Pharmacokinetics of oxytetracycline in rainbow trout Oncorhynchus mykiss following bolus intravenous administration

The present study examined the pharmacokinetics of oxytetracycline in rainbow trout Oncorhynchus mykiss. The pharmacokinetics of oxytetracycline were determined after intravenous administration (50 mg/kg body weight). Serum concentrations of oxytetracycline were determined using high performance liquid chromatography with direct injection. Serum levels could be fitted to a two-compartment model. The calculated half-lives for the distribution phase (T-1/2 alpha) and the elimination phase (T-1/2 beta) were 0.5 and 52 h, respectively. The apparent volume of distribution (V-d beta) and total body clearance (Cl-B) were calculated to be 1.46 l/kg and 19.6 ml/kg/h, respectively. The area under the serum concentration-time curve was 2554 mu g . h/ml. Serum protein binding in vivo of oxytetracycline was 51.1 +/- 7.4%. As an application of this pharmacokinetic study, the oral bioavailability and the dosage regimens of oxytetracycline in rainbow trout were briefly evaluated.