Abstract
A structural change in the stratum corneum of hairless rat skin by subcutaneous enhancers and its enhancing effect on indomethacin permeation through the full-thickness skin was examind. The stratum corneum was characterized in terms of a bound water content and a extraction by an enhancer. Enhanced permeation of indomethacin was observed by particular treatments, which lowered a bound water content and showed some extraction. This result suggests that the exchange of bound water in polar lipids by enhancer molecules showed the solubilization and extraction of some lipids from the stratum corneum to cause a reconstructed structure of lipids with the enhancer molecules for accerelating the indomethacin permeation. On the contrary, some treatments which showed an increase in bound water content in the stratum cornuem exhibited a suppressive effect on the permeation. This result suggests that such natural moisturing factors penetrate the hydrated layers of intracellular lipid layers to increase the barrier property of the stratum cormeum. Thus, it is concluded that such a characterization of the stratum corneum can be a useful method on evaluating structural changes in skin and predicting the enhancing properties of several subcutaneous enhancers on drug permeation.
