Development, Characterization and Skin Interaction of Capsaicin-Loaded Microemulsion-Based Nonionic Surfactant.

The aim of this study was to develop novel microemulsions (MEs) for the transdermal delivery of capsaicin. Microemulsion-based nonionic surfactants consisting of isopropyl myristate as the oil phase, various nonionic surfactants as the surfactant (S), various glycols or alcohol as the co-surfactant (CoS), and reverse osmosis water as the aqueous phase were formulated. Based on the optimal ME obtained from Design Expert, MEs containing a fixed concentration of oil, water or surfactant were prepared while varying the amounts of the other two fractions.

Application of Design Expert for the investigation of capsaicin-loaded microemulsions for transdermal delivery.

Our previous study reported that the Design Expert® Software showed a beneficial role in the development of microemulsions (ME) for transdermal drug delivery. To fully confirm the reproducibility and the reliability of simultaneous optimal ME formulations, the optimal ME formulations predicted by the Design Expert® Software were experimentally formulated and verified for their skin permeability. Ternary phase diagrams were used to predict the optimal ME area, and the ME formulations selected from outside this area were considered as candidate ME systems.