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Home / Equine Research Bank / Ir Vet J / Pemoline and tetramisole ‘positives’ in english ...
Irish veterinary journal2010; 63(8); 498; doi: 10.1186/2046-0481-63-8-498

Pemoline and tetramisole ‘positives’ in english racehorses following levamisole administration.

Abstract: 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.
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Publication Date: 2010-08-01 PubMed ID: 21777496PubMed Central: PMC4177197DOI: 10.1186/2046-0481-63-8-498Google Scholar: Lookup
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  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research article investigates the appearance of pemoline, an illicit substance in racehorses, confirming that it’s a probable metabolite from the administration of levamisole. The researchers advise against the use of levamisole in competing horses due to its metabolization to two stimulants, aminorex and pemoline.

Objective and Background

  • The researchers sought to understand why pemoline – a substance primarily used to treat attention-deficit hyperactivity disorder and narcolepsy in humans – was detected in English racehorses.
  • Pemoline serves as an evidence of illicit practices aimed at enhancing horse performance in races and thus, its presence is prohibited.
  • The study was sparked by two recent occurrences of pemoline detection in English racehorses.

Chemical Relationships

  • The team traced the source of pemoline by exploring the chemical relationships between tetramisole, levamisole, aminorex, and pemoline.
  • The researchers discovered that pemoline is a simple oxidation product of aminorex.
  • Previous research indicated that aminorex is an equine metabolite of levamisole in the United States and other regions.

Conclusions and Recommendations

  • The researchers affirmed that levamisole can metabolize to pemoline in horses, making it very likely that the detected pemoline in horses post levamisole administration originated from the levamisole.
  • Due to clear structural relationships between aminorex and pemoline, this conclusion seemed plausible.
  • The study consequently cautions against administering levamisole to competing horses. This is due to its ability to metabolize to two central nervous system stimulants – aminorex and pemoline – which would violate competing standards and affect the integrity of the competition.

Cite This Article

APA
Gutierrez J, Eisenberg RL, Koval NJ, Armstrong ER, Tharappel J, Hughes CG, Tobin T. (2010). Pemoline and tetramisole ‘positives’ in english racehorses following levamisole administration. Ir Vet J, 63(8), 498. https://doi.org/10.1186/2046-0481-63-8-498

Publication

Irish veterinary journal
ISSN: 0368-0762
NlmUniqueID: 0100762
Country: Ireland
Language: English
Volume: 63
Issue: 8
Pages: 498

Researcher Affiliations

Gutierrez, J
  • Department of Veterinary Science, The Maxwell H. Gluck Equine Research Center, University of Kentucky Lexington, KY 40546 USA
Eisenberg, RL
  • Frontier Biopharm, P. O. Box 614, Richmond, KY 40476 USA
Koval, NJ
  • Department of Veterinary Science, The Maxwell H. Gluck Equine Research Center, University of Kentucky Lexington, KY 40546 USA
Armstrong, ER
  • Department of Veterinary Science, The Maxwell H. Gluck Equine Research Center, University of Kentucky Lexington, KY 40546 USA
Tharappel, J
  • Department of Veterinary Science, The Maxwell H. Gluck Equine Research Center, University of Kentucky Lexington, KY 40546 USA
Hughes, CG
  • Department of Veterinary Science, The Maxwell H. Gluck Equine Research Center, University of Kentucky Lexington, KY 40546 USA
Tobin, T
  • Department of Veterinary Science, The Maxwell H. Gluck Equine Research Center, University of Kentucky Lexington, KY 40546 USA

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Citations

This article has been cited 5 times.
  1. Brewer K, Machin J, Maylin G, Fenger C, Morales-Briceño A, Tobin T. Gabapentin, a human therapeutic medication and an environmental substance transferring at trace levels to horses: a case report. Ir Vet J 2022 Oct 4;75(1):19.
    doi: 10.1186/s13620-022-00226-5pubmed: 36192810google scholar: lookup
  2. Kudrimoti S, Machin J, Arojojoye AS, Awuah SG, Eisenberg R, Fenger C, Maylin G, Lehner AF, Tobin T. Synthesis and characterization of d(5) -barbarin for use in barbarin-related research. Drug Test Anal 2023 Jan;15(1):42-46.
    doi: 10.1002/dta.3357pubmed: 35975356google scholar: lookup
  3. Bedenice D, Johnson AL. Neurologic conditions in the sport horse. Anim Front 2022 Jun;12(3):37-44.
    doi: 10.1093/af/vfac036pubmed: 35711509google scholar: lookup
  4. Waller P, Lomnicka I, Lucas C, Johnson S, Dirikolu L. The medication violations in racehorses at Louisiana racetracks from 2016 to 2020. Vet Med Sci 2022 Mar;8(2):553-560.
    doi: 10.1002/vms3.724pubmed: 34989156google scholar: lookup
  5. Maylin G, Fenger C, Machin J, Kudrimoti S, Eisenberg R, Green J, Tobin T. Aminorex identified in horse urine following consumption of Barbarea vulgaris; a preliminary report. Ir Vet J 2019;72:15.
    doi: 10.1186/s13620-019-0153-5pubmed: 31890155google scholar: lookup
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