Section 15 · Monograph
Rifampin
Reviewed Nov 2026FDA label
RifadinAntimycobacterial (rifamycin)
- Forms
- Cap: 150, 300mg | IV: 600mg
- Dose
- TB meningitis: 10mg/kg/day (max 600mg) in standard regimens; intensified dosing under study
- MOA
- Inhibits bacterial RNA polymerase
Indications
- Pulmonary and extrapulmonary tuberculosis; meningococcal carriersFDA-labeled
Mechanism of Action
- Inhibits bacterial DNA-dependent RNA polymerase; potent inducer of CYP3A4, CYP2C9, CYP2C19 and P-glycoprotein
Full Dosing
Adult / usual
- Tuberculosis: 10mg/kg/day (max 600mg) PO or IV in standard regimens; take on an empty stomach
- TB meningitis: part of a four-drug regimen then isoniazid plus rifampin; higher rifampin doses have been studied — follow current guideline
- Adjust companion drug doses and monitoring for the many interactions
Contraindications
- Hypersensitivity to rifamycins
- Concomitant use with certain HIV protease inhibitors or other drugs for which rifampin makes treatment ineffective (check current label)
Drug Interactions
- Markedly lowers levels of phenytoin, carbamazepine, lamotrigine, clobazam, zonisamide, valproate and many other CNS drugs
- Warfarin, DOACs (avoid), hormonal contraceptives, corticosteroids (including dexamethasone), methadone, voriconazole (contraindicated), praziquantel (contraindicated)
- Isoniazid and pyrazinamide increase hepatotoxicity
Adverse Effects
- Hepatotoxicity
- Orange discoloration of body fluids
- Flu-like syndrome, thrombocytopenia
- Nausea, rash
Monitoring Parameters
- Liver enzymes at baseline and periodically
- CBC with platelets
- Drug level monitoring for coadministered antiepileptics and anticoagulants
Pregnancy & Lactation
- Used in pregnancy when needed; give vitamin K to the newborn if exposed late in pregnancy
- Compatible with breastfeeding