Subcutaneous pharmacokinetics of ceftazidime in buffalo calves

The pharmacokinetics and urinary excretion of ceftazidime, a third generation cephalosporin, was investigated in buffalo calves (6) following a single subcutaneous administration (10 mg/kg). Ceftazidime concentrations in plasma and urine were estimated by microbiological assay technique using Escherichia coli as test organism. Pharmacokinetic analysis of disposition data indicated that subcutaneous administration data were best described by I-compartment open model. The peak plasma levels of ceftazidime were 24.1 +/- 0.26 mu g/ml at 45 min and the drug was detected upto 14 h. The absorption half-life and elimination half-life were 0.38 +/- 0.07 h and 3.32 +/- 0.23 h, respectively. The apparent volume of distribution and total body clearance were 0.18 +/- 0.01 L/kg and 39.2 +/- 1.22 ml/kg/h, respectively. The urinary excretion of ceftazidime in 36 h, was 29.9 +/- 5.34% of total administrated dose. An efficacy predictor, measured as the time over which the active drug exceeds the bacterial minimum inhibitory concentration (T > MIC), was calculated. T > MIC was in the range 91-137% of the recommended dosing interval (8-12 h) after subcutaneous administration, for bacteria with a MIC90 <= 25 mu g/ml.