Pharmacokinetic studies of levofloxacin after oral administration in healthy and febrile cow calves

The present experiment was designed to study the pharmacokinetics of levofloxacin in six healthy cross bred female cow calves (4 to 6 months age) weighing between 40 to 80 kg. Plasma from blood was separated by centrifugation at 10,000 rpm. Quantitative estimation of levofloxacin was done by UV-VIS spectrophotometer at 286 nm. The mean maximum plasma concentration (Cpmax ) of levofloxacin in febrile calves (5.28 ± 0.32 µg/ml) did not differ significantly as compared with healthy calves (4.50 ± 0.22 µg/ml) after single dose (20 mg/kg) oral administration. The mean therapeutic plasma concentration ( Cpther ) of levofloxacin was maintained for longer period in febrile calves (10 h) as compared to healthy calves ( 8 h). The mean maximum urine concentration (Cumax) in febrile (40.86 ± 2.19 µg/ml) also did not differ significantly as compared with healthy calves (39.38 ± 2.43 µg/ml). No significant difference in various pharmacokinetic parameters of plasma was observed in healthy calves ( β = 0.23 ± 0.01/h ; t1/2 β = 3.00 ± 0.17 h and MRT = 4.66 ± 0.14 h ) and febrile calves ( β = 0.23 ± 0.01/ h; t1/2 β = 3.05 ± 0.16 h and MRT = 5.04 ± 0.14 h ) . The mean value of β, and t ½ β calculated in urine also did not differ between healthy and febrile calves. However, the value of MRT(3.79 ± 0.07 h) and ClB(1.65 ± 0.09 ml/kg/min) calculated in urine of febrile calves significantly(p < 0.05) differ to healthy calves(MRT = 3.15 ± 0.03 h;ClB = 2.09 ± 0.13 ml/kg/min). Based on kinetic profile levofloxacin may be given orally at the dose rate of 1.49 mg/kg B.W.at 8 h intervals in febrile calves.