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Methadone screening of racehorses
H W Hagedorn1, H Meiser, H Zankl
1Institute of Pharmacology, Toxicology, and Pharmacy, University of Munich, Germany.
Abstract:
The misuse of opiates in racehorses relates to their effect of increasing locomotor activity. Because methadone, a narcotic analgesic, has been suspected of use as a doping compound in the past, it was added to the list of banned drugs and should be considered in doping control. Because the literature fails to provide information on detection of methadone in blood or urine of horses, an enzyme-linked immunosorbent assay was developed to monitor this narcotic in equine body fluids. Combined with high-performance liquid chromatography, the immunoassay also served to confirm positives indicated by screening. Following intravenous administration of methadone (0.1 mg/kg), the drug was found for up to 24 h in blood but was never identified in urine (10-pg/mL detection limit). Thus, urine is dismissed as a source of methadone control, and the use of blood to screen racehorses for this narcotic analgesic is suggested.
Insights
Methadone, a banned opiate, can be detected in racehorse blood for up to 24 hours after administration. This study suggests blood, not urine, is a reliable source for detecting methadone doping in horses.
Area of Science:
- Veterinary Pharmacology
- Analytical Chemistry
- Equine Sports Medicine
Background:
- Opiate misuse in racehorses is linked to enhanced locomotor activity.
- Methadone, a narcotic analgesic, is a banned substance due to its potential use as a doping agent.
- Limited data exists on methadone detection in equine biological fluids.
Purpose of the Study:
- To develop and validate an immunoassay for detecting methadone in equine body fluids.
- To establish the detection window for methadone in horse blood and urine.
- To inform doping control strategies for methadone in racehorses.
Main Methods:
- Development of an enzyme-linked immunosorbent assay (ELISA) for methadone screening.
- Confirmation of positive results using high-performance liquid chromatography (HPLC).
- Intravenous administration of methadone (0.1 mg/kg) to horses followed by sample collection.
Main Results:
- Methadone was detected in horse blood for up to 24 hours post-administration.
- Methadone was not detected in urine, even with a sensitive detection limit of 10 pg/mL.
- The developed immunoassay combined with HPLC proved effective for methadone detection.
Conclusions:
- Urine is not a suitable matrix for methadone doping control in horses.
- Blood analysis is recommended for screening racehorses for methadone.
- This study provides crucial data for equine anti-doping programs regarding methadone.