Detecting Equine Antipsychotic Drug Abuse

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Researchers from The Hong Kong Jockey Club, Sha Tin Racecourse, Hong Kong, China, have developed a comprehensive screening method for the detection of antipsychotics in horses, using liquid chromatography tandem mass spectrometry (LC–MS/MS) (1).

Antipsychotics are typically used to treat psychotic symptoms in disorders such as schizophrenia or bipolar. However, antipsychotics are also classified as neuroleptics or major tranquilizers, which reduce agitation and result in a calming effect. This gives them a high potential for abuse in equine sports where calming the animal athletes can result in improved performance. For example, prothipendyl, an azaphenothiazine neuroleptic, was suspected to have been administered illegally at low doses to race-horses to improve their performance (2), and in a high profile case from 2004 the antipsychotic drugs fluphenazine and zuclopenthixol were found in the urine and blood samples collected from Waterford Crystal, the horse ridden by Olympic showjumping gold medalist Cian O’Connor in 2004 (3). Therefore, antipsychotics have a long history of abuse in equine sports and effective screening is critical to maintain parity in competitive sports.

Antipsychotic drug usage in humans has risen in recent decades with numerous detection methodologies filling the analytical need to monitor these drugs, however, there are limited publications on the detection of these drugs in equine biological samples, with most being single target methods. Researchers consequently aimed to develop a new method that could simultaneously detect 58 antipsychotics, 19 antidepressants, along with two antihypertensives, an anaesthetic, and a decongestant in equine plasma at sub-parts-per-billion (ppb) to low-ppb levels after solid-phase extraction (SPE).

The resulting method showed sufficient sensitivity and robustness for regular qualitative screening. The method is capable of simultaneously detecting 81 antipsychotics, antidepressants, and other prohibited substances in horse plasma. The applicability of the method was demonstrated by analysing two equine plasma samples reported to contain the drugs reserpine and lidocaine. In combination with the authors’ previous publication using SPE and high resolution accurate mass screening (HRAMS) to detect over 320 other drug targets in equine plasma (4), these two methods are capable of screening over 400 drug targets from one SPE procedure.

References

1. A.S.Y. Wong et al., J. Chroma. B.1147, 122132 (2020).
2. H. Hagedorn, S. Zuck, and R. Schultz, Dtsch Tierarztl Wochenschr.103(4), 125–127 (1996).
3. Waterford Crystal B sample tests positive. The Irish Times. 9 Nov 2004, www.irishtimes.com/news/waterford-crystal-b-sample-tests-positive-1.994582.
4. E.N. Ho et al., Drug Test. Anal.5(7), 509–528 (2013).