Rifabutin is indicated for the prevention of disseminated Mycobacterium avium complex (MAC) disease in patients with advanced HIV infection.
Rifabutin is a spiropiperidyl derivative of rifamycin S with distinctive pharmacokinetic properties compared to rifampin.
Rifabutin inhibits DNA-dependent RNA polymerase in susceptible bacterial strains but not in mammalian cells.
Standard dose: 300 mg orally once daily.
For GI upset: 150 mg twice daily with food; may be mixed with applesauce.
Renal impairment: Reduce dose by 50% for CrCl 30 mL/min if toxicity is suspected; no adjustment needed for mild-to-moderate renal impairment.
Hepatic impairment: No dose modification for mild impairment; pharmacokinetics in moderate-to-severe hepatic impairment are unknown.
Must not be used for MAC prophylaxis in patients with active TB.
Monotherapy in active TB risks development of resistance to both rifabutin and rifampin.
Uveitis: Particularly when co-administered with clarithromycin or fluconazole; patients should be referred to ophthalmology if suspected.
Hypersensitivity reactions including anaphylaxis may occur.
DRESS syndrome has been reported; early withdrawal is essential.
C. difficile-associated diarrhea may occur.
Drug Interactions:
Rifabutin is a CYP3A inducer and may decrease plasma concentrations of CYP3A-metabolized drugs, including protease inhibitors, bictegravir, elvitegravir, rilpivirine, doravirine, and sofosbuvir-containing regimens.
Concomitant use with protease inhibitors may require at least a 50% reduction in rifabutin dose, with possible adjustment of the antiretroviral dose.
Rifabutin reduces plasma concentrations of itraconazole, clarithromycin, and saquinavir.
CYP3A inhibitors (e.g., clarithromycin, fluconazole) can increase rifabutin levels, raising the risk of uveitis and other toxicities.
Periodic hematologic studies are recommended due to the risk of neutropenia and, more rarely, thrombocytopenia.
Rifabutin may cause brown-orange discoloration of urine, feces, saliva, sputum, tears, perspiration, and skin; soft contact lenses may be permanently stained.
It has relatively low oral bioavailability (~20%), a very large volume of distribution (9.3 L/kg), and a long terminal half-life of approximately 45 hours.
Tissue concentrations substantially exceed plasma levels, with a lung-to-plasma ratio of approximately 6.5 at 12 hours post-dose.
About 85% is protein-bound, and its active metabolite (25-O-desacetyl rifabutin) contributes up to 10% of total antimicrobial activity.
A key clinical advantage of rifabutin over rifampin is its weaker induction of CYP3A4, making it the preferred rifamycin in patients on protease inhibitor-based antiretroviral therapy or other CYP3A-metabolized medications such as immunosuppressants in transplant recipients.
Approved indication is MAC prophylaxis, rifabutin is widely used in several additional settings:
Tuberculosis treatment as a substitute for rifampin in patients on medications with significant CYP3A interactions (e.g., HIV protease inhibitors, immunosuppressants).
A Cochrane review found rifabutin-containing regimens to have similar efficacy to rifampin-containing regimens in newly diagnosed pulmonary TB.
MAC treatment as a component of multidrug regimens, typically with clarithromycin or azithromycin plus ethambutol.
Refractory Helicobacter pylori infection-rifabutin-based triple therapy is used as a salvage regimen after failure of standard eradication therapies.
Rifabutin is used as a rescue/salvage therapy for H. pylori when standard regimens have failed.
Rifabutin is considerably more active in vitro than rifampin against MAC and at least as active against M. tuberculosis.
It also demonstrates activity against some rifampin-resistant M. tuberculosis isolates (10-30% of cases), though substantial cross-resistance exists.
Beyond mycobacteria, rifabutin has activity against staphylococci, Neisseria species, H. influenzae, H. pylori, C. trachomatis, and Toxoplasma gondii, with poor activity against Enterobacteriaceae and Pseudomonas.
Resistance to clarithromycin and metronidazole is rising globally, making first-line therapies less effective
Rifabutin retains activity against most clarithromycin- and metronidazole-resistant strains
Resistance to rifabutin itself remains low (<1–2% in most regions).
Standard rifabutin-based regimen
Typically used as a triple therapy for 10–14 days:
Rifabutin 150 mg twice daily (or 300 mg once daily)
Amoxicillin 1 g twice daily
PPI (e.g., omeprazole 40 mg or esomeprazole 40 mg) twice daily
An FDA-approved formulation — Talicia — combines all three in a single capsule (omeprazole 10 mg / amoxicillin 250 mg / rifabutin 12.5 mg), taken as 4 capsules three times daily with food for 14 days.
Eradication rates
Generally 70–90% in salvage settings, even after multiple prior treatment failures
Higher rates in penicillin-sensitive patients
Key side effects
Leukopenia — the main concern; CBC monitoring recommended
Uveitis — at higher doses (less common at standard H. pylori doses)
GI upset, rash
Not a first-line agent — reserved for 3rd-line or later due to cost and the need to preserve rifamycin sensitivity for TB/MAC treatment
Avoid in patients on rifampin (redundant) or with potential TB exposure (rifabutin monotherapy can mask TB and drive resistance)
CYP3A4 inducer — check for drug interactions (antiretrovirals, azole antifungals)
Contraindicated in severe hepatic impairment
Typically considered after failure of at least two prior regimens (e.g., clarithromycin triple + bismuth quadruple, or after vonoprazan-based therapy failure).