Subcutaneous pharmacokinetic interaction of tulathromycin With flunixin meglumine in goats

Abstract

The pharmacokinetic aspects of tulathromycin(2.5 mg/kg) administered alone and in combination with flunixin meglumine (2.2 mg/kg) after a single subcutaneous (SC) administration, werestudied in clinically healthy goats. The animals were divided into two groups: the 1st group was given tulathromycin alone and the 2nd group was given tulathromycin concurrently with flunixin meglumine. Serum concentrations of tulathromycin were determined using microbiological assay method. Tulathromycin was rapidly absorbed with a half-life of absorption (t(0.5)ab) of 0.54 h and the peak plasma concentration (Cmax) was 3.7ug/ml was attained after 0.98 h (Tmax). Flunixin significantly altered the pharmacokinetics of tulathromycin by increasing its absorption and delay its elimination from body where t0.5(ab)were 0.54 and0.34 h and the elimination half-lives (t0.5(el)) were 1.35 and 1.8 h, for alone and combination groups, respectively. Significant decreases (39.8%) in the area under the curve (AUC) and (22.6%) in the elimination rate constant (Kel) from the central compartment were found following coadministration with flunixin compared with administration of tulathromycin alone. It was concluded that the combination of tulathromycin and flunixin negatively altered the kinetics of tulathromycin.