Design and Evaluation of An Oral Controlled Release Microparticulate Drug Delivery...
Transcript of Design and Evaluation of An Oral Controlled Release Microparticulate Drug Delivery...
Journal of Scientific & Industrial Research Vol.58, September 1999, pp 717-722
Design and Evaluation of An Oral Controlled Release Microparticulate Drug Delivery System of Nimesulide by Ionotropic Gelation Technique
and Statistical Optimization by Factorial Analysis
A Manna, I Ghosh, N Goswami, L K Ghosh and B K Gupta* Division of Pharmaceutics, Biopharmaceutics and Clinical Pharmacokinetics,Department of Pharmaceutical Technology, Jadavpur
Universi ty,_Calcutta 700 032, India
Received: 31 March 1999; accepted: 22 June 1999
An attempt was made to prepare aqueous solvent based mi cropelletization of nimesulide by ionotropic gelation technique, with a view to deliver the drug at sustained manner in the gastro-intes tinal tract and consequently into the systemic circulation. Present method being aqueous solvent based, it eliminates the problems and hazards associated with the organi c solvent. Two types of micropell ets were prepared ; one batch was prepared with sodium alginate and other batches were prepared with sod ium alginate and hydroxypropyl methylcellulose (HPMC) using calCium chloride as counter ion soluti on. Prepared micropellets were spherical and free fl owing. These micropell ets were subjected to different physico-chemical evaluation, dissolution and continuous pH dissolution study, which gave sati sfa~tory results . Micropellets prepared with sodium alginate were capable of sustai ning the ac tion for 5-6 h and those prepared with both sodium alginate and HPMC were capable of sustaining action for 8 h. Finally statistical optimization was done with two-way
analysis of variance (ANOVA) and linear regression analysis.
Introduction
Micropelletization 1-3 has become a common technique in the production of controlled release dosage form s. A great deal of work has been done by the scientists about the current application and future possibility for altering the drug activity and stability by packing them in micropellets . The problems associated with organic so lvent-based micropelletization procedure (cost, safety and environmental pollution)
Materials and Methods Nimesulide; Sodium Alginate (Lamina ria hyperqoria );
HPMC (Methocel K-15M) of Dow Chemical ; Calcium chloride, dihydrate (Analytical grade, E. Merck , Germany); Potass ium dihydrogen phosphate (E. Merck) . All other reagents are of analytical grades and used without further
purification .
I Preparation of Micropellets Two sets of micropellets were prepared. In the first set
four batches of micropellet s were prepared (A I ,A2,A3,A4 ) using sodium alginate as the coating poly-
* Author for correspondence
mer. To 50 ml of sodium alginate 2 - 4 per cent (w/v) mucilage in distilled water, 500 mg of nimesulide was added and thoroughly mixed in an electric stirrer at 500 rpm . For bead formation , 50 ml of aqueous solution was introduced dropwise from a needle into 100 ml of aqueous calc ium chloride 4 - 6 per cent (w/v) being stirred at 100 rpm . After addition of last drop to the counter ion solution, it was harvested for 10minutes, the beads were washed with di stilled water, and dried at 70°C for 6 h. in an oven. and the advantages of aqueous systems have long been known . There is a tendency in industry to switch from organic coating to aqueous coating.
Nimesulide4 , chemically, 4-nitro- 2- phenoxy methane
sulphonamide, is a relatively new non-steroidal anti-infl ammatory analgesic drug. It is widely used for the treatment of inflammatory condition associated with rheumatoid arthritis, respiratory tract infection, soft tissue and oral cavity inflammation. The drug appears to be parti cularly useful for patients having allergic hypersensitivity to aspirin and other non-steroidal anti-inflammatory drugs 5.
