Optimization and characterization of indomethacin-loaded plai oil microemulsion using 23 full factorial design

Abstract

This study aimed for the optimized plai oil microemulsion in the presence and absence of indomethacin using a 23 full factorial design. Independent variables were weight ratios of surfactant to cosurfactant, the addition of indomethacin, and the concentration of surfactant cosurfactant mixture. Physicochemical properties of formulations were characterized. In vitro skin permeation through shed snakeskin as well as formulation stability was evaluated. The obtained formulations were transparent, homogenous yellowish microemulsions with o/w type. The average particle sizes were in the range of 44.57–92.70 nm. All three variables played a significant role in decreasing the skin permeation flux of terpinen-4-ol. Both terpinen-4-ol and indomethacin showed good skin absorption. The optimized formulations consisted of 14% plai oil, 45% Tween® 80-absolute ethanol (1:1), and water in the presence and absence of indomethacin. The results suggested that indomethacin-loaded plai oil microemulsion is promising as a potential candidate for a topical anti-inflammatory preparation suitable for further commercial development.