Plasma Disposition and Urinary Excretion of Levofloxacin following a Single Intravenous Administration in Buffalo Calves

Disposition kinetics and urinary excretion of levofl oxacin was investigated after a single intravenous dose of 3 mg.kg-1 in male buffalo calves. The drug concentration was estimated in plasma and urine by microbiological assay using E. coli as the test organism. Disposition kinetic parameters were determined using a two-compartment open model and an appropriate dosage schedule was computed. Drug levels above MIC in plasma were detected up to 10 h. Levofl oxacin was rapidly distributed from blood to the tissue compartment as evidenced by high values of the distribution rate constant (7.46 ± 0.28 h-1) and the micro rate constant of transfer of drug from the central to the peripheral compartment (4.88 ± 0.21 h -1). The elimination half-life, AUC and volume of distribution were 2.56 ± 0.09 h, 10.5 ± 0.11 μg.h.ml-1 and 1.08 ± 0.05 L.kg-1, respectively. Approximately 25% of the microbiological activity of the administered levofl oxacin was recovered in the urine of calves within 24 h. On the basis of disposition kinetic parameters, an appropriate intravenous dosage regimen for levofl oxacin in buffalo calves would be 3.0 mg.kg-1 to be repeated at 12 h intervals. The observations on urinary excretion indicated that levofl oxacin may be effective against urinary tract infections in buffalo species.