsulationand release methodologyrdquo Drug Delivery and TranslationalResearch vol 2 no 4 pp 284ndash292 2012

[46] D Juenemann E Jantratid C Wagner C Reppas M Vertzoniand J B Dressman ldquoBiorelevant in vitro dissolution testingof products containing micronized or nanosized fenofibratewith a view to predicting plasma profilesrdquo European Journal ofPharmaceutics and Biopharmaceutics vol 77 no 2 pp 257ndash2642011

[47] P F Yue X Y Lu Z Z Zhang et al ldquoThe study on theentrapment efficiency and in vitro release of puerarin submi-cron emulsionrdquoAAPS PharmSciTech vol 10 no 2 pp 376ndash3832009

[48] M Mahkam F Hosseinzadeh and M Galehassadi ldquoPrepara-tion of ionic liquid functionalized silica nanoparticles for oraldrug deliveryrdquo Journal of Biomaterials amp Nanobiotechnologyvol 3 pp 391ndash395 2012

[49] A S Ham M R Cost A B Sassi C S Dezzutti andL C Rohan ldquoTargeted delivery of PSC-RANTES for HIV-1prevention using biodegradable nanoparticlesrdquo PharmaceuticalResearch vol 26 no 3 pp 502ndash511 2009

[50] Y I Kim L Fluckiger M Hoffman I Lartaud-IdjouadieneJ Atkinson and P Maincent ldquoThe antihypertensive effect oforally administered nifedipine-loaded nanoparticles in sponta-neously hypertensive ratsrdquoThe British Journal of Pharmacologyvol 120 no 3 pp 399ndash404 1997

[51] P Liu O de Wulf J Laru et al ldquoDissolution studies of poorlysoluble drug nanosuspensions in non-sink conditionsrdquo AAPSPharmSciTech vol 14 no 2 pp 748ndash756 2013

[52] L Sievens-Figueroa N Pandya A Bhakay et al ldquoUsing USPI and USP IV for discriminating dissolution rates of nano-

and microparticle-loaded pharmaceutical strip-filmsrdquo AAPSPharmSciTech vol 13 no 4 pp 1473ndash1482 2013

[53] G P Yan R F Zong L Li T Fu F Liu and X H YuldquoAnticancer drug-loaded nanospheres based on biodegradableamphiphilic 120576-caprolactone and carbonate copolymersrdquo Phar-maceutical Research vol 27 no 12 pp 2743ndash2752 2010

[54] P Calvo J L Vila-Jato and M J Alonso ldquoComparative invitro evaluation of several colloidal systems nanoparticlesnanocapsules and nanoemulsions as ocular drug carriersrdquoJournal of Pharmaceutical Sciences vol 85 no 5 pp 530ndash5361996

[55] M SMuthu and S Singh ldquoPoly (D L-lactide) nanosuspensionsof risperidone for parenteral delivery formulation and in-vitroevaluationrdquoCurrent DrugDelivery vol 6 no 1 pp 62ndash68 2009

[56] MY Levy and S Benita ldquoDrug release from submicronized owemulsion a new in vitro kinetic evaluationmodelrdquo InternationalJournal of Pharmaceutics vol 66 no 1ndash3 pp 29ndash37 1990

[57] X Xu M A Khan and D J Burgess ldquoA two-stage reversedialysis in vitro dissolution testing method for passive targetedliposomesrdquo International Journal of Pharmaceutics vol 426 no1-2 pp 211ndash218 2012

[58] B E Kilfoyle L Sheihet Z Zhang M Laohoo J Kohn and BBMichniak-Kohn ldquoDevelopment of paclitaxel-TyroSpheres fortopical skin treatmentrdquo Journal of Controlled Release vol 163no 1 pp 18ndash24 2012

[59] S Uprit R K Sahu A Roy and A Pare ldquoPreparation and char-acterization of minoxidil loaded nanostructured lipid carriergel for effective treatment of alopeciardquo Saudi PharmaceuticalJournal vol 21 pp 379ndash385 2013

[60] B Qiu M Ji X Song et al ldquoCo-delivery of docetaxel andendostatin by a biodegradable nanoparticle for the synergistictreatment of cervical cancerrdquo Nanoscale Research Letters vol 7article 666 2012

[61] S S DrsquoSouza and P P DeLuca ldquoDevelopment of a dialysis invitro release method for biodegradable microspheresrdquo AAPSPharmSciTech vol 6 no 2 article 42 2005

[62] Y Gao J Zuo N Bou-Chacra et al ldquoIn vitro release kineticsof antituberculosis drugs from nanoparticles assessed usinga modified dissolution apparatusrdquo BioMed Research Interna-tional vol 2013 Article ID 136590 9 pages 2013

[63] M Joshi S Pathak S Sharma and V Patravale ldquoDesignand in vivo pharmacodynamic evaluation of nanostructuredlipid carriers for parenteral delivery of artemether nanojectrdquoInternational Journal of Pharmaceutics vol 364 no 1 pp 119ndash126 2008

[64] J W Kostanski and P P DeLuca ldquoA novel in vitro releasetechnique for peptide-containing biodegradable microspheresrdquoAAPS PharmSciTech vol 1 article 4 2000

[65] J P K Tan C H Goh and K C Tam ldquoComparative drugrelease studies of two cationic drugs from pH-responsivenanogelsrdquo European Journal of Pharmaceutical Sciences vol 32no 4-5 pp 340ndash348 2007

[66] K M Rosenblatt D Douroumis and H Bunjes ldquoDrug releasefrom differently structured monooleinpoloxamer nanodisper-sions studied with differential pulse polarography and ultrafil-tration at low pressurerdquo Journal of Pharmaceutical Sciences vol96 no 6 pp 1564ndash1575 2007

[67] N Charalampopoulos K Avgoustakis and C G KontoyannisldquoDifferential pulse polarography a suitable technique for mon-itoring drug release from polymeric nanoparticle dispersionsrdquoAnalytica Chimica Acta vol 491 no 1 pp 57ndash62 2003

12 Advances in Pharmaceutics

[68] P Kayaert B Li I Jimidar P Rombaut F Ahssini and G Vanden Mooter ldquoSolution calorimetry as an alternative approachfor dissolution testing of nanosuspensionsrdquo European Journal ofPharmaceutics and Biopharmaceutics vol 76 no 3 pp 507ndash5132010

[69] M T Crisp C J Tucker T L Rogers R O Williams III andK P Johnston ldquoTurbidimetric measurement and prediction ofdissolution rates of poorly soluble drug nanocrystalsrdquo Journalof Controlled Release vol 117 no 3 pp 351ndash359 2007

[70] M V Chaubal and C Popescu ldquoConversion of nanosus-pensions into dry powders by spray drying a case studyrdquoPharmaceutical Research vol 25 no 10 pp 2302ndash2308 2008

[71] A Helle S Hirsjarvi L Peltonen J Hirvonen S K Wied-mer and T Hyotylainen ldquoNovel dynamic on-line analyticalseparation system for dissolution of drugs from poly(lacticacid) nanoparticlesrdquo Journal of Pharmaceutical and BiomedicalAnalysis vol 51 no 1 pp 125ndash130 2010

[72] V Domınguez-Villegas B Clares-Naveros M L Garcıa-Lopez et al ldquoDevelopment and characterization of two nano-structured systems for topical application of flavanones isolatedfrom Eysenhardtia platycarpardquo Colloids and Surfaces B Bioint-erfaces vol 116 pp 183ndash192 2014

[73] M Barzegar-Jalali K AdibkiaHValizadeh et al ldquoKinetic anal-ysis of drug release from nanoparticlesrdquo Journal of Pharmacyand Pharmaceutical Sciences vol 11 no 1 pp 167ndash177 2008

[74] L Zeng L An and X Wu ldquoModeling drug-carrier interactionin the drug release from nanocarriersrdquo Journal of Drug Deliveryvol 2011 Article ID 370308 15 pages 2011

[75] L Zeng andXWu ldquoModeling the sustained release of lipophilicdrugs from liposomesrdquo Applied Physics Letters vol 97 no 7Article ID 073701 2010

[76] FDA Guidance for Industry Extended Release Oral DosageForms Development Evaluation and Application of In VitroInVivo Correlations 1997

[77] J G Wagner and E Nelson ldquoPer cent absorbed time plotsderived fromblood level andor urinary excretion datardquo Journalof Pharmaceutical Sciences vol 52 pp 610ndash611 1963

Submit your manuscripts athttpwwwhindawicom

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Pharmaceutics

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MEDIATORSINFLAMMATION

of

Advances in Pharmaceutics 5

Sampling from inner compartment

Dialyzer cap

Inner compartment containing release media

Dialysis membrane

Outer compartment containing nanosuspension

Stir bar

Figure 3 ldquoReverse dialysisrdquo set-up

Receiver compartment

Dialysis membrane

Stir bar

Sampling

Nanoemulsion in donor compartment

Figure 4 ldquoSide-by-side dialysisrdquo set-up (adapted from [26])

the nanoparticles are introduced into a dialysis bag contain-ing release media (inner mediacompartment) that is subse-quently sealed and placed in a larger vessel containing releasemedia (outer mediacompartment) agitated to minimizeunstirred water layer effects [32 55] In general the volumeenclosed in a dialysis bag (inner media) is significantlysmaller than the outer media For instance inner mediavolumes reported in literature range from 1 to 10mL whereasthe outermedia volume ismuch greater typically around 40ndash90mL [32 53 55] Thus container size will depend on thetotal volume of release media required for the in vitro releasestudy In the regular dialysis technique drug released fromthe nanoparticles diffuses through the dialysis membraneto the outer compartment from where it is sampled foranalysis (Figure 2) In contrast with the reverse dialysis set-up the nanoparticles are placed in the outer compartment(agitated to minimize the unstirred water layer) and theinner compartment is sampled for drug release (Figure 3)[54 56 57] Other adaptations of the DM include the side-by-side dialysis set-up where donor and receiver cells bothcontaining equal volumes of media agitated with a magneticstirrer are separated by a dialysis membrane and samplingoccurs from the receiver cell (Figure 4) and a vertical Franzdiffusion cell [26 58 59]

As with other methods drug solubility in the releasemedia is essential to its transport across the dialysis mem-brane Apart from release media the importance of selectingan appropriate molecular weight cut-off (MWCO) for thedialysis membrane cannot be overlooked Indeed the basicpremise of the DM is that drug that is released from thedosage form will diffuse rapidly from one compartmentthrough the membrane and enter the second compartmentfrom where it is sampled for analysis Thus membranes witha sufficiently high membrane MWCO are often selected forin vitro release studies so that drug transport is not a limitingfactor As an example in a study with 3 dosage forms ofIndomethacin (eg nanoparticles and nanocapsules usingpoly-120576-caprolactone and a submicron emulsion) Calvo et alnoted that nearly 85 of drug was released within 2 hoursand complete release was achieved in 4 hours when a 12 kDamembranewas used [54] However the rationale for selectinga MWCO is rather subjective For instance a MWCO ashigh as 10ndash14 kDa was used to study drug release of smallmolecules like Risperidone and Indomethacin and aMWCOas low as 1 kDa though suitable for assessing in vitro releaseof a large molecule pDNA proved to be limiting for thediffusion of Cefuroxime Axetil a cephalosporin antibiotic[32 38 55 60] In general the MWCO should be sufficientlylarge to permit drug transport

The ease of set-up and sampling with the DM make ita very simple and straightforward technique to study drugrelease from a wide variety of nano-sized dosage forms likenanospheres liposomes emulsions nanosuspensions andso forth [53ndash55] However issues have been reported withthe regular dialysis method If incorrectly sealed leakage ofmedia and dosage form may occur from both ends of thedialysis bag set-up Incomplete release data may be observedif nonsink conditions exist or equilibration times are high[38] On the other hand the difference in equilibration timescan be exploited as a discriminatory tool to distinguish releasebehavior between fast and slow releasing dosage forms [50]Another factor to be considered is that the DM cannotbe used with drugs that bind to the dialyzing membraneAs stated in a review paper on microparticulate dosageforms it is recommended that the suitability of the dialyzingmembrane be assessed prior to use [21 61]

24 CombinationMethods A fewpublications havemodifiedthe set-ups used in the SS CF and DM methods to evaluatedrug release from nano-sized dosage forms In most of thesereports the set-up of the SS method is combined with adialyzer to allow ease of sampling In other publications theDM and the CF set-up is used to assess in vitro release fromnanoparticulates

As an example Mottaleb et al compared release profilesof Ibuprofen from liposomes and lipid nanocapsules andnanoparticles using the regular dialysis method (dialysis bag)and modified USP I (basket) set-up where the shaft wasaffixed with a glass basket having a dialysis membrane atthe bottom that is glass basket dialysis (GBD) and placedin a larger vessel (Figure 5) [27] Sampling was performedfrom the outer vessel Unlike the dialysis bag that had a large

6 Advances in Pharmaceutics

Glass basket

Dialysis membrane

Figure 5 Comparison ofUSP I (left) and glass basket dialysis (right)set-ups (adapted from [27])

membrane surface area the GBD was able to discriminatedifferences between release profiles from different formu-lations (lipid nanocapsules nanoparticles liposomes) Inanother study Lobenberg et al compared drug release fromRifampicin and Moxifloxacin hydrochloride nanoparticleswith the regular dialysis method (dialysis bag) as well as anadaptation of USP I (basket) where a cylinder containing adialysis membrane at the bottom was attached to the basketshaft [62] Results from this study showed that modifiedUSP I set-up was more discriminatory in nature and couldbe attributed to the reduced surface area of the dialysismembrane In yet another modification of the USP I (basket)set-up a dialysis bag containing nanostructured lipid carriersof Artemether was placed inside the basket and drug releasemonitored over time [63] Though most studies have utilizedthe USP I set-up others have used the USP II (paddle) set-upin combination with the DM For example Cao et al affixeddialysis bags containing Silybin meglumine nanoparticlesonto a USP II (paddle) apparatus and assessed drug releasein five different release media [33 35]

A combination of aDM previously reported byKostanskiet al and CF method was utilized to assess drug releasefrom 5-Fluorouracil loaded BSA nanoparticles [28 64] Thesetup comprised a glass tube (with a dialysis membrane atthe bottom) that was placed into a larger vessel containingbuffer (Figure 6) Sampling as well as buffer replacement wasperformed from the larger vessel with the aid of two pumpshaving the same flow rate The combined DM-CF set-up wasable to demonstrate sustained levels of 5-Fluorouracil andthe absence of burst release from the BSA nanoparticles Analternate dialysis-CFmethod utilized a dialysis adaptor insidethe CF set-up (Figure 7) [29]

25 New Methods Apart from the commonly reported SSCF and DM methods a few alternate approaches have beenutilized tomonitor drug release Amajority of these appear tobe targeted towards electroactive drugsWhile the techniquesmay differ in principle or application they possess a fewcommon elements in that physical separation of the dosageform from the release media is not required Additionallythese techniques offer the possibility of measurement underreal-time conditions

Detector

Waste

Dialysis membrane

Nanosuspension

Stir bar

Pump 2Pump 1

Release media

Figure 6 Continuous flow dialysis set-up with two pumps (adaptedfrom [28])

Flow through cell

Releasemedia

Pump

Detector

Filter

Glass beads

Dialyzer containingnanosuspension

Figure 7 Dialysis adapter inside a continuous flow set-up (adaptedfrom [29])

As such electrochemical methods offer the possibility ofrapid in situ measurements while avoiding the interferencecaused by the presence of undissolved dosage form in therelease media In one such approach a potentiometric drugselective electrode was used to monitor real-time release ofProcaine hydrochloride from pH-responsive nanogels [65]In another report by Mora et al a highly sensitive repetitivesquare-wave voltammetric technique was utilized to measurethe redox reaction of Doxorubicin hydrochloride (Figure 8)[30] Similarly differential pulse polarography was used toassess continuous drug release from Piroxicam Chloram-phenicol and Diazepam [66 67] Apart from the fact thatonly electroactive drugs can be measured by the abovemethods these methods suffer from additional drawbacksFor example the sensitivity as well as responsiveness ofeach technique varies greatly Also the sensors used may bespecific to a particular drug

Nonelectrochemical methods like calorimetry turbidim-etry and laser diffraction have also been evaluated as invitro release methods Solution calorimetry was employedby Kayaert et al during in vitro release measurement ofNaproxen Cinnarizine and Compound A (investigational

Advances in Pharmaceutics 7

Working electrode

Reference electrode

Counter electrode

Release media

Redox reactionAox Ared

A Liposome containing drug ldquoArdquo

Figure 8 Electrochemical cell set-up for real-time measurement ofdrug release (adapted from [30])

Pump control

Syringe Analyte

NanosuspensionMicrodialysis probe

pump

Figure 9 Microdialysis set-up (adapted from [31])

API) from nanocrystals [68] The principle of this tech-nique is based on detection of the net proportion of heatchange during in vitro release Challenges with calorimetricmeasurements include long equilibration times Further theheat produced by all the processes needs to be consideredTurbidimetric and laser diffraction approaches utilizing thechange light scattering properties of nanoparticles dispersedin release media have also been utilized [69 70] Concernswith these methods include the long equilibration timeslimited range of particle size and initial concentration ofsamples that can be used

Helle et al designed a novel online system for evaluatingthe drug release from Indomethacin and Beclomethasonedipropionate nanoparticles In thismethod nanoparticles arepacked into small column which is connected to multiportmodulation valve attached to an HPLC system allowingfor rapid analysis [71] Other new methods reported inliterature include a vertical diffusion Franz cell and an invitro lipolysis model [37 72] Microdialysis another set-up utilized to measure drug release from nanoparticules isbased on passive diffusion of drug through a concentrationgradient across a semipermeable membrane (Figure 9) [3147] Drug release can be measured in real-time conditionsusing analytical methods like HPLC However care shouldbe taken when surfactants are used in the release media asrecovery may be affected

3 Modeling Drug Release

Very few publications have attempted to describe drug releaseprofiles from nanoparticulate dosage forms using mathe-matical models This is not surprising given that nano-sizeddosage forms are complex and drug release evaluations arenot straightforward However a few authors have discussedthe importance of mathematical models and endeavored tocharacterize drug release For instance Barzegar-Jalali et alsuggested the use of reciprocal powered time (RPT) as generalmodel to analyze the complex nature of drug release fromnanoparticles with alternate approaches being the Weibulland log-probabilitymodels [73] In another report Zeng et aldeveloped a three-parameter model that considers reversibledrug-carrier interaction as well as diffusional drug releasefrom liposomes [74 75]

Use of mathematical models to describe drug releaseprofiles offers several advantages It permits the elucidationof drug release mechanisms and can be used to guide for-mulation development efforts Furthermodel parameters canserve to represent as well as compare in vitro release profilesHowever caution must be used when applying mathematicalmodels to complex drug release mechanisms

4 IVIVC

The US FDA defines IVIVC as ldquoA predictive mathematicalmodel describing the relationship between an in vitro prop-erty of an extended release dosage form (usually the rate orextent of drug in vitro release or release) and a relevant invivo response for example plasma drug concentration oramount of drug absorbedrdquo [76] Thus establishment of anIVIVC described as a correlation between in vitro release andin vivo behavior enhances the utility of an in vitro study Fromthe 1997 FDA guidance document an IVIVC will reduce theregulatory burden by paring the number of in vivo studiesneeded for product approval Additionally it promotes thesetting of clinically relevant in vitro release specifications [76]

The FDA guidance also categorizes IVIVCs into threelevels Level A represents a linear or nonlinear point-to-point relationship between the in vitro and in vivo releaseprofiles If the relationship is nonlinear suitable modelingor scaling is required Of the three IVIVC levels Level Adescribes the highest correlation and is most commonly usedto obtain a biowaiver On the other hand a Level B correlationis a comparison of summary parameters such as the meanin vitro dissolution time with mean in vivo dissolution timeor mean residence time (MRT) Since several in vivo curveswill produce a similarMRT value ormean in vitro dissolutiontime Level B correlations are not as discriminatory as LevelA but acceptable for an IVIVC A Level C correlationdescribes a relationship between an in vitro release parameter(eg dissolved at a particular time) and a pharmacokineticparameter (eg 119862max) However a Level C correlation is notdescriptive of the complete shape of the in vivo release profileand though acceptable seldom used

As such the FDA guidance is intended for oral extendedrelease products However principles of the FDA guidance

8 Advances in Pharmaceutics

Table 2 Examples of IVIVC with nano-sized dosage forms in animal models

Drug and dosage form In vitro release set-up In vivo studies IVIVC type Reference

Indomethacin gelatin nanoparticles Dialysis bags Wistar Albinorats Level A [32]

Silybin meglumine hollow-spheremesoporous silica nanoparticles Combination (USP Imdashdialysis bag) Beagle dogs Level A [33]

Silybin 72-hour SLB andPSNs (porous silica nanoparticles) Combination (USP Imdashdialysis bag) Beagle dogs Level A [35]

Simvastatin nanostructured lipidcarriers and nanoparticles Dialysis bag BalbC mice Level A [34]

Fenofibrate nanosuspension USP I apparatus SpragueDawley rats Level A [36]

Fenofibrate lipid matrix particles In vitro lipolysis model SpragueDawley rats Rank order [37]

Table 3 Level A IVIVC with two Silybin preparations (data from reference [35])

Formulation absorbed equals 1198772

72-hour SLB 11379 times dissolved + 88688 09831Silybin PSNs (porous silica nanoparticles) 08915 times dissolved minus 10152 09831

have been used to demonstrate an IVIVC from severalnonoral dosage forms including nano-sized preparationsMost published literature on IVIVC compares the in vitrorelease behavior with the in vivo absorption profile thelatter calculated by the FDA recommended Wagner-Nelsonmethod [76 77] Once the fraction absorbed is computeda correlation is obtained by comparing it with the in vitrorelease profile and the type of IVIVC (Level A level B etc) isdetermined

Over the last decade a few reports on IVIVC from nano-sized dosage forms have been published (Table 2) In someinstances a rank order correlation was observed while inothers a Level A IVIVC was established with some or allof the formulations evaluated in the study As an example arank order correlation was observed with three preparationsof Fenofibrate with drug release and absorption from 100 nmlipid matrix particles gt microparticles gt control (crystallinesuspension) [37] In another study on Fenofibrate nanosus-pensions Xu et al attempted to elucidate the absorptionmechanism using in situ gut perfusion model [36] Dataanalysis between in vitro dissolution (119875) in situ intestinalabsorption (119865) and in vivo absorption (119865

119886) demonstrated

a Level A correlation (1198772 gt 095) As a result the authorsconcluded that the in situ intestinal perfusion model couldbe a predictor of in vivo pharmacokinetic behavior for thenanosuspension

In a recent report Kumar et al investigated the relation-ship between in vitro and in vivo release from Indomethacingelatin nanoparticles administered orally to Wistar albinorats [32] Study results indicated that a good correlation wasobtained by plotting the fraction absorbed in vivo (Wagner-Nelson method) against the fraction released the latter per-formed using regular dialysis (dialysis bags) (Figure 10) TheWagner-Nelsonmethod was also used in another publication

0

20

40

60

80

100

120

0 20 40 60 80 100

In v

ivo

abso

rptio

n (

)

In vitro release ()

R2 = 0981

y = 1121x

Figure 10 Level A IVIVC from Indomethacin gelatin nanoparticlesusing regular dialysis (redrawn from [32])

where the in vivo absorption fromSilybinmeglumine hollow-sphere mesoporous silica nanoparticles dosed orally to bea-gle dogs was compared with in vitro results obtained using acombination USP I (paddle) dialysis bag set-up [33] Of thefive different releasemedia used in the study a Level A IVIVC(1198772 gt 097) was obtained with 006M Na

