Topical L-ascorbic acid: percutaneous absorption studies. Dermatol Surg

background. Reactive oxygen species generated by ultraviolet light result in photocarcinogenic and photoaging changes in the skin. Antioxidants protect skin from these insults. objective. This study defines formulation characteristics for delivering L-ascorbic acid into the skin to supplement the skin’s natural antioxidant reservoir. methods. L-ascorbic acid or its derivatives were applied to pig skin. Skin levels of L-ascorbic acid were measured to determine percutaneous delivery. results. L-ascorbic acid must be formulated at pH levels less than 3.5 to enter the skin. Maximal concentration for optimal percutaneous absorption was 20%. Tissue levels were saturated after three daily applications; the half-life of tissue disappear-ance was about 4 days. Derivatives of ascorbic acid including magnesium ascorbyl phosphate, ascorbyl-6-palmitate, and dehy-droascorbic acid did not increase skin levels of L-ascorbic acid. conclusions. Delivery of topical L-ascorbic acid into the skin is critically dependent on formulation characteristics. IN THE PRESENCE of our oxygen-rich atmosphere, ultraviolet light generates reactive oxygen species in skin. In addition to sunlight, other inflammatory in-sults including smoking and pollution generate reac-tive oxygen species. Reactive oxygen species, in turn, cause oxidation of nucleic acids, proteins, and lipids. Reactive oxygen species alter DNA