Pharmacokinetics of Flunixin Meglumine After Intravenous and Intramuscular Administration in Pigs

Pharmacokinetics of flunixin meglumine (FM) was investigated in 14 healthy pigs following single intravenous (i.v.) and intramuscular (i.m.) administration of the drug at the dosage of 2.2 and 1.1 mg kg−1. Blood samples were collected at different intervals after administration, and concentrations of FM were determined by HPLC method with a limit of detection of 0.1 μ mL−1. The FM concentration-time data were fitted to a two-compartment open model after single i.v. dosing in pigs. The main pharmacokinetic parameters were as follows: t1/2a' 0.49 ± 0.03 and 0.58 ± 0.07 h; t1/2β' 6.28 ± 0.13 and 7.37 ± 0.59 h; V/F, 0.01 ± 0.001 and 0.01 ± 0.002 L kg−1; CL, 0.01 ± 0.002 and 0.01 ± 0.002 Lh−1; AUC, 237.73 ± 52.46 and 147.71 ± 36.76 μg h−1 mL−1. The drug concentration-time data were fitted to a two-compartment model with first-order absorption after single i.m. administration in pigs. The main pharmacokinetic parameters were as follows: t1/2α' 0.90 ± 0.07 and 0.86 ± 0.10 h; t1/2β 8.79 ± 0.85 and 9.60 ± 0.10 h; V/F, 0.02 ± 0.004 and 0.02 ± 0.003 L kg−1; CL, 0.01 ± 0.002 and 0.01 ± 0.003 Lh−1; AUC, 174.63 ± 45.84 and 112.42 ± 31.19 μ h−1 mL−1. The results of the present study showed that FM was rapidly absorbed, extensively distributed, and slowly eliminated in pigs. The drug was completely absorbed after single i.m. administration and a good bioavailability in pigs.