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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, Columbus, OH. Table 1 – ARCI reported identifications of NIK and NEN in US Thoroughbred (TB) Standardbred (STB) and Quarter Horse (QH) racing for years 2022 and 2023, showing date, racetrack, horse breed, sample type and where available, estimated concentration, analytical laboratory, split sample status and where available, penalty status. Tabelle 1 – ARCI meldete Identifizierungen von NIK und NEN bei US-amerikanischen Vollblut- (TB) Standardbred- (STB) und Quarter Horse- (QH) Rennen für die Jahre 2022 und 2023, mit Angabe von Datum, Rennbahn, Pferderasse, Probentyp und (sofern verfügbar) geschätzter Konzentration, Analyselabor, Status der Teilprobe und (sofern verfügbar) Strafstatus. Date State Track Breed Sample Type (amt) Lab. Split Sample Suspension Fine NIK NEN 2/26/22 NJ Freehold Raceway STB Blood Industrial 1 year $5000 No Yes 3/4/22 NJ Freehold Raceway STB Blood Industrial $5000 No Yes 6/21/22 OH Thistledown TB Urine (2.99 ng/mL) OH Dept. of Agriculture Analytical Laboratory 1 year $1000 No Yes 7/16/22 NM Ruidoso Downs QH Blood Industrial Declined 1 year $25,000 Yes No 9/3/23 NM Ruidoso Downs QH Blood Industrial UC Davis Dismissed No Yes 9/11/23 CO Arapahoe Park QH Blood (66 pg/mL) Industrial New York Dismissed No Yes 9/12/23 OK Will Rogers Downs QH Blood Industrial Dismissed No Yes 10/19/23 LA Evangeline Downs QH Industrial Declined 6 Months Yes No 10/27/23 LA Evangeline Downs QH Industrial Declined 6 Months Yes No 11//11/23 MI Northville Downs STB Blood (214 pg/mL Industrial No Yes 11/15/23 DE Dover Downs STB Industrial 30 days $2000 No Yes 11/22/23 PA Meadows STB Blood (740 pg/mL) PETRL Illinois No Yes Trace level identifications of n-Ethylnicotinamide in racing horses Clara Fenger et al. Compendium Pferdeheilkunde 2025 269 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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