Penetration of 5 fluorouracil in excised skin

Abstract

Total penetration of 5 fluorouracil (FU) through human and hairless mouse skin was measured in vitro and the results were compared using radioactively labeled drug and a gas chromatographic method specific for the free FU molecule. Both methods were used to determine whether metabolism, either in the skin during penetration or in the penetration wells, could have affected the percent penetration as calculated by the radioactivity method. The results indicate significantly greater drug penetration in the mouse samples using both methods of detection, with somewhat greater variations between identical samples occurring with the chromatographic method. The percent penetrating the human samples, approximately 12% after 20 hr, agreed with the previously reported in vivo data. These studies indicate that further in vitro studies may be useful to study the factors affecting the penetration of FU when applied topically in a variety of skin diseases.