Effect of formulation on the topical delivery of alpha-tocopherol.

The objective of this research was to investigate the effect of concentration and delivery system on skin permeation of alpha-tocopherol (alpha-T). Also, the addition of sunscreens and oleic acid on alpha-T permeation was studied using an in vitro micro-Yucatan pig skin model. Various delivery systems of alpha-T (1%) were formulated, which included simple solution, gels, emulsions, and microemulsions. The experimental design chosen for this study was a statistical randomized complete block design. alpha-T delivery was proportional to its concentration. The hydroalcoholic gel delivered significantly higher amounts of alpha-T into the receptor than the other gels used. A microemulsion containing isopropyl myristate emerged as the best delivery system for alpha-T among all the systems studied. Pig skin is a suitable in vitro model for studying the permeation of alpha-T and possibly other antioxidants, though in vivo experiments in humans are required to further corroborate the data.