Dosing and uses of Mycobutin (rifabutin)
Adult dosage forms and strengths
capsule
- 150mg
oral solution
- 10mg/mL
- 20mg/mL
MAC Prophylaxis
Indicated for prefention of disseminated Mycobacterium avium complex (MAC) disease in paitents with advanced HIV infection
300 mg PO qDay
Patients with N/V diathesis: 150 mg PO BID with food
Active TB (off-label)
5 mg/kg PO qD or 2-3x/week + other antitubercular agents, no more than 300 mg/dose
MAC Treatment (Orphan)
Treatment of disseminated Mycobacterium avium complex disease
Orphan indication sponsor
- Pfizer, Inc; 235 East 42nd Street; New York, NY 10017
Crohn Disease (Orphan)
Combination of clarithromycin, rifabutin, and clofazimine for treatment of pediatric Crohn disease
Orphan indication sponsor
- RedHill Biopharma Ltd; 42 Givati St; Israel
Renal Impairment
CrCl<30mL/min dose should be reduced by 50%
Other Indications & Uses
MAC, TB
Off-label: resistant H. pylori (300 mg/d + amoxicillin 1000 mg BID + pantoprazole 40 mg BID x10 d); Treatment of active TB (concomitant with other anti-TB agents)
Pediatric dosage forms and strengths
capsule
- 150mg
oral solution
- 10mg/mL
- 20mg/mL
Mycobacterium Avium Complex (MAC)
Treatment: 5-10 mg/kg PO qD ; no more than 300 mg/d
Prophylaxis: 1st episode in HIV/recurrence: 5 mg/kg PO qD; no more than 300 mg/d
Active TB with HIV (Off-label)
10-20 mg/kg PO qD OR 2x/week + other antitubercular agents; no more than 300 mg/dose
Mycobutin (rifabutin) adverse (side) effects
>10%
Discoloration of urine (30%)
Neutropenia (25%)
Leukopenia (17%)
Rash (11%)
1-10%
Incr AST/ALT (7-9%)
Thrombocytopenia (5%)
Abdominal pain (4%)
Diarrhea (3%)
Eructation (3%)
Headache (3%)
Nausea/vomiting (3%)
Anorexia (2%)
Flatulence (2%)
Anemia
Myalgia
Postmarketing reports
Blood and lymphatic system disorders: Agranulocytosis, lymphopenia, granulocytopenia, white blood cell ccount decreased, neutrophil count ddecreased), platelet count decreased
Immune system disorders: Hypersensitivity, bronchospasm
Gastrointestinal disorders: Clostridium difficile colitis/ Clostridium difficile associated diarrhea
Pyrexia, rash and other hypersensitivity reactions such as eosinophilia, bronchospasm and shock might occur, as has been seen with other antibacterials; a limited number of skin discoloration have been reported
Warnings
Contraindications
Hypersensitivity to rifamycins
Concomitant live bacterial vaccines
Cautions
Monitor hematologic status
Eye pain, redness, loss of vision may indicate inflammatory ocular condition
Joint stiffness, swelling, tenderness or paresthesia may indicate arthralgias or myositis
May have brown-orange color of urine, feces, saliva, sputum, perspiration, tears, & skin
Pregnancy and lactation
Pregnancy category: B
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Mycobutin (rifabutin)
Lacatation: unknown
Absorption: readily, 53%
Distribution: body tissues including the lungs, liver, spleen, eyes, & kidneys
Vd: 9.32 L/kg
Protein Bound: 85%
Bioavailability: absolute: HIV: 20%
Half-Life, Elim45 hr (range: 16-69 hr)
Peak Plasma Time: 2-4 hr
Metabolism: hepatic CYP3A4 to active and inactive metabolites
Excretion
Urine: 10% as unchanged drug, 53% as metabolites
Feces: 10% as unchanged drug, 30% as metabolites
Mechanism of action
Inhibits DNA-dependent RNA polymerase
