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The pharmacokinetics and in vitro cyclooxygenase selectivity of deracoxib in horses
Author(s) -
DAVIS J. L.,
MARSHALL J. F.,
PAPICH M. G.,
BLIKSLAGER A. T.,
CAMPBELL N. B.
Publication year - 2011
Publication title -
journal of veterinary pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.527
H-Index - 60
eISSN - 1365-2885
pISSN - 0140-7783
DOI - 10.1111/j.1365-2885.2010.01185.x
Subject(s) - pharmacokinetics , bioavailability , pharmacology , cyclooxygenase , oral administration , horse , chemistry , in vitro , dosing , medicine , enzyme , biology , biochemistry , paleontology
Davis, J. L., Marshall, J. F., Papich, M. G., Blikslager, A. T., Campbell, N. B. The pharmacokinetics and in vitro cyclooxygenase selectivity of deracoxib in horses. J. vet. Pharmacol. Therap. 34 , 12–16. 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 ( t 1/2 k 10 ) of 12.49 ± 1.84 h. The average maximum plasma concentration (C max ) 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 in vitro 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 50 and IC 80 , respectively. Dosing simulations showed that concentrations above the IC 80 for COX‐2 would be maintained following 2 mg/kg PO q12h, and above the IC 50 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.