Flunixin meglumine (FM) was investigated for the effectiveness of plasma, oral fluid, and urine\nconcentrations to predict tissue residue depletion profiles in finishing-age swine, along with the potential for\nuntreated pigs to acquire tissue residues following commingled housing with FM-treated pigs. Twenty pigs were\nhoused in groups of three treated and one untreated control. Treated pigs received one 2.2 mg/kg dose of FM\nintramuscularly. Before treatment and at 1, 3, 6, 12, 24, 36, and 48 h (h) after treatment, plasma samples were taken.\nAt 1, 4, 8, 12 and 16 days (d) post-treatment, necropsy and collection of plasma, urine, oral fluid, muscle, liver,\nkidney, and injection site samples took place. Analysis of flunixin concentrations using liquid chromatography/\ntandem mass spectrometry was done. A published physiologically based pharmacokinetic (PBPK) model for flunixin\nin cattle was extrapolated to swine to simulate the measured data.\nResults: Plasma concentrations of flunixin were the highest at 1 h post-treatment, ranging from 1534 to 7040 ng/\nmL, and were less than limit of quantification (LOQ) of 5 ng/mL in all samples on Day 4. Flunixin was detected in\nthe liver and kidney only on Day 1, but was not found 4â??16 d post-treatment. Flunixin was either not seen or\nfound less than LOQ in the muscle, with the exception of one sample on Day 16 at a level close to LOQ. Flunixin\nwas found in the urine of untreated pigs after commingled housing with FM-treated pigs. The PBPK model\nadequately correlated plasma, oral fluid and urine concentrations of flunixin with residue depletion profiles in liver,\nkidney, and muscle of finishing-age pigs, especially within 24 h after dosing.
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