Pharmacokinetics of the Novel Cyclooxygenase 2 Inhibitor Cimicoxib in Donkeys

Cimicoxib is a novel COX-2 inhibitor drug approved for use in dogs. Assessing pharmacokinetic profiles in target species is pivotal for extra label applications. The purpose of the present study was to evaluate the pharmacokinetic profiles of cimicoxib after intra-gastric administration in six healthy jennies. Plasma concentrations of cimicoxib were determined by HPLC with fluorescence detector. A pilot study was carried out with two animal groups (n = 3) in fasted or fed conditions receiving 2 mg/kg of cimicoxib. Due to the relatively low Cmax (0.03 μg/mL) from the pilot study, the dose was increased (5 mg/kg) for the subsequent full scale cross-over study. Single administration of 5 mg/kg did not show any adverse effects. However, the Cmax (0.02 μg/mL) and AUC (0.14 hour*μg/mL) values obtained after 5 mg/kg administration were not dose dependent compared to those in the 2 mg/kg pilot study. The results from this study could provide basic but essential information for the use of cimicoxib. Further pharmacodynamic studies are required to assess clinical efficacy in donkeys at these low plasma concentrations.