The board approved the regulation based on research by scientists at the University of California Davis indicating that this concentration will not alter the athletic performance of a horse. Based on separate studies, it is recommended that clenbuterol be administered at the level of 0.8 micrograms per kilogram of body weight, so that urine concentration will be below 5 ng/ml by four days after the last drug administration.
A regulatory amendment adding clenbuterol to the list of therapeutic medications for which trace levels are permitted in post-race equine urine samples received final approval Wednesday from the Office of Administrative Law (OAL).Clenbuterol is now permitted at a level not to exceed five nanograms per mililiter in an official post-race urine test.