Caffeine and theobromine identifications in post-race urines: threshold levels and regulatory significance of such identifications.

Caffeine is a widespread environmental substance, and testing for caffeine is now highly sensi-tive. Currently, many authorities in North America are not concerned about plasma caffeineconcentrations of 100 ng/ml, equivalent to 300 ng/ml in urine. This is because such lowcaffeine concentrations are likely to be associated with environmental exposure to caffeine andare also unlikely to be associated with pharmacological responses. Authors’ addresses: Gradu-ate Center for Toxicology, Health Sciences Research Building, University of Kentucky, Lexington,KY 40536 (Budhraja); Maxwell Gluck Equine Research Center, Farm Lane and NicholasvilleRoad, University of Kentucky, Lexington, KY 40546 (Camargo, Hughes, Tobin); U.K. LivestockDisease Diagnostic Center, 1490 Bull Lea Road, Lexington, KY 40512 (Lehner); Florida Horse-men’s Benevolent and Protective Association, PO Box 1808 Calder race course, Opa-Locka, FL33056 (Stirling); and Connolly’s Redmills, Goresbridge, Kilkenny, Ireland (Brennan, Dowling);e-mail: ttobin@uky.edu (Tobin). © 2007 AAEP. *Presenting author.