Pharmacokinetics, dosage regimen and in vitro plasma protein binding of intramuscular levofloxacin in buffalo calves

The pharmacokinetics of levofloxacin following its single intramuscular administration (3 mg/kg) was investigated in six male buffalo calves. Peak plasma level of 2.95 +/- 0.13 mu g/ml was observed at 1 h and the drug level above MIC90 in plasma was detected up to 12 h of administration. The bioavailability was 68.1 +/- 5.4% and levofloxacin was bound to the plasma proteins to the extent of 19.1 +/- 1.5%. High values of AUC (8.81 +/- 0.37 mu g.h/ml) and Vd(area) (1.06 +/- 0.04 L/kg) reflected a vast area of body covered by drug concentration and appropriate penetration of levofloxacin into various body fluids and tissues. The elimination half-life and mean residence time were 3.27 +/- 0.31 h and 5.4 +/- 0.59 h, respectively. The total body clearance was 343.2 +/- 14.1 ml/kg/h. An appropriate intramuscular dosage regimen for levofloxacin in buffalo calves would be 1.7 mg/kg repeated at 12-h intervals.