Rifampicin — Indications & Side Effects

(10-Mark Final Year General Medicine Answer)

INTRODUCTION

INDICATIONS

A. Tuberculosis (Primary Indication)

1. Drug-Sensitive TB — National TB Elimination Programme (NTEP) / India National Guidelines

• Dose: 10 mg/kg/day (range 8–12 mg/kg), max 600 mg/day orally, taken on an empty stomach (1 hour before or 2 hours after meals for maximum absorption).
• Paediatric dose: 15 mg/kg/day (max 600 mg/day).

2. Specific TB Forms (Harrison's 22E)

• Pulmonary TB — standard 6-month HRZE/HR regimen
• Extrapulmonary TB (lymphadenitis, pleural, pericardial, bone/joint, meningeal) — 6–12 months (9–12 months for CNS TB and bone TB)
• Latent TB Infection (LTBI): 3HR (3 months isoniazid + rifampicin) — recommended in India's NTEP TB Preventive Treatment (TPT) guidelines
• 4R regimen (4 months rifampicin monotherapy) — alternative LTBI regimen per WHO/NTEP

3. Non-Tuberculous Mycobacterial (NTM) Infections

• MAC (Mycobacterium avium complex): Rifamycin + macrolide + ethambutol (foundation of MAC pulmonary/disseminated therapy)
• M. kansasii: Isoniazid 300 mg + Rifampin 600 mg + Ethambutol 15 mg/kg/day for ≥1 year
• M. marinum: Macrolide + ethambutol + rifamycin combination (Harrison's 22E, p. 1461)

4. Leprosy (MDT — WHO/NLEP Regimen)

• Paucibacillary leprosy: Rifampicin 600 mg once monthly (supervised) + Dapsone 100 mg daily × 6 months
• Multibacillary leprosy: Rifampicin 600 mg once monthly + Clofazimine 300 mg once monthly + Dapsone 100 mg daily × 12 months (Goldman-Cecil Medicine; Harrison's 22E)

5. Meningococcal Prophylaxis

• Rifampicin is used as chemoprophylaxis for close contacts of Neisseria meningitidis infection.
• Dose: 600 mg twice daily × 2 days (adults); 10 mg/kg BD × 2 days (children > 1 month)

6. Haemophilus influenzae type b (Hib) Prophylaxis

• 20 mg/kg/day (max 600 mg) × 4 days for household contacts of invasive Hib disease

7. Brucellosis

• Rifampicin 600–900 mg/day + Doxycycline 200 mg/day × 6 weeks (WHO-recommended regimen)

8. Staphylococcal Infections (Adjunctive)

• Rifampicin added to standard therapy in prosthetic valve endocarditis (S. aureus/CoNS), prosthetic joint infections, and foreign body-related infections — leveraging its intracellular bactericidal activity and biofilm penetration.

9. Legionella pneumophila (Severe cases)

• Rifampicin may be added to fluoroquinolone/macrolide therapy in severe Legionnaire's disease.

10. Biliary Pruritus (Cholestatic)

• Rifampicin 150–300 mg BD used for pruritus of cholestasis (e.g., primary biliary cholangitis) — acts by inducing pregnane X receptor and reducing bile acid reabsorption.

SIDE EFFECTS / ADVERSE EFFECTS

A. Characteristic / Hallmark Side Effects

1. Reddish-Orange Discolouration

• The most characteristic effect: Rifampicin colours all body secretions — urine, tears, saliva, sweat, sputum, faeces, and CSF orange-red.
• Harmless but alarming to patients; stains soft contact lenses permanently.
• Patients must be warned in advance. (Harrison's 22E; Goldman-Cecil Medicine)

B. Gastrointestinal (Common)

• Nausea, vomiting, epigastric distress — most common GI complaints
• Diarrhoea, abdominal cramping
• Anorexia, heartburn
• Usually mild; taking the drug with a light snack reduces GI symptoms (though absorption is slightly reduced)

C. Hepatotoxicity (Most Important Adverse Effect)

"The most important adverse effect is hepatitis, which is usually not serious, unless compounded by another drug that also affects the liver." — Goldman-Cecil Medicine / Harrison's 22E

• Asymptomatic rise in serum transaminases (AST/ALT) — occurs in up to 10–20% of patients; usually transient and self-limiting
• Clinical hepatitis — jaundice, hepatomegaly, dark urine; incidence ~1%
• Rifampicin-induced hepatotoxicity is potentiated when combined with isoniazid (both are hepatotoxic; combination risk is additive)
• Monitor LFTs at baseline and periodically during therapy
• Contraindicated in severe pre-existing hepatic disease

D. Immunological / Hypersensitivity Reactions (Especially Intermittent Use)

E. Drug Interactions — Potent CYP450 Inducer ⚠️

"Rifampicin also induces liver enzymes, so some other drugs (e.g., oral contraceptives) may be rendered less effective because they are metabolized more quickly." — Harrison's 22E / Goldman-Cecil

F. Other Adverse Effects

CONTRAINDICATIONS

• Severe hepatic disease / active hepatitis
• Hypersensitivity to rifamycins
• Concurrent use with saquinavir/ritonavir (marked reduction in PI levels)
• Porphyria (relative contraindication)
• First trimester of pregnancy (teratogenic potential in animals — use cautiously, Category C)

MONITORING DURING THERAPY

• Baseline: LFTs, CBC, serum bilirubin, serum creatinine
• Monthly: Clinical assessment for symptoms of hepatitis, jaundice, rash
• LFTs if symptomatic or baseline abnormal
• Platelet count if intermittent therapy used
• Warn about: Orange secretions, drug interactions, strict adherence

SUMMARY TABLE

• Harrison's Principles of Internal Medicine, 22E (2025) — Chapters on Tuberculosis, Leprosy, NTM (blocks 20–21)
• Goldman-Cecil Medicine, International Edition — Chapter 301 (Leprosy), Chapter on TB Chemotherapy
• National TB Elimination Programme (NTEP) / Central TB Division, India — Standard Treatment Workflows & TPT Guidelines (2023)
• WHO MDT Guidelines for Leprosy