Drug Characteristics
  • Formulation

    Capsules: 150 mg

  • Dose

    Atypical mycobacterial infections, DMAC:

    300 mg orally once a day, as part of a combination regimen

    MAC prophylaxis: in patients with CD4 counts less than 75:

    300 mg orally once a day but azithromycin preferred prophylaxis agent

  • Side Effects

    Raised LFTs and jaundice; orange body secretions; uveitis (high doses); bone marrow suppression; arthralgia, gastrointestinal disturbances (nausea and vomiting)

  • Interactions

    Rifabutin is metabolized by and is an enzyme inducer of the cytochrome P450 isoenzyme system

    Plasma rifabutin concentrations increased by HIV PIs – dosage should be reduced with concomitant boosted PIs or atazanavir

    Plasma rifabutin concentrations are decreased by NNRTIs. Increase dosage of rifabutin to 450 mg/day (unless PIs are also included in regimen)

    Plasma levels of co-administered drugs metabolized in the same way will be reduced e.g. warfarin, phenytoin, carbamazepine, protease inhibitors, oral contraceptives, and methadone

    Plasma concentration of rifabutin increased by fluconazole – risk of uveitis

    The dose of rifabutin is often modified when given in combination with protease inhibitors or non-nucleoside reverse transcriptase inhibitors (NNRTIs). Always check which antiretrovirals are being co-prescribed and modify doses –see SmPC

  • Renal

    Dose in renal impairment

    GFR (ml/min) 30–50: Dose as in normal renal function

    GFR (ml/min) <30: 150 mg once a day

  • Hepatic

    Mild hepatic impairment does not require dosage adjustment. It should be used with caution in severe liver disease

  • Pregnancy

    No Human Data – Animal Data Suggest Low Risk

  • Other Information