Transfollicular percutaneous absorption. Skin model for quantitative studies.

Theoretically percutaneous absorption comprises two components: the transepidermal route and the transappendageal route, so-called 'shunt' diffusion. The relative importance of 'shunt' diffusion was investigated with a model of appendage-free skin. After treatment with 60 degrees C water for exactly 1 min, hairless dorsal rat skin regrows as a continuous epidermis. We present preliminary results of hydrocortisone diffusion in vitro, in appendage-free skin relative to normal skin. With intact skin under our experimental conditions, the steady-state flux and the total diffusion in 24 h were 50-fold larger.