Liposomes: Benchmark in the Era of Drug Carriers for Semisolid Based Topical Delivery System

A liposome is a microscopic vesicle consisting of an aqueous core enclosed in one or more phospholipid layers, used to convey vaccines, drugs, enzymes, or other substances to target cells or organs. Liposomes are bilayered structures made of amphipathic (both hydrophobic and hydrophilic) phospholipids/cholesterol that spontaneously form closed structures when hydrated in aqueous solutions. Liposomes are acceptable and superior carriers having ability to encapsulate hydrophilic and lipophilic drugs and protect them from degradation. Topical liposomes have similarity to biological membranes they can store water-soluble and lipophilic substances in their different phases. Moreover, they are similar to the epidermis with respect to their lipid composition, which enables them to penetrate the epidermal barrier to a greater extent compared to other dosage forms. According to studies performed so far liposomes are biodegradable and non-toxic. The really new aspect with liposomes is that they are thought to act not only as drug transporters but also drug localizers. Thus vehicles can transport drugs to the wanted site of action within the skin by preventing systemic absorption and consecutively unwanted effects. The liposomal semisolid formulations could perform therapeutically better effects than the conventional formulations, as prolonged and controlled release topical dosage forms, which may lead to improved efficiency and better patient compliance. Such review giving an emphasis on topically applied liposomal formulations which encompasses methods of preparation, evaluation, mechanisms for enhancement in drug delivery through the skin and regulatory requirements necessitates as topical dosage form.