Updated: May 8
Flunixin meglumine has a relatively short elimination half-life in horses compared with most other species (horses 1.6-2.5 hours: cows: 8 hours). Despite the short half-life and the relatively quick onset of action (within 2 hours) in horses, its duration of action persists up to 30 hours. A single IV dose of 1.1mg/kg of flunixin suppresses PGE, production in inflammatory exudates (usually at the site of NSAID accumulation) for 12-24 hours.
Flunixin meglumine is considered one of the most potent analgesics and is most frequently used for the treatment of equine colic. Flunixin meglumine also has demonstrated improvement in the cardiovascular status in horses suffering from endotoxemia.
Administration of low-dose flunixin meglumine (.25mg/kg) has been advocated for its ability to block the effects of endotoxin. These findings were based on a study of experimentally induced endotoxemia in adult horses that were pretreated with .25mg/kg of flunixin and demonstrated depression of thromboxane generation. Many clinicians use the dose rates of .25mg/kg every 6 hours in endotoxemic horses and .25mg/kg every 8-12 hours in endotoxemic horses that also have some evidence of renal compromise. Such horses should be maintained on IV fluids to minimize the effects of renal papillary necrosis.
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