The objective of the study was to prepare a oral controlled delivery of nimesulide for the better management of arthritis and algesia and reduce gastric irritation and ulceration. In the present study an attempt was made to prepare alginate micropellets of nimesulide by ionotropic
718 J SCI IND RES VOL.58 SEPTEMBER 1999
Table I - Formulation design and physicochemical characteristics of nimesulide micropellets
Batch no. .Sodium Calcium chloride HPMC Drug load (mg) Entrapment LSC TSO alginate
Al SOO
A2 + SOO
A3 + SOO
A4 + + SOO
BI + SOO
B2 + + SOO
B3 + + SOO
84· + + + SOO
Level Sodium alginate HPMC
+ 4 per cent (w/v) 2 per cent (w/v) 2 per cent (w/v) I per cent (w/v)
gelation technique 6. 7. Nimesulide was incorporated into beads by two polymers. In the first phase drug was coated with alginate polymer and in the second phase drug was coated both with alginate and hydroxyl propyl methyl cell u 10se(HPMC) (ref. 8) by reacting sodium alginate in presence of polyvalent cation calcium(Ca+2) in situ. The effect of each polymer and counter ion solution on the release profile and drug entrapment efficiency was investigated and other desired physico chemical properties were also investigated. Finally statistical optimization was carried out by two-way analysis of variance (ANOVA).
In the second set also four batches of micropellets were prepared (B I,B2,B3 ,B4 ) using coating polymer sodium alginate and HPMC. To 50 ml of distilled water, HPMC I - 2 per cent (w/v) were added and stirred with the electric stirrer unti l it forms mucilage. Then sodium alginate 4 per cent was added to form uniform mucilage. Then finally 500 mg of the drug was added and the fi nal mixture was subjected to bead formation as described earlier. The formulation design of the micropellets is given in Table 1.
2 Physico Chemical Properties The micropellets prepared were subjected to various
physico chemical studies to assess different physico chemical properties of interest. These studies included :
(i) Granulometric Study As the particle size is a very significant effect on the
release profile of micropellets , granulometric study was conducted to determine the particle size distribution pat-
Efficiency Per cent Per cent Per cent
73 .432 9.4 3. 11
71.841 8.0 3.SI
81.IS2 6.3 3.79
79.S80 4.9 4.2 1
79.62 4. 1 S.18
78 .07 3.8 5.39
88.12 2.2 6.07
84.69 2.2 5.77
Calcium chloride 6 per cent (w/v) 4 per cent (w/v)
tern. For this study, sieve analysis was carried out us.ing a mechanical sieve, using different meshes ( #12, #16, #20, #30) of American Society of Testing Materials (ASTM). The size distribution of the micropellets is reported in Table 2. (ii) Drug Entrapment Efficiency (DEE)
Accurately weighed 25 mg micropellets of (#16 sieve size) was suspended in 100 ml of Nil 00 of NaOH (pH- I 2) and it was kept for 24 h. Next day it was stirred for 15 min, after filtration and proper dilution nimesulide content in the filtrate was analyzed spectrophotometrically at 394 nm wavelength in Beckman DU 64 spectrophotometer. The results obtained are reported in Table 1.
(iii) Loose Surface Crystal Study (LSC Study) In this study9 accurately weighed 25 mg of micropellets
(# 16) was suspended in the phosphate buffer pH 7.2 and was shaken vigorously for 5 min. The drug leached out from the surface of the micropellets was analyzed at 394 nm wavelength spectrophotometrically. Results are reported in Table I .
(iv) Surface Study This study was done on the micropellets using SEM
Hitachi- S 4 I 5A at the foll owing condition (a) thickness of the gold coating was 200 AO (b) potential applied 25 KV (c) tilt was 0°, (d) working di stance was kept at 15 nm.
(v) Flow Property Angle of repose lO method was employed to assess the
flow ability. Micropellets were allowed to fall freely through
MANNA e/ al.: MICROPARTICULATE DRUG DELIVERY SYSTEM OF NIMESULIDE 719
100 ~Al
90 - -1'.2 ____ A3
80 -D-A4
1 70 -Bl
i 60 --.-82.
