Formulary
Rifampicin (Rifampin): Uses, Dosing, Side Effects and Indian Brand Names
Rifampicin inhibits bacterial RNA polymerase and is the key sterilising drug in TB therapy, with the most extensive CYP enzyme induction profile of any drug, colouring body fluids orange-red.
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Rifampicin (Rifampin): Uses, Dosing, Side Effects and Indian Brand Names
Rifampicin inhibits bacterial RNA polymerase and is the key sterilising drug in TB therapy, with the most extensive CYP enzyme induction profile of any drug, colouring body fluids orange-red.
NEET PG High-Yield: Most potent CYP inducer of any drug (CYP3A4, 2C9, 2C19, 2B6, P-gp). Inhibits bacterial RNA polymerase (rpoB mutation = resistance). Sterilising activity against semi-dormant persisters. Orange-red body fluids. Flu-like syndrome with intermittent dosing. OCP failure. Warfarin interaction. Cannot use with PI-based HIV regimens (use rifabutin instead). Meningococcal prophylaxis (2 days). Monthly supervised dose in leprosy MDT. Take on empty stomach.
Clinical overview
Rifampicin is the single most important drug for sterilising tuberculous lesions and is the backbone of short-course chemotherapy. Its unique ability to kill semi-dormant 'persister' bacilli in caseous tissue is what allows the modern 6-month treatment regimen -- without rifampicin, treatment would require 12-18 months. The drug is also the most potent inducer of the cytochrome P450 system (particularly CYP3A4, CYP2C9, CYP2C19, and CYP2B6) and of P-glycoprotein, creating an extraordinarily wide range of drug interactions that are among the most commonly tested topics in pharmacology examinations. Rifampicin reduces levels of oral contraceptives, warfarin, HIV protease inhibitors, corticosteroids, digoxin, theophylline, and virtually every CYP-metabolised drug. Women on rifampicin must use non-hormonal contraception. The drug colours bodily fluids (urine, tears, sweat, saliva) orange-red, which is harmless but must be communicated to patients to avoid alarm and to monitor adherence -- absence of discolouration suggests non-compliance. Hepatotoxicity is the most serious adverse effect and is additive with isoniazid. Rifampicin must be taken on an empty stomach for optimal absorption. Under NTEP, rifampicin is present in the intensive phase of all regimens and, combined with isoniazid, forms the continuation phase backbone. Monotherapy with rifampicin must be avoided to prevent resistance emergence.
Pharmacological class
Rifampicin (Rifampin) belongs to the First-Line Antitubercular Agents (Rifamycin) class. Inhibits DNA-dependent RNA polymerase (specifically the beta subunit, encoded by rpoB gene) of mycobacteria and many other bacteria, blocking transcription initiation. This mechanism is highly selective -- bacterial RNA polymerase differs significantly from human RNA polymerase, providing the basis for selective toxicity. Rifampicin is bactericidal against both actively growing and semi-dormant (slowly metabolising) M. tuberculosis.
Indian brand names and formulations
Available as: R-Cinex (Lupin, FDC with INH), Rifadin (Sanofi), Rimactane (Sandoz/Novartis), Rifacom (Macleods).
Capsules: 150 mg, 300 mg, 450 mg, 600 mg. Syrup: 100 mg/5 mL. IV infusion: 600 mg vial. FDCs: with isoniazid (R-Cinex), with isoniazid + pyrazinamide (Akurit-3), with isoniazid + pyrazinamide + ethambutol (Akurit-4/NTEP kit).
Regulatory status
Rifampicin (Rifampin) is classified under Schedule H in India under the Drugs and Cosmetics Act, 1940. Prescription-only. Supplied free under NTEP. Must never be dispensed as monotherapy for TB. Schedule H1 considerations apply when prescribed outside NTEP.
Indications
- Active tuberculosis (always in combination)
- Latent TB infection (alternative to isoniazid: 4 months rifampicin, or 3 months rifampicin + isoniazid)
- Leprosy (part of WHO MDT regimen -- 600 mg monthly, supervised)
- Staphylococcal prosthetic device infections (with another anti-staphylococcal agent)
- Meningococcal and H. influenzae type b prophylaxis (close contacts)
- Brucellosis (with doxycycline)
Dosing
TB: 10 mg/kg/day (max 600 mg) on empty stomach, 30-60 min before food. Intermittent (thrice weekly): 10 mg/kg (max 600 mg). Meningococcal prophylaxis: 600 mg twice daily for 2 days (adults); 10 mg/kg twice daily for 2 days (children). Leprosy: 600 mg once monthly (supervised, with dapsone and clofazimine in MB-MDT).
