Iontophoresis promotes percutaneous absorption of l-ascorbic acid in rat skin

Background: Percutaneous absorption of ascorbic acid is limited by its impermeability and instability. Objective: We attempted to improve the percutaneous absorption of ascorbic acid by use of iontophoresis after topical application of ascorbic acid. Methods: Radioactivities extracted from epidermal, dermal and blood compartments after topical application of [ 14C]ascorbic acid was measured in the presence or absence of iontophoresis. Autoradiography was also performed to study the histological distribution of the radioactivity of ascorbic acid. Results: Iontophoresis greatly enhanced percutaneous absorption of [ 14C]ascorbic acid in the rat skin. Radioactive ascorbic acid in the dermis reached a maximum level at 1 h after application whereas, in the topical application method, the uptake of ascorbic acid in both epidermis and dermis was quite low. Autoradiography of skin specimens indicated that iontophoresis accelerated the absorption of ascorbic acid through both transepidermal and pilo-sebaceous routes. Conclusion: Iontophoretic delivery system of ascorbic acid may provide a more efficient tool for its percutaneous absorption than a simple topical application.