Serum disappearance and urinary excretion of sulfamethoxypyridazine in goats

Abstract

Pharmacokinetics and urinary excretion of sulfamethoxypyridazine were determined in goats following single intravenous administration (100 mg/kg body weight). The disposition kinetics of sulfamethoxypyridazine could be best described by a 2-compartment open model. The distribution and elimination half life of the drug were 0.10 ± 0.03 and 6.28 ± 0.44 h, respectively. The values of apparent volume of distribution at steady state and total body clearance were found to be 0.39 ± 0.02 l/kg and 0.73 ± 0.06 ml/kg/min, respectively. The degree of acetylation was low as it ranged between 4.49 ± 1.96 to 25.07 ± 6.31 % of the total drug in serum with an overall mean of 11.99 ± 1.66 %. Cumulative urinary excretion of sulfamethoxypyridazine was very low as only 2.97 ± 0.50 % of the total administered dose was excreted in urine during 24 h. The dosage regimen in goats would be 37.00 and 27.15 mg/kg body weight as the priming and maintenance doses respectively, to be repeated at 12 h intervals by intravenous route to achieve the bacteriostatic level of ≥ 25 µg/ml.