Abstract

MICROEMULSION AND ITS APPLICATIONS NOVEL APPROACH TOWARDS THE DRUG DELIVERY

Suchita.G.Waghmare*, Rasika R.Nikhade, Mahesh A.Hadke

ABSTRACT

A microemulsion is a system of water, oil and an amphiphiles which is a single optically isotropic and thermodynamically stable liquid solution. Microemulsions can be considered as small-scale versions of emulsions, i.e., droplet type dispersions either of oil-in-water (o/w) or of water-in-oil (w/o), with a size range in the order of 5−50 nm in drop radius. Microemulsion formation is dependent on surfactant type and structure. The microemulsion formulations consist of one or more surfactants in combination with co-surfactant and drug dissolved in oil. If the surfactant is ionic and contains a single hydrocarbon chain microemulsion are only formed if a co-surfactant and/or electrolyte are also present. With double chain ionic and some non-ionic surfactants a co-surfactant is not necessary. Oils form a distinct core in the interior of the surfactant aggregate, resulting in enhanced solubilizing capacity of the oils with improved drug loading capacities of the microemulsion. Microemulsions are optically isotropic and thermodynamically stable liquid solutions of oil, water and amphiphile. Microemulsions are readily distinguished from normal emulsions by their transparency, low viscosity and more fundamentally their thermodynamic stability. It is well established that medium chain fatty acids influence tight junctions of the epithelial cells, and long chain fatty acids stimulate the lipoprotein synthesis and subsequent lymphatic absorption. Microemulsions are shown to be effective dermal delivery mechanism for several active ingredients for pharmaceutical and cosmetic applications. Topical microemulsion allows rapid penetration of active molecules due to the large surface area of the internal phase, and their components reduce the barrier property of stratum corneum. Microemulsions thereby enhance dermal absorption compared with conventional formulations and are therefore a promising vehicle due to their potential for transdermal drug delivery.

Keywords: Microemulsions, Surfactant, Thermodynamically stable, amphiphile.