THE INFLUENCE OF ISOPROPANOL, N-PROPANOL AND N-BUTANOL ON STRATUM-CORNEUM LIPID PHASE-BEHAVIOR

The intercellular lipid multilayers of stratum corneum, the outermost layer of mammalian skin, is generally accepted as the rate determining pathway of transmembrane diffusion for lipophilic solutes. The short chain alcohols, iso-propanol, n-propanol and n-butanol, are known to e nhance permeation through the stratum corneum at low concentrations. T he effects of these alcohols, at concentrations giving equivalent pene tration enhancement, on the stratum corneum lipid alkyl chain packing, mobility and conformational order as measured by Fourier transform in frared (FTIR) spectroscopy have been investigated. Reference is made t o studies of model DSPC/DSPA phospholipid multilamellar vesicles in th e presence of the alcohols. Iso-propanol and n-butanol do not alter th e stratum corneum lipid interchain interactions and gel-gel phase tran sition. n-Butanol is shown to increase the lipid chain freedom of moti on above 45-degrees-C. However, only n-propanol appears to alter the s tratum corneum lipid gel to liquid-crystalline phase transition. In th e densely packed gel state (below 45-degrees-C), n-butanol was demonst rated to decrease the alkyl chain freedom of motion.