Liposomes in drug delivery.

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Liposomes In Drug DeliveryPresented by :

Chinchole Pravin Sonu(M.PHARM 2nd SEM)

DEPARTMENT OF PHARMACEUTICS & QUALITY ASSURANCE

R. C. Patel Institute of Pharmaceutical Education and Research, shirpur .

Overview•Definition of liposomes•Classification of liposomes •Structure of liposomes•Preparation of liposomes•Purification of liposomes•Characterization of liposomes•Liposome-cell interaction•Liposomes as drug delivery systems•Targeted Drug Delivery

Definition

•Liposomes are spherical microscopic vesicles consisting phospholipids bilayers which

enclose aqueous compartments

Classification•Small unilamellar vesicles

(SUV), 25 to 100 nm in size that consist of a single

bilayer•Large unilamellar vesicle

(LUV), 100 to 500 nm in size that consist of a single

bilayer•Multilamellar vesicle

(MLV), 200 nm to several microns,that consist of two or more concentric bilayer

–Described by Bangham in 1965–Study of membranes

Structure of Liposomes: Phospholipids

Three carbon glycerol

Polar Head Groups

Structure of Liposomes: Phospholipids

Phase Transition Temperature Tm

Membrane permeability

Cholesterol•Because of its rigid steroid ring system which interferes with

motion of fatty acid tails, stabilizes the lipid bilayer and decrease the leakage of encapsulated drug

DSC of Chol/DSPC

10 20 30 40 50 60 70 80

12 DSPC 5% Chol 10% Chol 20% Chol 30% Chol 35% Chol 40% Chol 50% Chol 60% Chol SChcPC

Temperature (ºC)

MHC of SChcPC and DSPC

Non Structural Components

Preparation of liposomes: Mechanical Dispersion

Processing of lipids hydrated (MLVs) by physical means

•Micro-emulsification of liposomes

Processing of lipids hydrated (MLVs) by physical means

EmulsiFlex High Pressure Homogenizar

Processing of lipids hydrated (MLVs) by physical means: EmulsiFlex High Pressure Homogenizar

Purification of Liposomes

•Gel Filtration Column Chromatography

•Dialysis

•Centrifugation

Stability of Liposomes

•Chemical degradation•Physical degradation•Prevention of chemical

degradation•Prevention of physical

degradation

Preparation of Sterile Liposomes

Liposome Characterization

•Determination of Drug Content•Determination of Percent Capture•Lamellarity•Phosphate assay•Cholesterol assay

Liposome characterization•Size distribution•Zeta potential•Tm by DSC•Stability: Drug, lipid and liposome

Liposome-cell interaction

Liposomes in drug delivery

•Protect the encapsulated drug from metabolic degradation

•Increase the half-life of drug•Reduce the systemic toxicity of drugs•Could be used as sustained release vehicles•It is possible to target them to selected tissues

or cell•Biodegradable and biocompatible

Types of liposomes

Stealth or PEG-Liposomes