Rifampicin is a semisynthetic, bactericidal antibiotic belonging to the rifamycin group. It is a cornerstone of first-line anti-tuberculosis therapy in India, used in combination with other drugs to treat all forms of tuberculosis (TB). It is also a key agent for prophylaxis and treatment of leprosy and other mycobacterial infections. Its unique mechanism involves inhibition of bacterial DNA-dependent RNA polymerase.
Adult: Tuberculosis: 10 mg/kg (usual dose 450mg for <50kg, 600mg for ≥50kg) once daily. The 300mg strength is often used in fixed-dose combinations (FDCs) or for weight-based dosing in lighter adults. Leprosy: 600mg once monthly (supervised) as part of MDT.
Note: Must be taken on an empty stomach, at least 1 hour before or 2 hours after meals, with a full glass of water. For patients experiencing GI upset, taking with a small, low-fat snack may be considered, acknowledging the reduced bioavailability. Capsules should be swallowed whole.
Rifampicin binds with high affinity to the beta subunit of bacterial DNA-dependent RNA polymerase. This binding forms a stable drug-enzyme complex, thereby inhibiting the initiation step of RNA synthesis. It is bactericidal against actively dividing organisms.
Pregnancy: Pregnancy Category C (US FDA). Considered compatible with pregnancy for the treatment of active TB by WHO and NTEP (India). Benefits of treating active TB outweigh potential risks. Adequate folate supplementation is recommended. Neonatal bleeding has been reported; vitamin K may be advised.
Driving: Generally safe. However, patients should be cautioned about potential dizziness or visual disturbances.
| Oral Contraceptives, Hormone Replacement Therapy | Decreased efficacy due to increased metabolism; risk of unintended pregnancy. | Major |
| Warfarin, Acenocoumarol | Decreased anticoagulant effect; requires increased warfarin dose and frequent INR monitoring. | Major |
| Antiretroviral Protease Inhibitors (e.g., Atazanavir, Darunavir) & Non-Nucleoside Reverse Transcriptase Inhibitors (e.g., Efavirenz, Nevirapine) | Significant reduction in ARV levels leading to treatment failure and resistance. Requires dose adjustment or alternative regimens. | Major |
| Ketoconazole, Itraconazole, Posaconazole | Marked decrease in azole levels, leading to antifungal failure. | Major |
| Corticosteroids (e.g., Prednisolone) | Increased metabolism, reducing corticosteroid efficacy. | Moderate |
| Oral Hypoglycemics (e.g., Gilbenclamide, Glimepiride) | Reduced hypoglycemic effect. | Moderate |
| Digoxin | Reduced digoxin serum levels. | Moderate |
| Isoniazid | Additive risk of hepatotoxicity. | Moderate |
| Pyrazinamide | Additive risk of hepatotoxicity and hyperuricemia. | Moderate |