Liposomes as a Novel Drug Delivery System: A Comprehensive Review on Component, Classification, Preparation Methods, Mechanism of Action, Stability, Marketed Formulations and Therapeutic Application

Liposomes are spherical, concentric vesicles originating from greek words lipos meaning fat and soma meaning body. The science of liposomolgy was founded by British scientist alec bangham and associate at babraham Cambridge in mid-1960, who in 1961 accidently scattered phosphatidylcholine molecules in water and discovered closed bilayer structure in 1964 liposomes are self –assembling (phosphor) lipid –based drug vesicles that enclose a core aqueous compartment in a bilayer (uni-lamellar) or a concentric series of several bilayer multilamellar. They are colloidal carries with diameter ranging from 0.01 to 5.0 um with phospholipid bilayer thickness 4-5 nm ranging from 30 nm to micrometre scale, though for drug delivery application typically unilamellar with diameter 50-150 nm as bigger liposomes are quickly eliminated from blood stream .they are tiny, spherical artificial vesicles made from natural nontoxic phospholipid and cholesterol. The main structural elements are phospholipid – phophatidylcholine (lecithin) pc being most widely utilized amphipathic molecule consisting of hydrophilic polar head group phosphocholine Glycerol Bridge and two acyl hydrophobic polar head group.