Assessment of the Biotransformation of Low-Turnover Drugs in the H µ REL Human Hepatocyte Coculture Model

• Published in: Drug metabolism and disposition 2018-11, Vol.46 (11), p.1617-1625
• Main Authors: Burton, Richard D, Hieronymus, Todd, Chamem, Taysir, Heim, David, Anderson, Shelby, Zhu, Xiaochun, Hutzler, J Matthew
• Format: Article
• Language: English
• Subjects: Biotransformation - physiology; Cells, Cultured; Cytochrome P-450 Enzyme System - metabolism; Glycine - metabolism; Hepatocytes - metabolism; Humans; Metabolic Clearance Rate - physiology; Metabolic Networks and Pathways - physiology; Oxidation-Reduction; Pharmaceutical Preparations - metabolism; Taurine - metabolism
• ISSN: 0090-9556; 1521-009X
• DOI: 10.1124/dmd.118.082867

Metabolic profiles of four drugs possessing diverse metabolic pathways (timolol, meloxicam, linezolid, and XK469) were compared following incubations in both suspended cryopreserved human hepatocytes and the H REL hepatocyte coculture model. In general, minimal metabolism was observed following 4-hour incubations in both suspended hepatocytes and the H REL model, whereas incubations conducted up to 7 days in the H REL coculture model resulted in more robust metabolic turnover. In the case of timolol, in vivo human data suggest that 22% of the dose is transformed via multistep oxidative opening of the morpholine moiety. Only the first-step oxidation was detected in suspended hepatocytes, whereas the relevant downstream metabolites were produced in the H REL model. For meloxicam, both the hydroxymethyl and subsequent carboxylic acid metabolites were abundant following incubation in the H REL model, while only a trace amount of the hydroxymethyl metabolite was observed in suspension. Similar to timolol, linezolid generated substantially higher levels of morpholine ring-opened carboxylic acid metabolites in the H REL model. Finally, while the major aldehyde oxidase-mediated mono-oxidative metabolite of XK469 was minimally produced in hepatocyte suspension, the H REL model robustly produced this metabolite, consistent with a pathway reported to account for 54% of the total urinary excretion in human. In addition, low-level taurine and glycine conjugates were identified in the H REL model. In summary, continuous metabolite production was observed for up to 7 days of incubation in the H REL model, covering cytochrome P450, aldehyde oxidase, and numerous conjugative pathways, while predominant metabolites correlated with relevant metabolites reported in human in vivo studies.