A two phase series model for the transport of steroids across the fully hydrated stratum corneum

Abstract

A two phase series model for the permeability behaviour of the fully hydrated stratum corneum has been examined using Scheuplein's data on steroids, since these strongly encouraged the investigation of possible heterogeneous diffusion models that showed the dependence of the effective diffusion coefficient, De, upon the effective partition coefficient, Ke. The model described can be characterized by Ve and Vw, the volume fractions for the “cytoplasm” and the “cell wall” phases, Ke and Kw, the solute partition coefficients for the “cytoplasm” and the “cell wall” phases and De and Dw, the respective diffusion coefficient for the two phases. Reasonable correlations were found between the experimental Pe, effective permeability coefficient, values and the partition coefficients obtained with amyl caproate and those obtained with hexadecane. Also the magnitude of Dw was estimated and found to be about 10−13 and 10−11 cm2/s when the lipoidal nature of the cell wall was equated to hexadecane or amyl caproate. In general, reasonable self-consistencies among the various experimental results and parameters of the model were found.