Evaluation of the CYP metabolic activities in the presence of albumin in human liver microsomes
Cytochrome P450 (CYP) isoforms are responsible for the metabolism of the majority of drugs in human. An intrinsic clearance (CLint) determined from in vitro intrinsic clearance can be used to predict the in vivo hepatic metabolic clearance (CLH) of drugs in humans. However, in vitro-in vivo extrapolation (IV-IVE) commonly underestimates the in vivo CLint and CLH of drugs metabolized by CYP isoforms. Recently, it was reported that the addition of albumin to the in vitro incubation system increased the metabolic activities of some CYP isoforms due to inhibition of the effect of polyunsaturated long-chain fatty acids (PUFAs). Therefore, we evaluated the effect of bovine serum albumin (BSA) on the metabolic activities of CYP isoforms in human liver microsomes (HLM). We found that some CYP isoforms were observed to show enhancement of CLu,met in the presence of albumin. In this presentation, we have summarized the effect of albumin on the metabolic activity of each CYP isoform in HLM.