Disposition kinetics and urinary excretion of levofloxacin on concomitant administration with meloxicam in cross-bred calves

The disposition kinetics and urinary excretion study of levofloxacin was conducted in 5 male cross-bred calves following its single intravenous administration (4 mg kg−1) concurrently with meloxicam (0.5 mg kg−1). Levofloxacin was estimated by microbiological assay. The drug levels above MIC90 in plasma, were detected up to 10 h. Disposition kinetic parameters were calculated by two-compartment open model. Rapid distribution of levofloxacin was evidenced by a small distribution half-life (0.13 ± 0.01 h) and high K12/K21 ratio (2.21 ± 0.15). High ratio of AUC/MIC (90.2 ± 3.41) indicated good antibacterial activity of levofloxacin. The AUC, Vdarea, elimination half-life, MRT and total body clearance were 9.02 ± 0.34 μg ml−1 h, 1.38 ± 0.05 l kg−1, 2.16 ± 0.08 h, 2.58 ± 0.11 h and 0.45 ± 0.02 l kg−1 h−1, respectively. About 38.4% of the administered dose of levofloxacin was excreted in urine within 24 h. A suitable intravenous dosage regimen for levofloxacin would be 1.8 mg kg−1 repeated at 8 h intervals when prescribed with meloxicam in calves.