What does ethionamide mean?
Ethionamide is a synthetic antibiotic belonging to the thioamide class, used primarily as a second-line treatment for tuberculosis. Chemically designated 2-ethylpyridine-4-carbothioamide, it works by blocking the synthesis of mycolic acids, essential components of the mycobacterial cell wall. Because it is less effective and more toxic than first-line drugs like isoniazid or rifampicin, ethionamide is generally reserved for cases involving multidrug-resistant strains, where it is combined with several other antibiotics in prolonged regimens lasting months to years. Its use is associated with notable side effects, including gastrointestinal distress, liver dysfunction, and hypothyroidism, which often complicate long-term therapy. The word appears almost exclusively in clinical, pharmacological, and public-health literature, making it unfamiliar outside specialist circles. Its name reflects both its chemistry and its lineage: an ethyl-substituted thioamide derived from the same chemical family as nicotinamide, the compound from which isoniazid was also developed.
nounA synthetic antibiotic of the thioamide class used to treat tuberculosis and related mycobacterial infections, typically reserved for cases resistant to first-line drugs such as isoniazid.
- A synthetic thioamide antibiotic (2-ethylpyridine-4-carbothioamide) used as a second-line treatment for drug-resistant tuberculosis and other mycobacterial infections.
"Because her strain proved multidrug-resistant, the physician added ethionamide to the treatment regimen."
"The patient tolerated ethionamide therapy despite significant gastrointestinal side effects."
"Resistance testing revealed mutations conferring cross-resistance between isoniazid and ethionamide."
When tuberculosis shrugs off its strongest medicines, doctors reach for a 1950s-era backup called ethionamide — a drug so harsh it's nicknamed 'the last resort' in TB wards.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of ethionamide
The word ethionamide is a modern pharmaceutical coinage built from transparent chemical parts: 'eth-' from ethyl, referring to the molecule's ethyl substituent, '-ion-' reflecting the thio (sulfur) character of the compound's carbothioamide group, and '-amide,' denoting the amide functional class common to many antibiotics. It was developed in the mid-twentieth century alongside other nicotinic acid derivatives such as isoniazid, sharing that family's chemical ancestry even though it substitutes sulfur into the amide linkage. The suffix '-amide' itself traces back to Latin ammonia-derived chemical nomenclature of the nineteenth century.
How ethionamide is actually used
Ethionamide is almost exclusively encountered in medical and pharmacological contexts. It carries no informal or figurative usage, and its connotations are clinical rather than everyday.
Easily confused with ethionamide
Ethambutol is a different anti-tuberculosis antibiotic that works by inhibiting cell-wall synthesis, whereas ethionamide is a thioamide that disrupts mycolic acid production.
Isoniazid is a first-line hydrazine-based tuberculosis drug structurally related to nicotinamide, while ethionamide is a second-line thioamide used when isoniazid resistance occurs.