Pharmacology · Antituberculosis drugs
Rifabutin !
A rifamycin that induces liver enzymes less than rifampicin, so it fits better with HIV protease inhibitors. It prevents Mycobacterium avium in advanced HIV.
Updated 2026-11-01
The figure shows rifabutin bound to the RNA polymerase of Thermus thermophilus, in the same rifamycin pocket of the β subunit as in M. tuberculosis.
Mechanism of action
Like rifampicin, rifabutin blocks bacterial DNA-dependent RNA polymerase. It is a weaker inducer of liver enzymes and is itself broken down by CYP3A, so it is the rifamycin chosen when strong interactions must be avoided. Used alone in active tuberculosis it can select resistance to both rifabutin and rifampicin.
- Rifabutin binds the β subunit of RNA polymerase
- Bacterial transcription stops
- It induces CYP3A less than rifampicin
Pharmacokinetics
- Absorption
- Low oral bioavailability; fatty meals slow but do not reduce absorption
- Distribution
- Very lipophilic: high levels inside cells and tissues
- Metabolism
- Liver, partly by CYP3A
- Elimination
- Urine and faeces, as metabolites
- Half-life
- Long: about 45 hours
Indications
- Prevention of disseminated Mycobacterium avium complex disease in advanced HIV Nontuberculous mycobacterial infections (MAC, M. abscessus, Buruli ulcer) →
- Tuberculosis in people whose antiretrovirals cannot be combined with rifampicin (such as protease inhibitors) Tuberculosis →
Adverse effects
Common
- Brown-orange colour of urine, faeces, saliva, sweat, tears and skin; stains soft contact lenses
- Neutropenia
- Rash
Contraindications
- Hypersensitivity to any rifamycin
- Use with long-acting injectable cabotegravir/rilpivirine
Key interactions
- HIV protease inhibitors
- They raise rifabutin levels: its dose is reduced by the team
- Clarithromycin, fluconazole
- Raise rifabutin and the risk of uveitis
- Hormonal contraceptives
- Lower their levels: an additional or non-hormonal method is used
- Bedaquiline
- Combination avoided
What is monitored
- Active tuberculosis is ruled out before MAC prophylaxis (monotherapy breeds rifamycin resistance)
- Blood counts periodically
- Eye pain, redness or blurred vision
- Rash and diarrhoea
Administration and safety
- By mouth
- Look-alike names: rifabutin is not rifampicin or rifapentine
- Its dose is set according to the antiretrovirals being taken
Nursing care
- Warn about brown-orange body fluids and stained soft lenses
- Teach to report eye pain, redness or blurred vision at once
- Review the full list of antiretrovirals and antifungals
- Advise added or non-hormonal contraception
Pregnancy and breastfeeding
Used only if the benefit justifies the risk to the fetus; animal studies showed fetal effects at high doses.
Test yourself
Think of the answer, then tap the question to see it.
Why is rifabutin preferred over rifampicin in someone taking an HIV protease inhibitor?
It induces CYP3A much less, so the protease inhibitor keeps effective levels.
Which eye complication is linked to rifabutin?
Uveitis, more likely when clarithromycin or fluconazole raise its levels.
What must be ruled out before using rifabutin as MAC prophylaxis?
Active tuberculosis, because rifabutin alone would select rifamycin-resistant bacilli.
Related drugs
Related conditions
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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - RIFABUTIN capsule (DailyMed (U.S. National Library of Medicine), 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 65 (McGraw Hill, 2023); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 64 (McGraw Hill, 2023); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.