Effect of penetration enhancers on the permeation of mannitol, hydrocortisone and progesterone through human skin
Barry, B.W.; Bennett, S.L.
Journal of Pharmacy and Pharmacology 39(7): 535-546
Mannitol, hydrocortisone and progesterone were selected as model penetrants to assess the mode of action of eight potential penetration enhancers in human skin. Their partition coefficients, octanol:water and stratum corneum:water were measured and correlated with their postulated routes of penetration through human skin. The results suggest that mannitol penetrated via a polar route, hydrocortisone by a mainly lipid route and progesterone via a lipid pathway but its penetration rate was probably affected by aqueous layers. From permeation studies through cadaver skin in which an in-vivo mimic method was used, it was concluded that the penetration enhancers fell into three main categories: (1) solvents which enhanced permeation of polar and non-polar compounds e.g. 2-pyrrolidione, N-methylpyrrolidone, N-methylformamide and propylene glycol plus Azone; (2) enhancers which preferentially affected the polar route e.g. propylene glycol plus decylmethylsulphoxide, and (3) accelerants which mainly modified the non-polar route e.g. propylene glycol plus oleic acid, propylene glycol alone and, to a limited extent, water.