A racing industry group that devises recommendations for U.S. medication policies on Tuesday approved withdrawal times and threshold levels for four therapeutic medications, completing a process to establish the parameters for a list of 24 therapeutic drugs that will be allowed to be administered to racehorses under new model rules.The board of the Racing Medication and Testing Consortium adopted the withdrawal times and threshold levels for procaine penicillin, lidocaine, detomidine, and xylazine. All four drugs are on a “special interest” sub-category of the larger list that includes seven drugs, all of which will be subject to stricter regulations than the other 17 medications because they are used to treat illness or injury, rather than relatively minor respiratory or gastric conditions or common aches and pains. The adoption of the regulatory parameters for the final four drugs on the list will allow supporters of uniform rules to press for adoption of the complete list. Already, eight states along the Eastern seaboard and in the Mid-Atlantic have pledged to adopt the list and the regulations accompanying them by the end of the year, including New York, Pennsylvania, New Jersey, and Maryland. “These guidelines will pave the way for uniform adoption of medication regulations across the country,” said Dr. Robert Lewis, the chairman of the RMTC.Racing industry groups have been working for two years to set the parameters for the medications on the list. The list has so far generated wide support from most racing organizations, though horsemen’s groups have expressed some reservations about minor aspects of the rules that could complicate the adoption process in some states.Under the uniform rules, the finding of any drug other than the 24 medications on the approved list will result in a penalty. Traces of the 24 medications will be allowed to appear in post-race samples, but only at concentrations – threshold levels – that have been determined to be pharmacologically insignificant. The establishment of threshold levels allows horsemen to treat horses with the medications while the horses are in training as long as the drugs do not affect a horse’s performance on raceday. All racing jurisdictions around the world use threshold levels for a variety of medications, as do the drug-testing bodies of other sports. The RMTC also approved a new regulation that seeks to prevent horsemen from using multiple painkillers in low doses, a process called “stacking.” Under the regulation, if two painkillers are found in a post-race sample, the second painkiller will be subjected to a lower threshold level than the standard threshold level, to prevent horsemen from using the two drugs to bring about a higher pain-killing effect than contemplated under the regulations for the use of one of the drugs. “The administration of multiple [painkillers] is a welfare and safety concern for our equine and human athletes,” said Dr. Rick Arthur, the chairman of the RTMC’s Scientific Advisory Committee and the California Horse Racing Board’s Equine Medical Director.