The metabolism of steroids, toxins and drugs by 11β-hydroxysteroid dehydrogenase 1

11β-Hydroxysteroid dehydrogenase isoform 1 (11β-HSD1) is a member of the alcohol short-chain family enzyme, and catalyzes the interconversion between active glucocorticoid cortisol (in human) and inactive cortisone. The redox ratio of NADP+/NADPH determines its direction with NADPH favoring its reductase activity and NADP+ favoring its oxidase activity. In many tissues such as the liver and lung, 11β-HSD1 behaves primarily as a reductase because of the intracellular enzyme coupling with hexose-6-phosphate dehydrogenase, which uses the NADP+ as cofactor to supply NADPH driving 11β-HSD1 to function as a reductase. 11β-HSD1 catalyzes the metabolism of 7- or 11-keto steroids as well as many toxins and drugs. Some steroids, drugs and toxins are metabolically activated. The present review discusses the steroid, drug and toxin metabolism by 11β-HSD1.