Pharmacokinetics and effects on thromboxane B2 production following intravenous administration of flunixin meglumine to exercised thoroughbred horses

Heather K Knych, Rick Arthur, D. S. Mckemie, N. Chapman

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

Flunixin meglumine is commonly used in horses for the treatment of musculoskeletal injuries. The current ARCI threshold recommendation is 20 ng/mL when administered at least 24 h prior to race time. In light of samples exceeding the regulatory threshold at 24 h postadministration, the primary goal of the study reported here was to update the pharmacokinetics of flunixin following intravenous administration, utilizing a highly sensitive liquid chromatography-mass spectrometry (LC-MS). An additional objective was to characterize the effects of flunixin on COX-1 and COX-2 inhibition when drug concentrations reached the recommended regulatory threshold. Sixteen exercised adult horses received a single intravenous dose of 1.1 mg/kg. Blood samples were collected up to 72 h postadministration and analyzed using LC-MS. Blood samples were collected from 8 horses for determination of TxB2 and PGE2 concentrations prior to and up to 96 h postflunixin administration. Mean systemic clearance, steady-state volume of distribution and terminal elimination half-life was 0.767 ± 0.098 mL/min/kg, 0.137 ± 0.12 L/kg, and 4.8 ± 1.59 h, respectively. Four of the 16 horses had serum concentrations in excess of the current ARCI recommended regulatory threshold at 24 h postadministration. TxB2 suppression was significant for up to 24 h postadministration.

Original languageEnglish (US)
Pages (from-to)313-320
Number of pages8
JournalJournal of Veterinary Pharmacology and Therapeutics
Volume38
Issue number4
DOIs
StatePublished - Aug 1 2015

ASJC Scopus subject areas

  • Pharmacology
  • veterinary(all)

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