Contraindications
- Active hepatic disease or jaundice
- Concomitant use with HIV protease inhibitors (saquinavir/ritonavir -- profound reduction in PI levels)
- Hypersensitivity to rifamycins
- Porphyria
Adverse effects
- Orange-red discolouration of urine, tears, sweat, saliva (harmless -- warn patients; stains contact lenses permanently)
- Hepatotoxicity (dose-dependent; additive with isoniazid; monitor LFTs in first 2 months)
- GI disturbances (nausea, vomiting, abdominal pain)
- Flu-like syndrome (fever, chills, myalgia -- typically with intermittent dosing or re-introduction after interruption)
- Thrombocytopaenia (immune-mediated, especially with intermittent use)
- Renal failure (interstitial nephritis, rare)
Drug interactions
- Warfarin: rifampicin induces CYP2C9, dramatically reducing warfarin effect; may need 2-3x dose increase; monitor INR very frequently
- Oral contraceptives: efficacy abolished; use barrier or IUD contraception during and for 4 weeks after rifampicin
- HIV protease inhibitors and NNRTIs: levels reduced by 80-95% (use rifabutin instead of rifampicin with most antiretroviral regimens)
- Corticosteroids: halved bioavailability; may need to double steroid dose
- Cyclosporine, tacrolimus: drastically reduced levels, risk of transplant rejection
- Methadone: reduced levels, may precipitate withdrawal
- Digoxin: reduced absorption and increased clearance via P-glycoprotein induction
- Statins: reduced levels of atorvastatin and simvastatin; may need dose adjustment
Pregnancy and lactation
Category C. Used in pregnancy when treating active TB -- untreated TB poses a far greater risk. Vitamin K supplementation recommended in the last few weeks of pregnancy and for the neonate (rifampicin may cause neonatal bleeding due to vitamin K depletion). Not teratogenic in human data.
Exam-style clinical scenario
A 40-year-old woman on DOTS therapy for pulmonary TB is also on oral contraceptive pills. She becomes pregnant 3 months into treatment. What went wrong? Rifampicin induced CYP3A4, accelerating metabolism of ethinyl oestradiol and levonorgestrel, rendering the OCP ineffective. All women on rifampicin must use non-hormonal contraception (barrier methods or copper IUD).
Cost in India
Rs 10-30 per capsule (450 mg or 600 mg). Supplied free under NTEP. FDC kits distributed through DOTS centres at no cost to patients.
Clinical governance
Author: MedNext Editorial Team. Clinical reviewer: Awaiting clinical review. Jurisdiction: India (Drugs and Cosmetics Act, 1940). Sources: CIMS India, Indian Pharmacopoeia. Publication state: Awaiting clinical review. Correction: Report errors at support@mednext.academy.
Frequently Asked Questions
Why is rifampicin the most important drug for shortening TB treatment?
Rifampicin uniquely kills semi-dormant 'persister' bacilli that are metabolically inactive and hidden in caseous tissue. Isoniazid rapidly kills actively multiplying bacilli (high EBA), but cannot reach persisters. Without rifampicin's sterilising activity, these persisters reactivate and relapse is much higher -- treatment would need 12-18 months instead of 6 months. This is why rifampicin must be present in both the intensive and continuation phases.
Why is rifabutin used instead of rifampicin in HIV-TB co-infection?
Rifampicin is such a potent CYP3A4 and P-glycoprotein inducer that it reduces levels of HIV protease inhibitors by 80-95% and NNRTIs by 20-60%, making antiretroviral therapy ineffective. Rifabutin is a weaker CYP inducer (less effect on PIs and NNRTIs) and can be used with dose adjustments alongside most antiretroviral regimens. This is a critical NEET PG point.
What causes the flu-like syndrome with rifampicin?
The flu-like syndrome (fever, chills, myalgia, headache, sometimes thrombocytopaenia) is an immune-mediated reaction caused by anti-rifampicin antibodies. It occurs almost exclusively with intermittent dosing (especially once-weekly) or when rifampicin is restarted after an interruption. The reaction can be severe and rarely causes renal failure and shock. Switching to daily dosing usually prevents recurrence.
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