Update on rifampin, rifabutin, and rifapentine drug interactions

Rifampin is a potent inducer of both cytochrome P-450 oxidative enzymes and the P-glycoprotein transport system. Among numerous well documented, clinically significant interactions, examples include warfarin, oral contraceptives, itraconazole, digoxin, verapamil, simvastatin, and human immunodeficiency virus-related protease inhibitors. Rifabutin reduces serum concentrations of antiretroviral agents, but less so than rifampin. Rifapentine is also an inducer of drug metabolism.A literature search of English language journals from 2008 to March 2012 was completed using several databases, including PubMed, EMBASE, and SCOPUS. Search terms included rifampin, rifabutin, rifapentine AND drug interactions.Examples of clinically relevant interactions with rifampin demonstrated by recent reports include posaconazole, voriconazole, oxycodone, risperidone, mirodenafil, and ebastine.To avoid a reduced therapeutic response, therapeutic failure, or toxic reactions when rifampin, rifabutin, or rifapentine are added to or discontinued from medication regimens, clinicians need to be aware of these interactions. Recent studies have indicated that other transporter systems play a role in these drug interactions. As reports of rifampin drug interactions continue to grow, this review is a reminder to clinicians to be vigilant.