MOLECULAR STRUCTURE AND DIFFUSIONAL PROCESSES ACROSS INTACT EPIDERMIS
Final comprehensive summary rept. for Jul 1964-Jul 1965
HARVARD MEDICAL SCHOOL BOSTON MA
Pagination or Media Count:
The penetration rate for small molecular weight alcohols is approximately given by the expression Js Kp Km dCs, where Kp 0.001-3 cm hr. is essentially the permeability constant for water in the membrane, Km is the membrane-water partition coefficient for the alcohol and dCs is the concentration difference across the membrane. The activation energy for the penetration water and the polar alcohols, through hydrated stratum corneum is approximately 15 Kcalmole. Extensive immersion in water effects the barrier function of stratum corneum only slightly principally by opening pores which contribute to the diffusion a parallel flux which is relatively small above room temperature. Penetration through the stratum corneum is not primarily intercellular or appendageal. The hydrated stratum corneum seems to be best described as a dense, effectively homogeneous phase into which small molecular weight polar non-electrolytes dissolve with strong chemical interaction and through which diffusion occurs remarkably slowly.
- Anatomy and Physiology