Preparation and Characterization of Naproxen Loaded Microemulsion Formulations for Dermal Application

The aim of this study was to prepare new w/o microemulsions of naproxen (Np) for topical application and evaluate in vitro permeation of Np. The Pseudo-ternary phase diagrams were constructed for various microemulsions composed of isopropyl myristate (IPM) as oil phase, Span 80, Labrafil M, Labrasol, Cremophor EL as surfactants, ethanol as co-surfactant and water as aqueous phase. Finally, concentration of Np in all microemulsions was 10% (w/w). The physicochemical properties of microemulsions such as conductivity, droplet size, viscosity and pH were measured. The in vitro permeability of Np compared with commercial (C) and microemulsions. The permeation rates of Np from microemulsions were higher (1.2 times) than C gel formulation. Finally, according the histological examination of microemulsions did not show irritant effect on treated skin. In conclusion, the results of this study indicated that the microemulsions especially M2Np can be considered as potentially useful vehicles for topical application of Np.