An in vitro human skin model for assaying topical drugs against dermatophytic fungi

Abstract

A shortened modification of Dittmar´s in vitro human skin assay reliably predicts the efficacy of topical antifungals against ringworm fungi. Cadaver skin was treated with the test agents for 4 or 24 h. After heat separation of the epidermis for one minute at 60 degrees C, the undersurface was point inoculated with a spore suspension of T. mentagrophytes. In untreated skin fluffy, 3 mm colonies develop after 4 to 5 days of incubation. Effective fungistats produce complete inhibition of growth. Commercial formulations of the imidazoles, tolnaftate and ciclopirox were highly effective. Haloprogin, undecylenate, and hydroxyquinoline in proprietary form were inactive. There was a high correspondence between in vitro and in vivo effectiveness. The method should be useful for screening new antifungals and for optimal selection of vehicles.