Microemulsion: A Potential Novel Drug Delivery System

Abstract

Microemulsions are isotropic, thermodynamically stable transparent (or translucent) systems of oil, water and surfactant, frequently in combination with a cosurfactant with a droplet size usually in the range of 20–200 nm. They have emerged as novel vehicles for drug delivery which allow controlled or sustained release for ocular, percutaneous, topical, transdermal, and parenteral administration of medicaments. Microemulsions can be easily distinguished from normal emulsions by their low viscosity, transparency and more accurately their thermodynamic stability. Microemulsions have a very crucial importance in the drug delivery system as well as in the industrial process. They can be used to optimize drug targeting without a concomitant increase in systemic absorption. The role of microemulsion in providing novel solutions to overcome the problems of poor aqueous solubility of highly lipophilic drug compounds and provide high, more consistent and reproducible bioavailability. The objective of this review is to provide an overview of the structures, methods of microemulsion formation, techniques which may be used for characterization and application.