Transdermal solid delivery of epigallocatechin-3-gallate using self-double-emulsifying drug delivery system as vehicle: Formulation, evaluation and vesicle-skin interaction.

The present study investigated a self-double-emulsifying drug delivery system loaded with epigallocatechin-3-gallate to improve epigallocatechin-3-gallate skin retention. The long chain solid lipids (cetostearyl alcohol) and macadamia oil were utilized as a carrier to deliver the bioactive ingredient. Response surface methodology was used to optimize the formulation, and the solid lipid to total lipid weight ratio, concentration of epigallocatechin-3-gallate and hydrophilic surfactant on skin retention were found to be the principal factors. The optimum formulation with high encapsulation efficiency (95.75%), self-double-emulsification performance (99.58%) and skin retention (87.24%) were derived from the fitted models and experimentally examined, demonstrating a reasonable agreement between experimental and predicted values. Epigallocatechin-3-gallate-self-double-emulsifying drug delivery system was found to be stable for 3 months. Transdermal studies could explain a higher skin diffusion of epigallocatechin-3-gallate from the self-double-emulsifying drug delivery system compared with EGCG aqueous solution. In vitro cytotoxicity showed that epigallocatechin-3-gallate-self-double-emulsifying drug delivery system did not exert hazardous effect on L929 cells up to 1:10.