Novel Application of Mixed Solvency Concept for the Development of Topical Emulgel Formulations of Poorly Water-Soluble Drug, Piroxicam, and their Evaluations

Aim: The objective of this research was to investigate the mixed solvency concept as a means to enhance the solubility of Piroxicam and to develop an optimized microemulsion-based gel formulation suitable for topical application. Materials and Methods: Piroxicam-loaded microemulsion gel was prepared by using a combination of a pseudo-ternary phase diagram and a D-Optimal mixture design approach. This involved conducting 15 trial runs with three key variables: the percentage of oil blend, water content, and the optimized ratio of surfactant to co-surfactant. The responses assessed were the percentage transmittance and globule size. The Piroxicam microemulsion was formulated using Tween 80 as the surfactant and butanol as the co-surfactant, a combination of Castor oil and Capmul oil as the oil blend, and water. Carbopol 940 was utilized as a gelling agent to formulate the gel for the microemulsion. Results: The optimized microemulsion underwent characterization for pH, globule size, transmittance, drug content, viscosity, and texture analysis. Transmission Electron Microscopy (TEM) was employed to investigate the surface morphology of the microemulsion globules. Additionally, an in vitro drug release study (flux) was conducted using a Franz diffusion cell fitted with a dialysis membrane. It was observed that the microemulsion gel formulations demonstrated a notably accelerated in vitro membrane release rate of Piroxicam in comparison to the marketed formulation. Conclusion: Overall, the developed microemulsion gel formulations show promising carriers for the topical delivery of Piroxicam.