liposomes- a novel drug delivery system
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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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