Generation of major human excretory and circulating drug metabolites using a hepatocyte relay method

The prediction of human drug metabolites using in vitro experiments containing human-derived reagents is an important approach in modern drug research; however, this can be challenging for drugs that are slowly metabolized. In this report, we describe the use of a recently developed human hepatocyte relay method for the purpose of predicting human drug metabolite profiles. Five compounds for which in vivo human metabolism data were available were selected for the investigation of this method, and the results were compared with data gathered in hepatocyte suspensions as well as previous data from a micropatterned hepatocyte coculture method. The hepatocyte relay method demonstrated an improved performance (generation of 75% of human in vivo metabolites) for those drugs for which previous methods showed a relatively low rate of success (50% of human in vivo metabolites). Metabolites included those arising from both oxidative and conjugative reactions and metabolites that required sequential reactions. Two 4-hour relays were shown to adequately generate metabolites, and no further benefit was derived from more relays. Overall, it can be concluded that the hepatocyte relay assay method can be successfully used in the generation of relevant human metabolites, even for challenging drugs.