[The effect of foreign-substance-metabolizing enzymes on skin diseases]

Multiple drug-metabolizing enzymes are located in the skin of animals and humans: cytochrome P-450, epoxide hydrases, transferases and reductases. The distribution of cytochrome P-450 in the skin is not homogeneous; rather, it is more active in the basal epidermis, keratinocytes of the hair follicle, and sebaceous cells. The activity of drug-metabolizing enzyme can be induced, but it can also be inhibited by multiple endogenous and exogenous compounds. These enzymes detoxify many xenobiotics, but if the balance is disturbed there is the risk that xenobiotics will be activated to highly toxic compounds, which are even involved in the pathogenesis of skin cancer. Recent results indicate that cytochrome P-450 isoenzymes are also involved in the pathogenesis of psoriasis and drug-induced skin diseases.