In vitro human skin percutaneous penetration: does a second topical application effect flux of first application?

Hui, Xiaoying; Maibach, Howard

INTRODUCTION Skin care products are often utilized in conjunction with topical treatment for skin disease. However, these appears insufficient body of experimental data to advise the health care worker or patient. Examine penetration effect (hence potential for altering efficacy and toxicity) - dosing with one topical after another and how quickly such a potential phenomenon might occur. METHODS A marketed moisturizer applied on human skin with an in vitro diffusion system. At 1, 15, and 30 min post application, [14C]-benzoic acid dosed the same skin site for 24 h. Amounts of chemical retained in skin and permeation flux rats were measured to determine penetration effect of the prior moisturizer application. RESULTS Exposure of a water-enriched moisturizer before a hydrophilic chemical immediate application favors the chemical penetration, especial in 1 and 15 min moisturizer exposure groups. The enhancement effect was expressed as an earlier lag time and a rapid absorption peak when compared to related non-moisturizer control. CONCLUSION This experiment opens up a large door: what would be the result with many complex topical products and different tracers was used here, of varying hydrophilicity and lipophilicity. We do not wish to overgeneralize until such studies are confirmed in vivo.