Quantitative distribution of locally applied lindane in human skin and subcutaneous fat in vitro. Dependence of penetration on the applied concentration, skin state, duration of action and nature and time of washing.

Commercial concentrations of radiolabelled lindane emulsion were applied to human skin specimens. Penetration of the substance into the different layers of the skin was examined quantitatively under the common conditions of therapy, but with variation of the period of action (3, 10 and 24 h), condition of skin specimens (intact, stripped), concentration of the emulsion applied (0.3 and 1%) and washing with water only or water and soap after different periods of action (3 and 10 h) and examination at different times after the washing procedure (7 and 14 h). The flux of lindane in the skin was found to be time-dependent. Generally, the concentration increased with the depth of the layer. An increased availability of lindane (in absence of the stratum corneum, and at long application period) resulted in a preferential accumulation in the epidermis and not in the subcutaneous fat. When the intact skin had been washed with soap and water 3 h after application, the concentration of lindane found in the layer below the stratum corneum 7 h later was higher than the one found when the skin had not been washed. When intact skin had been washed after a short penetration period (3 h), this resulted in an introduction of lindane by the washing process. This effect did not occur with stripped skin. Lindane could be more efficiently removed from the stratum corneum with soap and water than with water alone. A threefold increase of the lindane concentration applied resulted in a threefold increase of the concentration in all layers of intact skin specimens. In stripped skin specimens, an increase could be observed.(ABSTRACT TRUNCATED AT 250 WORDS)