LIPOSOMES

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LIPOSOMES:

LIPOSOMES By T.Shivaram B.PHARMACY Shiva.pharmacist@gmail.com 1

LIPOSOMES:

Liposome are membranous vesicles formed by dispersion of phospholipids in aqueous media. They are small hollow spheres bound by a double layer of lipid molecules in which the hydrophilic heads of the molecules form the inner and outer surface of the sphere, while the lipophillic tails interwine in the middle. 2 LIPOSOMES

LIPOSOME:

3 LIPOSOME HYDROPHOBIC HYDROPHILIC

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ADVANTAGES: Flexibility in the structure in entrapment of water soluble as well as insoluble drugs. Biodegradability Efficient control of release. Resemblance to natural membrane structures. Increased targeting prospects. Beneficial modification of pharmacokinetics of the drug. Facilitation of transport across membranes. Adjuanticity of vaccines 4

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DISADVANTAGES: The development of liposomes at industrial level is difficult due to its physiological and physicochemical instability. They aggregate and fuse together upon prolonged storage disturbing the reproducibility. They are prone to degradation by oxidation and hydrolysis. 5

CHARACTERISATION:

Size and size distribution Lamellarity Entrapped volume Solute distribution 6 CHARACTERISATION

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Classification b ased on structural parameters 7 Based on structural MLV Multilamellar Large vesicles (>0.5 um) OLV oligolamellar vesicles (>0.1-1.0 um) UV UnilamellarVesicles (all size ranges) MVV Multivesicularvesicles (> 1.0 UM) MUV GUV >1um SUV 20-100nm LUV >100nm

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8 Multilamellar vesicles Unilamellar vesicles

MECHANISM OF ACTION:

Endocytosis Adsorption to cell surface Fusion with plasma cell membrane Transfer of liposomal content 9 MECHANISM OF ACTION

METHODS OF PREPARATION:

Physical dispersion methods Solvent dispersion Detergent solubilisation 10 METHODS OF PREPARATION

Physical dispersion methods:

Hand shaking method Non shaking method Pro liposomes Freeze drying method 11 Physical dispersion methods

HAND SHAKING METHOD:

12 HAND SHAKING METHOD

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SOLVENT DISPERSION METHODS: Ethanol injection Ether injection Water in organic phase Double emulsion vesicles 13

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Ethanol/Ether injection method 14

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Handling of liposomes : Liposomes have a standard composition- egg, lecithin, cholesterol, phosphotidyl glycerol in molar ratio of 0.9:1:0.1. these lipids are stored as solids or in organic solution at -20°C or -70°C in order to reduce oxidation. The solvent is mixture of chloroform and methanol(2:1). Stored in dark glass vessels. Drying : Gentle warming at 20°C to 40°C under reduced pressure. Rapid rotation increase surface area for evaporation. 15

PURIFICATION OF LIPOSOMES:

Commonly purified by gel filtration column chromatography or dialysis or centrifugation. In column chromatographic separation, Sephadex G-50 is most widely used material. In dialysis method, hollow fiber dialysis cartridge may be used. The separation of liposomes by centrifugation method depends on the size as well as the composition of the bilayers. 16 PURIFICATION OF LIPOSOMES

INVITRO BEHAVIOUR OF LIPOSOMES:

IV route is the most popular route. Three pathways are there for drug release. Destabilization of liposomes Delivery of liposomes to the monounuclear phagocyte system(MPS) Sustained release of liposome encapsulated drug by long circulating liposomes. 17 INVITRO BEHAVIOUR OF LIPOSOMES

APPLICATIONS:

Enzyme replacement therapy Delivery of antibodies, antigens and vaccines Hormones and blood factors Blood substitutes Interferon 18 APPLICATIONS

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19 Thank you

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