Abstract:

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 disappearance was about 4 days. Derivatives of ascorbic acid including magnesium ascorbyl phosphate, ascorbyl-6-palmitate, and dehydroascorbic 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.

Document Type: Research article

Affiliations: 1: Duke University Medical Center, Durham, North Carolina, 2: College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, and 3: PhytoCeuticals, Elmwood Park, New Jersey, 4: National Institute of Diabetes & Digestive & Kidney Diseases, NIH, Bethesda, Maryland