Rifabutin for Mycobacterial Infections (PDF Version)
Most slow growing mycobacteria are inhibited.
Mechanism of Action:
Rifamycins bind to and inhibit DNA-dependant RNA polymerase
Most likely concentration dependent killing (peak/MIC and AUC/MIC)
Cmax: 0.2-0.6mg/L; Tmax: 2.5-4 hours; Bioavailability: 20%; Protein binding: 71-85%; Table 3
Hepatic: hepatotoxicity, jaundice, hepatitis
Hematologic: Thrombocytopenia, hemolytic anemia
GI: Nausea, vomiting, loss of appetite
Kidneys: Acute renal failure, interstitial nephritis,
Other: shock, flu-like syndrome (at least with related rifampin), body fluid discoloration (tears, sweat may be orange colored)
Usual dose 300 mg once daily. Lower doses (150 mg once daily or 3 times weekly) used with some ritonavir-containing HAART regimens. Note that therapeutic drug monitoring may be advisable for such situations, as underdosing has been associated with clinical failure and the selection of rifamycin-resistant TB.
Contraindications/Warnings/Precautions: Precautions: Hepatic impairment
Due to its known induction of P450 liver isoenzymes, caution should be exercised when administering this agent with other drugs metabolized in the liver. Please see the “Drug Interactions” section in the text/website for a complete list of relevant interactions. Heparin may negate the action of rifabutin.
Category B: No evidence of risk in humans but studies inadequate
Toxic: baseline liver function tests, bilirubin, serum creatinine, complete blood count and platelet count.
Therapeutic drug monitoring in selected cases, especially patients slow to respond, or those with complex drug interactions.
Rifabutin (Various manufacturers worldwide)
Alfacid - Grunenthal, Germany
Ansamycin - Adria Laboratories
Ansatipine - Pharmacia, France
Ansatipin - Kenfarma, Spain, Finland
Mycobutin - Pharmacia , USA, Greece, Canada, Netherlands, Portugal, Switzerland, Australia, Austria, Belgium, Czech Republic, Germany, Hong Kong, Israel, Italy, New Zealand, South Africa, United Kingdom, Greece