I -0-83
so -84
1 40 -Ir- B3(COnI
1 30 ___ ~'i\conl pH)
20
10
0 0 2 10
Tore (H')
Fig I - In-vitro dissolut ion profile of Nimesulide from various batches of micropellets
a funnel fixed at I em above the horizontal flat surface, until the apex of the conical pile just touched the tip of the funnel. The angle of repose (a) was determined by the formula :
a = arctan(H/R); H = Cone height of micropellets; R = /'
Radius of the circultr base formed by the micropellels on the ground.
3 In- Vitro Dissolution Study
In -vitro drug release profi Ie of the micropellets were evaluated using USP XXIII rotating basket dissolution apparatus with the basket covered with 100 mesh nylon cloth to prevent escaping of the micropellets. Dissolution fluid was 900 ml of phosphate buffer pH 7.2, maintained at 37 ± 10 C and the basket was rotated at 100 ± 2 rpm. Accurately weighed amount of micropellets was placed in the
Figure 2a - SEM photographs of sodium alginate
haskets. At 30 min intervals 10 ml of the aliquots were removed and replaced by same volume of phosphate buffer of pH 7.2. Amount of nimesulide released was assayed spectrophotometrically at 394 nm wavelength. TheT50 per cent release ofnimesu lide from micropellets (Table 2). The continuous pH study I I was also carried out for batch A I and B3 to determine the effect of pH on the drug release profile. The release profile of the drug is shown in Figure 1.
Results and Discussion The micropellets formed by th; ionotropic gelation of
sodi um alginate and calcium ch loride, are sufficiently hard and spherical in shape. Stirring speed and the harvesting time of the feed has significant effect on the bead size and entrapment efficiency of the drug. From the preliminary studies it is observed that with the increase in stirring speed
Table 2 - Size di stribution of the sodium alginate micropellets and the sodium alginateHPMC micropellets of nimesulide
Batch Per cent weight retained on various sieve size* no.
# 12 (1.68 mm) # 16 (1.19 mm) # 20 (0.84 mm) # 30 (0.59 mm)
A l 18.6 69 .68 8.48 3.24 A2 10.22 79.22 7.37 3.19 A3 14.43 73 .04 10.11 2.42 A4 13.62 74.61 6.86 4.91 B1 19.63 73.99 5.12 1.26 B2 17.53 75.62 4.96 1.89 B3 18.47 71 .35 7.46 2.72 B4 25.18 67 .82 6. 11 0.89
* United States Sieve Series
720 J SCI IND RES VOL.58 SEPTEMBER 1999
Figure 2b- SEM photographs of sodium alginate micropellets before dissolution HPMCmicropellets before dissolution
Figure 2c - SEM photographs of sodium alginateHPMC micropellets after dissolution
Hydration starts slowly
011 the surface, and forms
'a gel layer.
CORE Drug depleted swollen gel
Dry pellet 1- 1-- /J~ //'. ---"-" // ""
--(~ 'I \ ' \ -------1~ I \
'II ) , , Ii \ / Dissolution \ / '~ ___ // Completed \"', //
Swollen 1 Layer ~ MedIUm .... -.... ./ (PH==7.2)
(1) HPMC prevent rapid swelling of the interior (2) Drug diffuses through gel layer.
Figure 3 - Hypothesis of the swelling controlled release mechanism of Nimesulide Micropellets in dissolution medium.
of the calcium chloride (counter ion solution) , the bead size is decreased. Also it is found that with the increase in harvesting time, the beads formed in calcium ch loride solution in tum decrease the drug entrapment efficiency.
In the granulometric study it is observed from the Table 2 that about 67 to 79 per cent of the micropellets were of 16 mesh size, which proves the flexibility of the method i.e. particle size can easily be controlled by adjusting bore of the needle. It is observed that with the increase in the percentage of sodium alginate, maximum amount of the pellets of desired size is obtained. on the other hand with the increase in HPMC percentage, the distribution of the particle size shifts to the higher sieve size due to increase
in the internal viscosity of the medium .
