## Drug of Choice for Lepromatous Leprosy **Key Point:** Rifampicin is the backbone of all leprosy regimens and is the most potent anti-leprosy drug, making it the drug of choice for lepromatous leprosy. ### WHO Multidrug Therapy (MDT) Regimen for Lepromatous Leprosy The standard 12-month regimen consists of: | Drug | Dose | Frequency | Role | |------|------|-----------|------| | Rifampicin | 600 mg | Monthly supervised + daily unsupervised | Backbone; most potent | | Dapsone | 100 mg | Daily | Bacteriostatic; steroid-sparing | | Clofazimine | 100 mg | Daily | Anti-inflammatory; slow-acting | **High-Yield:** Rifampicin is the most bactericidal agent against *Mycobacterium leprae* and is essential in all WHO MDT regimens. It renders patients non-infectious within 2 weeks of therapy. ### Mechanism of Action 1. Rifampicin inhibits bacterial RNA polymerase → rapid bactericidal effect 2. Dapsone inhibits dihydropteroate synthase → bacteriostatic 3. Clofazimine generates reactive oxygen species → slow antimicrobial and anti-inflammatory effects **Clinical Pearl:** The combination of three drugs prevents emergence of drug resistance. Monotherapy with any single agent leads to treatment failure and relapse in lepromatous leprosy due to the high bacillary load (>10^6 bacilli). **Mnemonic:** **RDC** = Rifampicin (Backbone), Dapsone (Bacteriostatic), Clofazimine (anti-inflammatory) — the MDT triad for lepromatous leprosy. ### Why Rifampicin is Superior - Most potent bactericidal agent - Achieves highest intracellular concentrations - Renders patients non-infectious fastest (2 weeks) - Essential in all WHO regimens (both tuberculoid and lepromatous) - Prevents relapse when combined with other agents [cite:Park 26e Ch 30]
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