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Abstract

Cocaine is a widely used human recreational substance routinely transferring at pharmacologically irrelevant trace level amounts to non-user humans and horses. Horses and humans rapidly demethylate cocaine to benzoylecgonine which is excreted in urine at concentrations approaching two thousand times higher than the corresponding plasma cocaine concentrations. In human workplace drug testing, these usually pharmacologically irrelevant trace level urinary detections of benzoylecgonine are handled by application of a 100 ng/ml urinary “cut-off“, as presented by the Substance Abuse and Mental Health Services Administration (SAMHSA). In horse racing several American states have long used published urinary “cut-offs“ for benzoylecgonine of from 50 to 150 ng/ml. More recently, on September 13th 2023, the Horseracing Integrity and Welfare Unit (HIWU) “called“ a plasma benzoylecgonine “positive“ at 76 picograms/mL, thereby raising the matter of defining a benzoylecgonine “cut-off“ in equine plasma equivalent to the long in place 100 ng/ml or thereabouts urinary “cut-offs“ for benzoylecgonine used in equine medication regulation. We therefore reviewed the relevant published scientific data and proposed 1.0 nanogram/ ml of benzoylecgonine as an equine plasma/serum benzoylecgonine “cut-off“ equivalent to a 100 ng/ml urinary “cut-off“. We communicated this analysis to the Pennsylvania Horsemen’s Benevolent and Protective Association (PAHBPA) on September 14th and 24th 2023 as preliminary draft communications. Soon thereafter, on or about November 17th 2023, the HIWU authority withdrew its case in the above referenced matter and also a second case involving another Pennsylvania trainer with a presumably similar benzoylecgonine plasma/serum identification. We specifically note that trace level amounts of cocaine are found on US currency, leading to widespread exposure of individuals and horses to pharmacologically irrelevant amounts of cocaine which is excreted as its benzoylecgonine metabolite at readily detectable but pharmacologically irrelevant concentrations in human and equine urine. Given the long in place and well established 100 nanogram/ml SAMHSA “cut-off“ for urinary cocaine in human workplace testing we now formally present 1.0 ng/ml plasma “cut-off“ level as a plasma/serum regulatory “cutoff“ for trace level identifications of benzoylecgonine in equine plasma/serum which “cut-off“ was also communicated by the Horseracing Integrity and Welfare Unit on May 14th, 2024.

Document Type

Article

Publication Date

2025

Digital Object Identifier (DOI)

DOI 10.21836/Compendium20250102

Funding Information

This research was made possible by research support from The Equine Health and Welfare Alliance, Inc, Versailles, Kentucky, and the United States Trotting Association, Columbus, OH. Further support came from the National Institute of Food and Agriculture, U.S. Department of Agriculture, Hatch Program under project KY014066 Accession Number 7001029.  

Other support includes research support from The National Horsemen’s Benevolent and Protective Association and the Alabama, Arizona, Arkansas, Ontario, Canada; Charles Town, WV; Florida, Indiana, Iowa, Kentucky, Louisiana, Michigan, Minnesota, Nebraska, Ohio, Oklahoma, Oregon, Pennsylvania, Tampa Bay Downs, Florida, Texas, Washington State, and West Virginia Horsemen’s Benevolent and Protective Associations.

Funding sources provided no role in the design of the study, nor in the collection, analysis, and interpretation of all presented and referenced data.

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