{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,13]],"date-time":"2025-10-13T10:10:29Z","timestamp":1760350229811,"version":"build-2065373602"},"reference-count":21,"publisher":"Wiley","issue":"10","license":[{"start":{"date-parts":[[2018,6,21]],"date-time":"2018-06-21T00:00:00Z","timestamp":1529539200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"funder":[{"name":"Racing Medication and Testing Consortium"},{"name":"California Horse Racing Board"}],"content-domain":{"domain":["analyticalsciencejournals.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Drug Testing and Analysis"],"published-print":{"date-parts":[[2018,10]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>Ethylphenidate is a psychostimulant and analog of the commonly prescribed compound, methylphenidate (Ritalin\u00ae). There are a limited number of studies describing the disposition and pharmacologic\/toxicological effects of ethylphenidate in any species. The abuse potential in equine athletes along with the limited data available regarding administration in horses necessitates further study. The objectives of the current study were to describe drug concentrations, develop an analytical method that could be used to regulate its use, and describe the pharmacodynamic effects of ethylphenidate in horses. To that end, 12 horses were randomized into 3 dose groups (intravenous: 10\u00a0mg or 40\u00a0mg, oral: 40\u00a0mg). Ethylphenidate was administered and blood and urine samples were collected prior to and for up to 72\u00a0hours post drug administration. Concentrations of D\u2010threo ethylphenidate and the metabolite ritalinic acid were measured using Liquid Chromatography\u2013tandem Mass Spectrometry. L\u2010threo ethylphenidate concentrations were estimated from D\u2010threo ethylphenidate concentrations. Serum concentrations of ethylphenidate were below detectable levels by 8, 18, and 12\u00a0hours following intravenous administration of 10\u00a0mg and 40\u00a0mg and oral administration of 40\u00a0mg, respectively. Ritalinic acid was non\u2010detectable at 72\u00a0hours in the group that received a 10\u2010mg intravenous and 40\u2010mg oral dose of ethylphenidate. Ritalinic acid concentrations were below the LOQ at 72\u00a0hours following intravenous administration of 40\u00a0mg of ethylphenidate. While the number of animals per dose group were small, no stimulatory behavior or significant changes in heart rate were noted. Untoward effects including gastrointestinal adverse effects were noted in all dose groups.<\/jats:p>","DOI":"10.1002\/dta.2408","type":"journal-article","created":{"date-parts":[[2018,5,22]],"date-time":"2018-05-22T11:19:26Z","timestamp":1526987966000},"page":"1508-1517","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["L\u2010 and D\u2010threo ethylphenidate concentrations, pharmacokinetics, and pharmacodynamics in horses"],"prefix":"10.1002","volume":"10","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8676-4970","authenticated-orcid":false,"given":"Heather K.","family":"Knych","sequence":"first","affiliation":[{"name":"K.L. Maddy Equine Analytical Chemistry Laboratory, School of Veterinary Medicine University of California  Davis California"},{"name":"Department of Veterinary Molecular Biosciences, School of Veterinary Medicine University of California  Davis California"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Dan S.","family":"McKemie","sequence":"additional","affiliation":[{"name":"K.L. Maddy Equine Analytical Chemistry Laboratory, School of Veterinary Medicine University of California  Davis California"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kelsey","family":"Seminoff","sequence":"additional","affiliation":[{"name":"K.L. 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