Role of intercellular lipids in stratum corneum in the percutaneous permeation of drugs.

The effect of the depletion of intercellular lipids from human stratum corneum and shed snake skin on the permeability to salicylic acid (SA) was investigated in vitro. Shed snake skin was used as a model membrane for human stratum corneum. Lipid depletion with a mixture of chloroform and methanol increased the permeability of those skins to the ionized form but not to the unionized form of SA. Moreover, lipid depletion increased dramatically the permeability of shed snake skin to compounds with low lipophilicity, although it did not have a significant effect on the more lipophilic compounds. As a hypothesis to explain the marked increase of skin permeability to compounds of low lipophilicity, including the ionized form of SA, we suggest increased water transport.