2CO3and 008M

Na2CO3solutions (Figure 11) In another study with Silybin

an IVIVC was achieved with a 72-hour release formulationof Silybin (72-hour SLB) that consisted of a solid dispersiongel matrix and porous silica nanoparticles (PSNs) (Table 3)[35] Similar to the earlier study the authors compared invivo release from beagle dogs with in vitro release assessedusing a combination USP I (paddle) dialysis bag set-upIn another paper Tiwari et al demonstrated a Level A

Advances in Pharmaceutics 9

0

20

40

60

80

100

0 20 40 60 80 100

Abso

rbed

()

Abso

rbed

()

0 20 40 60 80 1000

20

40

60

80

100

In vitro release ()

In vitro release ()

y = 23417x minus 78256

R2 = 09741

y = 16114x minus 56752

R2 = 09931

006M Na2CO3

008M Na2CO3

Figure 11 Level A IVIVC from Silybin meglumine hollow-typemesoporous silica nanoparticles using a combined USP II-dialysisbag set-up (redrawn from [33])

correlation between in vitro release (dialysis bag) and percentdrug absorbed (Wagner Nelson method) for Simvastatinnanostructured lipid carriers as well as nanoparticles (1198772 gt094) (Figure 12) [34]

5 Conclusions

For novel dosage forms like nanoparticles where no regu-latory or compendial standards exist in vitro drug releaseassessment assumes greater significance in serving as anindicator of product quality and performance A plethoraof methods have been used each with their advantages anddrawbacks with respect to ease of set-up sampling and rapidbuffer replacement Ideally an in vitro release method shouldsimulate in vivo conditions release mechanisms and enablethe establishment of an IVIVC Future research should focuson developing relevant mathematical models to predict drugrelease behavior as well as release mechanisms applicable to awide range of nano-sized dosage forms

Conflict of Interests

The author declares that there is no conflict of interestsregarding the publication of this paper

0

20

40

60

80

100

120

Dru

g ab

sorb

ed (

)

0

20

40

60

80

100

120

Dru

g ab

sorb

ed (

)

Simvastatin loaded nanostructured lipid carriers

Simvastatin loaded solid lipid nanoparticles

0 20 40 60 80 100In vitro release ()

0 20 40 60 80 100In vitro release ()

R2 = 09404

R2 = 0941

Figure 12 Level A correlation of Simvastatin from two nano-sizeddosage forms (redrawn from [34])

References

[1] N Al Khouri Fallouh L Roblot-Treupel and H Fessi ldquoDevel-opment of a new process for the manufacture of polyisobutyl-cyanoacrylate nanocapsulesrdquo International Journal of Pharma-ceutics vol 28 no 2-3 pp 125ndash132 1986

[2] C Losa P Calvo E Castro J L Vila-Jato and M J AlonsoldquoImprovement of ocular penetration of amikacin sulphate byassociation to poly(butylcyanoacrylate) nanoparticlesrdquo Journalof Pharmacy and Pharmacology vol 43 no 8 pp 548ndash552 1991

[3] C Losa L Marchal-Heussler F Orallo J L Vila Jato andM J Alonso ldquoDesign of new formulations for topical ocularadministration polymeric nanocapsules containing metipra-nololrdquo Pharmaceutical Research vol 10 no 1 pp 80ndash87 1993

[4] C N Cruz K M Tyner L Velazquez et al ldquoCDER riskassessment exercise to evaluate potential risks from the use ofnanomaterials in drug productsrdquo AAPS Journal vol 15 no 3pp 623ndash628 2013

[5] G Verreck I Chun J Rosenblatt et al ldquoIncorporation of drugsin an amorphous state into electrospun nanofibers composedof a water-insoluble nonbiodegradable polymerrdquo Journal ofControlled Release vol 92 no 3 pp 349ndash360 2003

[6] H Heiati R Tawashi R R Shivers and N C PhillipsldquoSolid lipid nanoparticles as drug carriers I incorporation andretention of the lipophilic prodrug 31015840-azido-31015840-deoxythymidinepalmitaterdquo International Journal of Pharmaceutics vol 146 no1 pp 123ndash131 1997

10 Advances in Pharmaceutics

[7] M Cetin A Atila and Y Kadioglu ldquoFormulation and in vitrocharacterization of Eudragit L100 and Eudragit L100-PLGAnanoparticles containing diclofenac sodiumrdquo AAPS Pharm-SciTech vol 11 pp 1250ndash1256 2010

[8] A Hanafy H Spahn-Langguth G Vergnault et al ldquoPharma-cokinetic evaluation of oral fenofibrate nanosuspensions andSLN in comparison to conventional suspensions of micronizeddrugrdquo Advanced Drug Delivery Reviews vol 59 no 6 pp 419ndash426 2007

[9] T M Allen W W K Cheng J I Hare and K M LaginhaldquoPharmacokinetics and pharmacodynamics of lipidic nano-particles in cancerrdquoAnti-Cancer Agents in Medicinal Chemistryvol 6 no 6 pp 513ndash523 2006

[10] J Kreuter ldquoNanoparticle-based drug delivery systemsrdquo Journalof Controlled Release vol 16 no 1-2 pp 169ndash176 1991

[11] M L Etheridge S A Campbell A G Erdman C L Haynes SMWolf and JMcCullough ldquoThe big picture on nanomedicinethe state of investigational and approved nanomedicine prod-uctsrdquo Nanomedicine Nanotechnology Biology and Medicinevol 9 no 1 pp 1ndash14 2013

[12] S Nie ldquoUnderstanding and overcoming major barriers incancer nanomedicinerdquoNanomedicine vol 5 no 4 pp 523ndash5282010

[13] W H de Jong and P J A Borm ldquoDrug delivery andnanoparticles applications and hazardsrdquo International Journalof Nanomedicine vol 3 no 2 pp 133ndash149 2008

[14] S DrsquoSouza J A Faraj R Dorati and P P DeLuca ldquoA short termquality control tool for biodegradable microspheresrdquo AAPSPharmSciTech vol 15 no 3 pp 530ndash541 2014

[15] P Buch P Holm J Q Thomassen et al ldquoIVIVC for fenofibrateimmediate release tablets using solubility and permeability as invitro predictors for pharmacokineticsrdquo Journal of Pharmaceuti-cal Sciences vol 99 no 10 pp 4427ndash4436 2010

[16] S DrsquoSouza J A Faraj S Giovagnoli and P P DeLuca ldquoIVIVCfrom long acting olanzapine microspheresrdquo International Jour-nal of Biomaterials vol 2014 Article ID 407065 11 pages 2014

[17] L C Amann M J Gandal R Lin Y Liang and S J SiegelldquoIn vitro-in vivo correlations of scalable PLGA-Risperidoneimplants for the treatment of schizophreniardquo PharmaceuticalResearch vol 27 no 8 pp 1730ndash1737 2010

[18] G Zackrisson G Ostling B Skagerberg and T Anfalt ldquoACcel-erated Dissolution Rate Analysis (ACDRA) for controlledrelease drugs Application to Roxiamrdquo Journal of Pharmaceu-tical and Biomedical Analysis vol 13 no 4-5 pp 377ndash383 1995

[19] S S DSouza J A Faraj and P P DeLuca ldquoA model-dependentapproach to correlate accelerated with real-time release frombiodegradable microspheresrdquo AAPS PharmSciTech vol 6 arti-cle 70 no 4 2005

[20] D J Burgess A S Hussain T S Ingallinera and M ChenldquoAssuring quality and performance of sustained and controlledrelease parenterals workshop reportrdquo AAPS PharmSci vol 4article E7 2002

[21] S S DrsquoSouza and P P DeLuca ldquoMethods to assess in vitrodrug release from injectable polymeric particulate systemsrdquoPharmaceutical Research vol 23 no 3 pp 460ndash474 2006

[22] M Siewert J Dressman C K Brown and V P ShahldquoFIPAAPS guidelines to dissolutionin vitro release testing ofnovelspecial dosage formsrdquo AAPS PharmSciTech vol 4 article7 2003

[23] C K Brown H D Friedel A R Barker et al ldquoFIPAAPSjoint workshop report dissolutionin vitro release testing of

novelspecial dosage formsrdquo AAPS PharmSciTech vol 12 no2 pp 782ndash794 2011

[24] MMartinezM Rathbone D Burgess andMHuynh ldquoIn vitroand in vivo considerations associated with parenteral sustainedrelease products a review based upon information presentedand points expressed at the 2007 Controlled Release SocietyAnnual Meetingrdquo Journal of Controlled Release vol 129 no 2pp 79ndash87 2008

[25] M N Martinez M J Rathbone D Burgess and M HuynhldquoBreakout session summary from AAPSCRS joint workshopon critical variables in the in vitro and in vivo performanceof parenteral sustained release productsrdquo Journal of ControlledRelease vol 142 no 1 pp 2ndash7 2010

[26] N Chidambaram and D J Burgess ldquoA novel in vitro releasemethod for submicron-sized dispersed systemsrdquo AAPS Pharm-Sci vol 1 no 3 pp 32ndash40 1999

[27] M M A Abdel-Mottaleb and A Lamprecht ldquoStandardized invitro drug release test for colloidal drug carriers using modifiedUSP dissolution apparatus Irdquo Drug Development and IndustrialPharmacy vol 37 no 2 pp 178ndash184 2011

[28] A Maghsoudi S A Shojaosadati and E Vasheghani Farahanildquo5-Fluorouracil-loaded BSA nanoparticles formulation opti-mization and in vitro release studyrdquo AAPS PharmSciTech vol9 no 4 pp 1092ndash1096 2008

[29] U Bhardwaj and D J Burgess ldquoA novel USP apparatus 4 basedrelease testing method for dispersed systemsrdquo InternationalJournal of Pharmaceutics vol 388 no 1-2 pp 287ndash294 2010

[30] L Mora K Y Chumbimuni-Torres C Clawson L HernandezL Zhang and J Wang ldquoReal-time electrochemical monitoringof drug release from therapeutic nanoparticlesrdquo Journal ofControlled Release vol 140 no 1 pp 69ndash73 2009

[31] C B Michalowski S S Guterres and T Dalla CostaldquoMicrodialysis for evaluating the entrapment and release of alipophilic drug from nanoparticlesrdquo Journal of Pharmaceuticaland Biomedical Analysis vol 35 no 5 pp 1093ndash1100 2004

[32] R Kumar R C Nagarwal M Dhanawat and J K PanditldquoIn-vitro and in-vivo study of indomethacin loaded gelatinnanoparticlesrdquo Journal of Biomedical Nanotechnology vol 7 no3 pp 325ndash333 2011

[33] X Cao W W Deng M Fu et al ldquoIn vitro release and in vitro-in vivo correlation for silybin meglumine incorporated intoHollow-type mesoporous silica nanoparticlesrdquo InternationalJournal of Nanomedicine vol 7 pp 753ndash762 2012

[34] R Tiwari and K Pathak ldquoNanostructured lipid carrier versussolid lipid nanoparticles of simvastatin comparative analysis ofcharacteristics pharmacokinetics and tissue uptakerdquo Interna-tional Journal of Pharmaceutics vol 415 no 1-2 pp 232ndash2432011

[35] X Cao W Deng M Fu et al ldquoSeventy-two-hour releaseformulation of the poorly soluble drug silybin based on poroussilica nanoparticles in vitro release kinetics and in vitroin vivocorrelations in beagle dogsrdquo European Journal of Pharmaceuti-cal Sciences vol 48 no 1-2 pp 64ndash71 2013

[36] Y Xu Y Wang X M Li et al ldquoStudy on the release offenofibrate nanosuspension in vitro and its correlation with insitu intestinal and in vivo absorption kinetics in ratsrdquo DrugDevelopment and Industrial Pharmacy vol 40 no 7 pp 972ndash979 2014

[37] N Borkar D Xia R Holm et al ldquoInvestigating the correlationbetween in vivo absorption and in vitro release of fenofibratefrom lipid matrix particles in biorelevant mediumrdquo EuropeanJournal of Pharmaceutical Sciences vol 51 pp 204ndash210 2014

Advances in Pharmaceutics 11

[38] D Heng D J Cutler H K Chan J Yun and J A RaperldquoWhat is a suitable dissolutionmethod for drug nanoparticlesrdquoPharmaceutical Research vol 25 no 7 pp 1696ndash1701 2008

[39] A C Kilic Y Capan I Vural et al ldquoPreparation and characteri-zation of PLGA nanospheres for the targeted delivery of NR2B-specific antisense oligonucleotides to the NMDA receptors inthe brainrdquo Journal of Microencapsulation vol 22 no 6 pp 633ndash641 2005

[40] Y Zhang H Wang C Li et al ldquoA novel three-dimensionallarge-pore mesoporous carbon matrix as a potential nanove-hicle for the fast release of the poorly water-soluble drugcelecoxibrdquoPharmaceutical Research vol 31 pp 1059ndash1070 2014

[41] V Sanna A M Roggio S Siliani et al ldquoDevelopment of novelcationic chitosan-and anionic alginate-coated poly(DL-lactide-co-glycolide) nanoparticles for controlled release and light pro-tection of resveratrolrdquo International Journal of Nanomedicinevol 7 pp 5501ndash5516 2012

[42] F Danhier N Lecouturier B Vroman et al ldquoPaclitaxel-loadedPEGylated PLGA-based nanoparticles In vitro and in vivoevaluationrdquo Journal of Controlled Release vol 133 no 1 pp 11ndash17 2009

[43] Y Li Y Pei X Zhang et al ldquoPEGylated PLGA nanoparticlesas protein carriers synthesis preparation and biodistributionin ratsrdquo Journal of Controlled Release vol 71 no 2 pp 203ndash2112001

[44] S Prabha W-Z Zhou J Panyam and V Labhasetwar ldquoSize-dependency of nanoparticle-mediated gene transfection stud-ies with fractionated nanoparticlesrdquo International Journal ofPharmaceutics vol 244 no 1-2 pp 105ndash115 2002

[45] S J Wallace J Li R L Nation and B J Boyd ldquoDrug releasefrom nanomedicines selection of appropriate encapsulationand release methodologyrdquo Drug Delivery and TranslationalResearch vol 2 no 4 pp 284ndash292 2012

[46] D Juenemann E Jantratid C Wagner C Reppas M Vertzoniand J B Dressman ldquoBiorelevant in vitro dissolution testingof products containing micronized or nanosized fenofibratewith a view to predicting plasma profilesrdquo European Journal ofPharmaceutics and Biopharmaceutics vol 77 no 2 pp 257ndash2642011

[47] P F Yue X Y Lu Z Z Zhang et al ldquoThe study on theentrapment efficiency and in vitro release of puerarin submi-cron emulsionrdquoAAPS PharmSciTech vol 10 no 2 pp 376ndash3832009

[48] M Mahkam F Hosseinzadeh and M Galehassadi ldquoPrepara-tion of ionic liquid functionalized silica nanoparticles for oraldrug deliveryrdquo Journal of Biomaterials amp Nanobiotechnologyvol 3 pp 391ndash395 2012

[49] A S Ham M R Cost A B Sassi C S Dezzutti andL C Rohan ldquoTargeted delivery of PSC-RANTES for HIV-1prevention using biodegradable nanoparticlesrdquo PharmaceuticalResearch vol 26 no 3 pp 502ndash511 2009

[50] Y I Kim L Fluckiger M Hoffman I Lartaud-IdjouadieneJ Atkinson and P Maincent ldquoThe antihypertensive effect oforally administered nifedipine-loaded nanoparticles in sponta-neously hypertensive ratsrdquoThe British Journal of Pharmacologyvol 120 no 3 pp 399ndash404 1997

[51] P Liu O de Wulf J Laru et al ldquoDissolution studies of poorlysoluble drug nanosuspensions in non-sink conditionsrdquo AAPSPharmSciTech vol 14 no 2 pp 748ndash756 2013

[52] L Sievens-Figueroa N Pandya A Bhakay et al ldquoUsing USPI and USP IV for discriminating dissolution rates of nano-

and microparticle-loaded pharmaceutical strip-filmsrdquo AAPSPharmSciTech vol 13 no 4 pp 1473ndash1482 2013

[53] G P Yan R F Zong L Li T Fu F Liu and X H YuldquoAnticancer drug-loaded nanospheres based on biodegradableamphiphilic 120576-caprolactone and carbonate copolymersrdquo Phar-maceutical Research vol 27 no 12 pp 2743ndash2752 2010

[54] P Calvo J L Vila-Jato and M J Alonso ldquoComparative invitro evaluation of several colloidal systems nanoparticlesnanocapsules and nanoemulsions as ocular drug carriersrdquoJournal of Pharmaceutical Sciences vol 85 no 5 pp 530ndash5361996

[55] M SMuthu and S Singh ldquoPoly (D L-lactide) nanosuspensionsof risperidone for parenteral delivery formulation and in-vitroevaluationrdquoCurrent DrugDelivery vol 6 no 1 pp 62ndash68 2009

[56] MY Levy and S Benita ldquoDrug release from submicronized owemulsion a new in vitro kinetic evaluationmodelrdquo InternationalJournal of Pharmaceutics vol 66 no 1ndash3 pp 29ndash37 1990

[57] X Xu M A Khan and D J Burgess ldquoA two-stage reversedialysis in vitro dissolution testing method for passive targetedliposomesrdquo International Journal of Pharmaceutics vol 426 no1-2 pp 211ndash218 2012

[58] B E Kilfoyle L Sheihet Z Zhang M Laohoo J Kohn and BBMichniak-Kohn ldquoDevelopment of paclitaxel-TyroSpheres fortopical skin treatmentrdquo Journal of Controlled Release vol 163no 1 pp 18ndash24 2012

[59] S Uprit R K Sahu A Roy and A Pare ldquoPreparation and char-acterization of minoxidil loaded nanostructured lipid carriergel for effective treatment of alopeciardquo Saudi PharmaceuticalJournal vol 21 pp 379ndash385 2013

[60] B Qiu M Ji X Song et al ldquoCo-delivery of docetaxel andendostatin by a biodegradable nanoparticle for the synergistictreatment of cervical cancerrdquo Nanoscale Research Letters vol 7article 666 2012

[61] S S DrsquoSouza and P P DeLuca ldquoDevelopment of a dialysis invitro release method for biodegradable microspheresrdquo AAPSPharmSciTech vol 6 no 2 article 42 2005

[62] Y Gao J Zuo N Bou-Chacra et al ldquoIn vitro release kineticsof antituberculosis drugs from nanoparticles assessed usinga modified dissolution apparatusrdquo BioMed Research Interna-tional vol 2013 Article ID 136590 9 pages 2013

[63] M Joshi S Pathak S Sharma and V Patravale ldquoDesignand in vivo pharmacodynamic evaluation of nanostructuredlipid carriers for parenteral delivery of artemether nanojectrdquoInternational Journal of Pharmaceutics vol 364 no 1 pp 119ndash126 2008

[64] J W Kostanski and P P DeLuca ldquoA novel in vitro releasetechnique for peptide-containing biodegradable microspheresrdquoAAPS PharmSciTech vol 1 article 4 2000

[65] J P K Tan C H Goh and K C Tam ldquoComparative drugrelease studies of two cationic drugs from pH-responsivenanogelsrdquo European Journal of Pharmaceutical Sciences vol 32no 4-5 pp 340ndash348 2007

[66] K M Rosenblatt D Douroumis and H Bunjes ldquoDrug releasefrom differently structured monooleinpoloxamer nanodisper-sions studied with differential pulse polarography and ultrafil-tration at low pressurerdquo Journal of Pharmaceutical Sciences vol96 no 6 pp 1564ndash1575 2007

[67] N Charalampopoulos K Avgoustakis and C G KontoyannisldquoDifferential pulse polarography a suitable technique for mon-itoring drug release from polymeric nanoparticle dispersionsrdquoAnalytica Chimica Acta vol 491 no 1 pp 57ndash62 2003

12 Advances in Pharmaceutics

[68] P Kayaert B Li I Jimidar P Rombaut F Ahssini and G Vanden Mooter ldquoSolution calorimetry as an alternative approachfor dissolution testing of nanosuspensionsrdquo European Journal ofPharmaceutics and Biopharmaceutics vol 76 no 3 pp 507ndash5132010

[69] M T Crisp C J Tucker T L Rogers R O Williams III andK P Johnston ldquoTurbidimetric measurement and prediction ofdissolution rates of poorly soluble drug nanocrystalsrdquo Journalof Controlled Release vol 117 no 3 pp 351ndash359 2007

[70] M V Chaubal and C Popescu ldquoConversion of nanosus-pensions into dry powders by spray drying a case studyrdquoPharmaceutical Research vol 25 no 10 pp 2302ndash2308 2008

[71] A Helle S Hirsjarvi L Peltonen J Hirvonen S K Wied-mer and T Hyotylainen ldquoNovel dynamic on-line analyticalseparation system for dissolution of drugs from poly(lacticacid) nanoparticlesrdquo Journal of Pharmaceutical and BiomedicalAnalysis vol 51 no 1 pp 125ndash130 2010

[72] V Domınguez-Villegas B Clares-Naveros M L Garcıa-Lopez et al ldquoDevelopment and characterization of two nano-structured systems for topical application of flavanones isolatedfrom Eysenhardtia platycarpardquo Colloids and Surfaces B Bioint-erfaces vol 116 pp 183ndash192 2014

[73] M Barzegar-Jalali K AdibkiaHValizadeh et al ldquoKinetic anal-ysis of drug release from nanoparticlesrdquo Journal of Pharmacyand Pharmaceutical Sciences vol 11 no 1 pp 167ndash177 2008

[74] L Zeng L An and X Wu ldquoModeling drug-carrier interactionin the drug release from nanocarriersrdquo Journal of Drug Deliveryvol 2011 Article ID 370308 15 pages 2011

[75] L Zeng andXWu ldquoModeling the sustained release of lipophilicdrugs from liposomesrdquo Applied Physics Letters vol 97 no 7Article ID 073701 2010

[76] FDA Guidance for Industry Extended Release Oral DosageForms Development Evaluation and Application of In VitroInVivo Correlations 1997

[77] J G Wagner and E Nelson ldquoPer cent absorbed time plotsderived fromblood level andor urinary excretion datardquo Journalof Pharmaceutical Sciences vol 52 pp 610ndash611 1963

Submit your manuscripts athttpwwwhindawicom

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ToxinsJournal of

VaccinesJournal of

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AntibioticsInternational Journal of

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StrokeResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Drug DeliveryJournal of

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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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Pharmaceutics

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MEDIATORSINFLAMMATION

of

6 Advances in Pharmaceutics

Glass basket

Dialysis membrane

Figure 5 Comparison ofUSP I (left) and glass basket dialysis (right)set-ups (adapted from [27])

membrane surface area the GBD was able to discriminatedifferences between release profiles from different formu-lations (lipid nanocapsules nanoparticles liposomes) Inanother study Lobenberg et al compared drug release fromRifampicin and Moxifloxacin hydrochloride nanoparticleswith the regular dialysis method (dialysis bag) as well as anadaptation of USP I (basket) where a cylinder containing adialysis membrane at the bottom was attached to the basketshaft [62] Results from this study showed that modifiedUSP I set-up was more discriminatory in nature and couldbe attributed to the reduced surface area of the dialysismembrane In yet another modification of the USP I (basket)set-up a dialysis bag containing nanostructured lipid carriersof Artemether was placed inside the basket and drug releasemonitored over time [63] Though most studies have utilizedthe USP I set-up others have used the USP II (paddle) set-upin combination with the DM For example Cao et al affixeddialysis bags containing Silybin meglumine nanoparticlesonto a USP II (paddle) apparatus and assessed drug releasein five different release media [33 35]

A combination of aDM previously reported byKostanskiet al and CF method was utilized to assess drug releasefrom 5-Fluorouracil loaded BSA nanoparticles [28 64] Thesetup comprised a glass tube (with a dialysis membrane atthe bottom) that was placed into a larger vessel containingbuffer (Figure 6) Sampling as well as buffer replacement wasperformed from the larger vessel with the aid of two pumpshaving the same flow rate The combined DM-CF set-up wasable to demonstrate sustained levels of 5-Fluorouracil andthe absence of burst release from the BSA nanoparticles Analternate dialysis-CFmethod utilized a dialysis adaptor insidethe CF set-up (Figure 7) [29]

