Abstract

Topical microemulsions of nimesulide, a poorly water-soluble nonsteroidal antiinflammatory drug, using olive oil as oil phase and Tween 80/iso-octanol as surfactant/co-surfactant were designed. Various concentrations of surfactant: co-surfactant (2:1, 3:1, 4:1) were used in constructing a pseudoternary phase diagram. Oil-in-water microemulsions with ratio 15/35/50 (o/w/s) was chosen for the present study after evaluating various parameters like centrifugation, viscosity and stability. Using 4:1 ratio of surfactant : co-surfactant, a microemulsion-based gel of nimesulide was prepared with 1% Carbopol 934. In vitro permeation study of the gel was carried out through excised hairless rat skin and compared with a marketed preparation. The drug release after 24 h from the prepared microemulsion gel and marketed formulation was found to be 72% and 81% respectively. No significant difference was observed between the release rates of nimesulide from both formulations despite their differences in alcohol content. Microemulsion-based gel of poorly water-soluble nimesulide was successfully developed with in vitro release rates comparable to that of the marketed gel formulation.