Disposition kinetics and urinary excretion of cefpirome after intravenous injection in buffalo calves.

We investigated the disposition kinetics and urinary excretion of cefpirome in buffalo calves after a single intravenous administration of 10 mg/kg. Also, an appropriate dosage regimen was calculated. At 1 min after injection, the concentration of cefpirome in the plasma was 57.4 +/- 0.72 microg/ml, which declined to 0.22 +/- 0.01 microg/ml at 24 h. The cefpirome was rapidly distributed from the blood to the tissue compartment as shown by the high distribution coefficient values (8.67 +/- 0.46/h), and by the drug's rate of transfer constant from the central to the peripheral compartment, K(12) (4.94 +/- 0.31/h). The elimination halflife and the volume of distribution were 2.14 +/- 0.02 h and 0.42 +/- 0.005 l/kg, respectively. Once the distribution equilibrium was reached between the tissues and plasma, the total body clearance (Cl(B)) and the ratio of the drug present in the peripheral to the central compartment (T/P ratio) were 0.14 +/- 0.002 l/kg/h and 1.73 +/- 0.06, respectively. Based on the pharmacokinetic parameters we obtained, an appropriate intravenous cefpirome dosage regimen for treating cefpiromesensitive bacteria in buffalo calves would be 8.0 mg/kg repeated at 12 h intervals for 5 days, or until persistence of the bacterial infection occurred.