25 New Methods Apart from the commonly reported SSCF and DM methods a few alternate approaches have beenutilized tomonitor drug release Amajority of these appear tobe targeted towards electroactive drugsWhile the techniquesmay differ in principle or application they possess a fewcommon elements in that physical separation of the dosageform from the release media is not required Additionallythese techniques offer the possibility of measurement underreal-time conditions

Detector

Waste

Dialysis membrane

Nanosuspension

Stir bar

Pump 2Pump 1

Release media

Figure 6 Continuous flow dialysis set-up with two pumps (adaptedfrom [28])

Flow through cell

Releasemedia

Pump

Detector

Filter

Glass beads

Dialyzer containingnanosuspension

Figure 7 Dialysis adapter inside a continuous flow set-up (adaptedfrom [29])

As such electrochemical methods offer the possibility ofrapid in situ measurements while avoiding the interferencecaused by the presence of undissolved dosage form in therelease media In one such approach a potentiometric drugselective electrode was used to monitor real-time release ofProcaine hydrochloride from pH-responsive nanogels [65]In another report by Mora et al a highly sensitive repetitivesquare-wave voltammetric technique was utilized to measurethe redox reaction of Doxorubicin hydrochloride (Figure 8)[30] Similarly differential pulse polarography was used toassess continuous drug release from Piroxicam Chloram-phenicol and Diazepam [66 67] Apart from the fact thatonly electroactive drugs can be measured by the abovemethods these methods suffer from additional drawbacksFor example the sensitivity as well as responsiveness ofeach technique varies greatly Also the sensors used may bespecific to a particular drug

Nonelectrochemical methods like calorimetry turbidim-etry and laser diffraction have also been evaluated as invitro release methods Solution calorimetry was employedby Kayaert et al during in vitro release measurement ofNaproxen Cinnarizine and Compound A (investigational

Advances in Pharmaceutics 7

Working electrode

Reference electrode

Counter electrode

Release media

Redox reactionAox Ared

A Liposome containing drug ldquoArdquo

Figure 8 Electrochemical cell set-up for real-time measurement ofdrug release (adapted from [30])

Pump control

Syringe Analyte

NanosuspensionMicrodialysis probe

pump

Figure 9 Microdialysis set-up (adapted from [31])

API) from nanocrystals [68] The principle of this tech-nique is based on detection of the net proportion of heatchange during in vitro release Challenges with calorimetricmeasurements include long equilibration times Further theheat produced by all the processes needs to be consideredTurbidimetric and laser diffraction approaches utilizing thechange light scattering properties of nanoparticles dispersedin release media have also been utilized [69 70] Concernswith these methods include the long equilibration timeslimited range of particle size and initial concentration ofsamples that can be used

Helle et al designed a novel online system for evaluatingthe drug release from Indomethacin and Beclomethasonedipropionate nanoparticles In thismethod nanoparticles arepacked into small column which is connected to multiportmodulation valve attached to an HPLC system allowingfor rapid analysis [71] Other new methods reported inliterature include a vertical diffusion Franz cell and an invitro lipolysis model [37 72] Microdialysis another set-up utilized to measure drug release from nanoparticules isbased on passive diffusion of drug through a concentrationgradient across a semipermeable membrane (Figure 9) [3147] Drug release can be measured in real-time conditionsusing analytical methods like HPLC However care shouldbe taken when surfactants are used in the release media asrecovery may be affected

3 Modeling Drug Release

Very few publications have attempted to describe drug releaseprofiles from nanoparticulate dosage forms using mathe-matical models This is not surprising given that nano-sizeddosage forms are complex and drug release evaluations arenot straightforward However a few authors have discussedthe importance of mathematical models and endeavored tocharacterize drug release For instance Barzegar-Jalali et alsuggested the use of reciprocal powered time (RPT) as generalmodel to analyze the complex nature of drug release fromnanoparticles with alternate approaches being the Weibulland log-probabilitymodels [73] In another report Zeng et aldeveloped a three-parameter model that considers reversibledrug-carrier interaction as well as diffusional drug releasefrom liposomes [74 75]

Use of mathematical models to describe drug releaseprofiles offers several advantages It permits the elucidationof drug release mechanisms and can be used to guide for-mulation development efforts Furthermodel parameters canserve to represent as well as compare in vitro release profilesHowever caution must be used when applying mathematicalmodels to complex drug release mechanisms

4 IVIVC

The US FDA defines IVIVC as ldquoA predictive mathematicalmodel describing the relationship between an in vitro prop-erty of an extended release dosage form (usually the rate orextent of drug in vitro release or release) and a relevant invivo response for example plasma drug concentration oramount of drug absorbedrdquo [76] Thus establishment of anIVIVC described as a correlation between in vitro release andin vivo behavior enhances the utility of an in vitro study Fromthe 1997 FDA guidance document an IVIVC will reduce theregulatory burden by paring the number of in vivo studiesneeded for product approval Additionally it promotes thesetting of clinically relevant in vitro release specifications [76]

The FDA guidance also categorizes IVIVCs into threelevels Level A represents a linear or nonlinear point-to-point relationship between the in vitro and in vivo releaseprofiles If the relationship is nonlinear suitable modelingor scaling is required Of the three IVIVC levels Level Adescribes the highest correlation and is most commonly usedto obtain a biowaiver On the other hand a Level B correlationis a comparison of summary parameters such as the meanin vitro dissolution time with mean in vivo dissolution timeor mean residence time (MRT) Since several in vivo curveswill produce a similarMRT value ormean in vitro dissolutiontime Level B correlations are not as discriminatory as LevelA but acceptable for an IVIVC A Level C correlationdescribes a relationship between an in vitro release parameter(eg dissolved at a particular time) and a pharmacokineticparameter (eg 119862max) However a Level C correlation is notdescriptive of the complete shape of the in vivo release profileand though acceptable seldom used

As such the FDA guidance is intended for oral extendedrelease products However principles of the FDA guidance

8 Advances in Pharmaceutics

Table 2 Examples of IVIVC with nano-sized dosage forms in animal models

Drug and dosage form In vitro release set-up In vivo studies IVIVC type Reference

Indomethacin gelatin nanoparticles Dialysis bags Wistar Albinorats Level A [32]

Silybin meglumine hollow-spheremesoporous silica nanoparticles Combination (USP Imdashdialysis bag) Beagle dogs Level A [33]

Silybin 72-hour SLB andPSNs (porous silica nanoparticles) Combination (USP Imdashdialysis bag) Beagle dogs Level A [35]

Simvastatin nanostructured lipidcarriers and nanoparticles Dialysis bag BalbC mice Level A [34]

Fenofibrate nanosuspension USP I apparatus SpragueDawley rats Level A [36]

Fenofibrate lipid matrix particles In vitro lipolysis model SpragueDawley rats Rank order [37]

Table 3 Level A IVIVC with two Silybin preparations (data from reference [35])

Formulation absorbed equals 1198772

72-hour SLB 11379 times dissolved + 88688 09831Silybin PSNs (porous silica nanoparticles) 08915 times dissolved minus 10152 09831

have been used to demonstrate an IVIVC from severalnonoral dosage forms including nano-sized preparationsMost published literature on IVIVC compares the in vitrorelease behavior with the in vivo absorption profile thelatter calculated by the FDA recommended Wagner-Nelsonmethod [76 77] Once the fraction absorbed is computeda correlation is obtained by comparing it with the in vitrorelease profile and the type of IVIVC (Level A level B etc) isdetermined

Over the last decade a few reports on IVIVC from nano-sized dosage forms have been published (Table 2) In someinstances a rank order correlation was observed while inothers a Level A IVIVC was established with some or allof the formulations evaluated in the study As an example arank order correlation was observed with three preparationsof Fenofibrate with drug release and absorption from 100 nmlipid matrix particles gt microparticles gt control (crystallinesuspension) [37] In another study on Fenofibrate nanosus-pensions Xu et al attempted to elucidate the absorptionmechanism using in situ gut perfusion model [36] Dataanalysis between in vitro dissolution (119875) in situ intestinalabsorption (119865) and in vivo absorption (119865

119886) demonstrated

a Level A correlation (1198772 gt 095) As a result the authorsconcluded that the in situ intestinal perfusion model couldbe a predictor of in vivo pharmacokinetic behavior for thenanosuspension

In a recent report Kumar et al investigated the relation-ship between in vitro and in vivo release from Indomethacingelatin nanoparticles administered orally to Wistar albinorats [32] Study results indicated that a good correlation wasobtained by plotting the fraction absorbed in vivo (Wagner-Nelson method) against the fraction released the latter per-formed using regular dialysis (dialysis bags) (Figure 10) TheWagner-Nelsonmethod was also used in another publication

0

20

40

60

80

100

120

0 20 40 60 80 100

In v

ivo

abso

rptio

n (

)

In vitro release ()

R2 = 0981

y = 1121x

Figure 10 Level A IVIVC from Indomethacin gelatin nanoparticlesusing regular dialysis (redrawn from [32])

where the in vivo absorption fromSilybinmeglumine hollow-sphere mesoporous silica nanoparticles dosed orally to bea-gle dogs was compared with in vitro results obtained using acombination USP I (paddle) dialysis bag set-up [33] Of thefive different releasemedia used in the study a Level A IVIVC(1198772 gt 097) was obtained with 006M Na

2CO3and 008M

Na2CO3solutions (Figure 11) In another study with Silybin

an IVIVC was achieved with a 72-hour release formulationof Silybin (72-hour SLB) that consisted of a solid dispersiongel matrix and porous silica nanoparticles (PSNs) (Table 3)[35] Similar to the earlier study the authors compared invivo release from beagle dogs with in vitro release assessedusing a combination USP I (paddle) dialysis bag set-upIn another paper Tiwari et al demonstrated a Level A

Advances in Pharmaceutics 9

0

20

40

60

80

100

0 20 40 60 80 100

Abso

rbed

()

Abso

rbed

()

0 20 40 60 80 1000

20

40

60

80

100

In vitro release ()

In vitro release ()

y = 23417x minus 78256

R2 = 09741

y = 16114x minus 56752

R2 = 09931

006M Na2CO3

008M Na2CO3

Figure 11 Level A IVIVC from Silybin meglumine hollow-typemesoporous silica nanoparticles using a combined USP II-dialysisbag set-up (redrawn from [33])

correlation between in vitro release (dialysis bag) and percentdrug absorbed (Wagner Nelson method) for Simvastatinnanostructured lipid carriers as well as nanoparticles (1198772 gt094) (Figure 12) [34]

5 Conclusions

For novel dosage forms like nanoparticles where no regu-latory or compendial standards exist in vitro drug releaseassessment assumes greater significance in serving as anindicator of product quality and performance A plethoraof methods have been used each with their advantages anddrawbacks with respect to ease of set-up sampling and rapidbuffer replacement Ideally an in vitro release method shouldsimulate in vivo conditions release mechanisms and enablethe establishment of an IVIVC Future research should focuson developing relevant mathematical models to predict drugrelease behavior as well as release mechanisms applicable to awide range of nano-sized dosage forms

Conflict of Interests

The author declares that there is no conflict of interestsregarding the publication of this paper

0

20

40

60

80

100

120

Dru

g ab

sorb

ed (

)

0

20

40

60

80

100

120

Dru

g ab

sorb

ed (

)

Simvastatin loaded nanostructured lipid carriers

Simvastatin loaded solid lipid nanoparticles

0 20 40 60 80 100In vitro release ()

0 20 40 60 80 100In vitro release ()

R2 = 09404

R2 = 0941

Figure 12 Level A correlation of Simvastatin from two nano-sizeddosage forms (redrawn from [34])

References

[1] N Al Khouri Fallouh L Roblot-Treupel and H Fessi ldquoDevel-opment of a new process for the manufacture of polyisobutyl-cyanoacrylate nanocapsulesrdquo International Journal of Pharma-ceutics vol 28 no 2-3 pp 125ndash132 1986

[2] C Losa P Calvo E Castro J L Vila-Jato and M J AlonsoldquoImprovement of ocular penetration of amikacin sulphate byassociation to poly(butylcyanoacrylate) nanoparticlesrdquo Journalof Pharmacy and Pharmacology vol 43 no 8 pp 548ndash552 1991

[3] C Losa L Marchal-Heussler F Orallo J L Vila Jato andM J Alonso ldquoDesign of new formulations for topical ocularadministration polymeric nanocapsules containing metipra-nololrdquo Pharmaceutical Research vol 10 no 1 pp 80ndash87 1993

[4] C N Cruz K M Tyner L Velazquez et al ldquoCDER riskassessment exercise to evaluate potential risks from the use ofnanomaterials in drug productsrdquo AAPS Journal vol 15 no 3pp 623ndash628 2013

[5] G Verreck I Chun J Rosenblatt et al ldquoIncorporation of drugsin an amorphous state into electrospun nanofibers composedof a water-insoluble nonbiodegradable polymerrdquo Journal ofControlled Release vol 92 no 3 pp 349ndash360 2003

[6] H Heiati R Tawashi R R Shivers and N C PhillipsldquoSolid lipid nanoparticles as drug carriers I incorporation andretention of the lipophilic prodrug 31015840-azido-31015840-deoxythymidinepalmitaterdquo International Journal of Pharmaceutics vol 146 no1 pp 123ndash131 1997

10 Advances in Pharmaceutics

[7] M Cetin A Atila and Y Kadioglu ldquoFormulation and in vitrocharacterization of Eudragit L100 and Eudragit L100-PLGAnanoparticles containing diclofenac sodiumrdquo AAPS Pharm-SciTech vol 11 pp 1250ndash1256 2010

[8] A Hanafy H Spahn-Langguth G Vergnault et al ldquoPharma-cokinetic evaluation of oral fenofibrate nanosuspensions andSLN in comparison to conventional suspensions of micronizeddrugrdquo Advanced Drug Delivery Reviews vol 59 no 6 pp 419ndash426 2007

[9] T M Allen W W K Cheng J I Hare and K M LaginhaldquoPharmacokinetics and pharmacodynamics of lipidic nano-particles in cancerrdquoAnti-Cancer Agents in Medicinal Chemistryvol 6 no 6 pp 513ndash523 2006

[10] J Kreuter ldquoNanoparticle-based drug delivery systemsrdquo Journalof Controlled Release vol 16 no 1-2 pp 169ndash176 1991

[11] M L Etheridge S A Campbell A G Erdman C L Haynes SMWolf and JMcCullough ldquoThe big picture on nanomedicinethe state of investigational and approved nanomedicine prod-uctsrdquo Nanomedicine Nanotechnology Biology and Medicinevol 9 no 1 pp 1ndash14 2013

[12] S Nie ldquoUnderstanding and overcoming major barriers incancer nanomedicinerdquoNanomedicine vol 5 no 4 pp 523ndash5282010

[13] W H de Jong and P J A Borm ldquoDrug delivery andnanoparticles applications and hazardsrdquo International Journalof Nanomedicine vol 3 no 2 pp 133ndash149 2008

[14] S DrsquoSouza J A Faraj R Dorati and P P DeLuca ldquoA short termquality control tool for biodegradable microspheresrdquo AAPSPharmSciTech vol 15 no 3 pp 530ndash541 2014

[15] P Buch P Holm J Q Thomassen et al ldquoIVIVC for fenofibrateimmediate release tablets using solubility and permeability as invitro predictors for pharmacokineticsrdquo Journal of Pharmaceuti-cal Sciences vol 99 no 10 pp 4427ndash4436 2010

[16] S DrsquoSouza J A Faraj S Giovagnoli and P P DeLuca ldquoIVIVCfrom long acting olanzapine microspheresrdquo International Jour-nal of Biomaterials vol 2014 Article ID 407065 11 pages 2014

[17] L C Amann M J Gandal R Lin Y Liang and S J SiegelldquoIn vitro-in vivo correlations of scalable PLGA-Risperidoneimplants for the treatment of schizophreniardquo PharmaceuticalResearch vol 27 no 8 pp 1730ndash1737 2010

[18] G Zackrisson G Ostling B Skagerberg and T Anfalt ldquoACcel-erated Dissolution Rate Analysis (ACDRA) for controlledrelease drugs Application to Roxiamrdquo Journal of Pharmaceu-tical and Biomedical Analysis vol 13 no 4-5 pp 377ndash383 1995

[19] S S DSouza J A Faraj and P P DeLuca ldquoA model-dependentapproach to correlate accelerated with real-time release frombiodegradable microspheresrdquo AAPS PharmSciTech vol 6 arti-cle 70 no 4 2005

[20] D J Burgess A S Hussain T S Ingallinera and M ChenldquoAssuring quality and performance of sustained and controlledrelease parenterals workshop reportrdquo AAPS PharmSci vol 4article E7 2002

[21] S S DrsquoSouza and P P DeLuca ldquoMethods to assess in vitrodrug release from injectable polymeric particulate systemsrdquoPharmaceutical Research vol 23 no 3 pp 460ndash474 2006

[22] M Siewert J Dressman C K Brown and V P ShahldquoFIPAAPS guidelines to dissolutionin vitro release testing ofnovelspecial dosage formsrdquo AAPS PharmSciTech vol 4 article7 2003

[23] C K Brown H D Friedel A R Barker et al ldquoFIPAAPSjoint workshop report dissolutionin vitro release testing of

novelspecial dosage formsrdquo AAPS PharmSciTech vol 12 no2 pp 782ndash794 2011

[24] MMartinezM Rathbone D Burgess andMHuynh ldquoIn vitroand in vivo considerations associated with parenteral sustainedrelease products a review based upon information presentedand points expressed at the 2007 Controlled Release SocietyAnnual Meetingrdquo Journal of Controlled Release vol 129 no 2pp 79ndash87 2008

[25] M N Martinez M J Rathbone D Burgess and M HuynhldquoBreakout session summary from AAPSCRS joint workshopon critical variables in the in vitro and in vivo performanceof parenteral sustained release productsrdquo Journal of ControlledRelease vol 142 no 1 pp 2ndash7 2010

[26] N Chidambaram and D J Burgess ldquoA novel in vitro releasemethod for submicron-sized dispersed systemsrdquo AAPS Pharm-Sci vol 1 no 3 pp 32ndash40 1999

[27] M M A Abdel-Mottaleb and A Lamprecht ldquoStandardized invitro drug release test for colloidal drug carriers using modifiedUSP dissolution apparatus Irdquo Drug Development and IndustrialPharmacy vol 37 no 2 pp 178ndash184 2011

[28] A Maghsoudi S A Shojaosadati and E Vasheghani Farahanildquo5-Fluorouracil-loaded BSA nanoparticles formulation opti-mization and in vitro release studyrdquo AAPS PharmSciTech vol9 no 4 pp 1092ndash1096 2008

[29] U Bhardwaj and D J Burgess ldquoA novel USP apparatus 4 basedrelease testing method for dispersed systemsrdquo InternationalJournal of Pharmaceutics vol 388 no 1-2 pp 287ndash294 2010

[30] L Mora K Y Chumbimuni-Torres C Clawson L HernandezL Zhang and J Wang ldquoReal-time electrochemical monitoringof drug release from therapeutic nanoparticlesrdquo Journal ofControlled Release vol 140 no 1 pp 69ndash73 2009

[31] C B Michalowski S S Guterres and T Dalla CostaldquoMicrodialysis for evaluating the entrapment and release of alipophilic drug from nanoparticlesrdquo Journal of Pharmaceuticaland Biomedical Analysis vol 35 no 5 pp 1093ndash1100 2004

[32] R Kumar R C Nagarwal M Dhanawat and J K PanditldquoIn-vitro and in-vivo study of indomethacin loaded gelatinnanoparticlesrdquo Journal of Biomedical Nanotechnology vol 7 no3 pp 325ndash333 2011

[33] X Cao W W Deng M Fu et al ldquoIn vitro release and in vitro-in vivo correlation for silybin meglumine incorporated intoHollow-type mesoporous silica nanoparticlesrdquo InternationalJournal of Nanomedicine vol 7 pp 753ndash762 2012

[34] R Tiwari and K Pathak ldquoNanostructured lipid carrier versussolid lipid nanoparticles of simvastatin comparative analysis ofcharacteristics pharmacokinetics and tissue uptakerdquo Interna-tional Journal of Pharmaceutics vol 415 no 1-2 pp 232ndash2432011

[35] X Cao W Deng M Fu et al ldquoSeventy-two-hour releaseformulation of the poorly soluble drug silybin based on poroussilica nanoparticles in vitro release kinetics and in vitroin vivocorrelations in beagle dogsrdquo European Journal of Pharmaceuti-cal Sciences vol 48 no 1-2 pp 64ndash71 2013

[36] Y Xu Y Wang X M Li et al ldquoStudy on the release offenofibrate nanosuspension in vitro and its correlation with insitu intestinal and in vivo absorption kinetics in ratsrdquo DrugDevelopment and Industrial Pharmacy vol 40 no 7 pp 972ndash979 2014

[37] N Borkar D Xia R Holm et al ldquoInvestigating the correlationbetween in vivo absorption and in vitro release of fenofibratefrom lipid matrix particles in biorelevant mediumrdquo EuropeanJournal of Pharmaceutical Sciences vol 51 pp 204ndash210 2014

Advances in Pharmaceutics 11

[38] D Heng D J Cutler H K Chan J Yun and J A RaperldquoWhat is a suitable dissolutionmethod for drug nanoparticlesrdquoPharmaceutical Research vol 25 no 7 pp 1696ndash1701 2008

[39] A C Kilic Y Capan I Vural et al ldquoPreparation and characteri-zation of PLGA nanospheres for the targeted delivery of NR2B-specific antisense oligonucleotides to the NMDA receptors inthe brainrdquo Journal of Microencapsulation vol 22 no 6 pp 633ndash641 2005

[40] Y Zhang H Wang C Li et al ldquoA novel three-dimensionallarge-pore mesoporous carbon matrix as a potential nanove-hicle for the fast release of the poorly water-soluble drugcelecoxibrdquoPharmaceutical Research vol 31 pp 1059ndash1070 2014

[41] V Sanna A M Roggio S Siliani et al ldquoDevelopment of novelcationic chitosan-and anionic alginate-coated poly(DL-lactide-co-glycolide) nanoparticles for controlled release and light pro-tection of resveratrolrdquo International Journal of Nanomedicinevol 7 pp 5501ndash5516 2012

[42] F Danhier N Lecouturier B Vroman et al ldquoPaclitaxel-loadedPEGylated PLGA-based nanoparticles In vitro and in vivoevaluationrdquo Journal of Controlled Release vol 133 no 1 pp 11ndash17 2009

[43] Y Li Y Pei X Zhang et al ldquoPEGylated PLGA nanoparticlesas protein carriers synthesis preparation and biodistributionin ratsrdquo Journal of Controlled Release vol 71 no 2 pp 203ndash2112001

[44] S Prabha W-Z Zhou J Panyam and V Labhasetwar ldquoSize-dependency of nanoparticle-mediated gene transfection stud-ies with fractionated nanoparticlesrdquo International Journal ofPharmaceutics vol 244 no 1-2 pp 105ndash115 2002

[45] S J Wallace J Li R L Nation and B J Boyd ldquoDrug releasefrom nanomedicines selection of appropriate encapsulationand release methodologyrdquo Drug Delivery and TranslationalResearch vol 2 no 4 pp 284ndash292 2012

[46] D Juenemann E Jantratid C Wagner C Reppas M Vertzoniand J B Dressman ldquoBiorelevant in vitro dissolution testingof products containing micronized or nanosized fenofibratewith a view to predicting plasma profilesrdquo European Journal ofPharmaceutics and Biopharmaceutics vol 77 no 2 pp 257ndash2642011

