Pharmacokinetic/pharmacodinamics integration of sulfametazine in buffalo and cattle

Abstract

Sulfamethazine is a sulfonamide that presents a broad spectrum of activity, including Gram-positive and Gram-negative bacteria, Chlamydia spp. and some protozoa and it commonly used in ruminants. The aim of our work was to study the possible inter-species differences in the pharmacokinetic behavior and pharmacokinetic/ pharmacodynamic(PK/PD) integration of sulfamethazine after intravenous administration in buffalo and bovine. A single intravenous dose of 60 mg/kg was administered to six bovine and five buffalo (3-4 month old and weighting 120±15kg). Plasma concentrations of sulfamethazine were determined by high performance liquid chromatography. Differences between bovine and buffalo calves were found in t1/2λ (buffaloes: t1/2λ =6.17±0.58h; bovine t1/2λ=7.46±1.05h), Cl (buffaloes: 45.31ml/h·kg; bovines 30.34ml/h·kg). As a consequence of the lower clearance in bovines, the AUC and t1/2λ values were higher in this species. Important differences between bovine and buffalo exist for microorganisms that have a MIC value<32μg/ml related to time over minimum inhibitory concentration and weighted AUC.