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Re-evaluation of the pharmacokinetics of xylazine administered to Thoroughbred horses.
Abstract: Xylazine is widely used worldwide as a short-acting sedative in general equine and racing practice. In the UK, although it has a legitimate use during training, equine anti-doping rules state it is a prohibited substance on race day. The aim of the study was to produce a detection time (DT) to better inform European veterinary surgeons so that xylazine can be used appropriately under regulatory rules. Previous publications have various limitations pertaining to analysis method, particularly for plasma and limited length of time of sample collection. In this study, pharmacokinetic data were produced for xylazine and 4-OH-xylazine in equine urine and plasma following a single intravenous xylazine dose of 0.4 mg/kg to six Thoroughbred horses. Pharmacokinetic parameters were generated from a 3-compartmental model with clearance = 15.8 ± 4.88 ml min kg , Vss = 1.44 ± 0.38 L/kg, terminal half-life = 29.8 ± 12.7 hr and a DT determined at 71 hr for the administration of xylazine (Chanazine ) in plasma and urine. Urine screening should aim to detect the 4-OH-xylazine metabolite, which can act as an indicator for the xylazine plasma concentration. A DT of 72 hr has been agreed by the European Horserace Scientific Liaison Committee, to be implemented in June 2019.
© 2019 John Wiley & Sons Ltd.
Publication Date: 2019-10-25 PubMed ID: 31652007DOI: 10.1111/jvp.12820Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Clinical Trial
- Veterinary
- 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 study investigates the pharmacokinetics of xylazine in Thoroughbred horses with an intent to provide a more accurate detection time (DT). This would help the horse-racing practice in Europe to avoid doping violations. The study coined a DT based on the administration of intravenous xylazine dose to six Thoroughbred horses and proposed urine screening as an effective way to detect the drug.
Objective of the Study
- The primary goal of the study was to produce a detection time (DT) for xylazine in Thoroughbred horses to help European veterinary surgeons use the drug more appropriately and in compliance with anti-doping rules. Xylazine is a widely used sedative in equine and racing practice, but is not allowed on race day.
Methodology
- A single intravenous dose of 0.4 mg/kg of xylazine was administered to six Thoroughbred horses as a part of the study.
- Pharmacokinetic data for xylazine and 4-OH-xylazine (a metabolite of xylazine) in equine urine and plasma were subsequently collected and assessed.
Findings
- Based on the collected data, pharmacokinetic parameters were produced from a 3-compartmental model. The data revealed a clearance of 15.8 ± 4.88 ml min kg, volume of distribution (Vss) of 1.44 ± 0.38 L/kg, and a terminal half-life of 29.8 ± 12.7 hours.
- The detection time (DT) for xylazine was determined at 71 hours in both plasma and urine.
Recommendations
- The study recommends urine screening for detecting the presence of 4-OH-xylazine, a reliable indicator of the xylazine plasma concentration.
- Based on the study’s findings, a detection time (DT) of 72 hours has been agreed upon by the European Horserace Scientific Liaison Committee and is due to be implemented as of June 2019.
Cite This Article
APA
Habershon-Butcher J, Cutler C, Viljanto M, Hincks PR, Biddle S, Paine SW.
(2019).
Re-evaluation of the pharmacokinetics of xylazine administered to Thoroughbred horses.
J Vet Pharmacol Ther, 43(1), 6-12.
https://doi.org/10.1111/jvp.12820 Publication
Researcher Affiliations
- British Horseracing Authority, London, UK.
- LGC, Fordham, UK.
- LGC, Fordham, UK.
- LGC, Fordham, UK.
- LGC, Fordham, UK.
- School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington, UK.
MeSH Terms
- Analgesics / administration & dosage
- Analgesics / pharmacokinetics
- Animals
- Area Under Curve
- Female
- Half-Life
- Horses / blood
- Male
- Xylazine / administration & dosage
- Xylazine / blood
- Xylazine / pharmacokinetics
Grant Funding
- The British Horseracing Authority
References
This article includes 14 references
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Citations
This article has been cited 2 times.- Cherdchutham W, Sukhong P, Sae-Oueng K, Supanwinijkul N, Wiangnak K, Srimuang J, Apichaimongkonkun T, Limratchapong S, Petchdee S. Effects of xylazine and adrenaline combinations: Preliminary clinical application for non-surgical protocols of nephrosplenic entrapment in horses. Vet World 2021 Dec;14(12):3188-3193.
- Jarosinski SK, Simon BT, Hatfield R, Matthews NS, Arnold CE. The effects of xylazine or detomidine when used as a pre-anesthetic sedative on recovery quality and duration in horses undergoing elective equine castration. Can Vet J 2021 Sep;62(9):982-986.
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