[47] P F Yue X Y Lu Z Z Zhang et al ldquoThe study on theentrapment efficiency and in vitro release of puerarin submi-cron emulsionrdquoAAPS PharmSciTech vol 10 no 2 pp 376ndash3832009

[48] M Mahkam F Hosseinzadeh and M Galehassadi ldquoPrepara-tion of ionic liquid functionalized silica nanoparticles for oraldrug deliveryrdquo Journal of Biomaterials amp Nanobiotechnologyvol 3 pp 391ndash395 2012

[49] A S Ham M R Cost A B Sassi C S Dezzutti andL C Rohan ldquoTargeted delivery of PSC-RANTES for HIV-1prevention using biodegradable nanoparticlesrdquo PharmaceuticalResearch vol 26 no 3 pp 502ndash511 2009

[50] Y I Kim L Fluckiger M Hoffman I Lartaud-IdjouadieneJ Atkinson and P Maincent ldquoThe antihypertensive effect oforally administered nifedipine-loaded nanoparticles in sponta-neously hypertensive ratsrdquoThe British Journal of Pharmacologyvol 120 no 3 pp 399ndash404 1997

[51] P Liu O de Wulf J Laru et al ldquoDissolution studies of poorlysoluble drug nanosuspensions in non-sink conditionsrdquo AAPSPharmSciTech vol 14 no 2 pp 748ndash756 2013

[52] L Sievens-Figueroa N Pandya A Bhakay et al ldquoUsing USPI and USP IV for discriminating dissolution rates of nano-

and microparticle-loaded pharmaceutical strip-filmsrdquo AAPSPharmSciTech vol 13 no 4 pp 1473ndash1482 2013

[53] G P Yan R F Zong L Li T Fu F Liu and X H YuldquoAnticancer drug-loaded nanospheres based on biodegradableamphiphilic 120576-caprolactone and carbonate copolymersrdquo Phar-maceutical Research vol 27 no 12 pp 2743ndash2752 2010

[54] P Calvo J L Vila-Jato and M J Alonso ldquoComparative invitro evaluation of several colloidal systems nanoparticlesnanocapsules and nanoemulsions as ocular drug carriersrdquoJournal of Pharmaceutical Sciences vol 85 no 5 pp 530ndash5361996

[55] M SMuthu and S Singh ldquoPoly (D L-lactide) nanosuspensionsof risperidone for parenteral delivery formulation and in-vitroevaluationrdquoCurrent DrugDelivery vol 6 no 1 pp 62ndash68 2009

[56] MY Levy and S Benita ldquoDrug release from submicronized owemulsion a new in vitro kinetic evaluationmodelrdquo InternationalJournal of Pharmaceutics vol 66 no 1ndash3 pp 29ndash37 1990

[57] X Xu M A Khan and D J Burgess ldquoA two-stage reversedialysis in vitro dissolution testing method for passive targetedliposomesrdquo International Journal of Pharmaceutics vol 426 no1-2 pp 211ndash218 2012

[58] B E Kilfoyle L Sheihet Z Zhang M Laohoo J Kohn and BBMichniak-Kohn ldquoDevelopment of paclitaxel-TyroSpheres fortopical skin treatmentrdquo Journal of Controlled Release vol 163no 1 pp 18ndash24 2012

[59] S Uprit R K Sahu A Roy and A Pare ldquoPreparation and char-acterization of minoxidil loaded nanostructured lipid carriergel for effective treatment of alopeciardquo Saudi PharmaceuticalJournal vol 21 pp 379ndash385 2013

[60] B Qiu M Ji X Song et al ldquoCo-delivery of docetaxel andendostatin by a biodegradable nanoparticle for the synergistictreatment of cervical cancerrdquo Nanoscale Research Letters vol 7article 666 2012

[61] S S DrsquoSouza and P P DeLuca ldquoDevelopment of a dialysis invitro release method for biodegradable microspheresrdquo AAPSPharmSciTech vol 6 no 2 article 42 2005

[62] Y Gao J Zuo N Bou-Chacra et al ldquoIn vitro release kineticsof antituberculosis drugs from nanoparticles assessed usinga modified dissolution apparatusrdquo BioMed Research Interna-tional vol 2013 Article ID 136590 9 pages 2013

[63] M Joshi S Pathak S Sharma and V Patravale ldquoDesignand in vivo pharmacodynamic evaluation of nanostructuredlipid carriers for parenteral delivery of artemether nanojectrdquoInternational Journal of Pharmaceutics vol 364 no 1 pp 119ndash126 2008

[64] J W Kostanski and P P DeLuca ldquoA novel in vitro releasetechnique for peptide-containing biodegradable microspheresrdquoAAPS PharmSciTech vol 1 article 4 2000

[65] J P K Tan C H Goh and K C Tam ldquoComparative drugrelease studies of two cationic drugs from pH-responsivenanogelsrdquo European Journal of Pharmaceutical Sciences vol 32no 4-5 pp 340ndash348 2007

[66] K M Rosenblatt D Douroumis and H Bunjes ldquoDrug releasefrom differently structured monooleinpoloxamer nanodisper-sions studied with differential pulse polarography and ultrafil-tration at low pressurerdquo Journal of Pharmaceutical Sciences vol96 no 6 pp 1564ndash1575 2007

[67] N Charalampopoulos K Avgoustakis and C G KontoyannisldquoDifferential pulse polarography a suitable technique for mon-itoring drug release from polymeric nanoparticle dispersionsrdquoAnalytica Chimica Acta vol 491 no 1 pp 57ndash62 2003

12 Advances in Pharmaceutics

[68] P Kayaert B Li I Jimidar P Rombaut F Ahssini and G Vanden Mooter ldquoSolution calorimetry as an alternative approachfor dissolution testing of nanosuspensionsrdquo European Journal ofPharmaceutics and Biopharmaceutics vol 76 no 3 pp 507ndash5132010

[69] M T Crisp C J Tucker T L Rogers R O Williams III andK P Johnston ldquoTurbidimetric measurement and prediction ofdissolution rates of poorly soluble drug nanocrystalsrdquo Journalof Controlled Release vol 117 no 3 pp 351ndash359 2007

[70] M V Chaubal and C Popescu ldquoConversion of nanosus-pensions into dry powders by spray drying a case studyrdquoPharmaceutical Research vol 25 no 10 pp 2302ndash2308 2008

[71] A Helle S Hirsjarvi L Peltonen J Hirvonen S K Wied-mer and T Hyotylainen ldquoNovel dynamic on-line analyticalseparation system for dissolution of drugs from poly(lacticacid) nanoparticlesrdquo Journal of Pharmaceutical and BiomedicalAnalysis vol 51 no 1 pp 125ndash130 2010

[72] V Domınguez-Villegas B Clares-Naveros M L Garcıa-Lopez et al ldquoDevelopment and characterization of two nano-structured systems for topical application of flavanones isolatedfrom Eysenhardtia platycarpardquo Colloids and Surfaces B Bioint-erfaces vol 116 pp 183ndash192 2014

[73] M Barzegar-Jalali K AdibkiaHValizadeh et al ldquoKinetic anal-ysis of drug release from nanoparticlesrdquo Journal of Pharmacyand Pharmaceutical Sciences vol 11 no 1 pp 167ndash177 2008

[74] L Zeng L An and X Wu ldquoModeling drug-carrier interactionin the drug release from nanocarriersrdquo Journal of Drug Deliveryvol 2011 Article ID 370308 15 pages 2011

[75] L Zeng andXWu ldquoModeling the sustained release of lipophilicdrugs from liposomesrdquo Applied Physics Letters vol 97 no 7Article ID 073701 2010

[76] FDA Guidance for Industry Extended Release Oral DosageForms Development Evaluation and Application of In VitroInVivo Correlations 1997

[77] J G Wagner and E Nelson ldquoPer cent absorbed time plotsderived fromblood level andor urinary excretion datardquo Journalof Pharmaceutical Sciences vol 52 pp 610ndash611 1963

Submit your manuscripts athttpwwwhindawicom

PainResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom

Volume 2014

ToxinsJournal of

VaccinesJournal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

AntibioticsInternational Journal of

ToxicologyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

StrokeResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Drug DeliveryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in Pharmacological Sciences

Tropical MedicineJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

AddictionJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

Emergency Medicine InternationalHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Autoimmune Diseases

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Anesthesiology Research and Practice

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Pharmaceutics

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MEDIATORSINFLAMMATION

of

Advances in Pharmaceutics 7

Working electrode

Reference electrode

Counter electrode

Release media

Redox reactionAox Ared

A Liposome containing drug ldquoArdquo

Figure 8 Electrochemical cell set-up for real-time measurement ofdrug release (adapted from [30])

Pump control

Syringe Analyte

NanosuspensionMicrodialysis probe

pump

Figure 9 Microdialysis set-up (adapted from [31])

API) from nanocrystals [68] The principle of this tech-nique is based on detection of the net proportion of heatchange during in vitro release Challenges with calorimetricmeasurements include long equilibration times Further theheat produced by all the processes needs to be consideredTurbidimetric and laser diffraction approaches utilizing thechange light scattering properties of nanoparticles dispersedin release media have also been utilized [69 70] Concernswith these methods include the long equilibration timeslimited range of particle size and initial concentration ofsamples that can be used

Helle et al designed a novel online system for evaluatingthe drug release from Indomethacin and Beclomethasonedipropionate nanoparticles In thismethod nanoparticles arepacked into small column which is connected to multiportmodulation valve attached to an HPLC system allowingfor rapid analysis [71] Other new methods reported inliterature include a vertical diffusion Franz cell and an invitro lipolysis model [37 72] Microdialysis another set-up utilized to measure drug release from nanoparticules isbased on passive diffusion of drug through a concentrationgradient across a semipermeable membrane (Figure 9) [3147] Drug release can be measured in real-time conditionsusing analytical methods like HPLC However care shouldbe taken when surfactants are used in the release media asrecovery may be affected

3 Modeling Drug Release

Very few publications have attempted to describe drug releaseprofiles from nanoparticulate dosage forms using mathe-matical models This is not surprising given that nano-sizeddosage forms are complex and drug release evaluations arenot straightforward However a few authors have discussedthe importance of mathematical models and endeavored tocharacterize drug release For instance Barzegar-Jalali et alsuggested the use of reciprocal powered time (RPT) as generalmodel to analyze the complex nature of drug release fromnanoparticles with alternate approaches being the Weibulland log-probabilitymodels [73] In another report Zeng et aldeveloped a three-parameter model that considers reversibledrug-carrier interaction as well as diffusional drug releasefrom liposomes [74 75]

Use of mathematical models to describe drug releaseprofiles offers several advantages It permits the elucidationof drug release mechanisms and can be used to guide for-mulation development efforts Furthermodel parameters canserve to represent as well as compare in vitro release profilesHowever caution must be used when applying mathematicalmodels to complex drug release mechanisms

4 IVIVC

The US FDA defines IVIVC as ldquoA predictive mathematicalmodel describing the relationship between an in vitro prop-erty of an extended release dosage form (usually the rate orextent of drug in vitro release or release) and a relevant invivo response for example plasma drug concentration oramount of drug absorbedrdquo [76] Thus establishment of anIVIVC described as a correlation between in vitro release andin vivo behavior enhances the utility of an in vitro study Fromthe 1997 FDA guidance document an IVIVC will reduce theregulatory burden by paring the number of in vivo studiesneeded for product approval Additionally it promotes thesetting of clinically relevant in vitro release specifications [76]

The FDA guidance also categorizes IVIVCs into threelevels Level A represents a linear or nonlinear point-to-point relationship between the in vitro and in vivo releaseprofiles If the relationship is nonlinear suitable modelingor scaling is required Of the three IVIVC levels Level Adescribes the highest correlation and is most commonly usedto obtain a biowaiver On the other hand a Level B correlationis a comparison of summary parameters such as the meanin vitro dissolution time with mean in vivo dissolution timeor mean residence time (MRT) Since several in vivo curveswill produce a similarMRT value ormean in vitro dissolutiontime Level B correlations are not as discriminatory as LevelA but acceptable for an IVIVC A Level C correlationdescribes a relationship between an in vitro release parameter(eg dissolved at a particular time) and a pharmacokineticparameter (eg 119862max) However a Level C correlation is notdescriptive of the complete shape of the in vivo release profileand though acceptable seldom used

As such the FDA guidance is intended for oral extendedrelease products However principles of the FDA guidance

8 Advances in Pharmaceutics

Table 2 Examples of IVIVC with nano-sized dosage forms in animal models

Drug and dosage form In vitro release set-up In vivo studies IVIVC type Reference

Indomethacin gelatin nanoparticles Dialysis bags Wistar Albinorats Level A [32]

Silybin meglumine hollow-spheremesoporous silica nanoparticles Combination (USP Imdashdialysis bag) Beagle dogs Level A [33]

Silybin 72-hour SLB andPSNs (porous silica nanoparticles) Combination (USP Imdashdialysis bag) Beagle dogs Level A [35]

Simvastatin nanostructured lipidcarriers and nanoparticles Dialysis bag BalbC mice Level A [34]

Fenofibrate nanosuspension USP I apparatus SpragueDawley rats Level A [36]

Fenofibrate lipid matrix particles In vitro lipolysis model SpragueDawley rats Rank order [37]

Table 3 Level A IVIVC with two Silybin preparations (data from reference [35])

Formulation absorbed equals 1198772

72-hour SLB 11379 times dissolved + 88688 09831Silybin PSNs (porous silica nanoparticles) 08915 times dissolved minus 10152 09831

have been used to demonstrate an IVIVC from severalnonoral dosage forms including nano-sized preparationsMost published literature on IVIVC compares the in vitrorelease behavior with the in vivo absorption profile thelatter calculated by the FDA recommended Wagner-Nelsonmethod [76 77] Once the fraction absorbed is computeda correlation is obtained by comparing it with the in vitrorelease profile and the type of IVIVC (Level A level B etc) isdetermined

Over the last decade a few reports on IVIVC from nano-sized dosage forms have been published (Table 2) In someinstances a rank order correlation was observed while inothers a Level A IVIVC was established with some or allof the formulations evaluated in the study As an example arank order correlation was observed with three preparationsof Fenofibrate with drug release and absorption from 100 nmlipid matrix particles gt microparticles gt control (crystallinesuspension) [37] In another study on Fenofibrate nanosus-pensions Xu et al attempted to elucidate the absorptionmechanism using in situ gut perfusion model [36] Dataanalysis between in vitro dissolution (119875) in situ intestinalabsorption (119865) and in vivo absorption (119865

119886) demonstrated

a Level A correlation (1198772 gt 095) As a result the authorsconcluded that the in situ intestinal perfusion model couldbe a predictor of in vivo pharmacokinetic behavior for thenanosuspension

In a recent report Kumar et al investigated the relation-ship between in vitro and in vivo release from Indomethacingelatin nanoparticles administered orally to Wistar albinorats [32] Study results indicated that a good correlation wasobtained by plotting the fraction absorbed in vivo (Wagner-Nelson method) against the fraction released the latter per-formed using regular dialysis (dialysis bags) (Figure 10) TheWagner-Nelsonmethod was also used in another publication

0

20

40

60

80

100

120

0 20 40 60 80 100

In v

ivo

abso

rptio

n (

)

In vitro release ()

R2 = 0981

y = 1121x

Figure 10 Level A IVIVC from Indomethacin gelatin nanoparticlesusing regular dialysis (redrawn from [32])

where the in vivo absorption fromSilybinmeglumine hollow-sphere mesoporous silica nanoparticles dosed orally to bea-gle dogs was compared with in vitro results obtained using acombination USP I (paddle) dialysis bag set-up [33] Of thefive different releasemedia used in the study a Level A IVIVC(1198772 gt 097) was obtained with 006M Na

2CO3and 008M

Na2CO3solutions (Figure 11) In another study with Silybin

an IVIVC was achieved with a 72-hour release formulationof Silybin (72-hour SLB) that consisted of a solid dispersiongel matrix and porous silica nanoparticles (PSNs) (Table 3)[35] Similar to the earlier study the authors compared invivo release from beagle dogs with in vitro release assessedusing a combination USP I (paddle) dialysis bag set-upIn another paper Tiwari et al demonstrated a Level A

Advances in Pharmaceutics 9

0

20

40

60

80

100

0 20 40 60 80 100

Abso

rbed

()

Abso

rbed

()

0 20 40 60 80 1000

20

40

60

80

100

In vitro release ()

In vitro release ()

y = 23417x minus 78256

R2 = 09741

y = 16114x minus 56752

R2 = 09931

006M Na2CO3

008M Na2CO3

Figure 11 Level A IVIVC from Silybin meglumine hollow-typemesoporous silica nanoparticles using a combined USP II-dialysisbag set-up (redrawn from [33])

correlation between in vitro release (dialysis bag) and percentdrug absorbed (Wagner Nelson method) for Simvastatinnanostructured lipid carriers as well as nanoparticles (1198772 gt094) (Figure 12) [34]

5 Conclusions

For novel dosage forms like nanoparticles where no regu-latory or compendial standards exist in vitro drug releaseassessment assumes greater significance in serving as anindicator of product quality and performance A plethoraof methods have been used each with their advantages anddrawbacks with respect to ease of set-up sampling and rapidbuffer replacement Ideally an in vitro release method shouldsimulate in vivo conditions release mechanisms and enablethe establishment of an IVIVC Future research should focuson developing relevant mathematical models to predict drugrelease behavior as well as release mechanisms applicable to awide range of nano-sized dosage forms

Conflict of Interests

The author declares that there is no conflict of interestsregarding the publication of this paper

0

20

40

60

80

100

120

Dru

g ab

sorb

ed (

)

0

20

40

60

80

100

120

Dru

g ab

sorb

ed (

)

Simvastatin loaded nanostructured lipid carriers

Simvastatin loaded solid lipid nanoparticles

0 20 40 60 80 100In vitro release ()

0 20 40 60 80 100In vitro release ()

R2 = 09404

R2 = 0941

Figure 12 Level A correlation of Simvastatin from two nano-sizeddosage forms (redrawn from [34])

References

[1] N Al Khouri Fallouh L Roblot-Treupel and H Fessi ldquoDevel-opment of a new process for the manufacture of polyisobutyl-cyanoacrylate nanocapsulesrdquo International Journal of Pharma-ceutics vol 28 no 2-3 pp 125ndash132 1986

[2] C Losa P Calvo E Castro J L Vila-Jato and M J AlonsoldquoImprovement of ocular penetration of amikacin sulphate byassociation to poly(butylcyanoacrylate) nanoparticlesrdquo Journalof Pharmacy and Pharmacology vol 43 no 8 pp 548ndash552 1991

[3] C Losa L Marchal-Heussler F Orallo J L Vila Jato andM J Alonso ldquoDesign of new formulations for topical ocularadministration polymeric nanocapsules containing metipra-nololrdquo Pharmaceutical Research vol 10 no 1 pp 80ndash87 1993

[4] C N Cruz K M Tyner L Velazquez et al ldquoCDER riskassessment exercise to evaluate potential risks from the use ofnanomaterials in drug productsrdquo AAPS Journal vol 15 no 3pp 623ndash628 2013

[5] G Verreck I Chun J Rosenblatt et al ldquoIncorporation of drugsin an amorphous state into electrospun nanofibers composedof a water-insoluble nonbiodegradable polymerrdquo Journal ofControlled Release vol 92 no 3 pp 349ndash360 2003

[6] H Heiati R Tawashi R R Shivers and N C PhillipsldquoSolid lipid nanoparticles as drug carriers I incorporation andretention of the lipophilic prodrug 31015840-azido-31015840-deoxythymidinepalmitaterdquo International Journal of Pharmaceutics vol 146 no1 pp 123ndash131 1997

10 Advances in Pharmaceutics

[7] M Cetin A Atila and Y Kadioglu ldquoFormulation and in vitrocharacterization of Eudragit L100 and Eudragit L100-PLGAnanoparticles containing diclofenac sodiumrdquo AAPS Pharm-SciTech vol 11 pp 1250ndash1256 2010

[8] A Hanafy H Spahn-Langguth G Vergnault et al ldquoPharma-cokinetic evaluation of oral fenofibrate nanosuspensions andSLN in comparison to conventional suspensions of micronizeddrugrdquo Advanced Drug Delivery Reviews vol 59 no 6 pp 419ndash426 2007

[9] T M Allen W W K Cheng J I Hare and K M LaginhaldquoPharmacokinetics and pharmacodynamics of lipidic nano-particles in cancerrdquoAnti-Cancer Agents in Medicinal Chemistryvol 6 no 6 pp 513ndash523 2006

[10] J Kreuter ldquoNanoparticle-based drug delivery systemsrdquo Journalof Controlled Release vol 16 no 1-2 pp 169ndash176 1991

[11] M L Etheridge S A Campbell A G Erdman C L Haynes SMWolf and JMcCullough ldquoThe big picture on nanomedicinethe state of investigational and approved nanomedicine prod-uctsrdquo Nanomedicine Nanotechnology Biology and Medicinevol 9 no 1 pp 1ndash14 2013

[12] S Nie ldquoUnderstanding and overcoming major barriers incancer nanomedicinerdquoNanomedicine vol 5 no 4 pp 523ndash5282010

[13] W H de Jong and P J A Borm ldquoDrug delivery andnanoparticles applications and hazardsrdquo International Journalof Nanomedicine vol 3 no 2 pp 133ndash149 2008

[14] S DrsquoSouza J A Faraj R Dorati and P P DeLuca ldquoA short termquality control tool for biodegradable microspheresrdquo AAPSPharmSciTech vol 15 no 3 pp 530ndash541 2014

[15] P Buch P Holm J Q Thomassen et al ldquoIVIVC for fenofibrateimmediate release tablets using solubility and permeability as invitro predictors for pharmacokineticsrdquo Journal of Pharmaceuti-cal Sciences vol 99 no 10 pp 4427ndash4436 2010

[16] S DrsquoSouza J A Faraj S Giovagnoli and P P DeLuca ldquoIVIVCfrom long acting olanzapine microspheresrdquo International Jour-nal of Biomaterials vol 2014 Article ID 407065 11 pages 2014

[17] L C Amann M J Gandal R Lin Y Liang and S J SiegelldquoIn vitro-in vivo correlations of scalable PLGA-Risperidoneimplants for the treatment of schizophreniardquo PharmaceuticalResearch vol 27 no 8 pp 1730ndash1737 2010

[18] G Zackrisson G Ostling B Skagerberg and T Anfalt ldquoACcel-erated Dissolution Rate Analysis (ACDRA) for controlledrelease drugs Application to Roxiamrdquo Journal of Pharmaceu-tical and Biomedical Analysis vol 13 no 4-5 pp 377ndash383 1995

[19] S S DSouza J A Faraj and P P DeLuca ldquoA model-dependentapproach to correlate accelerated with real-time release frombiodegradable microspheresrdquo AAPS PharmSciTech vol 6 arti-cle 70 no 4 2005

[20] D J Burgess A S Hussain T S Ingallinera and M ChenldquoAssuring quality and performance of sustained and controlledrelease parenterals workshop reportrdquo AAPS PharmSci vol 4article E7 2002

[21] S S DrsquoSouza and P P DeLuca ldquoMethods to assess in vitrodrug release from injectable polymeric particulate systemsrdquoPharmaceutical Research vol 23 no 3 pp 460ndash474 2006

[22] M Siewert J Dressman C K Brown and V P ShahldquoFIPAAPS guidelines to dissolutionin vitro release testing ofnovelspecial dosage formsrdquo AAPS PharmSciTech vol 4 article7 2003

[23] C K Brown H D Friedel A R Barker et al ldquoFIPAAPSjoint workshop report dissolutionin vitro release testing of

novelspecial dosage formsrdquo AAPS PharmSciTech vol 12 no2 pp 782ndash794 2011

[24] MMartinezM Rathbone D Burgess andMHuynh ldquoIn vitroand in vivo considerations associated with parenteral sustainedrelease products a review based upon information presentedand points expressed at the 2007 Controlled Release SocietyAnnual Meetingrdquo Journal of Controlled Release vol 129 no 2pp 79ndash87 2008

