Pharmacokinetic Studies of Enrofloxacin in Yak after Intramuscular Administration

The pharmacokinetic studies of enrofloxacin were investigated in yak (Bos grunniens L.) after administra-tion of enrofloxacin by intramuscular route at 5 mg⋅kg-1 body weight. Blood samples were collected from the jugular vein at predetermined time intervals after drug administration. Plasma was separated and ana-lysed for enrofloxacin by reverse-phase high performance liquid chromatography. Various pharmacoki-netic parameters were calculated using a non-compartmental model. The elimination half-life (t½), area under plasma concentration-time curve (AUC), area under the moment curve (AUMC), mean residence time (MRT), apparent volume of distribution (Vd), total body clearance (ClB) and apparent first-order elimi-nation rate constant (K) of enrofloxacin were 2.79±0.60 h, 5.35±1.29 μg⋅h⋅mL-1, 21.50±8.60 μg⋅h2⋅mL-1, 4.02±0.87 h, 3.76±0.83 L⋅kg-1, 935.09 ± 236.45 mL⋅h-1⋅kg-1 and 0.25±0.07 h-1, respectively after the ad-ministration of enrofloxacin. Because of faster elimination time, excellent tissue penetration, shorter half- life, low MRT after intramuscular administration of enrofloxacin at a dose rate of 5 mg⋅kg-1, it is recom-mended for use in yaks at therapeutic dose.