Rifabutin for Mycobacterial Infections  (PDF Version)


Antibiotic Class:



Antimicrobial Spectrum:

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


Adverse Effects:

Hepatic: hepatotoxicity, jaundice, hepatitis

Hematologic: Thrombocytopenia, hemolytic anemia

Musculo-skeletal: Arthralgias

Skin: Rash

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


Drug Interactions:

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


Monitoring Requirements:

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.


Brand names/Manufacturer:

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