Rifabutin
Pronunciation: RIFF-uh-BYOO-tin
Class: Antituberculosis agent
Trade Names
Mycobutin
- Capsules 150 mg
Pharmacology
Inhibits DNA-dependent RNA polymerase in susceptible strains of bacteria.
Pharmacokinetics
Absorption
Readily absorbed from GI tract (53%). C max is 375 ng/mL. T max is 3.3 h. Bioavailability is 20% (HIV-positive patients) or 85% (healthy patients). High fat meals slow the rate without influencing extent of absorption. Steady state is 9.3 L/kg.
Distribution
High lipophilicity demonstrates a high propensity for distribution and intracellular uptake. Protein binding is about 85%. Vd is 9.3 L/kg.
Metabolism
In the liver, there are 5 metabolites identified, 25-0-desacetyl and 31-hydroxy are the most predominant.
Elimination
Eliminated in the urine (53% excreted primarily as metabolites, 5% unchanged) and feces (30%; 5% unchanged). Systemic cl is 0.69 L/h/kg. Terminal t ½ is 45 h.
Special Populations
Renal Function ImpairmentCrCl is less than 30 mL/min. AUC is increased 71%. Reduction in dosage is recommended.
Indications and Usage
Prevention of disseminated Mycobacterium avium complex (MAC) disease in patients with advanced HIV infection.
Contraindications
Hypersensitivity to rifabutin or other rifamycins; active tuberculosis.
Dosage and Administration
AdultsPO 300 to 450 mg once daily.
Infants and ChildrenPO Up to 5 mg/kg/day.
Drug Interactions
Azole antifungal agents, benzodiazepines, beta blockers, buspirone, chloramphenicol, clarithromycin, clozapine, oral contraceptives, corticosteroids, cyclosporine, delavirdine, digitoxin, disopyramide, doxycycline, erythromycin, estrogens, haloperidol, hydantoins, indinavir, losartan, methadone, mexiletine, morphine, nelfinavir, ondansetron, oral anticoagulants, quinidine, quinine, ritonavir, sulfonylureas, tacrolimus, tamoxifen, theophyllines, tocainide, toremifene, tricyclic antidepressants, troleandomycin, verapamil, zolpidemTherapeutic efficacy may be decreased because of liver enzyme-inducing properties of rifabutin.
Indinavir, itraconazole, ritonavirMay elevate rifabutin plasma levels, increasing the risk of side effects.
KetoconazoleMay reduce rifabutin plasma levels, decreasing the therapeutic effects.
ZidovudineMay decrease plasma levels of zidovudine.
Laboratory Test Interactions
None well documented.
Adverse Reactions
Cardiovascular
Chest pain.
CNS
Asthenia; headache; insomnia.
Dermatologic
Rash.
EENT
Taste perversion.
GI
Anorexia; diarrhea; dyspepsia; abdominal pain; eructation; flatulence; nausea; vomiting.
Genitourinary
Discolored urine.
Hematologic
Anemia; eosinophilia; leukopenia; neutropenia; thrombocytopenia.
Metabolic
Increased alkaline phosphatase, AST, and ALT.
Miscellaneous
Myalgia; fever; discolored saliva, sputum, tears, or skin.
Precautions
Pregnancy
Category B .
Lactation
Unknown. Discontinue nursing or discontinue drug.
Children
Safety and efficacy not established. Based on the limited data available, there is no evidence that doses higher than 5 mg/kg daily are useful.
Patient Information
- Inform patient that body fluids (eg, urine, feces, saliva, sputum, perspiration, tears) may be brown-orange in color and that soft contact lenses may be permanently stained. Suggest use of glasses during drug therapy.
- Instruct patient to use nonhormonal methods of birth control while taking drug.
- Instruct patient to notify health care provider of rash, nausea, vomiting, anorexia, diarrhea, abdominal pain, change in color or consistency of stools, jaundice, arthralgias, myositis, chest pressure or pain with shortness of breath, seizure activity, paresthesia, aphasia, confusion, insomnia, excessive fatigue, fever, or infection.
- Instruct patient to report photophobia, excessive tearing, or eye pain immediately.
Copyright © 2009 Wolters Kluwer Health.
More Rifabutin resources
- Rifabutin Monograph (AHFS DI)
- rifabutin Concise Consumer Information (Cerner Multum)
- rifabutin MedFacts Consumer Leaflet (Wolters Kluwer)
- rifabutin Advanced Consumer (Micromedex) - Includes Dosage Information
- Mycobutin Prescribing Information (FDA)
