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rifabutin (Mycobutin)
Tradename: Mycobutin.
Indications:
1) prevention of disseminated Mycobacterium avium complex (MAC) in patients with advanced HIV infection
2) treatment of tuberculosis in combination with other agents
Contraindications:
1) leukopenia (WBC < 1000/mm3)
2) thrombocytopenia (platelets < 50,000/mm3)
Dosage:
1) 300 mg PO QD, or 150 mg PO BID
2) 150 mg PO QD if concurrent use of protease inhibitor (indinavir or nelfinavir are protease inhibitors of choice)
Capsule: 150 mg.
Pharmacokinetics:
1) distributes to body tissues including lungs, liver, spleen, eyes & kidneys
2) protein binding 85%
3) metabolized in the liver by cyt P450 3A4 to active & inactive metabolites
4) terminal elimination 1/2life: 16-69 hours
5) renal & biliary clearance of unchanged drug is 10%
6) 30% excreted in the feces
Adverse effects:
1) common (> 10%)
- discolored urine, neutropenia, leukopenia, rash
2) less common (1-10%)
- nausea/vomiting, abdominal pain, diarrhea, flatulence, anorexia, headache, myalgia, anemia, thrombocytopenia
3) uncommon (< 1%)
- chest pain, fever, insomnia, dyspepsia, taste disturbance
4) other
- uveitis [3]
- hepatitis [3]
- severe arthralgia [3]
- thrombocytopenia [3]
Drug interactions:
1) clarithromycin, fluconazole & antiretroviral protease inhibitors increase serum levels of rifabutin [3]
- dosage adjustment may be required [3]
2) indinavir or nelfinavir are protease inhibitors of choice with rifabutin
3) rifabutin increases levels of
a) saquinavir
b) clarithromycin
4) rifabutin may decrease ketoconazole levels
5) any drug that inhibits cyt P450 3A4 may increase levels of rifabutin
6) any drug that induces cyt P450 3A4 may diminish levels of rifabutin
7) rifabutin induces cyt P450 3A4, thus induces its own metabolism & metabolism of other cyt P450 3A4 substrates
Laboratory:
- rifabutin in serum/plasma
Interactions
drug interactions
Related
cytochrome P450 3A4 (cytochrome P450 C3, nifedipine oxidase, P450-PCN1, NF-25, CYP3A4)
General
rifamycin (rifamycin SV, Rifocin, Aemcolo)
Properties
MISC-INFO: elimination route LIVER
protein-binding 85%
1/2life 16-69 HOURS
pregnancy-category B
safety in lactation ?
Database Correlations
PUBCHEM correlations
References
- The Pharmacological Basis of Therapeutics, 9th ed.
Gilman et al, eds. Permagon Press/McGraw Hill, 1996
- Kaiser Permanente Northern California Regional Drug
Formulary, 1998
- Medical Knowledge Self Assessment Program (MKSAP) 11, 17.
American College of Physicians, Philadelphia 1998, 2015