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Pharmacokinetics of etodolac in the horse following oral and intravenous administration
Author(s) -
DAVIS J. L.,
PAPICH M. G.,
MORTON A. J.,
GAYLE J.,
BLIKSLAGER A. T.,
CAMPBELL N. B.
Publication year - 2007
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.1365-2885.2007.00811.x
Subject(s) - etodolac , pharmacokinetics , horse , bioavailability , oral administration , pharmacology , crossover study , volume of distribution , chemistry , medicine , pathology , biology , placebo , paleontology , alternative medicine
The purpose of this study was to determine the pharmacokinetics of etodolac following oral and intravenous administration to six horses. Additionally, in vitro cyclooxygenase (COX) selectivity assays were performed using equine whole blood. Using a randomized two‐way crossover design, horses were administered etodolac (20 mg/kg) orally or intravenously, with a minimum 3‐week washout period. Plasma samples were collected after administration for analysis using high pressure liquid chromatography with ultraviolet detection. Following intravenous administration, etodolac had a mean plasma half‐life ( t 1/2 ) of 2.67 h, volume of distribution ( V d ) of 0.29 L/kg and clearance ( Cl ) of 234.87 mL/h kg. Following oral administration, the average maximum plasma concentration ( C max ) was 32.57 μg/mL with a t 1/2 of 3.02 h. Bioavailability was approximately 77.02%. Results of in vitro COX selectivity assays showed that etodolac was only slightly selective for COX‐2 with a COX‐1/COX‐2 selectivity ratio effective concentration (EC) 50 of 4.32 and for EC 80 of 4.77. This study showed that etodolac is well absorbed in the horse after oral administration, and may offer a useful alternative for anti‐inflammatory treatment of various conditions in the horse.