Liposomes: Formation, preparation, properties and applications Dr. S.S.Apte Professor, Univ. College...
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Transcript of Liposomes: Formation, preparation, properties and applications Dr. S.S.Apte Professor, Univ. College...
Liposomes:
Formation, preparation, properties and applications
Dr. S.S.Apte
Professor, Univ. College of Pharm. Sci., Kakatiya University, Warangal
Presently:NDDS Divn, Natco Research CentreHyderabad
Liposomal Anthracycline Antibiotics Used in Therapy
Product Drug Marketed By Registration Year
DaunoXome Daunorubicin citrate
NeXstarPharmaceutical
Inc.
EnglandSwedenUSA
1995 r.1995 r.1996 r.
Doxil Doxorubicin SequusPharmaceutical
Inc.
USA 1995
Caelix Doxorubicin
Schering-Plough Selected EuropeanCountries
1995 r.
Definition of Liposomes
Liposomes are spherical, self closed structures composed of curved lipid bilayers which entrap part of the solvent, in which they freely float, into their interior. They may consist of one or several concentric membranes; their size ranges from 20 nm to several dozens µm, while thickness of the membrane is around 4 nm.
Salient features
Discovered in 1968 by Alec Bangham
Delivery system for hydrophilic, lipophilic, and amphiphilic APIs
Solubilization of lipophilic and amphiphilic APIs
Protection of the API
Reduction of side effects - toxicity of the active
Sustained release
Drug targeting
Low application dose
Classification of Liposomes
SUV = Small Unilamellar Vesicles LUV = Large Unilamellar Vesicles MLV = Multilamellar Vesicles LLC = Lamellar Liquid Crystalline Phase MVV = Multivesicular vesicles
Liposomes are composed of one to several
hundreds concentric membranes
Vesicles
Niosomes (Nonionic surfactants +cholesterol)
liposomes (phospholipids + Cholesterol)
Vesicular delivery systems
Preparation of vesicles:
Film casting via organic solvent
film hydration
ether-ethanol injection
Reverse phase evaporation
Through mixed micellar solution
Mechanical methods
Characterization of vesicles:
Size and size distribution - Dynamic light scattering
Electron microscopy
Coulter counter
Number of lamellae - NMR spectroscopy
small angle X ray scatter
Charge - Microelectrophoresis
Entrapment efficiency - Gel filtration
Capture volume - ultrafiltration
dialysis
protamine aggregation
ultracentrifugation
Release - Dialysis
Liposomal Delivery of Anti-Cancer Agents
Slow Release: reduced peak levels of free drug and prolonged
tumor exposure
Change in Biodistribution: avoiding drug deposition in certain
tissues will reduce tissue-specific toxicities
Tumor Targeting: passive accumulation by enhanced
permeability and retention (EPR) effect
Phospholipids in topical pharmaceutical applications
Drug Effects
Benzoyl peroxide
Flurbiprofen
Diclofenac
Heparin
Clindamycin phosphate
Aciclovir
Menthol & camphor
N,N-diethyl-meta-toluamide (DEET)
Povidone-Iodine
Tamoxifen
Econazol, Miconazol
Glycolic acid
Bethametasone 17-benzoate
improved drug delivery; higher anti-bacterial efficacy
better penetration; improved efficacy in pain treatment
improved drug delivery; higher drug efficacy
improved penetration; higher drug efficacy
sustained release, drug efficacy improvement
enhanced penetration
enhanced penetration, rapid onset of action
controlled release, inhibition of absorption
improved drug delivery & efficacy
improved penetration and drug retention in the skin
drug retention in the skin
controlled release
penetration enhancement