Title: Zomepirac
CAS Registry Number: 33369-31-2
CAS Name: 5-(4-Chlorobenzoyl)-1,4-dimethyl-1H-pyrrole-2-acetic acid
Additional Names: 1,4-dimethyl-5-(p-chlorobenzoyl)pyrrole-2-acetic acid
Molecular Formula: C15H14ClNO3
Molecular Weight: 291.73
Percent Composition: C 61.76%, H 4.84%, Cl 12.15%, N 4.80%, O 16.45%
Literature References: Prepn: J. R. Carson, DE 2102746; idem, US 3752826 (1971, 1973 both to McNeil); J. R. Carson, S. Wong, J. Med. Chem. 16, 172 (1973). Pharmacology: R. Sofia et al., Pharmacol. Res. Commun. 11, 179 (1979); P. O'Neill et al., J. Pharmacol. Exp. Ther. 209, 366 (1979). Determn in plasma by HPLC: K.-T. Ng, T. Snyderman, J. Chromatogr. 178, 241 (1979). Metabolism: J. M. Grindel et al., Drug Metab. Dispos. 8, 343 (1980); W. N. Wu et al., ibid. 349. Pharmacokinetics: R. K. Nayak et al., Clin. Pharmacol. Ther. 27, 395 (1980). Series of articles on pharmacology, kinetics, clinical studies: J. Clin. Pharmacol. 20, 213-424 (1980). Preclinical narcotic abuse liability evaluation: J. H. Woods et al., Arzneim.-Forsch. 33, 218 (1983). Multicenter clinical study in painful conditions: C. E. Steele, W. L. Jefferson, Curr. Med. Res. Opin. 8, 382 (1983). Review of pharmacology and therapeutic efficacy: P. A. Morley et al., Drugs 23, 250-275 (1982). Comprehensive description: M. Zinic et al., Anal. Profiles Drug Subs. 15, 673-698 (l986).
Properties: White cryst from 2-propanol, mp 178-179°.
Melting point: mp 178-179°
Derivative Type: Sodium salt dihydrate
CAS Registry Number: 64092-49-5
Trademarks: Zomax (McNeil); Zomaxin (Cilag); Zopirac (Sintyal)
Molecular Formula: C15H13ClNNaO3.2H2O
Molecular Weight: 349.74
Percent Composition: C 51.51%, H 4.90%, Cl 10.14%, N 4.00%, Na 6.57%, O 22.87%
Properties: Crystals from isopropanol + water, mp 295-296°.
Melting point: mp 295-296°
Therap-Cat: Analgesic; anti-inflammatory.
Keywords: Analgesic (Non-Narcotic); Anti-inflammatory (Nonsteroidal); Arylacetic Acid Derivatives.
Zonisamide Zopiclone Zopolrestat Zosuquidar Zotepine

Systematic (IUPAC) name
2-[5-(4-chlorobenzoyl)-1,4-dimethyl-pyrrol-2-yl]acetic acid
Clinical data
Legal status withdrawn
Routes oral
CAS number 33369-31-2 N
ATC code M01AB04
PubChem CID 5733
DrugBank DB04828
ChemSpider 5531 YesY
UNII 822G987U9J YesY
ChEBI CHEBI:35859 YesY
Chemical data
Formula C15H14ClNO3 
Mol. mass 291.729 g/mol
 N (what is this?)  (verify)

Zomepirac is an orally effective NSAID that has antipyretic actions. It was developed by McNeil Pharmaceutical and approved by the FDA in 1980 and sold as the sodium salt, zomepirac sodium, under the brand name Zomax. Due to its clinical effectiveness, it was preferred by doctors in many situations and obtained a large share of the analgesics market; however, it was subsequently withdrawn in March 1983 due to its tendency to cause serious anaphylaxis in an unpredictable subset of the patient population.[1][2]