In WHO multidrug therapy (MDT) for lepromatous leprosy, which drug is the most rapidly bactericidal and must be combined with dapsone to prevent resistance?

Explanation

## Rifampicin in Leprosy MDT **Key Point:** Rifampicin is a rifamycin antibiotic that rapidly kills *Mycobacterium leprae* by inhibiting bacterial RNA polymerase. It is the most potent bactericidal agent in antileprotic regimens and must always be paired with dapsone to prevent monotherapy resistance. ### WHO Multidrug Therapy Regimens | Leprosy Type | Duration | Core Drugs | Role of Rifampicin | |--------------|----------|-----------|--------------------| | Paucibacillary (TT, BT) | 6 months | Rifampicin + Dapsone | Bactericidal backbone | | Lepromatous (LL, BL) | 12 months | Rifampicin + Dapsone + Clofazimine | Bactericidal backbone | | Single lesion (SL) | 1 month | Single dose Rifampicin | Monotherapy acceptable | **High-Yield:** Rifampicin dosing in leprosy is 600 mg once monthly (supervised) in WHO-MDT, not the daily dosing used in tuberculosis. This monthly supervised regimen improves compliance. **Mnemonic:** **RIF** = **R**apid **I**nhibition of **F**actors (RNA polymerase) — remember rifampicin's speed in leprosy. **Clinical Pearl:** Rifampicin renders patients non-infectious within 2–3 weeks of therapy, making it critical for public health control of leprosy transmission. **Warning:** Never use rifampicin monotherapy in leprosy — it rapidly selects for resistant strains. Always combine with at least dapsone (and clofazimine in lepromatous disease).