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[Pharmacology](https://durgical.com/en/pharmacology/) · Class

# Antileprosy drugs

Medicines against Mycobacterium leprae. Leprosy is cured with multidrug therapy: rifampicin, dapsone and clofazimine.

Updated 2026-11-01

## What they are

WHO multidrug therapy (MDT) combines rifampicin, dapsone and clofazimine for 6 months in paucibacillary leprosy and 12 months in multibacillary leprosy; WHO supplies it free of charge. Colombia has used multidrug therapy since 1985 and its treatment is free. A single dose of rifampicin is also recommended as post-exposure prophylaxis for contacts.

## Mechanism of action

Dapsone imitates para-aminobenzoic acid (PABA) and blocks dihydropteroate synthase, so the bacillus cannot make folate. Clofazimine is a fat-soluble dye with several actions (membrane damage, interference with the respiratory chain) and also calms the inflammation of leprosy reactions. Rifampicin blocks bacterial RNA polymerase.

Target: Folate synthesis (dapsone) and mycobacterial membrane and respiratory chain (clofazimine)

## Key points

- MDT = rifampicin + dapsone + clofazimine; 6 months for paucibacillary and 12 months for multibacillary leprosy.
- Dapsone: check G6PD before starting; it causes haemolysis and methaemoglobinaemia.
- Clofazimine turns the skin red-brown and can prolong the QT interval.
- Leprosy reactions (type 1 and erythema nodosum leprosum) are immune flares, not allergy to the drugs, and do not mean MDT is stopped.

## Drugs in this class

- [**Dapsone** A sulfone used in leprosy multidrug therapy and dermatitis herpetiformis. It can cause haemolysis, especially in G6PD… Dihydropteroate synthase (folate pathway of mycobacteria)](https://durgical.com/en/pharmacology/dapsone/)
- [**Clofazimine** A red fat-soluble dye used in leprosy multidrug therapy and in drug-resistant tuberculosis. It turns the skin… Mycobacterial membrane and respiratory chain (several actions)](https://durgical.com/en/pharmacology/clofazimine/)

## Others in the class

- Rifampicin (an antituberculosis drug, also part of MDT and of post-exposure prophylaxis)

## Test yourself

Think of the answer, then tap the question to see it.

## Which three drugs make up WHO multidrug therapy for leprosy?

Rifampicin, dapsone and clofazimine.

## Which test is done before starting dapsone, and why?

G6PD activity, because dapsone causes severe haemolysis in G6PD deficiency.

## Which antileprosy drug discolours the skin?

Clofazimine (red-brown discoloration).

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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [Leprosy](https://www.who.int/news-room/fact-sheets/detail/leprosy) (World Health Organization (WHO), 2025); [Lepra o enfermedad de Hansen](https://www.minsalud.gov.co/salud/publica/PET/Paginas/Lepra.aspx) (Ministerio de Salud y Protección Social de Colombia, 2024); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 65 (McGraw Hill, 2023).

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Representative model, for educational purposes only.

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