|Systematic (IUPAC) name|
|Trade names||Trecator (Pfizer)|
|Protein binding||Approximately 30% bound to proteins.|
|Biological half-life||2 to 3 hours|
|ATC code||J04AD03 (WHO)|
|Molar mass||166.244 g/mol|
Ethionamide (INN; chemical name 2-ethylpyridine-4-carbothioamide) is an antibiotic used in the treatment of tuberculosis. It was discovered in 1956. It is sold under the brand name Trecator or Trecator SC  by Wyeth Pharmaceuticals which was purchased by Pfizer in 2009.
Ethionamide is part of a group of drugs used in the treatment of drug resistant TB called thioamides. It is used as part of treatment regimens, generally involving 5 medicines, to treat MDR and XDR TB. Ethionamide is used as part of a South Africa’s standard regimen to treat MDR TB. It has been proposed for use in combination with gatifloxacin.
It is on the World Health Organization's List of Essential Medicines, the most important medications need in a basic health system.
Ethionamide is indicated in combination with other antituberculosis agents for the treatment of all forms of tuberculosis caused by Mycobacterium tuberculosis. However, ethionamide is only indicated as a second-line antimycobacterial drug when resistance to or toxicity from first-line drugs has developed.
Ethionamide (ETA) pharmacokinetic parameters differed between TB patients and healthy volunteers, possibly due to differences in the completeness of absorption. Doses of at least 500 mg appear to be required to achieve serum concentrations above the typical ETA MIC.
ETA can be administered with food if tolerance is an issue.
Spectrum of activity
Trecator has been found to temporarily raise serum concentrations of isoniazid. Trecator may potentiate the adverse effects of other antituberculous drugs administered concomitantly. In particular, convulsions have been reported when ethionamide is administered with cycloserine and special care should be taken when the treatment regimen includes both of these drugs. Excessive ethanol ingestion should be avoided because a psychotic reaction has been reported.
Mechanism of action
Ethionamide is a prodrug It is activated by the enzyme EthA, a mono-oxygenase in Mycobacterium tuberculosis, and binds NAD+ to form an adduct which inhibits InhA in the same way as isoniazid. Expression of the ethA gene is controlled by EthR, a transcriptional repressor. It is understood that improving ethA expression will increase the efficacy of ethionamide and so EthR inhibitors are of great interest to co-drug developers. The action may be through disruption of mycolic acid.
Very sparingly soluble in water, ether ; sparingly soluble in methanol, ethanol, propylene glycol ; soluble in hot acetone, dichloroethane ; freely soluble in pyridine.
- Trecator (ethionamide) tablet, film coated (Wyeth Pharmaceuticals Company, a subsidiary of Pfizer Inc.) on DailyMed
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- Merck Index[full citation needed]
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