Pharmacokinetics of oxolinic acid and oxytetracycline in kuruma shrimp, Penaeus japonicus

The pharmacokinetics of oxolinic acid and oxytetracycline were examined in kuruma shrimp (Penaeus japonicus) after intra-sinus (10 and 25 mg/kg, respectively) and oral (50 mg/kg) administration. The shrimp were kept in tanks with recirculated artificial seawater at a salinity of 22-23 ppt. The water temperature was maintained at 25 +/- 0.6 degreesC. The hemolymph concentrations of both drugs after intra-sinus dosing were best described by a two-compartment open model. The distribution and elimination half-lives (t(1/2alpha) and t(1/2beta)) were found to be 0.59 and 33.2 h for oxolinic acid and 0.45 and 24.7 h for oxytetracycline, respectively. The apparent volume of distribution at a steady state (V-SS) and total body clearance (CLb) were estimated to be 1309 ml/kg and 28.8 ml/kg/h for oxolinic acid and 748 ml/kg and 22.7 ml/kg/h, respectively. The hemolymph concentration-time curves after oral administration did not fit by the nonlinear least squares method using one- and two-compartment model with first-order absorption in either of the drugs. The peak hemolymph concentration (C-max), the time to peak hemolymph concentration (t(max)) and the elimination half-life were found to be 17.8 mug/ml, 7 h and 34.3 h for oxolinic acid and 24.3 mug/ml, 10 h and 33.6 h for oxytetracycline, respectively. The bioavailability (F) after oral administration was 32.9% for oxolinic acid and 43.2% for oxytetracycline. The hemolymph protein binding in vivo was determined to be 36.7 +/- 8.5% for oxolinic acid and 22.9 +/- 4.8% for oxytetracycline. (C) 2004 Elsevier B.V. All rights reserved.