Pemoline and tetramisole 'positives' in english racehorses following levamisole administration

J. Gutierrez, R. L. Eisenberg, N. J. Koval, E. R. Armstrong, J. Tharappel, C. G. Hughes, T. Tobin

Research output: Contribution to journalReview articlepeer-review

18 Scopus citations


Pemoline is a central nervous system stimulant that has been used to treat attention-deficit hyperactivity disorder and narcolepsy in humans; its identification in horses could be considered evidence of attempts to influence performance. Two recent pemoline 'positives' in English racehorses led us to review the chemical relationships between tetramisole, levamisole, aminorex and pemoline. Pemoline is a simple oxidation product of aminorex, which has been shown in the United States and elsewhere to be an equine metabolite of levamisole. Based on the clear structural relationships between aminorex and pemoline, we conclude that levamisole can metabolise to pemoline in horses and that pemoline identifications in horses post levamisole administration are likely to be associated with levamisole administration. Levamisole should not be administered to horses about to compete because of its ability to metabolise to two central nervous system stimulants, aminorex and pemoline.

Original languageEnglish
Pages (from-to)498-500
Number of pages3
JournalIrish Veterinary Journal
Issue number8
StatePublished - Aug 2010

Bibliographical note

Funding Information:
Published as paper #382 from the Equine Pharmacology Therapeutics and Toxicology Program at the Maxwell H. Gluck Equine Research Center and Department of Veterinary Science, University of Kentucky. Published as Kentucky Agricultural Experiment Station Article # 10-14-023 with the approval of the Dean and Director, College of Agriculture and the Kentucky Agricultural Experimental Station. This work was made possible by research support from The National Horsemen’s Benevolent and Protective Association and the Alabama; Arizona; Arkansas; Canada; Charles Town, WV; Florida; Iowa; Kentucky; Louisiana; Michigan; Minnesota, Nebraska, Ohio, Oklahoma, Ontario Canada, Oregon, Pennsylvania, Tampa Bay Downs, Florida; Texas; Washington State; and West Virginia Horsemen’s Benevolent and Protective Associations.


  • Aminorex
  • Drug 'positives'
  • Horses
  • Levamisole
  • Metabolism
  • Pemoline
  • Tetramisole

ASJC Scopus subject areas

  • General Veterinary


Dive into the research topics of 'Pemoline and tetramisole 'positives' in english racehorses following levamisole administration'. Together they form a unique fingerprint.

Cite this