[25] M N Martinez M J Rathbone D Burgess and M HuynhldquoBreakout session summary from AAPSCRS joint workshopon critical variables in the in vitro and in vivo performanceof parenteral sustained release productsrdquo Journal of ControlledRelease vol 142 no 1 pp 2ndash7 2010

[26] N Chidambaram and D J Burgess ldquoA novel in vitro releasemethod for submicron-sized dispersed systemsrdquo AAPS Pharm-Sci vol 1 no 3 pp 32ndash40 1999

[27] M M A Abdel-Mottaleb and A Lamprecht ldquoStandardized invitro drug release test for colloidal drug carriers using modifiedUSP dissolution apparatus Irdquo Drug Development and IndustrialPharmacy vol 37 no 2 pp 178ndash184 2011

[28] A Maghsoudi S A Shojaosadati and E Vasheghani Farahanildquo5-Fluorouracil-loaded BSA nanoparticles formulation opti-mization and in vitro release studyrdquo AAPS PharmSciTech vol9 no 4 pp 1092ndash1096 2008

[29] U Bhardwaj and D J Burgess ldquoA novel USP apparatus 4 basedrelease testing method for dispersed systemsrdquo InternationalJournal of Pharmaceutics vol 388 no 1-2 pp 287ndash294 2010

[30] L Mora K Y Chumbimuni-Torres C Clawson L HernandezL Zhang and J Wang ldquoReal-time electrochemical monitoringof drug release from therapeutic nanoparticlesrdquo Journal ofControlled Release vol 140 no 1 pp 69ndash73 2009

[31] C B Michalowski S S Guterres and T Dalla CostaldquoMicrodialysis for evaluating the entrapment and release of alipophilic drug from nanoparticlesrdquo Journal of Pharmaceuticaland Biomedical Analysis vol 35 no 5 pp 1093ndash1100 2004

[32] R Kumar R C Nagarwal M Dhanawat and J K PanditldquoIn-vitro and in-vivo study of indomethacin loaded gelatinnanoparticlesrdquo Journal of Biomedical Nanotechnology vol 7 no3 pp 325ndash333 2011

[33] X Cao W W Deng M Fu et al ldquoIn vitro release and in vitro-in vivo correlation for silybin meglumine incorporated intoHollow-type mesoporous silica nanoparticlesrdquo InternationalJournal of Nanomedicine vol 7 pp 753ndash762 2012

[34] R Tiwari and K Pathak ldquoNanostructured lipid carrier versussolid lipid nanoparticles of simvastatin comparative analysis ofcharacteristics pharmacokinetics and tissue uptakerdquo Interna-tional Journal of Pharmaceutics vol 415 no 1-2 pp 232ndash2432011

[35] X Cao W Deng M Fu et al ldquoSeventy-two-hour releaseformulation of the poorly soluble drug silybin based on poroussilica nanoparticles in vitro release kinetics and in vitroin vivocorrelations in beagle dogsrdquo European Journal of Pharmaceuti-cal Sciences vol 48 no 1-2 pp 64ndash71 2013

[36] Y Xu Y Wang X M Li et al ldquoStudy on the release offenofibrate nanosuspension in vitro and its correlation with insitu intestinal and in vivo absorption kinetics in ratsrdquo DrugDevelopment and Industrial Pharmacy vol 40 no 7 pp 972ndash979 2014

[37] N Borkar D Xia R Holm et al ldquoInvestigating the correlationbetween in vivo absorption and in vitro release of fenofibratefrom lipid matrix particles in biorelevant mediumrdquo EuropeanJournal of Pharmaceutical Sciences vol 51 pp 204ndash210 2014

Advances in Pharmaceutics 11

[38] D Heng D J Cutler H K Chan J Yun and J A RaperldquoWhat is a suitable dissolutionmethod for drug nanoparticlesrdquoPharmaceutical Research vol 25 no 7 pp 1696ndash1701 2008

[39] A C Kilic Y Capan I Vural et al ldquoPreparation and characteri-zation of PLGA nanospheres for the targeted delivery of NR2B-specific antisense oligonucleotides to the NMDA receptors inthe brainrdquo Journal of Microencapsulation vol 22 no 6 pp 633ndash641 2005

[40] Y Zhang H Wang C Li et al ldquoA novel three-dimensionallarge-pore mesoporous carbon matrix as a potential nanove-hicle for the fast release of the poorly water-soluble drugcelecoxibrdquoPharmaceutical Research vol 31 pp 1059ndash1070 2014

[41] V Sanna A M Roggio S Siliani et al ldquoDevelopment of novelcationic chitosan-and anionic alginate-coated poly(DL-lactide-co-glycolide) nanoparticles for controlled release and light pro-tection of resveratrolrdquo International Journal of Nanomedicinevol 7 pp 5501ndash5516 2012

[42] F Danhier N Lecouturier B Vroman et al ldquoPaclitaxel-loadedPEGylated PLGA-based nanoparticles In vitro and in vivoevaluationrdquo Journal of Controlled Release vol 133 no 1 pp 11ndash17 2009

[43] Y Li Y Pei X Zhang et al ldquoPEGylated PLGA nanoparticlesas protein carriers synthesis preparation and biodistributionin ratsrdquo Journal of Controlled Release vol 71 no 2 pp 203ndash2112001

[44] S Prabha W-Z Zhou J Panyam and V Labhasetwar ldquoSize-dependency of nanoparticle-mediated gene transfection stud-ies with fractionated nanoparticlesrdquo International Journal ofPharmaceutics vol 244 no 1-2 pp 105ndash115 2002

[45] S J Wallace J Li R L Nation and B J Boyd ldquoDrug releasefrom nanomedicines selection of appropriate encapsulationand release methodologyrdquo Drug Delivery and TranslationalResearch vol 2 no 4 pp 284ndash292 2012

[46] D Juenemann E Jantratid C Wagner C Reppas M Vertzoniand J B Dressman ldquoBiorelevant in vitro dissolution testingof products containing micronized or nanosized fenofibratewith a view to predicting plasma profilesrdquo European Journal ofPharmaceutics and Biopharmaceutics vol 77 no 2 pp 257ndash2642011

[47] P F Yue X Y Lu Z Z Zhang et al ldquoThe study on theentrapment efficiency and in vitro release of puerarin submi-cron emulsionrdquoAAPS PharmSciTech vol 10 no 2 pp 376ndash3832009

[48] M Mahkam F Hosseinzadeh and M Galehassadi ldquoPrepara-tion of ionic liquid functionalized silica nanoparticles for oraldrug deliveryrdquo Journal of Biomaterials amp Nanobiotechnologyvol 3 pp 391ndash395 2012

[49] A S Ham M R Cost A B Sassi C S Dezzutti andL C Rohan ldquoTargeted delivery of PSC-RANTES for HIV-1prevention using biodegradable nanoparticlesrdquo PharmaceuticalResearch vol 26 no 3 pp 502ndash511 2009

[50] Y I Kim L Fluckiger M Hoffman I Lartaud-IdjouadieneJ Atkinson and P Maincent ldquoThe antihypertensive effect oforally administered nifedipine-loaded nanoparticles in sponta-neously hypertensive ratsrdquoThe British Journal of Pharmacologyvol 120 no 3 pp 399ndash404 1997

[51] P Liu O de Wulf J Laru et al ldquoDissolution studies of poorlysoluble drug nanosuspensions in non-sink conditionsrdquo AAPSPharmSciTech vol 14 no 2 pp 748ndash756 2013

[52] L Sievens-Figueroa N Pandya A Bhakay et al ldquoUsing USPI and USP IV for discriminating dissolution rates of nano-

and microparticle-loaded pharmaceutical strip-filmsrdquo AAPSPharmSciTech vol 13 no 4 pp 1473ndash1482 2013

[53] G P Yan R F Zong L Li T Fu F Liu and X H YuldquoAnticancer drug-loaded nanospheres based on biodegradableamphiphilic 120576-caprolactone and carbonate copolymersrdquo Phar-maceutical Research vol 27 no 12 pp 2743ndash2752 2010

[54] P Calvo J L Vila-Jato and M J Alonso ldquoComparative invitro evaluation of several colloidal systems nanoparticlesnanocapsules and nanoemulsions as ocular drug carriersrdquoJournal of Pharmaceutical Sciences vol 85 no 5 pp 530ndash5361996

[55] M SMuthu and S Singh ldquoPoly (D L-lactide) nanosuspensionsof risperidone for parenteral delivery formulation and in-vitroevaluationrdquoCurrent DrugDelivery vol 6 no 1 pp 62ndash68 2009

[56] MY Levy and S Benita ldquoDrug release from submicronized owemulsion a new in vitro kinetic evaluationmodelrdquo InternationalJournal of Pharmaceutics vol 66 no 1ndash3 pp 29ndash37 1990

[57] X Xu M A Khan and D J Burgess ldquoA two-stage reversedialysis in vitro dissolution testing method for passive targetedliposomesrdquo International Journal of Pharmaceutics vol 426 no1-2 pp 211ndash218 2012

[58] B E Kilfoyle L Sheihet Z Zhang M Laohoo J Kohn and BBMichniak-Kohn ldquoDevelopment of paclitaxel-TyroSpheres fortopical skin treatmentrdquo Journal of Controlled Release vol 163no 1 pp 18ndash24 2012

[59] S Uprit R K Sahu A Roy and A Pare ldquoPreparation and char-acterization of minoxidil loaded nanostructured lipid carriergel for effective treatment of alopeciardquo Saudi PharmaceuticalJournal vol 21 pp 379ndash385 2013

[60] B Qiu M Ji X Song et al ldquoCo-delivery of docetaxel andendostatin by a biodegradable nanoparticle for the synergistictreatment of cervical cancerrdquo Nanoscale Research Letters vol 7article 666 2012

[61] S S DrsquoSouza and P P DeLuca ldquoDevelopment of a dialysis invitro release method for biodegradable microspheresrdquo AAPSPharmSciTech vol 6 no 2 article 42 2005

[62] Y Gao J Zuo N Bou-Chacra et al ldquoIn vitro release kineticsof antituberculosis drugs from nanoparticles assessed usinga modified dissolution apparatusrdquo BioMed Research Interna-tional vol 2013 Article ID 136590 9 pages 2013

[63] M Joshi S Pathak S Sharma and V Patravale ldquoDesignand in vivo pharmacodynamic evaluation of nanostructuredlipid carriers for parenteral delivery of artemether nanojectrdquoInternational Journal of Pharmaceutics vol 364 no 1 pp 119ndash126 2008

[64] J W Kostanski and P P DeLuca ldquoA novel in vitro releasetechnique for peptide-containing biodegradable microspheresrdquoAAPS PharmSciTech vol 1 article 4 2000

[65] J P K Tan C H Goh and K C Tam ldquoComparative drugrelease studies of two cationic drugs from pH-responsivenanogelsrdquo European Journal of Pharmaceutical Sciences vol 32no 4-5 pp 340ndash348 2007

[66] K M Rosenblatt D Douroumis and H Bunjes ldquoDrug releasefrom differently structured monooleinpoloxamer nanodisper-sions studied with differential pulse polarography and ultrafil-tration at low pressurerdquo Journal of Pharmaceutical Sciences vol96 no 6 pp 1564ndash1575 2007

[67] N Charalampopoulos K Avgoustakis and C G KontoyannisldquoDifferential pulse polarography a suitable technique for mon-itoring drug release from polymeric nanoparticle dispersionsrdquoAnalytica Chimica Acta vol 491 no 1 pp 57ndash62 2003

12 Advances in Pharmaceutics

[68] P Kayaert B Li I Jimidar P Rombaut F Ahssini and G Vanden Mooter ldquoSolution calorimetry as an alternative approachfor dissolution testing of nanosuspensionsrdquo European Journal ofPharmaceutics and Biopharmaceutics vol 76 no 3 pp 507ndash5132010

[69] M T Crisp C J Tucker T L Rogers R O Williams III andK P Johnston ldquoTurbidimetric measurement and prediction ofdissolution rates of poorly soluble drug nanocrystalsrdquo Journalof Controlled Release vol 117 no 3 pp 351ndash359 2007

[70] M V Chaubal and C Popescu ldquoConversion of nanosus-pensions into dry powders by spray drying a case studyrdquoPharmaceutical Research vol 25 no 10 pp 2302ndash2308 2008

[71] A Helle S Hirsjarvi L Peltonen J Hirvonen S K Wied-mer and T Hyotylainen ldquoNovel dynamic on-line analyticalseparation system for dissolution of drugs from poly(lacticacid) nanoparticlesrdquo Journal of Pharmaceutical and BiomedicalAnalysis vol 51 no 1 pp 125ndash130 2010

[72] V Domınguez-Villegas B Clares-Naveros M L Garcıa-Lopez et al ldquoDevelopment and characterization of two nano-structured systems for topical application of flavanones isolatedfrom Eysenhardtia platycarpardquo Colloids and Surfaces B Bioint-erfaces vol 116 pp 183ndash192 2014

[73] M Barzegar-Jalali K AdibkiaHValizadeh et al ldquoKinetic anal-ysis of drug release from nanoparticlesrdquo Journal of Pharmacyand Pharmaceutical Sciences vol 11 no 1 pp 167ndash177 2008

[74] L Zeng L An and X Wu ldquoModeling drug-carrier interactionin the drug release from nanocarriersrdquo Journal of Drug Deliveryvol 2011 Article ID 370308 15 pages 2011

[75] L Zeng andXWu ldquoModeling the sustained release of lipophilicdrugs from liposomesrdquo Applied Physics Letters vol 97 no 7Article ID 073701 2010

[76] FDA Guidance for Industry Extended Release Oral DosageForms Development Evaluation and Application of In VitroInVivo Correlations 1997

[77] J G Wagner and E Nelson ldquoPer cent absorbed time plotsderived fromblood level andor urinary excretion datardquo Journalof Pharmaceutical Sciences vol 52 pp 610ndash611 1963

Submit your manuscripts athttpwwwhindawicom

PainResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom

Volume 2014

ToxinsJournal of

VaccinesJournal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

AntibioticsInternational Journal of

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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

StrokeResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Drug DeliveryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in Pharmacological Sciences

Tropical MedicineJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

AddictionJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

Emergency Medicine InternationalHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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Autoimmune Diseases

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Anesthesiology Research and Practice

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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Pharmaceutics

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MEDIATORSINFLAMMATION

of

8 Advances in Pharmaceutics

Table 2 Examples of IVIVC with nano-sized dosage forms in animal models

Drug and dosage form In vitro release set-up In vivo studies IVIVC type Reference

Indomethacin gelatin nanoparticles Dialysis bags Wistar Albinorats Level A [32]

Silybin meglumine hollow-spheremesoporous silica nanoparticles Combination (USP Imdashdialysis bag) Beagle dogs Level A [33]

Silybin 72-hour SLB andPSNs (porous silica nanoparticles) Combination (USP Imdashdialysis bag) Beagle dogs Level A [35]

Simvastatin nanostructured lipidcarriers and nanoparticles Dialysis bag BalbC mice Level A [34]

Fenofibrate nanosuspension USP I apparatus SpragueDawley rats Level A [36]

Fenofibrate lipid matrix particles In vitro lipolysis model SpragueDawley rats Rank order [37]

Table 3 Level A IVIVC with two Silybin preparations (data from reference [35])

Formulation absorbed equals 1198772

72-hour SLB 11379 times dissolved + 88688 09831Silybin PSNs (porous silica nanoparticles) 08915 times dissolved minus 10152 09831

have been used to demonstrate an IVIVC from severalnonoral dosage forms including nano-sized preparationsMost published literature on IVIVC compares the in vitrorelease behavior with the in vivo absorption profile thelatter calculated by the FDA recommended Wagner-Nelsonmethod [76 77] Once the fraction absorbed is computeda correlation is obtained by comparing it with the in vitrorelease profile and the type of IVIVC (Level A level B etc) isdetermined

Over the last decade a few reports on IVIVC from nano-sized dosage forms have been published (Table 2) In someinstances a rank order correlation was observed while inothers a Level A IVIVC was established with some or allof the formulations evaluated in the study As an example arank order correlation was observed with three preparationsof Fenofibrate with drug release and absorption from 100 nmlipid matrix particles gt microparticles gt control (crystallinesuspension) [37] In another study on Fenofibrate nanosus-pensions Xu et al attempted to elucidate the absorptionmechanism using in situ gut perfusion model [36] Dataanalysis between in vitro dissolution (119875) in situ intestinalabsorption (119865) and in vivo absorption (119865

119886) demonstrated

a Level A correlation (1198772 gt 095) As a result the authorsconcluded that the in situ intestinal perfusion model couldbe a predictor of in vivo pharmacokinetic behavior for thenanosuspension

In a recent report Kumar et al investigated the relation-ship between in vitro and in vivo release from Indomethacingelatin nanoparticles administered orally to Wistar albinorats [32] Study results indicated that a good correlation wasobtained by plotting the fraction absorbed in vivo (Wagner-Nelson method) against the fraction released the latter per-formed using regular dialysis (dialysis bags) (Figure 10) TheWagner-Nelsonmethod was also used in another publication

0

20

40

60

80

100

120

0 20 40 60 80 100

In v

ivo

abso

rptio

n (

)

In vitro release ()

R2 = 0981

y = 1121x

Figure 10 Level A IVIVC from Indomethacin gelatin nanoparticlesusing regular dialysis (redrawn from [32])

where the in vivo absorption fromSilybinmeglumine hollow-sphere mesoporous silica nanoparticles dosed orally to bea-gle dogs was compared with in vitro results obtained using acombination USP I (paddle) dialysis bag set-up [33] Of thefive different releasemedia used in the study a Level A IVIVC(1198772 gt 097) was obtained with 006M Na

2CO3and 008M

Na2CO3solutions (Figure 11) In another study with Silybin

an IVIVC was achieved with a 72-hour release formulationof Silybin (72-hour SLB) that consisted of a solid dispersiongel matrix and porous silica nanoparticles (PSNs) (Table 3)[35] Similar to the earlier study the authors compared invivo release from beagle dogs with in vitro release assessedusing a combination USP I (paddle) dialysis bag set-upIn another paper Tiwari et al demonstrated a Level A

Advances in Pharmaceutics 9

0

20

40

60

80

100

0 20 40 60 80 100

Abso

rbed

()

Abso

rbed

()

0 20 40 60 80 1000

20

40

60

80

100

In vitro release ()

In vitro release ()

y = 23417x minus 78256

R2 = 09741

y = 16114x minus 56752

R2 = 09931

006M Na2CO3

008M Na2CO3

Figure 11 Level A IVIVC from Silybin meglumine hollow-typemesoporous silica nanoparticles using a combined USP II-dialysisbag set-up (redrawn from [33])

correlation between in vitro release (dialysis bag) and percentdrug absorbed (Wagner Nelson method) for Simvastatinnanostructured lipid carriers as well as nanoparticles (1198772 gt094) (Figure 12) [34]

5 Conclusions

For novel dosage forms like nanoparticles where no regu-latory or compendial standards exist in vitro drug releaseassessment assumes greater significance in serving as anindicator of product quality and performance A plethoraof methods have been used each with their advantages anddrawbacks with respect to ease of set-up sampling and rapidbuffer replacement Ideally an in vitro release method shouldsimulate in vivo conditions release mechanisms and enablethe establishment of an IVIVC Future research should focuson developing relevant mathematical models to predict drugrelease behavior as well as release mechanisms applicable to awide range of nano-sized dosage forms

Conflict of Interests

The author declares that there is no conflict of interestsregarding the publication of this paper

0

20

40

60

80

100

120

Dru

g ab

sorb

ed (

)

0

20

40

60

80

100

120

Dru

g ab

sorb

ed (

)

Simvastatin loaded nanostructured lipid carriers

Simvastatin loaded solid lipid nanoparticles

0 20 40 60 80 100In vitro release ()

0 20 40 60 80 100In vitro release ()

R2 = 09404

R2 = 0941

Figure 12 Level A correlation of Simvastatin from two nano-sizeddosage forms (redrawn from [34])

References

[1] N Al Khouri Fallouh L Roblot-Treupel and H Fessi ldquoDevel-opment of a new process for the manufacture of polyisobutyl-cyanoacrylate nanocapsulesrdquo International Journal of Pharma-ceutics vol 28 no 2-3 pp 125ndash132 1986

[2] C Losa P Calvo E Castro J L Vila-Jato and M J AlonsoldquoImprovement of ocular penetration of amikacin sulphate byassociation to poly(butylcyanoacrylate) nanoparticlesrdquo Journalof Pharmacy and Pharmacology vol 43 no 8 pp 548ndash552 1991

[3] C Losa L Marchal-Heussler F Orallo J L Vila Jato andM J Alonso ldquoDesign of new formulations for topical ocularadministration polymeric nanocapsules containing metipra-nololrdquo Pharmaceutical Research vol 10 no 1 pp 80ndash87 1993

[4] C N Cruz K M Tyner L Velazquez et al ldquoCDER riskassessment exercise to evaluate potential risks from the use ofnanomaterials in drug productsrdquo AAPS Journal vol 15 no 3pp 623ndash628 2013

[5] G Verreck I Chun J Rosenblatt et al ldquoIncorporation of drugsin an amorphous state into electrospun nanofibers composedof a water-insoluble nonbiodegradable polymerrdquo Journal ofControlled Release vol 92 no 3 pp 349ndash360 2003

[6] H Heiati R Tawashi R R Shivers and N C PhillipsldquoSolid lipid nanoparticles as drug carriers I incorporation andretention of the lipophilic prodrug 31015840-azido-31015840-deoxythymidinepalmitaterdquo International Journal of Pharmaceutics vol 146 no1 pp 123ndash131 1997

10 Advances in Pharmaceutics

[7] M Cetin A Atila and Y Kadioglu ldquoFormulation and in vitrocharacterization of Eudragit L100 and Eudragit L100-PLGAnanoparticles containing diclofenac sodiumrdquo AAPS Pharm-SciTech vol 11 pp 1250ndash1256 2010

[8] A Hanafy H Spahn-Langguth G Vergnault et al ldquoPharma-cokinetic evaluation of oral fenofibrate nanosuspensions andSLN in comparison to conventional suspensions of micronizeddrugrdquo Advanced Drug Delivery Reviews vol 59 no 6 pp 419ndash426 2007

[9] T M Allen W W K Cheng J I Hare and K M LaginhaldquoPharmacokinetics and pharmacodynamics of lipidic nano-particles in cancerrdquoAnti-Cancer Agents in Medicinal Chemistryvol 6 no 6 pp 513ndash523 2006

[10] J Kreuter ldquoNanoparticle-based drug delivery systemsrdquo Journalof Controlled Release vol 16 no 1-2 pp 169ndash176 1991

[11] M L Etheridge S A Campbell A G Erdman C L Haynes SMWolf and JMcCullough ldquoThe big picture on nanomedicinethe state of investigational and approved nanomedicine prod-uctsrdquo Nanomedicine Nanotechnology Biology and Medicinevol 9 no 1 pp 1ndash14 2013

[12] S Nie ldquoUnderstanding and overcoming major barriers incancer nanomedicinerdquoNanomedicine vol 5 no 4 pp 523ndash5282010

[13] W H de Jong and P J A Borm ldquoDrug delivery andnanoparticles applications and hazardsrdquo International Journalof Nanomedicine vol 3 no 2 pp 133ndash149 2008

[14] S DrsquoSouza J A Faraj R Dorati and P P DeLuca ldquoA short termquality control tool for biodegradable microspheresrdquo AAPSPharmSciTech vol 15 no 3 pp 530ndash541 2014

[15] P Buch P Holm J Q Thomassen et al ldquoIVIVC for fenofibrateimmediate release tablets using solubility and permeability as invitro predictors for pharmacokineticsrdquo Journal of Pharmaceuti-cal Sciences vol 99 no 10 pp 4427ndash4436 2010

