No

Antibiotic, Miscellaneous; Antitubercular Agent

Prevention of disseminated Mycobacterium avium complex (MAC) in patients with advanced HIV infection; also utilized in multiple drug regimens for treatment of MAC

B

Hypersensitivity to rifabutin or any other rifamycins; rifabutin is contraindicated in patients with a WBC <1000/mm³ or a platelet count <50,000/mm³; concurrent use with ritonavir

Rifabutin as a single agent must not be administered to patients with active tuberculosis since its use may lead to the development of tuberculosis that is resistant to both rifabutin and rifampin; rifabutin should be discontinued in patients with AST >500 units/L or if total bilirubin is >3 mg/dL. Use with caution in patients with liver impairment; modification of dosage should be considered in patients with renal impairment.

>10%:

Dermatologic: Rash (11%)

Genitourinary: Discolored urine (30%)

Hematologic: Neutropenia (25%), leukopenia (17%)

1% to 10%:

Central nervous system: Headache (3%)

Gastrointestinal: Vomiting/nausea (3%), abdominal pain (4%), diarrhea (3%), anorexia (2%), flatulence (2%), eructation (3%)

Hematologic: Anemia, thrombocytopenia (5%)

Hepatic: Increased AST/ALT (7% to 9%)

Neuromuscular & skeletal: Myalgia

<1%: Chest pain, fever, insomnia, dyspepsia, taste perversion, uveitis

Symptoms of overdose include nausea, vomiting, hepatotoxicity, lethargy, CNS depression

Treatment is supportive; hemodialysis will remove rifabutin, its effect on outcome is unknown

CYP3A3/4 enzyme inducer

Increased concentration by indinavir; reduce to 1/2 standard dose when used with indinavir

Increased risk of rifabutin-induced hematologic and ocular toxicity (uveitis) with concurrent administration of drug that inhibits CYP-450 enzymes such as protease inhibitors, erythromycin, clarithromycin, ketoconazole, and itraconazole

Inhibits DNA-dependent RNA polymerase at the beta subunit which prevents chain initiation

Absorption: Oral: Readily absorbed 53%

Distribution: V_d: 9.32 L/kg; distributes to body tissues including the lungs, liver, spleen, eyes, and kidneys

Protein binding: 85%

Metabolism: To active and inactive metabolites

Bioavailability: Absolute, 20% in HIV patients

Half-life, terminal: 45 hours (range: 16-69 hours)

Peak serum level: Within 2-4 hours

Elimination: Renal and biliary clearance of unchanged drugs is 10%; 30% excreted in feces; 53% in urine as metabolites

Oral:

Adults: 300 mg once daily; for patients who experience gastrointestinal upset, rifabutin can be administered 150 mg twice daily with food

May be administered with meals or without food or mix with applesauce; high-fat meal may decrease the rate but not the extent of absorption

Periodic liver function tests, CBC with differential, platelet count

May rarely cause insomnia

Neutropenia is common; avoid clozapine and carbamazepine; rifabutin is a hepatic enzyme inducer; monitor for altered clinical effects when used concurrently with psychotropics

No information available to require special precautions

No effects or complications reported

May take with food if GI upset occurs. Will discolor urine, stool, saliva, tears, sweat, and other body fluid a red-brown color. Stains on clothing or contact lenses are permanent. Report skin rash, vomiting, fever, chills, flu-like symptoms, dark urine or pale stools, unusual bleeding or bruising, or unusual confusion, depression, or fatigue. Breast-feeding precautions: Consult prescriber if breast-feeding.

Monitor periodic liver function tests, CBC with differential, platelet count, hemoglobin, hematocrit

Capsule: 150 mg

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