Pharm

Rifampin

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Rifampin

  • Background
  1. Semisynthetic derivative of rifamycin
  2. Rifamycin produced by Streptomyces mediterranei
  3. Drug resistance emerges rapidly
    1. Must be used with other antituberculous drugs
  • Indications
  1. Active Tuberculosis
  • Contraindications
  1. Multiple Drug Interactions (especially lowering the serum levels of HIV Medications)
    1. Use only with caution with HIV Medications
  • Dosing
  1. Adult: 600 mg/day PO or IV
  2. Pediatric: 10-20 mg/kg/day (Max 600/day)
  3. No Renal Dosing adjustment needed
  • Adverse Effects
  1. Drug-Induced Hepatitis (see hepatotoxicity risks below)
  2. Hyperbilirubinemia (transient)
  3. Nephritis or Acute Renal Failure
  4. Pruritus with or without Rash
  5. Thrombocytopenia
  6. Hemolytic Anemia
  7. Influenza-like Syndrome
    1. Associated with infrequent dosing
  8. Immune Reconstitution Inflammatory Syndrome (HIV patients)
  9. False Positive on drug screening for Opiates
  10. Body fluids become orange tinged
    1. Urine
    2. Sweat
    3. Tears (may discolor Contact Lenses)
  • Adverse Effects
  • Hepatotoxicity - Risk Factors
  1. Slow acetylators
  2. Hepatitis C
  3. Hepatitis B
  4. Concurrent Hepatotoxin exposure
  5. Age over 50 years
  6. Pregnancy and postpartum (within 3 months)
  7. Malnutrition
  • Drug Interactions
  1. Background
    1. Strong CYP450 enzyme inducer
    2. Increases other drug elimination, decreased levels and decreased efficacy
  2. Warfarin (Coumadin)
    1. Obtain INR weekly until stable and then for at least one month after stopping Rifampin
    2. Warfarin dose may need to increase up to 5x while on Rifampin
    3. (2014) Presc lett 21(8): 47
  3. Phenytoin (Dilantin)
  4. Oral Contraceptives (as well as Contraceptive Patch, Estrogen Ring)
    1. Consider alternative contraceptives (e.g. Depo Provera, IUD)
  5. Ketoconazole
  6. Chloramphenicol
  7. Methadone
  8. Antiretroviral therapy (HIV)
    1. Protease Inhibitors (reduced drug level and efficacy)
    2. Nonnucleoside reverse transcriptase inhibitors (reduced drug level and efficacy)
  • Monitoring
  1. Complete Blood Count
  2. Baseline Liver Function Tests
  3. Follow labs if abnormal or Active Tuberculosis develops
  • References
  1. (2000) MMWR Recomm Rep 49(RR-6): 1-51 [PubMed]
  2. Hartman-Adams (2014) Am Fam Physician 89(11): 889-96 [PubMed]