The loose surface crystal study is an important parameter by which, the bursting effect of micropellets can be known when it comes in contact with the GI fluid . The percentage LSC (Table 1) in case of sodium alginate micropellets is slightly higher than the sodium alginate HPMC micropellets , which gives an indication of comparatively rapid bursting of the micropellets prepared from the sodium alginate alone.
In all the batches the angle repose is less than 15°, which indicates that the micropellets, hi ghly free flowing .
The Scanning Electron Microscopy of the micropellets prepared from alone with alginate(Figure 2a) are spheri -
MANNA et al. : MICROPARTICULATE DRUG DELIVERY SYSTEM OF NIMESULIDE 72 1
cal in shape and exhibils uniformity and rough surface as well. However in case sodium alginate -HPMC micropellets (Figure 2b) the sphericity is slightly destroyed due to higher internal viscosity, but uniformity is maintained. Micropellets prepared only with the sodium alginate is not subjected to SEM studies after dissolution because they converted to gel type of matrix when dissolution is over. Sodium alginate-HPMC micropellets after dissolution (Figure 2c) indicates the presence of pores of unaltered shape, which implies a diffusion controlled release mechanism.
Drug Entrapment Efficiency (DEE) shows that with increase in percentage in sodium alginate there is significant effect on the drug efficiency. Increase in percentage of sodium alginate and HPMC, increase the DEE in the micropellets (Table I) . Amount of calcium chloride has less significant effect on the drug entrapment efficiency.
It is observed from the dissolution study that increase in percentage of sodium alginate offers more sustained effect of the drug (Figure I) . But the sustained effect does not last for more than 6 h. On the contrary sodium alginateHPMC beads give a sustained release for 8 h or more and the shape of the beads remain unaltered. The batches A I -A4 give a diffusion controlled release mechanism '2 and follows Higuchi type of release kinetics '3 ( correlation coefficient 0.995,0.989,0.977,0.980 for batch no. A I to A4 respectively) and batches B I-B4 follows zero order kinetics (correlation coefficients 0.993,0.991,0.995,0.996 for batch no. B I to B4 respectively). From the in-vitro release study t
50% is evaluated. Finally a high satisfactory results
are obtained in continuos pH dissolution study. It is observed that at pH 1-3.5, no release of drug occurs from the pellets and at pH higher than 4, the release of the drug initiates and gives a controlled release pattern for about 8 h in case of HPMC-sodium alginate micropellets. No release of drug occurs from the micropellets prepared with
. alginate alone, when the pH of the medium is 1-2.7. After then release of the drug initiates and increases with the increase of pH. A hypothetical model of the swelling controlled release mechanism of nimesulide micropellets in dissolution medium is shown in the Figure 3.
Statistical Optimization Application of statistical design experiments to phar
maceutical problems has appeared to be extremely useful in recent years . The effect of several factors and their interactions can be determined simultaneously by Factorial Design Experiments. The Factorial Design may be useful for screening purpose or an aid in identifying individual effects of complex systems. It offers a good degree of efficacy and possibility of detecting interactions between factors. Factor effectiveness can be expressed with a math-
ematical model that explains the influence numerically. The objeclive of this work is to outline 22 Factorial Design and to study the effects of polymers and calcium chloride on the release rate of nimesulide from micropellets. The ideal micropellets were found by evaluating these findings .
Statistical analysis'2.'4. '5 based on the strong mathematical model , was done for studying various effects of process variables on the dependent variables. In the first study sodium alginate and calcium chloride were fixed as process variables or independent variables and in the second study HPMC and calcium chloride were taken as process variables. These were fixed at 2 levels : high (+ I), and low (-I) The dependent variable was Higuchi permeation rate constants and drug entrapment efficiency. Statistical analysis was done , by (i) Analysis of Vari ance (ANOVA)'2.'4 and (ii) Linear Regression Models 12 . In the experiment duplicate results were obtained for each combination of factors fitting a linear equation, which is of fi~st order polynomial.
