In the fields of both human and animal toxicology, UCT Inc., is world renowned for its manufacture of the finest SPE sorbents. This is most eloquently demonstrated in an article published in Journal of Veterinary Pharmacology and Therapeutics ((2016) 39, 469–477) by H.K. Knych et al., (UCSF, Davis) detailing the pharmacokinetics of methocarbamol and phenylbutazone in exercised thoroughbred horses.
Methocarbamol (MCBL) is commonly used in performance horses for the treatment of skeletal muscle disorders. Current regulatory recommendations for show horses and racehorses are based on a single oral dose of 5 g, although doses in excess of this are often administered. The goal of the current study was to characterize the disposition of MCBL following higher dose administration in combination with another commonly used drug in performance horses, phenylbutazone (PBZ). Exercised thoroughbred horses were administered various doses of MCBL as a sole agent and MCBL in combination with PBZ. Urine samples were collected at various times, where concentrations of the MCBL were determined using UCT’s flagship sorbent Clean Screen®DAU (CSDAU 130 mg/3 mL) for extraction after enzymatic hydrolysis. Following elution with 3 mL of hexane-ethyl acetate mixture (1:1) and evaporation, the samples were analyzed by LC-MS/MS and pharmacokinetic parameters were calculated using compartmental analysis.
Results demonstrated that following administration of 15 g of MCBL, either as part of a single- or multiple-dose regimen, a number of horses exceeded the Association of Racing Commissioners International and the United States Equestrian Federation’s recommended regulatory threshold at the recommended withdrawal time. There was not a significant difference between horses that received only MCBL and those that received MCBL and PBZ. Results of the current study support an extended withdrawal guideline when doses in excess of 5 g are administered.
This paper shows that when researchers working in the area of equine toxicology need the finest SPE sorbents for their extractions, they routinely turn to UCT as their first choice.