vemurafenib + rifampin

**Vemurafenib + rifampin** is a drug combination consisting of vemurafenib, a selective small molecule inhibitor of the mutated BRAF V600 kinase, and rifampin (also known as rifampicin), a strong inducer of CYP3A4 and other drug metabolizing enzymes. Vemurafenib is primarily indicated for the treatment of BRAF V600 mutation-positive metastatic melanoma and Erdheim-Chester disease. Rifampin is an antibiotic primarily used in the treatment of tuberculosis and certain bacterial infections but is well-known as a potent inducer of drug-metabolizing enzymes. Concurrent use of these two drugs is not recommended due to a significant drug-drug interaction: rifampin markedly decreases the plasma exposure of vemurafenib (approximately 40% reduction), potentially reducing its clinical efficacy and risking sub-therapeutic treatment in cancer patients[1][2][5]. This interaction stems mainly from rifampin-induced upregulation of CYP3A4 and drug transporters, which enhance the metabolism and elimination of vemurafenib. No unique combination product exists—this interaction is a clinically significant but undesirable co-administration rather than a therapeutic regimen.