Pharmacokinetics, metabolism and urinary detection time of flunixin after intravenous administration in camels

The pharmacokinetics of flunixin were determined after an intravenous dose of 1.1 mg/kg body weight in six camels and 2.2 mg/kg body weight in four camels. The data obtained (mean ±  SEM) for the low and high dose, respectively, were as follows:
  The elimination half-lives ( t _½β) were 3.76 ± 0.24 and 4.08 ± 0.49 h, the steady state volumes of distribution ( V d_ss) were 320.61 ± 38.53 and 348.84 ± 35.36 mL/kg body weight, total body clearances ( Cl _T) were 88.96 ± 6.63 and 84.86 ± 4.95 mL/h/kg body weight and renal clearances ( Cl _r) were 0.52 ± 0.09 and 0.62 ± 0.18 mL/h/kg body weight. A hydroxylated metabolite of flunixin was identified by gas chromatography/mass spectrometry (GC/MS) under electron and chemical ionization and its major fragmentation pattern was verified by tandem mass spectrometry (GC/MS/MS) using neutral loss, daughter and parent scan modes. The detection times for flunixin and its hydroxylated metabolite in urine after an intravenous (i.v.) dose of 2.2 mg/kg body weight were 96 and 48 h, respectively.