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&plusmn;15kg). Plasma concentrations of sulfamethazine were determined by high performance liquid chromatography. Differences between bovine and buffalo calves were found in t&frac12;&lambda; (buffaloes: t1/2&lambda; =6.17&plusmn;0.58h; bovine t1/2&lambda;=7.46&plusmn;1.05h), Cl (buffaloes: 45.31ml/h&middot;kg; bovines 30.34ml/h&middot;kg). As a consequence of the lower clearance in bovines, the AUC and t&frac12;&lambda; values were higher in this species. Important differences between bovine and buffalo exist for microorganisms that have a MIC value<32&mu;g/ml related to time over minimum inhibitory concentration and weighted AUC.