[16] S DrsquoSouza J A Faraj S Giovagnoli and P P DeLuca ldquoIVIVCfrom long acting olanzapine microspheresrdquo International Jour-nal of Biomaterials vol 2014 Article ID 407065 11 pages 2014

[17] L C Amann M J Gandal R Lin Y Liang and S J SiegelldquoIn vitro-in vivo correlations of scalable PLGA-Risperidoneimplants for the treatment of schizophreniardquo PharmaceuticalResearch vol 27 no 8 pp 1730ndash1737 2010

[18] G Zackrisson G Ostling B Skagerberg and T Anfalt ldquoACcel-erated Dissolution Rate Analysis (ACDRA) for controlledrelease drugs Application to Roxiamrdquo Journal of Pharmaceu-tical and Biomedical Analysis vol 13 no 4-5 pp 377ndash383 1995

[19] S S DSouza J A Faraj and P P DeLuca ldquoA model-dependentapproach to correlate accelerated with real-time release frombiodegradable microspheresrdquo AAPS PharmSciTech vol 6 arti-cle 70 no 4 2005

[20] D J Burgess A S Hussain T S Ingallinera and M ChenldquoAssuring quality and performance of sustained and controlledrelease parenterals workshop reportrdquo AAPS PharmSci vol 4article E7 2002

[21] S S DrsquoSouza and P P DeLuca ldquoMethods to assess in vitrodrug release from injectable polymeric particulate systemsrdquoPharmaceutical Research vol 23 no 3 pp 460ndash474 2006

[22] M Siewert J Dressman C K Brown and V P ShahldquoFIPAAPS guidelines to dissolutionin vitro release testing ofnovelspecial dosage formsrdquo AAPS PharmSciTech vol 4 article7 2003

[23] C K Brown H D Friedel A R Barker et al ldquoFIPAAPSjoint workshop report dissolutionin vitro release testing of

novelspecial dosage formsrdquo AAPS PharmSciTech vol 12 no2 pp 782ndash794 2011

[24] MMartinezM Rathbone D Burgess andMHuynh ldquoIn vitroand in vivo considerations associated with parenteral sustainedrelease products a review based upon information presentedand points expressed at the 2007 Controlled Release SocietyAnnual Meetingrdquo Journal of Controlled Release vol 129 no 2pp 79ndash87 2008

[25] M N Martinez M J Rathbone D Burgess and M HuynhldquoBreakout session summary from AAPSCRS joint workshopon critical variables in the in vitro and in vivo performanceof parenteral sustained release productsrdquo Journal of ControlledRelease vol 142 no 1 pp 2ndash7 2010

[26] N Chidambaram and D J Burgess ldquoA novel in vitro releasemethod for submicron-sized dispersed systemsrdquo AAPS Pharm-Sci vol 1 no 3 pp 32ndash40 1999

[27] M M A Abdel-Mottaleb and A Lamprecht ldquoStandardized invitro drug release test for colloidal drug carriers using modifiedUSP dissolution apparatus Irdquo Drug Development and IndustrialPharmacy vol 37 no 2 pp 178ndash184 2011

[28] A Maghsoudi S A Shojaosadati and E Vasheghani Farahanildquo5-Fluorouracil-loaded BSA nanoparticles formulation opti-mization and in vitro release studyrdquo AAPS PharmSciTech vol9 no 4 pp 1092ndash1096 2008

[29] U Bhardwaj and D J Burgess ldquoA novel USP apparatus 4 basedrelease testing method for dispersed systemsrdquo InternationalJournal of Pharmaceutics vol 388 no 1-2 pp 287ndash294 2010

[30] L Mora K Y Chumbimuni-Torres C Clawson L HernandezL Zhang and J Wang ldquoReal-time electrochemical monitoringof drug release from therapeutic nanoparticlesrdquo Journal ofControlled Release vol 140 no 1 pp 69ndash73 2009

[31] C B Michalowski S S Guterres and T Dalla CostaldquoMicrodialysis for evaluating the entrapment and release of alipophilic drug from nanoparticlesrdquo Journal of Pharmaceuticaland Biomedical Analysis vol 35 no 5 pp 1093ndash1100 2004

[32] R Kumar R C Nagarwal M Dhanawat and J K PanditldquoIn-vitro and in-vivo study of indomethacin loaded gelatinnanoparticlesrdquo Journal of Biomedical Nanotechnology vol 7 no3 pp 325ndash333 2011

[33] X Cao W W Deng M Fu et al ldquoIn vitro release and in vitro-in vivo correlation for silybin meglumine incorporated intoHollow-type mesoporous silica nanoparticlesrdquo InternationalJournal of Nanomedicine vol 7 pp 753ndash762 2012

[34] R Tiwari and K Pathak ldquoNanostructured lipid carrier versussolid lipid nanoparticles of simvastatin comparative analysis ofcharacteristics pharmacokinetics and tissue uptakerdquo Interna-tional Journal of Pharmaceutics vol 415 no 1-2 pp 232ndash2432011

[35] X Cao W Deng M Fu et al ldquoSeventy-two-hour releaseformulation of the poorly soluble drug silybin based on poroussilica nanoparticles in vitro release kinetics and in vitroin vivocorrelations in beagle dogsrdquo European Journal of Pharmaceuti-cal Sciences vol 48 no 1-2 pp 64ndash71 2013

[36] Y Xu Y Wang X M Li et al ldquoStudy on the release offenofibrate nanosuspension in vitro and its correlation with insitu intestinal and in vivo absorption kinetics in ratsrdquo DrugDevelopment and Industrial Pharmacy vol 40 no 7 pp 972ndash979 2014

[37] N Borkar D Xia R Holm et al ldquoInvestigating the correlationbetween in vivo absorption and in vitro release of fenofibratefrom lipid matrix particles in biorelevant mediumrdquo EuropeanJournal of Pharmaceutical Sciences vol 51 pp 204ndash210 2014

Advances in Pharmaceutics 11

[38] D Heng D J Cutler H K Chan J Yun and J A RaperldquoWhat is a suitable dissolutionmethod for drug nanoparticlesrdquoPharmaceutical Research vol 25 no 7 pp 1696ndash1701 2008

[39] A C Kilic Y Capan I Vural et al ldquoPreparation and characteri-zation of PLGA nanospheres for the targeted delivery of NR2B-specific antisense oligonucleotides to the NMDA receptors inthe brainrdquo Journal of Microencapsulation vol 22 no 6 pp 633ndash641 2005

[40] Y Zhang H Wang C Li et al ldquoA novel three-dimensionallarge-pore mesoporous carbon matrix as a potential nanove-hicle for the fast release of the poorly water-soluble drugcelecoxibrdquoPharmaceutical Research vol 31 pp 1059ndash1070 2014

[41] V Sanna A M Roggio S Siliani et al ldquoDevelopment of novelcationic chitosan-and anionic alginate-coated poly(DL-lactide-co-glycolide) nanoparticles for controlled release and light pro-tection of resveratrolrdquo International Journal of Nanomedicinevol 7 pp 5501ndash5516 2012

[42] F Danhier N Lecouturier B Vroman et al ldquoPaclitaxel-loadedPEGylated PLGA-based nanoparticles In vitro and in vivoevaluationrdquo Journal of Controlled Release vol 133 no 1 pp 11ndash17 2009

[43] Y Li Y Pei X Zhang et al ldquoPEGylated PLGA nanoparticlesas protein carriers synthesis preparation and biodistributionin ratsrdquo Journal of Controlled Release vol 71 no 2 pp 203ndash2112001

[44] S Prabha W-Z Zhou J Panyam and V Labhasetwar ldquoSize-dependency of nanoparticle-mediated gene transfection stud-ies with fractionated nanoparticlesrdquo International Journal ofPharmaceutics vol 244 no 1-2 pp 105ndash115 2002

[45] S J Wallace J Li R L Nation and B J Boyd ldquoDrug releasefrom nanomedicines selection of appropriate encapsulationand release methodologyrdquo Drug Delivery and TranslationalResearch vol 2 no 4 pp 284ndash292 2012

[46] D Juenemann E Jantratid C Wagner C Reppas M Vertzoniand J B Dressman ldquoBiorelevant in vitro dissolution testingof products containing micronized or nanosized fenofibratewith a view to predicting plasma profilesrdquo European Journal ofPharmaceutics and Biopharmaceutics vol 77 no 2 pp 257ndash2642011

[47] P F Yue X Y Lu Z Z Zhang et al ldquoThe study on theentrapment efficiency and in vitro release of puerarin submi-cron emulsionrdquoAAPS PharmSciTech vol 10 no 2 pp 376ndash3832009

[48] M Mahkam F Hosseinzadeh and M Galehassadi ldquoPrepara-tion of ionic liquid functionalized silica nanoparticles for oraldrug deliveryrdquo Journal of Biomaterials amp Nanobiotechnologyvol 3 pp 391ndash395 2012

[49] A S Ham M R Cost A B Sassi C S Dezzutti andL C Rohan ldquoTargeted delivery of PSC-RANTES for HIV-1prevention using biodegradable nanoparticlesrdquo PharmaceuticalResearch vol 26 no 3 pp 502ndash511 2009

[50] Y I Kim L Fluckiger M Hoffman I Lartaud-IdjouadieneJ Atkinson and P Maincent ldquoThe antihypertensive effect oforally administered nifedipine-loaded nanoparticles in sponta-neously hypertensive ratsrdquoThe British Journal of Pharmacologyvol 120 no 3 pp 399ndash404 1997

[51] P Liu O de Wulf J Laru et al ldquoDissolution studies of poorlysoluble drug nanosuspensions in non-sink conditionsrdquo AAPSPharmSciTech vol 14 no 2 pp 748ndash756 2013

[52] L Sievens-Figueroa N Pandya A Bhakay et al ldquoUsing USPI and USP IV for discriminating dissolution rates of nano-

and microparticle-loaded pharmaceutical strip-filmsrdquo AAPSPharmSciTech vol 13 no 4 pp 1473ndash1482 2013

[53] G P Yan R F Zong L Li T Fu F Liu and X H YuldquoAnticancer drug-loaded nanospheres based on biodegradableamphiphilic 120576-caprolactone and carbonate copolymersrdquo Phar-maceutical Research vol 27 no 12 pp 2743ndash2752 2010

[54] P Calvo J L Vila-Jato and M J Alonso ldquoComparative invitro evaluation of several colloidal systems nanoparticlesnanocapsules and nanoemulsions as ocular drug carriersrdquoJournal of Pharmaceutical Sciences vol 85 no 5 pp 530ndash5361996

[55] M SMuthu and S Singh ldquoPoly (D L-lactide) nanosuspensionsof risperidone for parenteral delivery formulation and in-vitroevaluationrdquoCurrent DrugDelivery vol 6 no 1 pp 62ndash68 2009

[56] MY Levy and S Benita ldquoDrug release from submicronized owemulsion a new in vitro kinetic evaluationmodelrdquo InternationalJournal of Pharmaceutics vol 66 no 1ndash3 pp 29ndash37 1990

[57] X Xu M A Khan and D J Burgess ldquoA two-stage reversedialysis in vitro dissolution testing method for passive targetedliposomesrdquo International Journal of Pharmaceutics vol 426 no1-2 pp 211ndash218 2012

[58] B E Kilfoyle L Sheihet Z Zhang M Laohoo J Kohn and BBMichniak-Kohn ldquoDevelopment of paclitaxel-TyroSpheres fortopical skin treatmentrdquo Journal of Controlled Release vol 163no 1 pp 18ndash24 2012

[59] S Uprit R K Sahu A Roy and A Pare ldquoPreparation and char-acterization of minoxidil loaded nanostructured lipid carriergel for effective treatment of alopeciardquo Saudi PharmaceuticalJournal vol 21 pp 379ndash385 2013

[60] B Qiu M Ji X Song et al ldquoCo-delivery of docetaxel andendostatin by a biodegradable nanoparticle for the synergistictreatment of cervical cancerrdquo Nanoscale Research Letters vol 7article 666 2012

[61] S S DrsquoSouza and P P DeLuca ldquoDevelopment of a dialysis invitro release method for biodegradable microspheresrdquo AAPSPharmSciTech vol 6 no 2 article 42 2005

[62] Y Gao J Zuo N Bou-Chacra et al ldquoIn vitro release kineticsof antituberculosis drugs from nanoparticles assessed usinga modified dissolution apparatusrdquo BioMed Research Interna-tional vol 2013 Article ID 136590 9 pages 2013

[63] M Joshi S Pathak S Sharma and V Patravale ldquoDesignand in vivo pharmacodynamic evaluation of nanostructuredlipid carriers for parenteral delivery of artemether nanojectrdquoInternational Journal of Pharmaceutics vol 364 no 1 pp 119ndash126 2008

[64] J W Kostanski and P P DeLuca ldquoA novel in vitro releasetechnique for peptide-containing biodegradable microspheresrdquoAAPS PharmSciTech vol 1 article 4 2000

[65] J P K Tan C H Goh and K C Tam ldquoComparative drugrelease studies of two cationic drugs from pH-responsivenanogelsrdquo European Journal of Pharmaceutical Sciences vol 32no 4-5 pp 340ndash348 2007

[66] K M Rosenblatt D Douroumis and H Bunjes ldquoDrug releasefrom differently structured monooleinpoloxamer nanodisper-sions studied with differential pulse polarography and ultrafil-tration at low pressurerdquo Journal of Pharmaceutical Sciences vol96 no 6 pp 1564ndash1575 2007

[67] N Charalampopoulos K Avgoustakis and C G KontoyannisldquoDifferential pulse polarography a suitable technique for mon-itoring drug release from polymeric nanoparticle dispersionsrdquoAnalytica Chimica Acta vol 491 no 1 pp 57ndash62 2003

12 Advances in Pharmaceutics

[68] P Kayaert B Li I Jimidar P Rombaut F Ahssini and G Vanden Mooter ldquoSolution calorimetry as an alternative approachfor dissolution testing of nanosuspensionsrdquo European Journal ofPharmaceutics and Biopharmaceutics vol 76 no 3 pp 507ndash5132010

[69] M T Crisp C J Tucker T L Rogers R O Williams III andK P Johnston ldquoTurbidimetric measurement and prediction ofdissolution rates of poorly soluble drug nanocrystalsrdquo Journalof Controlled Release vol 117 no 3 pp 351ndash359 2007

[70] M V Chaubal and C Popescu ldquoConversion of nanosus-pensions into dry powders by spray drying a case studyrdquoPharmaceutical Research vol 25 no 10 pp 2302ndash2308 2008

[71] A Helle S Hirsjarvi L Peltonen J Hirvonen S K Wied-mer and T Hyotylainen ldquoNovel dynamic on-line analyticalseparation system for dissolution of drugs from poly(lacticacid) nanoparticlesrdquo Journal of Pharmaceutical and BiomedicalAnalysis vol 51 no 1 pp 125ndash130 2010

[72] V Domınguez-Villegas B Clares-Naveros M L Garcıa-Lopez et al ldquoDevelopment and characterization of two nano-structured systems for topical application of flavanones isolatedfrom Eysenhardtia platycarpardquo Colloids and Surfaces B Bioint-erfaces vol 116 pp 183ndash192 2014

[73] M Barzegar-Jalali K AdibkiaHValizadeh et al ldquoKinetic anal-ysis of drug release from nanoparticlesrdquo Journal of Pharmacyand Pharmaceutical Sciences vol 11 no 1 pp 167ndash177 2008

[74] L Zeng L An and X Wu ldquoModeling drug-carrier interactionin the drug release from nanocarriersrdquo Journal of Drug Deliveryvol 2011 Article ID 370308 15 pages 2011

[75] L Zeng andXWu ldquoModeling the sustained release of lipophilicdrugs from liposomesrdquo Applied Physics Letters vol 97 no 7Article ID 073701 2010

[76] FDA Guidance for Industry Extended Release Oral DosageForms Development Evaluation and Application of In VitroInVivo Correlations 1997

[77] J G Wagner and E Nelson ldquoPer cent absorbed time plotsderived fromblood level andor urinary excretion datardquo Journalof Pharmaceutical Sciences vol 52 pp 610ndash611 1963

Submit your manuscripts athttpwwwhindawicom

PainResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom

Volume 2014

ToxinsJournal of

VaccinesJournal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

AntibioticsInternational Journal of

ToxicologyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

StrokeResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Drug DeliveryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in Pharmacological Sciences

Tropical MedicineJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

AddictionJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

Emergency Medicine InternationalHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Autoimmune Diseases

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Anesthesiology Research and Practice

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Pharmaceutics

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MEDIATORSINFLAMMATION

of

Advances in Pharmaceutics 9

0

20

40

60

80

100

0 20 40 60 80 100

Abso

rbed

()

Abso

rbed

()

0 20 40 60 80 1000

20

40

60

80

100

In vitro release ()

In vitro release ()

y = 23417x minus 78256

R2 = 09741

y = 16114x minus 56752

R2 = 09931

006M Na2CO3

008M Na2CO3

Figure 11 Level A IVIVC from Silybin meglumine hollow-typemesoporous silica nanoparticles using a combined USP II-dialysisbag set-up (redrawn from [33])

correlation between in vitro release (dialysis bag) and percentdrug absorbed (Wagner Nelson method) for Simvastatinnanostructured lipid carriers as well as nanoparticles (1198772 gt094) (Figure 12) [34]

5 Conclusions

For novel dosage forms like nanoparticles where no regu-latory or compendial standards exist in vitro drug releaseassessment assumes greater significance in serving as anindicator of product quality and performance A plethoraof methods have been used each with their advantages anddrawbacks with respect to ease of set-up sampling and rapidbuffer replacement Ideally an in vitro release method shouldsimulate in vivo conditions release mechanisms and enablethe establishment of an IVIVC Future research should focuson developing relevant mathematical models to predict drugrelease behavior as well as release mechanisms applicable to awide range of nano-sized dosage forms

Conflict of Interests

The author declares that there is no conflict of interestsregarding the publication of this paper

0

20

40

60

80

100

120

Dru

g ab

sorb

ed (

)

0

20

40

60

80

100

120

Dru

g ab

sorb

ed (

)

Simvastatin loaded nanostructured lipid carriers

Simvastatin loaded solid lipid nanoparticles

0 20 40 60 80 100In vitro release ()

0 20 40 60 80 100In vitro release ()

R2 = 09404

R2 = 0941

Figure 12 Level A correlation of Simvastatin from two nano-sizeddosage forms (redrawn from [34])

References

[1] N Al Khouri Fallouh L Roblot-Treupel and H Fessi ldquoDevel-opment of a new process for the manufacture of polyisobutyl-cyanoacrylate nanocapsulesrdquo International Journal of Pharma-ceutics vol 28 no 2-3 pp 125ndash132 1986

[2] C Losa P Calvo E Castro J L Vila-Jato and M J AlonsoldquoImprovement of ocular penetration of amikacin sulphate byassociation to poly(butylcyanoacrylate) nanoparticlesrdquo Journalof Pharmacy and Pharmacology vol 43 no 8 pp 548ndash552 1991

[3] C Losa L Marchal-Heussler F Orallo J L Vila Jato andM J Alonso ldquoDesign of new formulations for topical ocularadministration polymeric nanocapsules containing metipra-nololrdquo Pharmaceutical Research vol 10 no 1 pp 80ndash87 1993

[4] C N Cruz K M Tyner L Velazquez et al ldquoCDER riskassessment exercise to evaluate potential risks from the use ofnanomaterials in drug productsrdquo AAPS Journal vol 15 no 3pp 623ndash628 2013

[5] G Verreck I Chun J Rosenblatt et al ldquoIncorporation of drugsin an amorphous state into electrospun nanofibers composedof a water-insoluble nonbiodegradable polymerrdquo Journal ofControlled Release vol 92 no 3 pp 349ndash360 2003

[6] H Heiati R Tawashi R R Shivers and N C PhillipsldquoSolid lipid nanoparticles as drug carriers I incorporation andretention of the lipophilic prodrug 31015840-azido-31015840-deoxythymidinepalmitaterdquo International Journal of Pharmaceutics vol 146 no1 pp 123ndash131 1997

10 Advances in Pharmaceutics

[7] M Cetin A Atila and Y Kadioglu ldquoFormulation and in vitrocharacterization of Eudragit L100 and Eudragit L100-PLGAnanoparticles containing diclofenac sodiumrdquo AAPS Pharm-SciTech vol 11 pp 1250ndash1256 2010

[8] A Hanafy H Spahn-Langguth G Vergnault et al ldquoPharma-cokinetic evaluation of oral fenofibrate nanosuspensions andSLN in comparison to conventional suspensions of micronizeddrugrdquo Advanced Drug Delivery Reviews vol 59 no 6 pp 419ndash426 2007

[9] T M Allen W W K Cheng J I Hare and K M LaginhaldquoPharmacokinetics and pharmacodynamics of lipidic nano-particles in cancerrdquoAnti-Cancer Agents in Medicinal Chemistryvol 6 no 6 pp 513ndash523 2006

[10] J Kreuter ldquoNanoparticle-based drug delivery systemsrdquo Journalof Controlled Release vol 16 no 1-2 pp 169ndash176 1991

[11] M L Etheridge S A Campbell A G Erdman C L Haynes SMWolf and JMcCullough ldquoThe big picture on nanomedicinethe state of investigational and approved nanomedicine prod-uctsrdquo Nanomedicine Nanotechnology Biology and Medicinevol 9 no 1 pp 1ndash14 2013

[12] S Nie ldquoUnderstanding and overcoming major barriers incancer nanomedicinerdquoNanomedicine vol 5 no 4 pp 523ndash5282010

[13] W H de Jong and P J A Borm ldquoDrug delivery andnanoparticles applications and hazardsrdquo International Journalof Nanomedicine vol 3 no 2 pp 133ndash149 2008

[14] S DrsquoSouza J A Faraj R Dorati and P P DeLuca ldquoA short termquality control tool for biodegradable microspheresrdquo AAPSPharmSciTech vol 15 no 3 pp 530ndash541 2014

[15] P Buch P Holm J Q Thomassen et al ldquoIVIVC for fenofibrateimmediate release tablets using solubility and permeability as invitro predictors for pharmacokineticsrdquo Journal of Pharmaceuti-cal Sciences vol 99 no 10 pp 4427ndash4436 2010

[16] S DrsquoSouza J A Faraj S Giovagnoli and P P DeLuca ldquoIVIVCfrom long acting olanzapine microspheresrdquo International Jour-nal of Biomaterials vol 2014 Article ID 407065 11 pages 2014

[17] L C Amann M J Gandal R Lin Y Liang and S J SiegelldquoIn vitro-in vivo correlations of scalable PLGA-Risperidoneimplants for the treatment of schizophreniardquo PharmaceuticalResearch vol 27 no 8 pp 1730ndash1737 2010

[18] G Zackrisson G Ostling B Skagerberg and T Anfalt ldquoACcel-erated Dissolution Rate Analysis (ACDRA) for controlledrelease drugs Application to Roxiamrdquo Journal of Pharmaceu-tical and Biomedical Analysis vol 13 no 4-5 pp 377ndash383 1995

[19] S S DSouza J A Faraj and P P DeLuca ldquoA model-dependentapproach to correlate accelerated with real-time release frombiodegradable microspheresrdquo AAPS PharmSciTech vol 6 arti-cle 70 no 4 2005

[20] D J Burgess A S Hussain T S Ingallinera and M ChenldquoAssuring quality and performance of sustained and controlledrelease parenterals workshop reportrdquo AAPS PharmSci vol 4article E7 2002

[21] S S DrsquoSouza and P P DeLuca ldquoMethods to assess in vitrodrug release from injectable polymeric particulate systemsrdquoPharmaceutical Research vol 23 no 3 pp 460ndash474 2006

