Biotransformation of drugs in human skin.

Although it is the largest organ of the human body, skin is often not considered in discussions of drug metabolism. However, there is growing evidence that most common drug-metabolizing enzymes are expressed in the skin. Evidence for expression of cytochromes P450, flavin monooxygenases, glutathione-S-transferases, N-acetyltransferases, and sulfotransferases in human skin and skin cells are presented. Additional discussion is focused on the evidence of actual metabolism of drugs. Finally, the potential clinical implications of metabolism within the skin are discussed briefly.