RMTC Defends Methocarbamol Threshold

A day after prominent trainer Graham Motion questioned the research conducted to determine the threshold level and withdrawal time for methocarbamol (Robaxin), the Racing Medication and Testing Consortium defended its efforts.

Motion-conditioned Kitten's Point was disqualified from her April victory in the Bewitch Stakes (gr. IIIT) at Keeneland following an overage for Robaxin, a muscle relaxant; which was the trainer's first medication violation in 23 years. 

Motion, who is appealing the finding that carries a five-day suspension and $500 fine, said the final time Kitten's Point received Robaxin was seven days before the race. Methocarbamol has a recommended withdrawal time of 48 hours. Kitten's Point tested at 2.9 nanograms per milliliter of blood for methocarbamol, which carries a 1.0 ng/ml threshold.

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RMTC executive director Dionne Benson said in a statement Oct. 8 that the withdrawal time and threshold are well-researched.

"The methocarbamol threshold is recommended by the RMTC and included in the Controlled Therapeutic Medication list that is part of the National Uniform Medication Program. The recommendation is based upon research that is published in Rumpler, M., et al., The pharmacokinetics of methocarbamol and guaifenesin after single intravenous and multiple-dose oral administration of methocarbamol in the horse, J. Vet. Pharmacol. Therap., 37(1): 25-34 (Feb. 2014)," the statement read. "The threshold is based upon a single 15 mg/kg intravenous dose, but a subset of the horses was also subject to an additional oral dose regimen of 5 grams of methocarbamol every 12 hours for five doses. At 48 hours, all oral dose horses were below 1 ng/ml of plasma with the highest concentration being at 0.5 ng/ml of plasma."

The statement noted that the threshold is based on standard-practice administration, stating:

"These treatment protocols were set based upon a survey of AAEP practitioners, as is our standard practice. Practitioners indicated a range of doses and a range of treatment protocols including, in some cases, a single 48-hour pre-race administration of methocarbamol intravenously. Many protocols and treatment plans are possible for horses. The RMTC publishes specific dose and route of administration protocols to provide the practitioner and trainer information on how to meet the regulatory threshold using the listed withdrawal guidelines."

Motion did not address the dosage issue involving Kitten's Point, but the statement noted that when a trainer or vet strays from standard protocol, it can be problematic.

"If a trainer or veterinarian elects to administer a higher dose, use a different route of administration, or a longer duration of treatment than described in the recommendation, the withdrawal guideline will not apply to their situation," the statement read. "It is imperative that when a trainer elects to deviate from the threshold protocol that they do so in consultation with their veterinarians or, as permitted in Kentucky and other states, submit a sample for analysis prior to entry to help ensure the medication concentration is below the regulatory threshold. Depending on drug, especially oral preparations, there is always the possibility a horse was mistakenly treated or not all drug treatments were recorded."