[22] M Siewert J Dressman C K Brown and V P ShahldquoFIPAAPS guidelines to dissolutionin vitro release testing ofnovelspecial dosage formsrdquo AAPS PharmSciTech vol 4 article7 2003

[23] C K Brown H D Friedel A R Barker et al ldquoFIPAAPSjoint workshop report dissolutionin vitro release testing of

novelspecial dosage formsrdquo AAPS PharmSciTech vol 12 no2 pp 782ndash794 2011

[24] MMartinezM Rathbone D Burgess andMHuynh ldquoIn vitroand in vivo considerations associated with parenteral sustainedrelease products a review based upon information presentedand points expressed at the 2007 Controlled Release SocietyAnnual Meetingrdquo Journal of Controlled Release vol 129 no 2pp 79ndash87 2008

[25] M N Martinez M J Rathbone D Burgess and M HuynhldquoBreakout session summary from AAPSCRS joint workshopon critical variables in the in vitro and in vivo performanceof parenteral sustained release productsrdquo Journal of ControlledRelease vol 142 no 1 pp 2ndash7 2010

[26] N Chidambaram and D J Burgess ldquoA novel in vitro releasemethod for submicron-sized dispersed systemsrdquo AAPS Pharm-Sci vol 1 no 3 pp 32ndash40 1999

[27] M M A Abdel-Mottaleb and A Lamprecht ldquoStandardized invitro drug release test for colloidal drug carriers using modifiedUSP dissolution apparatus Irdquo Drug Development and IndustrialPharmacy vol 37 no 2 pp 178ndash184 2011

[28] A Maghsoudi S A Shojaosadati and E Vasheghani Farahanildquo5-Fluorouracil-loaded BSA nanoparticles formulation opti-mization and in vitro release studyrdquo AAPS PharmSciTech vol9 no 4 pp 1092ndash1096 2008

[29] U Bhardwaj and D J Burgess ldquoA novel USP apparatus 4 basedrelease testing method for dispersed systemsrdquo InternationalJournal of Pharmaceutics vol 388 no 1-2 pp 287ndash294 2010

[30] L Mora K Y Chumbimuni-Torres C Clawson L HernandezL Zhang and J Wang ldquoReal-time electrochemical monitoringof drug release from therapeutic nanoparticlesrdquo Journal ofControlled Release vol 140 no 1 pp 69ndash73 2009

[31] C B Michalowski S S Guterres and T Dalla CostaldquoMicrodialysis for evaluating the entrapment and release of alipophilic drug from nanoparticlesrdquo Journal of Pharmaceuticaland Biomedical Analysis vol 35 no 5 pp 1093ndash1100 2004

[32] R Kumar R C Nagarwal M Dhanawat and J K PanditldquoIn-vitro and in-vivo study of indomethacin loaded gelatinnanoparticlesrdquo Journal of Biomedical Nanotechnology vol 7 no3 pp 325ndash333 2011

[33] X Cao W W Deng M Fu et al ldquoIn vitro release and in vitro-in vivo correlation for silybin meglumine incorporated intoHollow-type mesoporous silica nanoparticlesrdquo InternationalJournal of Nanomedicine vol 7 pp 753ndash762 2012

[34] R Tiwari and K Pathak ldquoNanostructured lipid carrier versussolid lipid nanoparticles of simvastatin comparative analysis ofcharacteristics pharmacokinetics and tissue uptakerdquo Interna-tional Journal of Pharmaceutics vol 415 no 1-2 pp 232ndash2432011

[35] X Cao W Deng M Fu et al ldquoSeventy-two-hour releaseformulation of the poorly soluble drug silybin based on poroussilica nanoparticles in vitro release kinetics and in vitroin vivocorrelations in beagle dogsrdquo European Journal of Pharmaceuti-cal Sciences vol 48 no 1-2 pp 64ndash71 2013

[36] Y Xu Y Wang X M Li et al ldquoStudy on the release offenofibrate nanosuspension in vitro and its correlation with insitu intestinal and in vivo absorption kinetics in ratsrdquo DrugDevelopment and Industrial Pharmacy vol 40 no 7 pp 972ndash979 2014

[37] N Borkar D Xia R Holm et al ldquoInvestigating the correlationbetween in vivo absorption and in vitro release of fenofibratefrom lipid matrix particles in biorelevant mediumrdquo EuropeanJournal of Pharmaceutical Sciences vol 51 pp 204ndash210 2014

Advances in Pharmaceutics 11

[38] D Heng D J Cutler H K Chan J Yun and J A RaperldquoWhat is a suitable dissolutionmethod for drug nanoparticlesrdquoPharmaceutical Research vol 25 no 7 pp 1696ndash1701 2008

[39] A C Kilic Y Capan I Vural et al ldquoPreparation and characteri-zation of PLGA nanospheres for the targeted delivery of NR2B-specific antisense oligonucleotides to the NMDA receptors inthe brainrdquo Journal of Microencapsulation vol 22 no 6 pp 633ndash641 2005

[40] Y Zhang H Wang C Li et al ldquoA novel three-dimensionallarge-pore mesoporous carbon matrix as a potential nanove-hicle for the fast release of the poorly water-soluble drugcelecoxibrdquoPharmaceutical Research vol 31 pp 1059ndash1070 2014

[41] V Sanna A M Roggio S Siliani et al ldquoDevelopment of novelcationic chitosan-and anionic alginate-coated poly(DL-lactide-co-glycolide) nanoparticles for controlled release and light pro-tection of resveratrolrdquo International Journal of Nanomedicinevol 7 pp 5501ndash5516 2012

[42] F Danhier N Lecouturier B Vroman et al ldquoPaclitaxel-loadedPEGylated PLGA-based nanoparticles In vitro and in vivoevaluationrdquo Journal of Controlled Release vol 133 no 1 pp 11ndash17 2009

[43] Y Li Y Pei X Zhang et al ldquoPEGylated PLGA nanoparticlesas protein carriers synthesis preparation and biodistributionin ratsrdquo Journal of Controlled Release vol 71 no 2 pp 203ndash2112001

[44] S Prabha W-Z Zhou J Panyam and V Labhasetwar ldquoSize-dependency of nanoparticle-mediated gene transfection stud-ies with fractionated nanoparticlesrdquo International Journal ofPharmaceutics vol 244 no 1-2 pp 105ndash115 2002

[45] S J Wallace J Li R L Nation and B J Boyd ldquoDrug releasefrom nanomedicines selection of appropriate encapsulationand release methodologyrdquo Drug Delivery and TranslationalResearch vol 2 no 4 pp 284ndash292 2012

[46] D Juenemann E Jantratid C Wagner C Reppas M Vertzoniand J B Dressman ldquoBiorelevant in vitro dissolution testingof products containing micronized or nanosized fenofibratewith a view to predicting plasma profilesrdquo European Journal ofPharmaceutics and Biopharmaceutics vol 77 no 2 pp 257ndash2642011

[47] P F Yue X Y Lu Z Z Zhang et al ldquoThe study on theentrapment efficiency and in vitro release of puerarin submi-cron emulsionrdquoAAPS PharmSciTech vol 10 no 2 pp 376ndash3832009

[48] M Mahkam F Hosseinzadeh and M Galehassadi ldquoPrepara-tion of ionic liquid functionalized silica nanoparticles for oraldrug deliveryrdquo Journal of Biomaterials amp Nanobiotechnologyvol 3 pp 391ndash395 2012

[49] A S Ham M R Cost A B Sassi C S Dezzutti andL C Rohan ldquoTargeted delivery of PSC-RANTES for HIV-1prevention using biodegradable nanoparticlesrdquo PharmaceuticalResearch vol 26 no 3 pp 502ndash511 2009

[50] Y I Kim L Fluckiger M Hoffman I Lartaud-IdjouadieneJ Atkinson and P Maincent ldquoThe antihypertensive effect oforally administered nifedipine-loaded nanoparticles in sponta-neously hypertensive ratsrdquoThe British Journal of Pharmacologyvol 120 no 3 pp 399ndash404 1997

[51] P Liu O de Wulf J Laru et al ldquoDissolution studies of poorlysoluble drug nanosuspensions in non-sink conditionsrdquo AAPSPharmSciTech vol 14 no 2 pp 748ndash756 2013

[52] L Sievens-Figueroa N Pandya A Bhakay et al ldquoUsing USPI and USP IV for discriminating dissolution rates of nano-

and microparticle-loaded pharmaceutical strip-filmsrdquo AAPSPharmSciTech vol 13 no 4 pp 1473ndash1482 2013

[53] G P Yan R F Zong L Li T Fu F Liu and X H YuldquoAnticancer drug-loaded nanospheres based on biodegradableamphiphilic 120576-caprolactone and carbonate copolymersrdquo Phar-maceutical Research vol 27 no 12 pp 2743ndash2752 2010

[54] P Calvo J L Vila-Jato and M J Alonso ldquoComparative invitro evaluation of several colloidal systems nanoparticlesnanocapsules and nanoemulsions as ocular drug carriersrdquoJournal of Pharmaceutical Sciences vol 85 no 5 pp 530ndash5361996

[55] M SMuthu and S Singh ldquoPoly (D L-lactide) nanosuspensionsof risperidone for parenteral delivery formulation and in-vitroevaluationrdquoCurrent DrugDelivery vol 6 no 1 pp 62ndash68 2009

[56] MY Levy and S Benita ldquoDrug release from submicronized owemulsion a new in vitro kinetic evaluationmodelrdquo InternationalJournal of Pharmaceutics vol 66 no 1ndash3 pp 29ndash37 1990

[57] X Xu M A Khan and D J Burgess ldquoA two-stage reversedialysis in vitro dissolution testing method for passive targetedliposomesrdquo International Journal of Pharmaceutics vol 426 no1-2 pp 211ndash218 2012

[58] B E Kilfoyle L Sheihet Z Zhang M Laohoo J Kohn and BBMichniak-Kohn ldquoDevelopment of paclitaxel-TyroSpheres fortopical skin treatmentrdquo Journal of Controlled Release vol 163no 1 pp 18ndash24 2012

[59] S Uprit R K Sahu A Roy and A Pare ldquoPreparation and char-acterization of minoxidil loaded nanostructured lipid carriergel for effective treatment of alopeciardquo Saudi PharmaceuticalJournal vol 21 pp 379ndash385 2013

[60] B Qiu M Ji X Song et al ldquoCo-delivery of docetaxel andendostatin by a biodegradable nanoparticle for the synergistictreatment of cervical cancerrdquo Nanoscale Research Letters vol 7article 666 2012

[61] S S DrsquoSouza and P P DeLuca ldquoDevelopment of a dialysis invitro release method for biodegradable microspheresrdquo AAPSPharmSciTech vol 6 no 2 article 42 2005

[62] Y Gao J Zuo N Bou-Chacra et al ldquoIn vitro release kineticsof antituberculosis drugs from nanoparticles assessed usinga modified dissolution apparatusrdquo BioMed Research Interna-tional vol 2013 Article ID 136590 9 pages 2013

[63] M Joshi S Pathak S Sharma and V Patravale ldquoDesignand in vivo pharmacodynamic evaluation of nanostructuredlipid carriers for parenteral delivery of artemether nanojectrdquoInternational Journal of Pharmaceutics vol 364 no 1 pp 119ndash126 2008

[64] J W Kostanski and P P DeLuca ldquoA novel in vitro releasetechnique for peptide-containing biodegradable microspheresrdquoAAPS PharmSciTech vol 1 article 4 2000

[65] J P K Tan C H Goh and K C Tam ldquoComparative drugrelease studies of two cationic drugs from pH-responsivenanogelsrdquo European Journal of Pharmaceutical Sciences vol 32no 4-5 pp 340ndash348 2007

[66] K M Rosenblatt D Douroumis and H Bunjes ldquoDrug releasefrom differently structured monooleinpoloxamer nanodisper-sions studied with differential pulse polarography and ultrafil-tration at low pressurerdquo Journal of Pharmaceutical Sciences vol96 no 6 pp 1564ndash1575 2007

[67] N Charalampopoulos K Avgoustakis and C G KontoyannisldquoDifferential pulse polarography a suitable technique for mon-itoring drug release from polymeric nanoparticle dispersionsrdquoAnalytica Chimica Acta vol 491 no 1 pp 57ndash62 2003

12 Advances in Pharmaceutics

[68] P Kayaert B Li I Jimidar P Rombaut F Ahssini and G Vanden Mooter ldquoSolution calorimetry as an alternative approachfor dissolution testing of nanosuspensionsrdquo European Journal ofPharmaceutics and Biopharmaceutics vol 76 no 3 pp 507ndash5132010

[69] M T Crisp C J Tucker T L Rogers R O Williams III andK P Johnston ldquoTurbidimetric measurement and prediction ofdissolution rates of poorly soluble drug nanocrystalsrdquo Journalof Controlled Release vol 117 no 3 pp 351ndash359 2007

[70] M V Chaubal and C Popescu ldquoConversion of nanosus-pensions into dry powders by spray drying a case studyrdquoPharmaceutical Research vol 25 no 10 pp 2302ndash2308 2008

[71] A Helle S Hirsjarvi L Peltonen J Hirvonen S K Wied-mer and T Hyotylainen ldquoNovel dynamic on-line analyticalseparation system for dissolution of drugs from poly(lacticacid) nanoparticlesrdquo Journal of Pharmaceutical and BiomedicalAnalysis vol 51 no 1 pp 125ndash130 2010

[72] V Domınguez-Villegas B Clares-Naveros M L Garcıa-Lopez et al ldquoDevelopment and characterization of two nano-structured systems for topical application of flavanones isolatedfrom Eysenhardtia platycarpardquo Colloids and Surfaces B Bioint-erfaces vol 116 pp 183ndash192 2014

[73] M Barzegar-Jalali K AdibkiaHValizadeh et al ldquoKinetic anal-ysis of drug release from nanoparticlesrdquo Journal of Pharmacyand Pharmaceutical Sciences vol 11 no 1 pp 167ndash177 2008

[74] L Zeng L An and X Wu ldquoModeling drug-carrier interactionin the drug release from nanocarriersrdquo Journal of Drug Deliveryvol 2011 Article ID 370308 15 pages 2011

[75] L Zeng andXWu ldquoModeling the sustained release of lipophilicdrugs from liposomesrdquo Applied Physics Letters vol 97 no 7Article ID 073701 2010

[76] FDA Guidance for Industry Extended Release Oral DosageForms Development Evaluation and Application of In VitroInVivo Correlations 1997

[77] J G Wagner and E Nelson ldquoPer cent absorbed time plotsderived fromblood level andor urinary excretion datardquo Journalof Pharmaceutical Sciences vol 52 pp 610ndash611 1963

Submit your manuscripts athttpwwwhindawicom

PainResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom

Volume 2014

ToxinsJournal of

VaccinesJournal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

AntibioticsInternational Journal of

ToxicologyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

StrokeResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Drug DeliveryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in Pharmacological Sciences

Tropical MedicineJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

AddictionJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

Emergency Medicine InternationalHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Autoimmune Diseases

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Anesthesiology Research and Practice

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Pharmaceutics

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MEDIATORSINFLAMMATION

of

10 Advances in Pharmaceutics

[7] M Cetin A Atila and Y Kadioglu ldquoFormulation and in vitrocharacterization of Eudragit L100 and Eudragit L100-PLGAnanoparticles containing diclofenac sodiumrdquo AAPS Pharm-SciTech vol 11 pp 1250ndash1256 2010

[8] A Hanafy H Spahn-Langguth G Vergnault et al ldquoPharma-cokinetic evaluation of oral fenofibrate nanosuspensions andSLN in comparison to conventional suspensions of micronizeddrugrdquo Advanced Drug Delivery Reviews vol 59 no 6 pp 419ndash426 2007

[9] T M Allen W W K Cheng J I Hare and K M LaginhaldquoPharmacokinetics and pharmacodynamics of lipidic nano-particles in cancerrdquoAnti-Cancer Agents in Medicinal Chemistryvol 6 no 6 pp 513ndash523 2006

[10] J Kreuter ldquoNanoparticle-based drug delivery systemsrdquo Journalof Controlled Release vol 16 no 1-2 pp 169ndash176 1991

[11] M L Etheridge S A Campbell A G Erdman C L Haynes SMWolf and JMcCullough ldquoThe big picture on nanomedicinethe state of investigational and approved nanomedicine prod-uctsrdquo Nanomedicine Nanotechnology Biology and Medicinevol 9 no 1 pp 1ndash14 2013

[12] S Nie ldquoUnderstanding and overcoming major barriers incancer nanomedicinerdquoNanomedicine vol 5 no 4 pp 523ndash5282010

[13] W H de Jong and P J A Borm ldquoDrug delivery andnanoparticles applications and hazardsrdquo International Journalof Nanomedicine vol 3 no 2 pp 133ndash149 2008

[14] S DrsquoSouza J A Faraj R Dorati and P P DeLuca ldquoA short termquality control tool for biodegradable microspheresrdquo AAPSPharmSciTech vol 15 no 3 pp 530ndash541 2014

[15] P Buch P Holm J Q Thomassen et al ldquoIVIVC for fenofibrateimmediate release tablets using solubility and permeability as invitro predictors for pharmacokineticsrdquo Journal of Pharmaceuti-cal Sciences vol 99 no 10 pp 4427ndash4436 2010

[16] S DrsquoSouza J A Faraj S Giovagnoli and P P DeLuca ldquoIVIVCfrom long acting olanzapine microspheresrdquo International Jour-nal of Biomaterials vol 2014 Article ID 407065 11 pages 2014

[17] L C Amann M J Gandal R Lin Y Liang and S J SiegelldquoIn vitro-in vivo correlations of scalable PLGA-Risperidoneimplants for the treatment of schizophreniardquo PharmaceuticalResearch vol 27 no 8 pp 1730ndash1737 2010

[18] G Zackrisson G Ostling B Skagerberg and T Anfalt ldquoACcel-erated Dissolution Rate Analysis (ACDRA) for controlledrelease drugs Application to Roxiamrdquo Journal of Pharmaceu-tical and Biomedical Analysis vol 13 no 4-5 pp 377ndash383 1995

[19] S S DSouza J A Faraj and P P DeLuca ldquoA model-dependentapproach to correlate accelerated with real-time release frombiodegradable microspheresrdquo AAPS PharmSciTech vol 6 arti-cle 70 no 4 2005

[20] D J Burgess A S Hussain T S Ingallinera and M ChenldquoAssuring quality and performance of sustained and controlledrelease parenterals workshop reportrdquo AAPS PharmSci vol 4article E7 2002

[21] S S DrsquoSouza and P P DeLuca ldquoMethods to assess in vitrodrug release from injectable polymeric particulate systemsrdquoPharmaceutical Research vol 23 no 3 pp 460ndash474 2006

[22] M Siewert J Dressman C K Brown and V P ShahldquoFIPAAPS guidelines to dissolutionin vitro release testing ofnovelspecial dosage formsrdquo AAPS PharmSciTech vol 4 article7 2003

[23] C K Brown H D Friedel A R Barker et al ldquoFIPAAPSjoint workshop report dissolutionin vitro release testing of

novelspecial dosage formsrdquo AAPS PharmSciTech vol 12 no2 pp 782ndash794 2011

[24] MMartinezM Rathbone D Burgess andMHuynh ldquoIn vitroand in vivo considerations associated with parenteral sustainedrelease products a review based upon information presentedand points expressed at the 2007 Controlled Release SocietyAnnual Meetingrdquo Journal of Controlled Release vol 129 no 2pp 79ndash87 2008

[25] M N Martinez M J Rathbone D Burgess and M HuynhldquoBreakout session summary from AAPSCRS joint workshopon critical variables in the in vitro and in vivo performanceof parenteral sustained release productsrdquo Journal of ControlledRelease vol 142 no 1 pp 2ndash7 2010

[26] N Chidambaram and D J Burgess ldquoA novel in vitro releasemethod for submicron-sized dispersed systemsrdquo AAPS Pharm-Sci vol 1 no 3 pp 32ndash40 1999

[27] M M A Abdel-Mottaleb and A Lamprecht ldquoStandardized invitro drug release test for colloidal drug carriers using modifiedUSP dissolution apparatus Irdquo Drug Development and IndustrialPharmacy vol 37 no 2 pp 178ndash184 2011

[28] A Maghsoudi S A Shojaosadati and E Vasheghani Farahanildquo5-Fluorouracil-loaded BSA nanoparticles formulation opti-mization and in vitro release studyrdquo AAPS PharmSciTech vol9 no 4 pp 1092ndash1096 2008

[29] U Bhardwaj and D J Burgess ldquoA novel USP apparatus 4 basedrelease testing method for dispersed systemsrdquo InternationalJournal of Pharmaceutics vol 388 no 1-2 pp 287ndash294 2010

[30] L Mora K Y Chumbimuni-Torres C Clawson L HernandezL Zhang and J Wang ldquoReal-time electrochemical monitoringof drug release from therapeutic nanoparticlesrdquo Journal ofControlled Release vol 140 no 1 pp 69ndash73 2009

[31] C B Michalowski S S Guterres and T Dalla CostaldquoMicrodialysis for evaluating the entrapment and release of alipophilic drug from nanoparticlesrdquo Journal of Pharmaceuticaland Biomedical Analysis vol 35 no 5 pp 1093ndash1100 2004

[32] R Kumar R C Nagarwal M Dhanawat and J K PanditldquoIn-vitro and in-vivo study of indomethacin loaded gelatinnanoparticlesrdquo Journal of Biomedical Nanotechnology vol 7 no3 pp 325ndash333 2011

[33] X Cao W W Deng M Fu et al ldquoIn vitro release and in vitro-in vivo correlation for silybin meglumine incorporated intoHollow-type mesoporous silica nanoparticlesrdquo InternationalJournal of Nanomedicine vol 7 pp 753ndash762 2012

[34] R Tiwari and K Pathak ldquoNanostructured lipid carrier versussolid lipid nanoparticles of simvastatin comparative analysis ofcharacteristics pharmacokinetics and tissue uptakerdquo Interna-tional Journal of Pharmaceutics vol 415 no 1-2 pp 232ndash2432011

[35] X Cao W Deng M Fu et al ldquoSeventy-two-hour releaseformulation of the poorly soluble drug silybin based on poroussilica nanoparticles in vitro release kinetics and in vitroin vivocorrelations in beagle dogsrdquo European Journal of Pharmaceuti-cal Sciences vol 48 no 1-2 pp 64ndash71 2013

[36] Y Xu Y Wang X M Li et al ldquoStudy on the release offenofibrate nanosuspension in vitro and its correlation with insitu intestinal and in vivo absorption kinetics in ratsrdquo DrugDevelopment and Industrial Pharmacy vol 40 no 7 pp 972ndash979 2014

[37] N Borkar D Xia R Holm et al ldquoInvestigating the correlationbetween in vivo absorption and in vitro release of fenofibratefrom lipid matrix particles in biorelevant mediumrdquo EuropeanJournal of Pharmaceutical Sciences vol 51 pp 204ndash210 2014

Advances in Pharmaceutics 11

[38] D Heng D J Cutler H K Chan J Yun and J A RaperldquoWhat is a suitable dissolutionmethod for drug nanoparticlesrdquoPharmaceutical Research vol 25 no 7 pp 1696ndash1701 2008

[39] A C Kilic Y Capan I Vural et al ldquoPreparation and characteri-zation of PLGA nanospheres for the targeted delivery of NR2B-specific antisense oligonucleotides to the NMDA receptors inthe brainrdquo Journal of Microencapsulation vol 22 no 6 pp 633ndash641 2005

[40] Y Zhang H Wang C Li et al ldquoA novel three-dimensionallarge-pore mesoporous carbon matrix as a potential nanove-hicle for the fast release of the poorly water-soluble drugcelecoxibrdquoPharmaceutical Research vol 31 pp 1059ndash1070 2014

[41] V Sanna A M Roggio S Siliani et al ldquoDevelopment of novelcationic chitosan-and anionic alginate-coated poly(DL-lactide-co-glycolide) nanoparticles for controlled release and light pro-tection of resveratrolrdquo International Journal of Nanomedicinevol 7 pp 5501ndash5516 2012

