Rifabutin

Information about Rifabutin

Rifabutin is a rifamycin antibiotic that is similar in structure and activity to rifampin and rifapentine and which is used largely in the prevention of Mycobacterium avium complex (MAC) disease in patients with advanced HIV infection. Rifabutin is associated with transient and asymptomatic elevations in serum aminotransferase and is a likely cause of clinically apparent, acute liver disease.

Mechanism of action of Rifabutin

Rifabutin (rif" a bue' tin) is a rifamycin antibiotic and a synthetic derivative of natural products of the bacterium, Amycolatopsis mediterranei. The rifamycins are complex macrocyclic antibiotics that have activity against several bacteria, but most prominently M. tuberculosis and several atypical mycobacterial species, probably as a result of inhibition of the DNA-dependent RNA polymerase of mycobacteria. These agents are considered bactericidal and are active against both intracellular and extracellular organisms. Rifabutin has similar activity and pharmacokinetics as rifampin, but it is less likely to induce hepatic microsomal, drug metabolizing enzymes and, thus, is an appropriate substitute for rifampin in patients on other medications that would be affected by alteration in the P450 system, such as some antiretroviral agents, benzodiazepines, cyclosporine, macrolide antibiotics, oral contraceptives, and warfarin. Rifabutin is available as 150 mg capsules under the trade name of Mycobutin. The current major indication is for prevention of mycobacterium avium complex (MAC) disease in patients with HIV infection, and treatment of tuberculosis is considered an off-label use. The recommended dose in adults is 300 mg daily in one or two divided doses. Pyridoxine (vitamin B6) is commonly given with rifabutin to prevent neuropathy. Side effects of rifabutin are uncommon, but include rash, fever, flu-like symptoms, gastrointestinal upset and orange discoloration of urine and sweat. Rifabutin has some, but far less activity than rifampin as an inducer of the hepatic microsomal drug metabolizing P450 enzymes (CYP 1A2, 2C9, 2C19 and 3A4), the relative potencies being: rifampin (1.0), rifapentine (0.85), and rifabutin (0.4). Nevertheless, use of other medications (such as birth control pills, beta-blockers, benzodiazepines, cyclosporine and oral anticoagulants) with rifabutin should be carefully considered and monitored. Rare but potentially severe adverse events include uveitis, hypersensitivity reactions and C. difficile diarrhea.

The following are list of antituberculosis medications that are discussed individually:

• Bedaquiline
• Capreomycin
• Cycloserine
• Ethambutol
• Ethionamide
• Isoniazid
• Pyrazinamide
• Rifabutin
• Rifampin
• Rifapentine
• Streptomycin

• Dailymed label info on Rifabutin
• FDA Rifabutin

Rifabutin Resources
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