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Ethionamide

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Ethionamide
150px
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Systematic (IUPAC) name
2-ethylpyridine-4-carbothioamide
Clinical data
Trade names Trecator (Pfizer)
AHFS/Drugs.com monograph
MedlinePlus a682402
  • C (US)
  • Rx only (US) [1]
oral administration
Pharmacokinetic data
Protein binding Approximately 30% bound to proteins.
Half-life 2 to 3 hours
Identifiers
536-33-4 7pxY
J04AD03
PubChem CID 2761171
DrugBank DB00609 7pxY
ChemSpider 2041901 7pxY
UNII OAY8ORS3CQ 7pxY
KEGG D00591 7pxY
ChEBI CHEBI:4885 7pxY
ChEMBL CHEMBL1441 7pxY
Chemical data
Formula C8H10N2S
166.244 g/mol
 14pxY (what is this?)  (verify)

Ethionamide (INN; chemical name 2-ethylpyridine-4-carbothioamide) is an antibiotic used in the treatment of tuberculosis. It was discovered in 1956.[2] It is sold under the brand name Trecator or Trecator SC [3] 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.[2] 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.[4]

It is on the World Health Organization's List of Essential Medicines, the most important medications need in a basic health system.[5]

Physicochemical properties

Pharmacopoeial properties

Ethionamide was described in an official monograph in several pharmacopoeia, e.g.The International Pharmacopoeia, USP and Ph.Eur.

Solubility

Very sparingly soluble in water, ether ; sparingly soluble in methanol, ethanol, propylene glycol ; soluble in hot acetone, dichloroethane ; freely soluble in pyridine.[6]

Basic biology information

In vitro potency against Mycobacterium tuberculosis

Minimum inhibitory concentration (MIC) against M.tuberculosis (H37Rv): 0.25 microgram/ml.[7]

Spectrum of activity

Antimicrobial spectrum of ethionamide comprises M. tuberculosis, M. bovis and M. segmatis.[7]

Mechanism of action

Ethionamide is a prodrug[8] 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.[2][9]

Efficacy

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.[10]

ADME data

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.[11]

ETA can be administered with food if tolerance is an issue.[12]

Adverse effects

Ethionamide is structurally similar to methimazole, has been shown to inhibit thyroid hormone synthesis, and was reported to cause hypothyroidism in several TB patients.[13]

Drug-drug interaction

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.[14]

Synonyms

  • 1314[15]
  • 2-ethylisothionicotinamide
  • Trecator
  • amidazine
  • thioamide

References

  1. ^ Trecator (ethionamide) tablet, film coated (Wyeth Pharmaceuticals Company, a subsidiary of Pfizer Inc.) on DailyMed
  2. ^ a b c "Ethionamide". TB Online. Global Tuberculosis Community Advisory Board. Retrieved 2012-08-18. 
  3. ^ "Trecator and Trecator SC tablet by Wyeth" |http://www.fda.gov/downloads/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/UCM164879.pdf
  4. ^ Cynamon, M. H.; Sklaney, M. (2003). "Gatifloxacin and Ethionamide as the Foundation for Therapy of Tuberculosis". Antimicrobial Agents and Chemotherapy 47 (8): 2442–4. PMC 166105. PMID 12878502. doi:10.1128/AAC.47.8.2442-2444.2003. 
  5. ^ "WHO Model List of Essential Medicines" (PDF). World Health Organization. October 2013. Retrieved 2 February 2015. 
  6. ^ Merck Index[full citation needed]
  7. ^ a b Rastogi, Nalin; Labrousse, Valérie; Goh, Khye Seng (1996). "In Vitro Activities of Fourteen Antimicrobial Agents Against Drug Susceptible and Resistant Clinical Isolates of Mycobacterium tuberculosis and Comparative Intracellular Activities Against the Virulent H37Rv Strain in Human Macrophages". Current Microbiology 33 (3): 167–75. PMID 8672093. doi:10.1007/s002849900095. 
  8. ^ Vannelli, T. A.; Dykman, A.; Ortiz De Montellano, P. R. (2002). "The Antituberculosis Drug Ethionamide is Activated by a Flavoprotein Monooxygenase". Journal of Biological Chemistry 277 (15): 12824–9. PMID 11823459. doi:10.1074/jbc.M110751200. 
  9. ^ Quemard, A; Laneelle, G; Lacave, C (1992). "Mycolic acid synthesis: A target for ethionamide in mycobacteria?". Antimicrobial Agents and Chemotherapy 36 (6): 1316–21. PMC 190338. PMID 1416831. doi:10.1128/aac.36.6.1316. 
  10. ^ http://apps.who.int/prequal/whopar/whoparproducts/TB133part4v1.pdf[full citation needed]
  11. ^ Zhu, M.; Namdar, R.; Stambaugh, J.J.; Starke, J.R.; Bulpitt, A.E.; Berning, S.E.; Peloquin, C.A. (2002). "Population pharmacokinetics of ethionamide in patients with tuberculosis". Tuberculosis 82 (2–3): 91–6. PMID 12356460. doi:10.1054/tube.2002.0330. 
  12. ^ Auclair, B.; Nix, D. E.; Adam, R. D.; James, G. T.; Peloquin, C. A. (2001). "Pharmacokinetics of Ethionamide Administered under Fasting Conditions or with Orange Juice, Food, or Antacids". Antimicrobial Agents and Chemotherapy 45 (3): 810–4. PMC 90379. PMID 11181366. doi:10.1128/AAC.45.3.810-814.2001. 
  13. ^ McDonnell, Marie E.; Braverman, Lewis E.; Bernardo, John (2005). "Hypothyroidism Due to Ethionamide". New England Journal of Medicine 352 (26): 2757–9. PMID 15987931. doi:10.1056/NEJM200506303522621. 
  14. ^ http://labeling.pfizer.com/showlabeling.aspx?id=473[full citation needed]
  15. ^ Somner, A.R. (1959). "2-Ethylisothionicotinamide (‘1314’) in pulmonary tuberculosis: A controlled trial of drug tolerance". Tubercle 40 (6): 457–461. PMID 13832783. 

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