140 likes | 653 Views
Liposomes: Formation, preparation, properties and applications. Dr. S.S.Apte Professor, Univ. College of Pharm. Sci., Kakatiya University, Warangal Presently: NDDS Divn, Natco Research Centre Hyderabad. Definition of Liposomes.
E N D
Liposomes: Formation, preparation, properties and applications Dr. S.S.Apte Professor, Univ. College of Pharm. Sci., Kakatiya University, Warangal Presently: NDDS Divn, Natco Research Centre Hyderabad
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