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14th March 2012

Illness and training injuries in racing and equestrian events are common, but appropriate treatment can be hampered by uncertainty about excretion and detection time for many theraputic drugs. A new report “The Pharmacokinetics of Equine Medications” provides information on 12 commonly used equine drugs including the time taken for each drug to reach its maximum concentration in the blood, its rate of metabolism and removal from the blood stream, and the time taken for the drug to be eliminated from the body via the urine. The results published in the report will allow racing authorities to provide relevent stakeholders with appropriate, accurate and reliable detection time for therapeutic substances. This work will also be shared internationally, enabling Australia to contribute to the international standardisation of drug testing protocols. Fact sheets for vets and a report for regulators will be available later this year. Queensland University of Technology Professor of Biosciences, Martin Sillence said ” Because horses are prohibited from racing with any trace of drugs in their system, the administration of therapeutic drugs to horses in need of care has been a risky business . This means it’s been all too easy to unwittingly be caught out with a winning horse on race day. The new schedule should change all this”.

With financial support from industry stakeholders, a consortium of the four Australian racing laboratories and four universities was formed to address this problem under the banner of Equine Therapeutics Research Australia (ETRA). The universities have jointly provided access to 24 horses, PK modelling and statistical expertise; while the laboratories have employed their analytical skills to process more than 20,000 blood and urine samples, as well as developing new forensic tests by investigating the pharmacodynamics (PD) and metabolism of selected compounds.

Using a large number of horses to test each drug has increased the accuracy of the estimated PK parameters and average excretion rates, and has generated important information about the variation between horses, which has been difficult to gauge from earlier work using fewer animals. Based on this variation, we have explored a different approach to estimating detection and withholding times by the application of Bayesian statistics. Using this method we have demonstrated that it is possible to report the probability of an individual horse returning a positive swab at any given time-point after treatment. Compared to the current system, this is an innovative and more realistic approach to the problem of drug detection times, which is essentially one of risk management.
Additional benefits from this project will accrue over time as further compounds are analysed, the data are reviewed by the racing authorities, and new recommendations about detection times are published. The ETRA group is also consulting with its counterparts in Asia, Europe and America, to share data, maximise the information available to Australian stakeholders, avoid duplication of effort and contribute to the international harmonisation of drug testing protocols.

The Pharmacokinetics of Equine Medications is availabe on the RIRDC website publication number 11/117.

Logans is a proud financial supporter to the RIRDC Equine Research branch.