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Abstract

Nikethamide, N,N-diethyl-3-pyridinecarboxamide (Coramine®) is a central nervous system stimulant at one time used therapeutically in human medicine but no longer marketed in the US. Nikethamide is classified a Drug Class 1, Penalty Class A substance by the Association of Racing Commissioners International (ARCI) and as a Horseracing Integrity and Safety Authority (HISA) SO or banned Stimulant that lacks FDA approval. Identifications of Nikethamide or its metabolite N-Ethylnicotinamide in racing samples can result in significant penalties in horse racing. Nikethamide is rapidly metabolized to N-Ethylnicotinamide, which remains detectable in plasma and urine leading to its use as a regulatory “marker” of Nikethamide administration. N-Ethylnicotinamide is also a manufacturing impurity of nicotinamide, a form of Vitamin B3. As such, it has been identified as a trace impurity in Vitamin B3 nicotinamide supplements administered to horses. Nikethamide has also been identified in certain Corydalis plants, another potential source of trace amounts of Nikethamide and or N-Ethylnicotinamide in equines. Current LC/MS-MS technology can detect Nikethamide at 10 pg/mL concentrations in plasma, making the identification of the N-Ethylnicotinamide metabolite unnecessary in the regulatory control of Nikethamide. We now present two recent regulatory cases involving picogram/ml plasma concentrations of N-Ethylnicotinamide linked to the administration of a vitamin supplement containing low nanogram/ ml concentrations of N-Ethylnicotinamide. These cases have since been dismissed, to our knowledge based on the identified source of the N-Ethylnicotinamide being a marketed vitamin supplement.

Document Type

Article

Publication Date

2025

Digital Object Identifier (DOI)

DOI 10.21836Compendium20250402

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, 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. Published as paper #524 from T Tobin and the Equine Pharmacology, Therapeutics and Toxicology Program at the Maxwell H. Gluck Equine Research Center and Department of Veterinary Science, University of Kentucky. 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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