FC‐57 Interspecies differences in the percutaneous permeation of substances with various lipophilicities

Abstract

In veterinary medicine, the percutaneous permeation of drugs has relevance to therapeutic and forensic problems. It is commonly investigated in Franz diffusion cells using the excised skin of different mammalian species. Drug permeation characteristics through skin are considered to be significantly influenced both by the biochemical constitution of the stratum corneum and by the number and depth of hair follicles. Drug absorbance characteristics thus show a marked interspecies variance. This complicates the comparison of results obtained in different studies using different species. We examined the species influence on permeation parameters of three test compounds with different lipophilicities (benzoic acid, caffeine and testosterone) in Franz diffusion cells under standardized conditions. While testosterone was found to have the highest permeation coefficient, the permeation coefficients of benzoic acid and caffeine were lower and similar in all species. As expected, the absolute permeabilities showed marked interspecies differences, but the order of permeabilities of the test compounds was conserved in all species. The intraindividual coefficient of variation showed no significant difference between the examined species; the interindividual variation was significantly less marked in bovine skin than in other species. We conclude that the skin of different species can be used for the examination of skin permeation. However, results are transferable to other species only if they were obtained under standardized test conditions. Funding: German Federal Ministry of Education and Research.