## Role of Rifampicin in Leprosy MDT **Key Point:** Rifampicin is the backbone drug of MDT for leprosy, responsible for rapid bactericidal activity and prevention of drug resistance. ### Mechanism and Efficacy of Rifampicin 1. **Bactericidal action:** Kills 99% of viable Mycobacterium leprae within 2 weeks 2. **Rapid reduction of bacillary load:** Reduces infectivity dramatically after the first dose 3. **Resistance prevention:** Used in combination with other drugs to prevent monotherapy resistance 4. **Penetration:** Excellent intracellular penetration, reaching high concentrations in macrophages and skin lesions ### Role of Other Drugs in MDT | Drug | Primary Role | Bactericidal/Static | | --- | --- | --- | | Rifampicin | Backbone; rapid kill; resistance prevention | Bactericidal | | Dapsone | Maintenance therapy; slow-acting backup | Bacteriostatic | | Clofazimine | Anti-inflammatory; slow bacteriostatic action | Bacteriostatic | | Ofloxacin | Reserve drug for rifampicin resistance | Bactericidal | **High-Yield:** Rifampicin monotherapy leads to resistance within 3–4 months; hence, it is ALWAYS combined with at least 2 other drugs in MDT. **Clinical Pearl:** Patients become non-infectious within 1–2 weeks of starting rifampicin, even though clinical improvement takes months. This is why rifampicin is given monthly as a supervised dose — to ensure compliance and prevent resistance. **Warning:** ~~Dapsone~~ and ~~clofazimine~~ are NOT the primary drugs for cure; they are adjuncts that prevent relapse and drug resistance. [cite:Harrison 21e Ch 189] 
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