Rifampicin for NTM Infections in HIV-Positive Patients
Rifampicin is NOT recommended for treating Non-Tuberculous Mycobacterial (NTM) infections in HIV-positive patients; rifabutin is the preferred rifamycin for NTM treatment, particularly for Mycobacterium avium complex (MAC), which represents over 90% of NTM infections in this population. 1, 2
Why Rifabutin Over Rifampicin for NTM
Rifabutin combined with macrolides (clarithromycin or azithromycin) plus ethambutol is the established treatment regimen for disseminated MAC infection in HIV patients. 3, 1
Rifampicin is reserved for tuberculosis treatment, not NTM infections, in HIV-positive patients. 4
The macrolide-based combinations (clarithromycin or azithromycin with ethambutol and rifabutin) have been shown to prolong survival and increase quality of life in AIDS patients with MAC. 1
Critical Drug-Drug Interactions with Antiretrovirals
When Rifabutin Must Be Used with Protease Inhibitors:
If the patient is on ritonavir (100-600 mg twice daily) combined with any other protease inhibitor, reduce rifabutin dose drastically to 150 mg two or three times per week (not daily). 4
For patients on saquinavir soft-gel capsule (a weak CYP450 inhibitor) with two NRTIs, maintain standard rifabutin dosing at 300 mg daily or two to three times per week. 4
When Rifabutin Must Be Used with NNRTIs:
- If the patient is on efavirenz, increase rifabutin dose to 450-600 mg daily or 600 mg two to three times per week to compensate for enzyme induction. 4
Special Case: Mycobacterium kansasii
For M. kansasii specifically (which causes TB-like pulmonary disease), the treatment regimen includes isoniazid, rifampin (not rifabutin), and ethambutol. 1
This is the exception where rifampin may be used for an NTM infection, but requires careful antiretroviral selection.
Antiretroviral Compatibility Considerations
If Rifampin Must Be Used (M. kansasii or TB):
Use dolutegravir 50 mg twice daily (not once daily) plus tenofovir/emtricitabine or lamivudine. 5
Alternatively, use efavirenz 600 mg daily plus two NRTIs without dose adjustment. 5, 6
Never use standard once-daily dolutegravir with rifampin—this causes treatment failure. 5
Contraindicated Antiretrovirals with Rifampin:
- Bictegravir, dolutegravir/lamivudine 2-drug regimen, darunavir with ritonavir or cobicistat, doravirine, elvitegravir/cobicistat, long-acting cabotegravir/rilpivirine, and rilpivirine-containing regimens cannot be used. 5
Management Approach
Consult with a physician experienced in HIV/NTM co-infection management for all cases requiring rifamycin therapy. 4
Monitor closely for TB treatment failure, antiretroviral treatment failure, paradoxical reactions, synergistic side effects, and rifamycin toxicity from elevated drug concentrations. 4
For complex combinations of protease inhibitors or NNRTIs where drug-drug interaction management is uncertain, consider non-rifamycin regimens, though this may be suboptimal for active TB. 4
Common Pitfalls to Avoid
Do not confuse rifampin and rifabutin—they are not interchangeable for NTM treatment. Rifabutin is specifically indicated for MAC, while rifampin is for TB (and M. kansasii as an exception). 3, 1
Never assume rifabutin dosing remains constant across different antiretroviral regimens—dose adjustments range from 150 mg three times weekly to 600 mg daily depending on the specific drug interactions. 4, 5
Do not use rifampin with most modern antiretroviral regimens without verifying compatibility and making necessary dose adjustments. 5, 7