Pharmacokinetics and urinary excretion of sulfadiazine in buffalo calves.

Pharmacokinetics and urinary excretion of sulfadiazine were determined in buffalo calves following single oral administration (150 mg/kg). Kinetic evaluation of plasma levels was performed using a 2-compartment model. The absorption half-life and elimination half-life were 3.41 +/- 0.63 and 13.75 +/- 1.94 h, respectively. Based on this study, an optimal dosage regimen of sulfadiazine in buffalo calves would be 165 mg/kg, followed by 75 mg/kg at 12-h intervals. Sulfadiazine was mainly excreted in the urine as free amine, while the percentage of acetylated sulfadiazine was comparatively low.