Tuberculosis and HIV disease

November 2004     View PDF     En español

Using rifampin and rifabutin with anti-HIV drugs

Rifampin interacts with protease inhibitor (PI) and non-nucleoside reverse transcriptase inhibitor (NNRTI) drugs. So people taking these classes of drugs should use rifabutin (Mycobutin, a treatment for MAC) rather than rifampin for treating TB.

There are a few exceptions to this general rule including when a person is taking 1) efavirenz (Sustiva) and two nucleoside analogues (NRTIs); 2) ritonavir (Norvir) and one or two NRTIs; or 3) ritonavir (Norvir), Fortovase and Invirase (Saquinavir) and a NARTI. However, if it is taken with ritonavir, the dose of rifabutin has to be dropped to 150mg 2–3 times a week. Lower doses may also be needed with other PIs. If rifabutin is used with efavirenz (Sustiva), its dose should be raised to 450–600mg daily, or 600mg 2–3 times a week. The bottom line is that drug interactions are a concern with anti-HIV therapies and some anti-TB drugs. Ask your doctor and pharmacist about the safety and appropriateness of taking your therapies together and if any dose modifications are needed because of drug interactions.

For people taking both PIs and NNRTIs, it may be hard to predict what effect rifabutin will have. If you’re taking these drugs, it’s wise to be checked often by your doctor for drug levels and side effects.