Identification of metabolites of azaperone in horse urine

Richard A. Sams, Diane F. Gerken, Randall L. Detra, Scott D. Stanley, William E. Wood, Thomas Tobin, Jyan Ming Yang, Hsin Hsinng Tai, Alwarsamy Jegananthan, David S. Watt

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7 Scopus citations


Two metabolites of the tranquilizer azaperone were extracted from alkalinized horse urine after treatment with β-glucuronidase/sulfatase from limpets (Patella vulgata). The metabolites were identified by a combination of independent chemical synthesis and GC/MS and 1H NMR analysis. The metabolites were identified as 1-(fluorophenyl)-4-[4-(5-hydroxy-2-pyridinyl)- 1-piperazinyl]-1-butanol, designated as 5'-hydroxyazaperol, and 1- (fluorophenyl)-4-[4-(5-hydroxy-2-pyridinyl)-1-piperazinyl]-1-butanone, designated as 5'-hydroxyazaperone. A TLC screening test was developed for detecting both metabolites in basic extracts of horse urine treated with β- glucuronidase/sulfatase. The screening test was used to detect azaperone metabolites in extracts of horse urine collected for 24 h alter intravenous administration of azaperone. The administration of azaperone to horses was confirmed by GC/MS identification of 5'-hydroxyazaperone and 5'- hydroxyazaperol from basic extracts of horse urine treated with β- glucuronidase/sulfatase. The extracted metabolites were treated with bis(trimethylsilyl)acetamide to produce trimethylsilyl (TMS) ether derivatives, and mass spectra and retention times were compared to those of the synthesized metabolites treated in the same manner.

Original languageEnglish
Pages (from-to)79-84
Number of pages6
JournalJournal of Pharmaceutical Sciences
Issue number1
StatePublished - Jan 1996

Bibliographical note

Funding Information:
We thank the American Horse Shows Association and the University of Kentucky for their generous financial support. Research performed at the University of Kentucky was supported by a grant entitled “Immunoassay Tests for High Potency Narcotic Analgesics in Racing Horses” from the Kentucky Equine Drug Research Council and the Kentucky State Racing and Harness Racing Commissions. One of us (R. A. S.) thanks Dr. C. E. Cottrell of The Ohio State University Physical Chemistry Instrument Center for NMR studies using a Bruker AM-500 FT-NMR funded in part by NIH Grant #1 S10 RR01458-01A1 and also David Chang for high-resolution mass spectral determinations.

ASJC Scopus subject areas

  • Pharmaceutical Science


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