MOLECULAR STRUCTURE AND DIFFUSIONAL PROCESSES ACROSS INTACT EPIDERMIS.
Abstract
This is a study of the permeability of human skin. Primary emphasis is placed upon the measurement of fundamental physical constants viz: the diffusivity, density, thickness, lipophilic solubility etc. of the principal layers of the skin in vitro. The effect of skin appendages on permeability is quantitatively evaluated and their potential role as diffusion shunts is discussed. The diffusional resistance of the superficial region of the skin is apportioned to the various skin layers in accord with their individual barrier properties. The stratum corneum membrane is emphasized as the principle rate limiting barrier and its structure and physical properties are investigated in great detail. Permeability constants of various homologous series through stratum corneum are measured; these include (1) aliphatic primary alcohols (C1-C8) (2) fatty acids (C1-C8), (3) ethers, ketones and diols, (4) steroids and water and other miscellaneous compounds. The effect of hydration on the permeability is studied. Water: membrane partition coefficients for these compounds and for acids and steroids are measured. Analyses were conducted by gas-liquid chromatography, isotope techniques, polarography and infra red spectroscopy. Aqueous solution and gas phase penetration rates of alcohols through stratum corneum membranes are compared. Activation energies and entropies for the diffusion of the alcohols were obtained. Polar and non-polar molecules appear to penetrate the skin by different molecular mechanisms. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1967
- Accession Number
- AD0822665
Entities
People
- Robert J. Scheuplein
Organizations
- Harvard Medical School