The pharmacokinetics and in vitro cyclooxygenase selectivity of deracoxib in horses

Davis, J., Marshall, J., Papich, M., Blikslager, A. and Campbell, N. (2010) The pharmacokinetics and in vitro cyclooxygenase selectivity of deracoxib in horses. Journal of Veterinary Pharmacology and Therapeutics, 34(1), pp. 12-16. (doi: 10.1111/j.1365-2885.2010.01185.x)

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The purpose of this study was to determine the pharmacokinetics of deracoxib following oral administration to horses. In addition, in vitro equine whole blood cyclooxygenase (COX) selectivity assays were performed. Six healthy adult horses were administered deracoxib (2 mg/kg) orally. Plasma samples were collected prior to drug administration (time 0), and 10, 20, 40 min and 1, 1.5, 2, 4, 6, 8, 12, 24, and 48 h after administration for analysis with high pressure liquid chromatography using ultraviolet detection. Following PO administration, deracoxib had a long elimination half-life (<i>t</i><sub>1/2</sub><i>k</i><sub>10</sub>) of 12.49 ± 1.84 h. The average maximum plasma concentration (C<sub>max</sub>) was 0.54 μg/mL, and was reached at 6.33 ± 3.44 h. Bioavailability was not determined because of the lack of an IV formulation. Results of <i>in vitro</i> COX selectivity assays showed that deracoxib was selective for COX-2 with a COX-1/COX-2 ratio of 25.67 and 22.06 for the IC<sub>50</sub> and IC<sub>80</sub>, respectively. Dosing simulations showed that concentrations above the IC<sub>80</sub> for COX-2 would be maintained following 2 mg/kg PO q12h, and above the IC50 following 2 mg/kg PO q24h. This study showed that deracoxib is absorbed in the horse after oral administration, and may offer a useful alternative for anti-inflammatory treatment of various conditions in the horse.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Marshall, Dr John
Authors: Davis, J., Marshall, J., Papich, M., Blikslager, A., and Campbell, N.
Subjects:R Medicine > RM Therapeutics. Pharmacology
College/School:College of Medical Veterinary and Life Sciences
Journal Name:Journal of Veterinary Pharmacology and Therapeutics

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