A Review on Microemulsion Based Gel: A Recent Approach for Topical Drug Delivery System

Abstract

Microemulsions, which are optically isotropic and thermodynamically stable systems of water, oil, surfactant, and/or co-surfactant, have been studied as drug delivery systems because of their capacity to solubilize poorly water soluble drugs as well as their enhancement of topical and systemic availability. It helps to solubilize the lipophilic drug moiety and it shows rapid and efficient penetration to the skin. So it is beneficial for topical drug delivery. For topical delivery, microemulsion is incorporated in polymer gel base to prolong the local contact to the skin. Many widely used topical agents like ointments, creams, lotions have many disadvantages like sticky in nature, causing uneasiness to the patient when applied, have lesser spreading co-efficient so applied by rubbing and they also exhibit the problem of stability. Microemulsion is having stability problem due to having low viscosity but can be overcome by incorporation into topical DDS causes improved viscosity and hydrating stratum corneum which will increase drug dermal permeation and the skin flux. Due to all these factors within the major group of semisolid preparations, the use of transparent gels has expanded in pharmaceutical preparations. In spite of the many advantages of gels, a major limitation is in the delivery of hydrophobic drugs. So to overcome this limitation microemulsion based approach is being used so that even a hydrophobic therapeutic moiety can be successfully incorporated and delivered through gels. Hydrophobic drugs can be incorporated into microemulsion based gel using drug/oil/water emulsions. Microemulsion based gel helps in the, incorporation of hydrophobic drugs into the oil phase and then oily globules are dispersed in an aqueous phase resulting in oil/water emulsion. Now a days various polymers are used as gelling agent which make help to reduce the interfacial tension of oil and aqueous phase of microemulsion and also increasing the viscosity of the aqueous phase. These systems are currently of interest to the pharmaceutical scientist of their unique characteristics and considerable potential to act as a drug delivery carrier by incorporating a wide range of drug molecules. In order to appreciate the potential of microemulsion gel as delivery carrier, this review gives a complete knowledge about properties, formulation consideration, phase behavior, advantages and application of microemulsion based gel for drug delivery system.