PHARMACOKINETIC AND TISSUE DISTRIBUTION STUDY OF OXYTETRACYCLINE IN RAINBOW-TROUT FOLLOWING BOLUS INTRAVENOUS ADMINISTRATION

Oxytetracycline pharmacokinetics and tissue distribution were studied in rainbow trout following bolus i.v. administration at 5 mg/kg. The mean serum (log) drug concentration data were plotted against time (linear). The decay curve was described by a three-component exponential decay function and a three-compartment model. The t1/2 of rapid distribution was 0.9 h, the t1/2 of the slow distribution was 5.9 h and the t1/2 elimination was 81.5 h. Clearance was 25.4 ml/kg/h and V(d(area)) 2988 ml/kg. Regression analysis of the serum levels for the three intervals, 0.5-2.0 h, 6.0-18.0 h, and 24-96 h, indicated that the rates of decay for each interval were 0.6151 h-1, 0.0564 h-1 and 0.0088 h-1 respectively. Rates of equilibration between tissues and serum were determined. Kidney equilibrated the fastest with t1/2 to equilibration of 1.1 h for H (anterior) kidney and 1.98 h for P (posterior) kidney. The highest drug levels were found in the liver and the lowest were in the brain.