Drug metabolism and disposition : the biological fate of chemicals
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Drug Metab. Dispos. · Dec 2009
Effect of rifampin and nelfinavir on the metabolism of methadone and buprenorphine in primary cultures of human hepatocytes.
We tested the hypothesis that primary cultures of human hepatocytes could predict potential drug interactions with methadone and buprenorphine. Hepatocytes (five donors) were preincubated with dimethyl sulfoxide (DMSO) (vehicle), rifampin, or nelfinavir before incubation with methadone or buprenorphine. Culture media (0-60 min) was analyzed by liquid chromatography-tandem mass spectrometry for R- and S-methadone and R- and S-2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) or for buprenorphine, norbuprenorphine, and their glucuronides [buprenorphine-3-glucuronide (B-3-G) and norbuprenorphine-3-glucuronide (N-3-G)]. ⋯ Although there was a trend for norbuprenorphine (2.8- and 4.9-fold) and N-3-G (1.7- and 1.9-fold) to increase after nelfinavir and rifampin, none of the changes were significant. To investigate low norbuprenorphine production, buprenorphine was incubated with human liver and small intestine microsomes fortified to support both N-dealkylation and glucuronidation; N-dealkylation predominated in small intestine and glucuronidation in liver microsomes. These studies support the hypothesis that methadone metabolism and its potential for drug interactions can be predicted with cultured human hepatocytes, but for buprenorphine the combined effects of hepatic and small intestinal metabolism are probably involved.