Fenclozic acid

Fenclozic acid
Clinical data
Trade namesMyalex
Identifiers
  • [2-(4-Chlorophenyl)-1,3-thiazol-4-yl]acetic acid
CAS Number
PubChem CID
ChemSpider
UNII
CompTox Dashboard (EPA)
Chemical and physical data
FormulaC11H8ClNO2S
Molar mass253.70 g·mol−1
3D model (JSmol)
  • c1cc(ccc1c2nc(cs2)CC(=O)O)Cl
  • InChI=1S/C11H8ClNO2S/c12-8-3-1-7(2-4-8)11-13-9(6-16-11)5-10(14)15/h1-4,6H,5H2,(H,14,15) N
  • Key:APBSKHYXXKHJFK-UHFFFAOYSA-N N
 NY (what is this?)  (verify)

Fenclozic acid (proposed brand name Myalex) is a nonsteroidal anti-inflammatory drug (NSAID) with analgesic, antipyretic, and anti-inflammatory properties developed in 1960s by ICI Pharmaceuticals.[1][2] It failed to pass Phase III clinical trial and was withdrawn from clinical development in 1971 due to severe dose-related hepatotoxicity and jaundice in human, despite showing excellent preclinical safety profile and promising clinical efficacy in animal testings.[3][4] It is considered a classic example of human-specific drug induced liver injury linked to unique metabolic activation in humans.[4][5]

References

  1. ^ Newbould, B. B. (1969). "The pharmacology of fenclozic acid (2-(4-chlorophenyl)-thiazol-4-ylacetic acid; I.C.I. 54,450; 'Myalex'); a new compound with anti-inflammatory, analgesic and antipyretic activityl". British Journal of Pharmacology. 35 (3): 487–497. doi:10.1111/j.1476-5381.1969.tb08290.x. ISSN 0007-1188. PMC 1703354. PMID 5809740. Retrieved 2026-03-18.
  2. ^ US 3538107, Hepworth W, Stacey GJ, "Aryl-thiazolyl-acetic acid derivatives", issued 1970, assigned to Imperial Chemical Industries Ltd 
  3. ^ Hart, F.D; Bain, L.S; Huskisson, E.C; Littler, T.R; Taylor, R.T (1970). "Hepatic effects of fenzlozic acid". Annals of the Rheumatic Diseases. 29 (6): 684. doi:10.1136/ard.29.6.684. PMC 1010604. PMID 5496073. Retrieved 2026-03-18.
  4. ^ a b Rodrigues, Alison V. M.; Rollison, Helen E.; Martin, Scott; Sarda, Sunil; Schulz-Utermoehl, Timothy; Stahl, Simone; Gustafsson, Frida; Eakins, Julie; Kenna, J. Gerry; Wilson, Ian D. (2013). "In vitro exploration of potential mechanisms of toxicity of the human hepatotoxic drug fenclozic acid". Archives of Toxicology. 87 (8): 1569–1579. doi:10.1007/s00204-013-1056-y. ISSN 0340-5761. Retrieved 2026-03-18.
  5. ^ Pickup, Kathryn; Martin, Scott; Partridge, Elizabeth A.; Jones, Huw B.; Wills, Jonathan; Schulz-Utermoehl, Tim; McCarthy, Alan; Rodrigues, Alison; Page, Chris; Ratcliffe, Kerry; Sarda, Sunil; Wilson, Ian D. (2017). "Acute liver effects, disposition and metabolic fate of [14C]-fenclozic acid following oral administration to normal and bile-cannulated male C57BL/6J mice". Archives of Toxicology. 91 (7): 2643–2653. doi:10.1007/s00204-016-1894-5. ISSN 0340-5761. PMC 5489613. PMID 27896398. Retrieved 2026-03-18.