In vitro percutaneous penetration through hairless rat skin: influence of temperature, vehicle and penetration enhancers.

Theoretically, a positive relation is expected between skin temperature and the percutaneous penetration of topically applied substances. The aim of the present study was to evaluate the influence of the temperature on the in vitro percutaneous penetration of dihydrotestosterone. Hairless rat skin was mounted in static diffusion cells placed in a water bath at different temperatures (28.6, 35.1 and 38.2 degrees C, respectively). Different vehicles were tested as well as the addition of penetration promoting molecules such as oleic acid and limonene. A saline buffer was used as the receptor phase. Penetration through the skin was evaluated by means of scintillation counting of the radiolabelled dihydrotestosterone. Experiments were followed for a period of 29 h. The total amount of penetrant, dihydrotestosterone, as well as the flux, were calculated from these kinetics. Our results demonstrate a temperature effect with the highest penetration at 38.2 degrees C. The vehicle was also found to influence the penetration of dihydrotestosterone in a significant way. Furthermore, limonene presented better penetration promoting properties compared with oleic acid. Copyright 1998 Elsevier Science B.V.