A 32-year-old man from rural Maharashtra presents with a 3-month history of cough, fever, and night sweats. Chest X-ray shows cavitary lesions in the right upper lobe. Sputum smear microscopy is positive for acid-fast bacilli. He has no prior TB treatment history and normal renal and hepatic function. What is the drug of choice as the backbone of his initial intensive phase regimen?
Rifampicin is the most potent bactericidal anti-TB agent and forms the backbone of all standard TB regimens, both in the intensive and continuation phases.
Role of Rifampicin in TB Treatment
Rifampicin is the single most important drug in TB therapy because it:
Has the highest bactericidal activity against Mycobacterium tuberculosis
Kills both intracellular and extracellular organisms
Reduces bacterial load most rapidly in the first 2 weeks
Is present in all standard TB regimens (2HRZE/4HR, 2HRZ/4HR)
Achieves excellent lung penetration
Standard Intensive Phase Regimen (2 months)
Table
Drug
Role
Dosing
Isoniazid (H)
Bactericidal; sterilizes lesions
5 mg/kg daily
Rifampicin (R)
Most potent; backbone drug
10 mg/kg daily
Pyrazinamide (Z)
Bactericidal; shortens duration
25 mg/kg daily
Ethambutol (E)
Bacteriostatic; prevents resistance
15 mg/kg daily
High-YieldNEET PG
The 4-drug combination (HRZE) for 2 months followed by 2-drug continuation (HR) for 4 months is the standard regimen for drug-susceptible TB. Rifampicin is never omitted from any TB regimen.
Why Rifampicin Is the Backbone
1.
Fastest bacterial kill rate — reduces viable organisms by 99% in first 2 weeks
2.
Prevents drug resistance — when used with other agents
3.
Sterilizes cavitary lesions — kills organisms in acidic, hypoxic environments
4.
Mandatory in all regimens — WHO and Indian TB guidelines mandate rifampicin in every TB patient
Clinical Pearl
Rifampicin's orange-red discoloration of body secretions (urine, tears, sweat) is a useful compliance marker and reassures patients of drug absorption.
Mnemonic
HRZE = Heavy hitter (Isoniazid) + Rapid killer (Rifampicin) + Zero resistance (Pyrazinamide) + Early addition (Ethambutol).
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