ATCvet Code: QM01AG90
Pharmacotherapeutic group: Anti-Inflammatory and antirheumatic products, non-steroids – Fenamates
Pharmacodynamic properties:
Flunixin meglumine is a relatively potent non-narcotic, non-steroidal analgesic with anti-inflammatory, anti-endotoxic and anti-pyretic properties.
Flunixin meglumine acts as a reversible inhibitor of cyclo-oxygenase, an important enzyme in the arachidonic acid cascade pathway which is responsible for converting arachidonic acid to cyclic endoperoxides. Consequently, synthesis of eicosanoids, important mediators of the inflammatory process involved in central pyresis, pain perception and tissue inflammation, is inhibited. Through its effects on the arachidonic acid cascade, flunixin also inhibits the production of thromboxane, a potent platelet pro-aggregator and vasoconstrictor which is released during blood clotting. Flunixin exerts its antipyretic effect by inhibiting prostaglandin E2 synthesis in the hypothalamus. By inhibiting the arachidonic acid cascade pathway, flunixin also produces an anti-endotoxic effect by suppressing eicosanoid formation and therefore preventing their involvement in endotoxin associated disease states.
Pharmacokinetic particulars:
Flunixin was administered intravenously to horses as a single dose of 1.1 mg/kg. At the first timepoint measured (10 minutes after administration) the plasma concentration was 11.45 µg/ml, AUC was 21.45 µg.h/ml and the elimination half-life was approximately 2 hours.
Flunixin was administered intravenously to cattle as a single dose of 2.2 mg/kg. At the first timepoint measured (10 minutes after administration) the plasma concentration was 12.32 µg/ml, AUC was 14.87 µg.h/ml and the elimination half-life was approximately 4 hours.
In an experimental study, flunixin was administered intravenously to pigs as a single dose of 2.0 mg/kg. Flunixin was >98% protein bound at all physiologically relevant concentrations, but also had a large volume of distribution at steady-state. All plasma concentrations were below the limit of quantitation (0.02 µg/ml) by 48 hours and the elimination half-life was 7.76 hours.
Environmental properties:
Flunixin is toxic to avian scavengers although foreseen low exposure leads to low risk.