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ANIRBAN SAHAAMITY INSTITUTE OF PHARMACY

M.Pharm (Pharmaceutics)

Semester- 2

Enrollment No: A10647014005

Liposomes are the simple microscopic vesicles in which aqueous layer is enclosed by phospho lipid bilayers that are used to transfer vaccines ,drugs ,enzymes and other substances to targetcells or organs

Structually ,liposomes are concentric bilayerd vesicles in which an aqueous volume is entirely enclosed by a membraneous lipid bilayer mainly composed of natural or synthetic phospholipids.

Can be produced from cholesterols, non toxic surfactants, sphingolipids, glycolipids, long chain fatty acids and even membrane proteins.

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COMPOSITION

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Phospholipids:Dilauryl phosphotidyl choline (DLPC), Dimyristoyl phosphotidyl choline(DMPC), Dipalmitoy phosphotidyl choline (DPPC), Distearoylphosphotidyl choline (DSPC), Dioleolyl phosphotidyl choline (DOPC),Dilauryl phosphotidyl glycerol (DLPG), Distearoyl phosphotidyl serine(DSPS).

Cholesterol:Act as intercalator with phospholipids molecules.Restrict the confirmational changes of lipids.Membrane stabilizer.

ADVANTAGES

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Non-toxic.

Biodegradable.

Non-immunogenic.

Lowers systemic toxicity.

Targeted delivery.

Protection of sensitive drug molecules.

Enhance drug solubilisation ( Amphoterecin, Cyclosporins).

Improved pharmacokinetic effects.

• Leakage of encapsulated drug during storage.

• Short half-life.

• Batch to batch variation.

• Difficult in large scale manufacturing and sterilization.

• Production cost is high.

• Once administered, liposomes can not be removed.

• Some times phospholipids undergoes hydrolysis andoxidation reactions

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COMMONLY USED

PHOSPHOLIPIDS

NATURAL

PHOSPHATIDYL

CHOLINE

PHOSPHATIDYL

ETHANOLAMINE

PHOSPHATIDYL

SERINE

SYNTHETIC

DIOLEOYL

PHOSPHATIDYL

CHOLINE

DISTEAROYL

PHOSPHOTIDYL

CHOLINE

DIOLEOYL

PHOSPHATIDYL

ETHANOLAMINE

COMMONLY USED PHOSPHOLIPIDS

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BASED ON PREPARATION METHOD

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General Method Of Liposome Formation

All the methods of preparing liposomes involves 3 to 4 steps.

Analysis of final product

Purification of resultant liposomes

Dispersion of lipids in aqueous media

Drying down lipids from organic solvents

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METHODS OF LIPOSOME

PREPARATION

PASSIVE LOADING

Involves loading of the entrapped

agents before or during the

manufacturing procedure

ACTIVE OR REMOTE LOADING

Certain types of compounds with

ionizable groups and those with

both lipid and solubility , can be

introduced into the liposomes after

the formation of the intact vesicles

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Classes of Liposomes

CONVENTIONAL LONG CIRCULATING

IMMUNO CATIONIC

PHARMACOKINETICS - Efficacy And Toxicity

Changes the absorbance and bio distribution

Deliver drug in desired form

Multidrug resistance

PROTECTION

Decrease harmful side effects

Change where drug accumulates in the body

Protects drug

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Lack long term stability (short shelf life)

Physical and chemical instability

Freeze dry and pH adjustment

Low “Pay Load” - Poor Encapsulation

Drugs and drugs without opposite charge

Modifications

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Y. Sultana., Liposomal Drug Delivery Systems: An Update Review. ,Current Drug Delivery 2007, 4, 297-305.

Sharma Shailesh, Sharma Neelam, Kumar Sandeep, Gupta GD.,Liposomes: Areview., Journal of Pharmacy Research 2009,2(7),1163-1167.

Mohammad Riaz., Liposomes Preparation Methods., PakistanJournal of Pharmaceutical Sciences Vol.19(1), January 1996, 65-77.

MU Uhumwangho and RS Okor., Current trends in the productionand biomedical applications of liposomes: a review ., JMBR June2005 Vol. 4(1) 9-21.

http://www.biopharminternational.com/biopharm/data/articlestandard/biopharm/032002/7278/article.pdf., web, 28.01.2012

http://www.ias.ac.in/jarch/currsci/68/00000742.pdf.,web,28.01.2012

D.D. Lasic., Applications of Liposomes., Handbook of BiologicalPhysics., Elsevier Science B.V.., 1995., Vol.1., 1-29

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