WHO Model Prescribing Information: Drugs Used in Mycobacterial Diseases
(1991; 44 pages) [French] [Spanish] View the PDF document
Table of Contents
View the documentPreface
Open this folder and view contentsTuberculosis
Close this folderLeprosy
View the documentClofazimine
View the documentDapsone
View the documentRifampicin
View the documentEthionamide and protionamide
Open this folder and view contentsNontuberculous mycobacterial diseases

Ethionamide and protionamide

Group: antileprosy agent
Tablet 125 mg, 250 mg

General information

The thioamides ethionamide and protionamide are derivatives of thioisonicotinic acid. Both are weakly bactericidal to M. leprae. Their biological properties and therapeutic potency are very similar.

They are readily absorbed from the gastrointestinal tract and widely distributed throughout body tissues. The plasma half-life of both compounds is approximately 2-4 hours and they are excreted in the urine largely as metabolites.

Clinical information


Treatment of multibacillary leprosy (in combination with dapsone and rifampicin), to prevent emergence of drug resistance. Because of their hepatotoxicity thioamides should be used only when clofazimine is unacceptable or not available.

Dosage and administration

Adults and children: 5.0 mg/kg daily (usual adult dose 250-375 mg).


• Known hypersensitivity.
• Hepatic dysfunction.
• Pregnancy.


Liver function tests must be performed at the start of treatment and repeated periodically throughout.

Adverse effects

Liver dysfunction and toxic hepatitis may occur.

Gastrointestinal disturbances are common. Other reported adverse effects include acne, allergic reactions, alopecia, convulsions, dermatitis, diplopia, dizziness, headache, hypotension, peripheral neuropathy and rheumatic pains.


Ethionamide and protionamide tablets should be kept in tightly closed containers protected from light.


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