RMTC Issues Guidance Regarding DMSO, Pentosan & Dantrolene

Advisory of HISA’s Anti-Doping and Medication Control (ADMC) Detection Times for Dimethyl Sulfoxide (DMSO), Pentosan, & Dantrolene

In response to the requests of industry stakeholders, the Racing Medication and Testing Consortium’s (RMTC) Scientific Advisory Committee (SAC) has performed an analysis of the Horseracing Integrity and Safety Authority’s (HISA) Anti-Doping and Medication Control (ADMC) screening limits and detection times and developed a withdrawal guidance for two (2) additional substances, Dimethyl Sulfoxide (DMSO) and Pentosan (Zycosan). 

“The intention is for the RMTC to provide the industry with scientifically derived information to aid attending veterinarians and horsemen in making medication decisions and to avoid preventable errors and promote compliance with HISA’s regulations”, said Dr. Michael Hardy, Executive Director, “The RMTC has been providing such guidance to the racing industry since the inception of its Scientific Advisory Committee and remains committed to providing relevant scientific information to the racing industry going forward.”

Following review of all available data, given a dose of 70 mL of 90% DMSO in 500 mL LRS IV single administration, the SAC recommends a withdrawal guidance of 120 hours with the understanding that the recommendation only applies to the FDA approved medical-grade product (e.g., RIMSO-50).  For Pentosan (Zycosan), given a dose of 3 mg/kg IM once weekly for four (4) weeks, the SAC recommends a Restricted Administration Time (RAT) of 48-hours. 

Additionally, RMTC’s SAC has been asked by industry stakeholders to review its withdrawal guidance of dantrolene.  In earlier work, the SAC provided withdrawal guidance of 96 hours for dantrolene, which was based on the rigorous, objective process considering administration data of both FDA approved capsules and compounded paste dosing forms.  Further review of administration data of FDA approved capsules, in both blood and urine, supports a 48-hour detection time.  Understanding the potential variables associated with use of compounded substances, given a 500 mg oral dose once daily for three (3) days, using the agreed-upon methodology, RMTC’s SAC recommends a withdrawal time of 72 hours with the understanding that the recommendation only applies to the FDA approved capsules.  This recommendation does not apply to compounded products. Further, there are risks associated with use of compounded products as drug concentrations in a formulation may differ from that declared on the product label, and from batch to batch for a single product.  For these reasons, there is no reliable withdrawal guidance for the use of any compounded product. 

The RMTC Withdrawal Guidance is subject to change. As new research becomes available for each medication, the RMTC may extend or decrease the time listed in the Withdrawal Guidance. Any subsequent change in this information based upon new research will be provided upon review by the Scientific Advisory Committee and approval by the RMTC Board. The complete Withdrawal Guidance of HISA’s ADMC Detection Times document reflects these updates.

The RMTC is a 501(c) 3 organization comprised of 23 industry stakeholder organizations with a shared commitment to engage in research, education, and advocacy for science-based initiatives that promote the health and safety of the racehorse and the integrity of competition. More information can be found at RMTCnet.com.