Author(s): Erickson DA, Mather G, Trager WF, Levy RH, Keirns JJ
Abstract Share this page
Abstract Nevirapine (NVP), a non-nucleoside inhibitor of HIV-1 reverse transcriptase, is concomitantly administered to patients with a variety of medications. To assess the potential for its involvement in drug interactions, cytochrome P-450 (CYP) reaction phenotyping of NVP to its four oxidative metabolites, 2-, 3-, 8-, and 12-hydroxyNVP, was performed. The NVP metabolite formation rates by characterized human hepatic microsomes were best correlated with probe activities for either CYP3A4 (2- and 12-hydroxyNVP) or CYP2B6 (3-and 8-hydroxyNVP). In studies with cDNA-expressed human hepatic CYPs, 2- and 3-hydroxyNVP were exclusively formed by CYP3A and CYP2B6, respectively. Multiple cDNA-expressed CYPs produced 8- and 12-hydroxyNVP, although they were produced predominantly by CYP2D6 and CYP3A4, respectively. Antibody to CYP3A4 inhibited the rates of 2-, 8-, and 12-hydroxyNVP formation by human hepatic microsomes, whereas antibody to CYP2B6 inhibited the formation of 3- and 8-hydroxyNVP. Studies using the CYP3A4 inhibitors ketoconazole, troleandomycin, and erythromycin suggested a role for CYP3A4 in the formation of 2-, 8-, and 12-hydroxyNVP. These inhibitors were less effective or ineffective against the biotransformation of NVP to 3-hydroxyNVP. Quinidine very weakly inhibited only 8-hydroxyNVP formation. NVP itself was an inhibitor of only CYP3A4 at concentrations that were well above those of therapeutic relevance (K(i) = 270 microM). Collectively, these data indicate that NVP is principally metabolized by CYP3A4 and CYP2B6 and that it has little potential to be involved in inhibitory drug interactions.
This article was published in Drug Metab Dispos
and referenced in Journal of Pharmacogenomics & Pharmacoproteomics