Pharmacokinetics, urinary excretion and plasma protein binding of ofloxacin in water buffalo calves (Bubalus bubalis)

Abstract

Pharmacokinetics and urinary excretion of an intravenous dose of 5 mg.kg^–1 ofloxacin were investigated in water buffalo calves. Plasma concentrations of ofloxacin were determined by high-performance liquid chromatography. Ofloxacin was rapidly distributed from the central to the peripheral compartment as evidenced by a short distribution half-life (0.09 h ± 0.003 h) and high K₁₂ (4.7 h^–1 ± 0.1 h^–1), and was detected in plasma for 8 h. The large volume of distribution (2.48 L.kg^–1 ± 0.18 L.kg^–1) obtained in this study indicated high distribution of ofloxacin in water buffalo calves. The elimination half-life, the area under the plasma drug concentration–time curve and total body clearance were 2.11 h ± 0.13 h, 6.20 µg.mL^—1 ± 0.23 µg.mL^—1.h and 0.81 mL.kg^–1.h^–1 ± 0.03 mL.kg^–1.h^–1, respectively. About 18.7% of administered drug was bound to plasma proteins and approximately 32.5% of the administered dose was recovered in urine within 48 h. The results of the study indicated a favourable pharmacokinetic profile of ofloxacin in water buffalo calves, which suggests that ofloxacin may be effective against urinary pathogens in this species.