Pharmacokinetics and dosage regimen of cefazolin following single intravenous administration in buffalo calves

The present study has been conducted on four male buffalo calves (Bubalus bubalis) to investigate the pharmacokinetics and urinary excretion of cefazolin after its single intravenous dose of 15 mg.kg(-1) The drug concentration was estimated in plasma and urine by microbiological assay using Escherichia colt as the test organism. Disposition kinetic parameters were determined using two-compartment open model and an appropriate dosage schedule was computed. The drug level above MIC90 in plasma, was detected upto 2 h. Cefazolin was rapidly distributed from blood to the tissue compartment as evidenced by high value of distribution rate constant (8.72 +/- 0.48 h(-1)). High value of AUC (19.1 +/- 1.22 mu g.ml(-1).h) indicated a vast area covered by drug concentration. Moderate tissue penetration was reflected by the steady-state volume of distribution of 0.79 +/- 0.04 L. kg(-1). The elimination half-life and total body clearance were 0.82 +/- 0.01 h and 795.7 +/- 52.9 ml.kg(-1).h(-1), respectively. On the basis of the disposition kinetic parameters, an appropriate intravenous dosage regimen for cefazolin in buffalo calves would be 13.5 mg.kg(-1) to be repeated at 4 h intervals.