[42] F Danhier N Lecouturier B Vroman et al ldquoPaclitaxel-loadedPEGylated PLGA-based nanoparticles In vitro and in vivoevaluationrdquo Journal of Controlled Release vol 133 no 1 pp 11ndash17 2009

[43] Y Li Y Pei X Zhang et al ldquoPEGylated PLGA nanoparticlesas protein carriers synthesis preparation and biodistributionin ratsrdquo Journal of Controlled Release vol 71 no 2 pp 203ndash2112001

[44] S Prabha W-Z Zhou J Panyam and V Labhasetwar ldquoSize-dependency of nanoparticle-mediated gene transfection stud-ies with fractionated nanoparticlesrdquo International Journal ofPharmaceutics vol 244 no 1-2 pp 105ndash115 2002

[45] S J Wallace J Li R L Nation and B J Boyd ldquoDrug releasefrom nanomedicines selection of appropriate encapsulationand release methodologyrdquo Drug Delivery and TranslationalResearch vol 2 no 4 pp 284ndash292 2012

[46] D Juenemann E Jantratid C Wagner C Reppas M Vertzoniand J B Dressman ldquoBiorelevant in vitro dissolution testingof products containing micronized or nanosized fenofibratewith a view to predicting plasma profilesrdquo European Journal ofPharmaceutics and Biopharmaceutics vol 77 no 2 pp 257ndash2642011

[47] P F Yue X Y Lu Z Z Zhang et al ldquoThe study on theentrapment efficiency and in vitro release of puerarin submi-cron emulsionrdquoAAPS PharmSciTech vol 10 no 2 pp 376ndash3832009

[48] M Mahkam F Hosseinzadeh and M Galehassadi ldquoPrepara-tion of ionic liquid functionalized silica nanoparticles for oraldrug deliveryrdquo Journal of Biomaterials amp Nanobiotechnologyvol 3 pp 391ndash395 2012

[49] A S Ham M R Cost A B Sassi C S Dezzutti andL C Rohan ldquoTargeted delivery of PSC-RANTES for HIV-1prevention using biodegradable nanoparticlesrdquo PharmaceuticalResearch vol 26 no 3 pp 502ndash511 2009

[50] Y I Kim L Fluckiger M Hoffman I Lartaud-IdjouadieneJ Atkinson and P Maincent ldquoThe antihypertensive effect oforally administered nifedipine-loaded nanoparticles in sponta-neously hypertensive ratsrdquoThe British Journal of Pharmacologyvol 120 no 3 pp 399ndash404 1997

[51] P Liu O de Wulf J Laru et al ldquoDissolution studies of poorlysoluble drug nanosuspensions in non-sink conditionsrdquo AAPSPharmSciTech vol 14 no 2 pp 748ndash756 2013

[52] L Sievens-Figueroa N Pandya A Bhakay et al ldquoUsing USPI and USP IV for discriminating dissolution rates of nano-

and microparticle-loaded pharmaceutical strip-filmsrdquo AAPSPharmSciTech vol 13 no 4 pp 1473ndash1482 2013

[53] G P Yan R F Zong L Li T Fu F Liu and X H YuldquoAnticancer drug-loaded nanospheres based on biodegradableamphiphilic 120576-caprolactone and carbonate copolymersrdquo Phar-maceutical Research vol 27 no 12 pp 2743ndash2752 2010

[54] P Calvo J L Vila-Jato and M J Alonso ldquoComparative invitro evaluation of several colloidal systems nanoparticlesnanocapsules and nanoemulsions as ocular drug carriersrdquoJournal of Pharmaceutical Sciences vol 85 no 5 pp 530ndash5361996

[55] M SMuthu and S Singh ldquoPoly (D L-lactide) nanosuspensionsof risperidone for parenteral delivery formulation and in-vitroevaluationrdquoCurrent DrugDelivery vol 6 no 1 pp 62ndash68 2009

[56] MY Levy and S Benita ldquoDrug release from submicronized owemulsion a new in vitro kinetic evaluationmodelrdquo InternationalJournal of Pharmaceutics vol 66 no 1ndash3 pp 29ndash37 1990

[57] X Xu M A Khan and D J Burgess ldquoA two-stage reversedialysis in vitro dissolution testing method for passive targetedliposomesrdquo International Journal of Pharmaceutics vol 426 no1-2 pp 211ndash218 2012

[58] B E Kilfoyle L Sheihet Z Zhang M Laohoo J Kohn and BBMichniak-Kohn ldquoDevelopment of paclitaxel-TyroSpheres fortopical skin treatmentrdquo Journal of Controlled Release vol 163no 1 pp 18ndash24 2012

[59] S Uprit R K Sahu A Roy and A Pare ldquoPreparation and char-acterization of minoxidil loaded nanostructured lipid carriergel for effective treatment of alopeciardquo Saudi PharmaceuticalJournal vol 21 pp 379ndash385 2013

[60] B Qiu M Ji X Song et al ldquoCo-delivery of docetaxel andendostatin by a biodegradable nanoparticle for the synergistictreatment of cervical cancerrdquo Nanoscale Research Letters vol 7article 666 2012

[61] S S DrsquoSouza and P P DeLuca ldquoDevelopment of a dialysis invitro release method for biodegradable microspheresrdquo AAPSPharmSciTech vol 6 no 2 article 42 2005

[62] Y Gao J Zuo N Bou-Chacra et al ldquoIn vitro release kineticsof antituberculosis drugs from nanoparticles assessed usinga modified dissolution apparatusrdquo BioMed Research Interna-tional vol 2013 Article ID 136590 9 pages 2013

[63] M Joshi S Pathak S Sharma and V Patravale ldquoDesignand in vivo pharmacodynamic evaluation of nanostructuredlipid carriers for parenteral delivery of artemether nanojectrdquoInternational Journal of Pharmaceutics vol 364 no 1 pp 119ndash126 2008

[64] J W Kostanski and P P DeLuca ldquoA novel in vitro releasetechnique for peptide-containing biodegradable microspheresrdquoAAPS PharmSciTech vol 1 article 4 2000

[65] J P K Tan C H Goh and K C Tam ldquoComparative drugrelease studies of two cationic drugs from pH-responsivenanogelsrdquo European Journal of Pharmaceutical Sciences vol 32no 4-5 pp 340ndash348 2007

[66] K M Rosenblatt D Douroumis and H Bunjes ldquoDrug releasefrom differently structured monooleinpoloxamer nanodisper-sions studied with differential pulse polarography and ultrafil-tration at low pressurerdquo Journal of Pharmaceutical Sciences vol96 no 6 pp 1564ndash1575 2007

[67] N Charalampopoulos K Avgoustakis and C G KontoyannisldquoDifferential pulse polarography a suitable technique for mon-itoring drug release from polymeric nanoparticle dispersionsrdquoAnalytica Chimica Acta vol 491 no 1 pp 57ndash62 2003

12 Advances in Pharmaceutics

[68] P Kayaert B Li I Jimidar P Rombaut F Ahssini and G Vanden Mooter ldquoSolution calorimetry as an alternative approachfor dissolution testing of nanosuspensionsrdquo European Journal ofPharmaceutics and Biopharmaceutics vol 76 no 3 pp 507ndash5132010

[69] M T Crisp C J Tucker T L Rogers R O Williams III andK P Johnston ldquoTurbidimetric measurement and prediction ofdissolution rates of poorly soluble drug nanocrystalsrdquo Journalof Controlled Release vol 117 no 3 pp 351ndash359 2007

[70] M V Chaubal and C Popescu ldquoConversion of nanosus-pensions into dry powders by spray drying a case studyrdquoPharmaceutical Research vol 25 no 10 pp 2302ndash2308 2008

[71] A Helle S Hirsjarvi L Peltonen J Hirvonen S K Wied-mer and T Hyotylainen ldquoNovel dynamic on-line analyticalseparation system for dissolution of drugs from poly(lacticacid) nanoparticlesrdquo Journal of Pharmaceutical and BiomedicalAnalysis vol 51 no 1 pp 125ndash130 2010

[72] V Domınguez-Villegas B Clares-Naveros M L Garcıa-Lopez et al ldquoDevelopment and characterization of two nano-structured systems for topical application of flavanones isolatedfrom Eysenhardtia platycarpardquo Colloids and Surfaces B Bioint-erfaces vol 116 pp 183ndash192 2014

[73] M Barzegar-Jalali K AdibkiaHValizadeh et al ldquoKinetic anal-ysis of drug release from nanoparticlesrdquo Journal of Pharmacyand Pharmaceutical Sciences vol 11 no 1 pp 167ndash177 2008

[74] L Zeng L An and X Wu ldquoModeling drug-carrier interactionin the drug release from nanocarriersrdquo Journal of Drug Deliveryvol 2011 Article ID 370308 15 pages 2011

[75] L Zeng andXWu ldquoModeling the sustained release of lipophilicdrugs from liposomesrdquo Applied Physics Letters vol 97 no 7Article ID 073701 2010

[76] FDA Guidance for Industry Extended Release Oral DosageForms Development Evaluation and Application of In VitroInVivo Correlations 1997

[77] J G Wagner and E Nelson ldquoPer cent absorbed time plotsderived fromblood level andor urinary excretion datardquo Journalof Pharmaceutical Sciences vol 52 pp 610ndash611 1963

Submit your manuscripts athttpwwwhindawicom

PainResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom

Volume 2014

ToxinsJournal of

VaccinesJournal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

AntibioticsInternational Journal of

ToxicologyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

StrokeResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Drug DeliveryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in Pharmacological Sciences

Tropical MedicineJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

AddictionJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

Emergency Medicine InternationalHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Autoimmune Diseases

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Anesthesiology Research and Practice

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Pharmaceutics

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MEDIATORSINFLAMMATION

of

Advances in Pharmaceutics 11

[38] D Heng D J Cutler H K Chan J Yun and J A RaperldquoWhat is a suitable dissolutionmethod for drug nanoparticlesrdquoPharmaceutical Research vol 25 no 7 pp 1696ndash1701 2008

[39] A C Kilic Y Capan I Vural et al ldquoPreparation and characteri-zation of PLGA nanospheres for the targeted delivery of NR2B-specific antisense oligonucleotides to the NMDA receptors inthe brainrdquo Journal of Microencapsulation vol 22 no 6 pp 633ndash641 2005

[40] Y Zhang H Wang C Li et al ldquoA novel three-dimensionallarge-pore mesoporous carbon matrix as a potential nanove-hicle for the fast release of the poorly water-soluble drugcelecoxibrdquoPharmaceutical Research vol 31 pp 1059ndash1070 2014

[41] V Sanna A M Roggio S Siliani et al ldquoDevelopment of novelcationic chitosan-and anionic alginate-coated poly(DL-lactide-co-glycolide) nanoparticles for controlled release and light pro-tection of resveratrolrdquo International Journal of Nanomedicinevol 7 pp 5501ndash5516 2012

[42] F Danhier N Lecouturier B Vroman et al ldquoPaclitaxel-loadedPEGylated PLGA-based nanoparticles In vitro and in vivoevaluationrdquo Journal of Controlled Release vol 133 no 1 pp 11ndash17 2009

[43] Y Li Y Pei X Zhang et al ldquoPEGylated PLGA nanoparticlesas protein carriers synthesis preparation and biodistributionin ratsrdquo Journal of Controlled Release vol 71 no 2 pp 203ndash2112001

[44] S Prabha W-Z Zhou J Panyam and V Labhasetwar ldquoSize-dependency of nanoparticle-mediated gene transfection stud-ies with fractionated nanoparticlesrdquo International Journal ofPharmaceutics vol 244 no 1-2 pp 105ndash115 2002

[45] S J Wallace J Li R L Nation and B J Boyd ldquoDrug releasefrom nanomedicines selection of appropriate encapsulationand release methodologyrdquo Drug Delivery and TranslationalResearch vol 2 no 4 pp 284ndash292 2012

[46] D Juenemann E Jantratid C Wagner C Reppas M Vertzoniand J B Dressman ldquoBiorelevant in vitro dissolution testingof products containing micronized or nanosized fenofibratewith a view to predicting plasma profilesrdquo European Journal ofPharmaceutics and Biopharmaceutics vol 77 no 2 pp 257ndash2642011

[47] P F Yue X Y Lu Z Z Zhang et al ldquoThe study on theentrapment efficiency and in vitro release of puerarin submi-cron emulsionrdquoAAPS PharmSciTech vol 10 no 2 pp 376ndash3832009

[48] M Mahkam F Hosseinzadeh and M Galehassadi ldquoPrepara-tion of ionic liquid functionalized silica nanoparticles for oraldrug deliveryrdquo Journal of Biomaterials amp Nanobiotechnologyvol 3 pp 391ndash395 2012

[49] A S Ham M R Cost A B Sassi C S Dezzutti andL C Rohan ldquoTargeted delivery of PSC-RANTES for HIV-1prevention using biodegradable nanoparticlesrdquo PharmaceuticalResearch vol 26 no 3 pp 502ndash511 2009

[50] Y I Kim L Fluckiger M Hoffman I Lartaud-IdjouadieneJ Atkinson and P Maincent ldquoThe antihypertensive effect oforally administered nifedipine-loaded nanoparticles in sponta-neously hypertensive ratsrdquoThe British Journal of Pharmacologyvol 120 no 3 pp 399ndash404 1997

[51] P Liu O de Wulf J Laru et al ldquoDissolution studies of poorlysoluble drug nanosuspensions in non-sink conditionsrdquo AAPSPharmSciTech vol 14 no 2 pp 748ndash756 2013

[52] L Sievens-Figueroa N Pandya A Bhakay et al ldquoUsing USPI and USP IV for discriminating dissolution rates of nano-

and microparticle-loaded pharmaceutical strip-filmsrdquo AAPSPharmSciTech vol 13 no 4 pp 1473ndash1482 2013

[53] G P Yan R F Zong L Li T Fu F Liu and X H YuldquoAnticancer drug-loaded nanospheres based on biodegradableamphiphilic 120576-caprolactone and carbonate copolymersrdquo Phar-maceutical Research vol 27 no 12 pp 2743ndash2752 2010

[54] P Calvo J L Vila-Jato and M J Alonso ldquoComparative invitro evaluation of several colloidal systems nanoparticlesnanocapsules and nanoemulsions as ocular drug carriersrdquoJournal of Pharmaceutical Sciences vol 85 no 5 pp 530ndash5361996

[55] M SMuthu and S Singh ldquoPoly (D L-lactide) nanosuspensionsof risperidone for parenteral delivery formulation and in-vitroevaluationrdquoCurrent DrugDelivery vol 6 no 1 pp 62ndash68 2009

[56] MY Levy and S Benita ldquoDrug release from submicronized owemulsion a new in vitro kinetic evaluationmodelrdquo InternationalJournal of Pharmaceutics vol 66 no 1ndash3 pp 29ndash37 1990

[57] X Xu M A Khan and D J Burgess ldquoA two-stage reversedialysis in vitro dissolution testing method for passive targetedliposomesrdquo International Journal of Pharmaceutics vol 426 no1-2 pp 211ndash218 2012

[58] B E Kilfoyle L Sheihet Z Zhang M Laohoo J Kohn and BBMichniak-Kohn ldquoDevelopment of paclitaxel-TyroSpheres fortopical skin treatmentrdquo Journal of Controlled Release vol 163no 1 pp 18ndash24 2012

[59] S Uprit R K Sahu A Roy and A Pare ldquoPreparation and char-acterization of minoxidil loaded nanostructured lipid carriergel for effective treatment of alopeciardquo Saudi PharmaceuticalJournal vol 21 pp 379ndash385 2013

[60] B Qiu M Ji X Song et al ldquoCo-delivery of docetaxel andendostatin by a biodegradable nanoparticle for the synergistictreatment of cervical cancerrdquo Nanoscale Research Letters vol 7article 666 2012

[61] S S DrsquoSouza and P P DeLuca ldquoDevelopment of a dialysis invitro release method for biodegradable microspheresrdquo AAPSPharmSciTech vol 6 no 2 article 42 2005

[62] Y Gao J Zuo N Bou-Chacra et al ldquoIn vitro release kineticsof antituberculosis drugs from nanoparticles assessed usinga modified dissolution apparatusrdquo BioMed Research Interna-tional vol 2013 Article ID 136590 9 pages 2013

[63] M Joshi S Pathak S Sharma and V Patravale ldquoDesignand in vivo pharmacodynamic evaluation of nanostructuredlipid carriers for parenteral delivery of artemether nanojectrdquoInternational Journal of Pharmaceutics vol 364 no 1 pp 119ndash126 2008

[64] J W Kostanski and P P DeLuca ldquoA novel in vitro releasetechnique for peptide-containing biodegradable microspheresrdquoAAPS PharmSciTech vol 1 article 4 2000

[65] J P K Tan C H Goh and K C Tam ldquoComparative drugrelease studies of two cationic drugs from pH-responsivenanogelsrdquo European Journal of Pharmaceutical Sciences vol 32no 4-5 pp 340ndash348 2007

[66] K M Rosenblatt D Douroumis and H Bunjes ldquoDrug releasefrom differently structured monooleinpoloxamer nanodisper-sions studied with differential pulse polarography and ultrafil-tration at low pressurerdquo Journal of Pharmaceutical Sciences vol96 no 6 pp 1564ndash1575 2007

[67] N Charalampopoulos K Avgoustakis and C G KontoyannisldquoDifferential pulse polarography a suitable technique for mon-itoring drug release from polymeric nanoparticle dispersionsrdquoAnalytica Chimica Acta vol 491 no 1 pp 57ndash62 2003

12 Advances in Pharmaceutics

[68] P Kayaert B Li I Jimidar P Rombaut F Ahssini and G Vanden Mooter ldquoSolution calorimetry as an alternative approachfor dissolution testing of nanosuspensionsrdquo European Journal ofPharmaceutics and Biopharmaceutics vol 76 no 3 pp 507ndash5132010

[69] M T Crisp C J Tucker T L Rogers R O Williams III andK P Johnston ldquoTurbidimetric measurement and prediction ofdissolution rates of poorly soluble drug nanocrystalsrdquo Journalof Controlled Release vol 117 no 3 pp 351ndash359 2007

[70] M V Chaubal and C Popescu ldquoConversion of nanosus-pensions into dry powders by spray drying a case studyrdquoPharmaceutical Research vol 25 no 10 pp 2302ndash2308 2008

[71] A Helle S Hirsjarvi L Peltonen J Hirvonen S K Wied-mer and T Hyotylainen ldquoNovel dynamic on-line analyticalseparation system for dissolution of drugs from poly(lacticacid) nanoparticlesrdquo Journal of Pharmaceutical and BiomedicalAnalysis vol 51 no 1 pp 125ndash130 2010

[72] V Domınguez-Villegas B Clares-Naveros M L Garcıa-Lopez et al ldquoDevelopment and characterization of two nano-structured systems for topical application of flavanones isolatedfrom Eysenhardtia platycarpardquo Colloids and Surfaces B Bioint-erfaces vol 116 pp 183ndash192 2014

[73] M Barzegar-Jalali K AdibkiaHValizadeh et al ldquoKinetic anal-ysis of drug release from nanoparticlesrdquo Journal of Pharmacyand Pharmaceutical Sciences vol 11 no 1 pp 167ndash177 2008

[74] L Zeng L An and X Wu ldquoModeling drug-carrier interactionin the drug release from nanocarriersrdquo Journal of Drug Deliveryvol 2011 Article ID 370308 15 pages 2011

[75] L Zeng andXWu ldquoModeling the sustained release of lipophilicdrugs from liposomesrdquo Applied Physics Letters vol 97 no 7Article ID 073701 2010

[76] FDA Guidance for Industry Extended Release Oral DosageForms Development Evaluation and Application of In VitroInVivo Correlations 1997

[77] J G Wagner and E Nelson ldquoPer cent absorbed time plotsderived fromblood level andor urinary excretion datardquo Journalof Pharmaceutical Sciences vol 52 pp 610ndash611 1963

Submit your manuscripts athttpwwwhindawicom

PainResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom

Volume 2014

ToxinsJournal of

VaccinesJournal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

AntibioticsInternational Journal of

ToxicologyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

StrokeResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Drug DeliveryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in Pharmacological Sciences

Tropical MedicineJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

AddictionJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

Emergency Medicine InternationalHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Autoimmune Diseases

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Anesthesiology Research and Practice

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Pharmaceutics

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MEDIATORSINFLAMMATION

of

12 Advances in Pharmaceutics

[68] P Kayaert B Li I Jimidar P Rombaut F Ahssini and G Vanden Mooter ldquoSolution calorimetry as an alternative approachfor dissolution testing of nanosuspensionsrdquo European Journal ofPharmaceutics and Biopharmaceutics vol 76 no 3 pp 507ndash5132010

[69] M T Crisp C J Tucker T L Rogers R O Williams III andK P Johnston ldquoTurbidimetric measurement and prediction ofdissolution rates of poorly soluble drug nanocrystalsrdquo Journalof Controlled Release vol 117 no 3 pp 351ndash359 2007

[70] M V Chaubal and C Popescu ldquoConversion of nanosus-pensions into dry powders by spray drying a case studyrdquoPharmaceutical Research vol 25 no 10 pp 2302ndash2308 2008

[71] A Helle S Hirsjarvi L Peltonen J Hirvonen S K Wied-mer and T Hyotylainen ldquoNovel dynamic on-line analyticalseparation system for dissolution of drugs from poly(lacticacid) nanoparticlesrdquo Journal of Pharmaceutical and BiomedicalAnalysis vol 51 no 1 pp 125ndash130 2010

[72] V Domınguez-Villegas B Clares-Naveros M L Garcıa-Lopez et al ldquoDevelopment and characterization of two nano-structured systems for topical application of flavanones isolatedfrom Eysenhardtia platycarpardquo Colloids and Surfaces B Bioint-erfaces vol 116 pp 183ndash192 2014

[73] M Barzegar-Jalali K AdibkiaHValizadeh et al ldquoKinetic anal-ysis of drug release from nanoparticlesrdquo Journal of Pharmacyand Pharmaceutical Sciences vol 11 no 1 pp 167ndash177 2008

[74] L Zeng L An and X Wu ldquoModeling drug-carrier interactionin the drug release from nanocarriersrdquo Journal of Drug Deliveryvol 2011 Article ID 370308 15 pages 2011

[75] L Zeng andXWu ldquoModeling the sustained release of lipophilicdrugs from liposomesrdquo Applied Physics Letters vol 97 no 7Article ID 073701 2010

[76] FDA Guidance for Industry Extended Release Oral DosageForms Development Evaluation and Application of In VitroInVivo Correlations 1997

[77] J G Wagner and E Nelson ldquoPer cent absorbed time plotsderived fromblood level andor urinary excretion datardquo Journalof Pharmaceutical Sciences vol 52 pp 610ndash611 1963

Submit your manuscripts athttpwwwhindawicom

PainResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom

Volume 2014

ToxinsJournal of

VaccinesJournal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

AntibioticsInternational Journal of

ToxicologyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

StrokeResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Drug DeliveryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in Pharmacological Sciences

Tropical MedicineJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

AddictionJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

Emergency Medicine InternationalHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Autoimmune Diseases

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Anesthesiology Research and Practice

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Pharmaceutics

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MEDIATORSINFLAMMATION

of

Submit your manuscripts athttpwwwhindawicom

PainResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom

Volume 2014

ToxinsJournal of

VaccinesJournal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

AntibioticsInternational Journal of

ToxicologyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

StrokeResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Drug DeliveryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in Pharmacological Sciences

Tropical MedicineJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

AddictionJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

Emergency Medicine InternationalHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Autoimmune Diseases

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Anesthesiology Research and Practice

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Pharmaceutics

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MEDIATORSINFLAMMATION

of