In the first study when sodium alginate and calcium chloride were variable factors:
On the drug entrapment efficiency (Y) The effect of sodium alginate is significant, p < 0.01
The effect of calcium chloride is not significant, p > 0.0 I The fitted first order polynomial model obtained by linear regression analysis is: Y
I :;:: 95.55 - 4.48(XI -3) - 1.07(X
2 -5)
XI' X2
are the percentage (w/v) of sodium alginate and calcium chloride.
On the drug release rate_ (Y2
)
The effect of sodium alginate is significant, p < 0.0 I The effect of calcium chloride is significant, p < 0.0 I
The fitted first order polynomial model obtained by linear regression analysis is:
Y2
:;:: 70.237 - 4.325(X, -3) - 1.735(X2 ~5)
XI ,X2
are the percentage (w/v) of sodium alginate and calcium chloride.
In the second study when HPMC and calcium chloride were variable factors;
On the drug entrapment efficiency (>'.1)
The effect of HPMC is significant, p < 0.0 I The effect of calcium chloride is significant, p < 0.0 1
722 J SCI IND RES VOL.58 SEPTEMBER 1999
The fitted first order polynomial model obtained by linear regression analysis is:
Y3 = 102.466 - 7.177 *2 (X3 -1.5) - 1 .39( X2 -5) X
3, X
2 are the percentage in (w/v) of HPMC and
calcium chloride.
On the drug release rate (Y4
)
The effect of HPMC is significant, p < 0.01 The effect of calcium chloride is not
significant , p > 0.0 I .
The fitted first order polynomial model obtained by linear regression analysis is:
Y4 = 48.9225 - 5.145 *2 (Xl -1.5) Xl - 0.7075 (X2 -5)
Xl' X2
are the percentage (w/v) of HPMC and calcium chloride.
keferences
Joseph R, Robinson & Vincent H L Lee, Controlled Drug Deli Fer.\', 2nd ed (Mercel Dekker, New York) 1987, 374-421
2 Liberman H A, Lachman L & Schwart z J B, Bioavailabilit), of Tablet Technology in Phannaceutical Dosage Forms-Tablets Vol 2, 2nd ed (Mercel Dekker, New York) 1990, 394-402.
3 Lachman L, Uebennan H A & .Kanig J K, The Th eory and Practice of Industrial Pharmacy 3rd ed (Varaghese Publishing House) 199 I, 243··290
4 Kapoor A, Majumdar 0 K & Yadav M R, indian J Chern 37B ( 1998), 572-575.
5 Tripathy K 0, Essentials of Medical Pharmacology, 3rd ed (Jaypee Brothers Medical Publishers Printers Limited) 1994, 410-429 .
6 Lim.L Y, Wan Lucy S C & Thai P Y, Drug Dev Ind Pharm, 23(10) (1997) 98 I -985
7 Lim L Y & Wan Lucy S C, Drug Dev Ind Pharm , 23(10) (1997) 973-980.
8 Handbook of Pharmaceutical Excipiellts (American Pharmaceutical Association and Pharmaceutical Society, Great Britain) 138-140,257··258
9 Abu- Izza Khaw la, Garcia-Contreras Lucil a & Robert Lu 0 , J Phanna Sc, 85 (No.6) (1996), 575-576.
10 Martin Alfred, Physical Pharmacy, 4th edn (B I Waverly Pvt Ltd, Delhi) 1995,330-337,423-448.
II Das Sudip, In vito Dissolulion Profile of Theophylline Loaded Ethyl Cellulose Microspheres prepared by Emul sifi cation Solvent Evaporation Drug Dev Ind PhQ/m , 17 (18) (1991) 2521-2528.
12 Ozyazici M, Sevgi F & Ertan G, Drug Dev Ind Pharm, 23 (8) (1997) 761 -770.
13 Gibaldi Milo & Perrier Donald, Pharmacokinetics (Marcel Dekker, New York) 1975.
14 Montgomery Dougl as C, Design and Analysis of experiments, 4th ed (John Wi ley & Sons, USA) 1996
15 Cochran W G, Statistical Methods , 6th edn (The Iowa State Uni versity Press, USA) 1967, 135-170.