RESUMO
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.
Assuntos
Antioxidantes/administração & dosagem , Antioxidantes/farmacocinética , Ácido Ascórbico/administração & dosagem , Ácido Ascórbico/farmacocinética , Absorção Cutânea , Protetores Solares/administração & dosagem , Protetores Solares/farmacocinética , Administração Cutânea , Animais , Ácido Ascórbico/análogos & derivados , Ácido Desidroascórbico/administração & dosagem , Ácido Desidroascórbico/farmacocinética , Concentração de Íons de Hidrogênio , Pele/metabolismo , SuínosRESUMO
UV light reacts with skin to produce undesirable changes, including photoaging and skin cancer. Sunscreen strategies are useful for protection against UV-B and short-wave UV-A, but complete protection against long-wave UV-A has not been achieved. Because UV-A is especially efficient at generating reactive oxygen species, it is being recognized increasingly as an important cause of photoaging and skin cancer.
