This guideline presents general principles for measuring dermal absorption and delivery of a test substance using excised skin. Skin from many mammalian species, including 3D reconstructed skin, humans explants, or pigskin, can be used. The permeability properties of skin are maintained after excision from the body because the principal diffusion barrier is the stratum corneum.
The test substance, which may be radiolabelled, is applied to the surface of a skin sample separating the two chambers of a diffusion cell. The chemical remains on the skin for a specified time under specified conditions, before removal by an appropriate cleansing procedure. The receptor fluid is sampled at time points throughout the experiment and analysed for the test chemical and/or metabolites using HPLC-MS/MS, ELISA, etc.