Skin permeability

The histochemical and physicochemical aspects of skin permeability and transdermal drug permeation are reviewed under preponderant consideration of the past years' literature supplied by relevant investigations from the author's laboratories. The chemical composition and the physical order of the horny layer lipids as well as the interactions of drugs and vehicle components with these lipids are the basis of understanding drug penetration, its influencing by vehicles and penetration enhancement. By means of measuring drug concentration profiles in human skin the mechanisms of vehicle effects and penetration enhancement are demonstrated. The consequences of increased permeability and xenobiotic enrichment in pathologically altered skin are discussed.