Extrahepatic MetabolismIn vitro Metabolism
• In vitro metabolism in intestine, kidney, skin, plasma
• Microsomes, S9 and homogenates
Although the liver is the major drug metabolising organ in the body, also some other tissues, such as intestine, kidney and skin may have a significant role in the metabolism of xenobiotic compounds. The role of each organ varies depending on the administration route and distribution of the compound between the organs. The abundance of metabolising enzymes (CYPs and conjugative enzymes) also varies in each organ/tissue even with qualitative differences. From the experimental point of view, different tissue subfractions are routinely used together with modern analytical techniques. For more thorough evaluation of in vivo role of each organ, evaluation of kinetic parameters Vmax and Km with organ-dependent preparates would be advisable.