Pharmacokinetics of oxytetracycline in black tiger shrimp, Penaeus monodon, and the effect of cooking on the residues

The present study examined the pharmacokinctics and bioavailability of oxytetracycline (OTC) in black tiger shrimp (Penaeus monodon) after intra-sinus (10 mg/kg) and oral (50 mg/kg) administration in water (salinity of 5 ppt) at 29-30 degrees C and also investigated the net changes of OTC residues in the shrimp using cooking procedures (boiling, baking and frying). The hemolymph concentrations of OTC after intra-sinus dosing were best described by a two-compartment open model. The distribution and elimination half-lives were found to be 0.20 h and 16.2 h, respectively. The apparent volume of distribution at a steady state and the total body clearance were estimated to be 869 ml/kg and 38.7 ml/kg/h, respectively. The bioavailability of OTC after an oral administration in black tiger shrimp was found to be 35.6%. The hemolymph protein binding in vivo of OTC was 49.0 +/- 7.6%. The protein binding was constant over the concentration range tested at each sampling time point. The peak hemolymph concentration, the time to peak hemolymph concentration and the elimination half-life were found to be 21.1 mu g/ml, 4 h and 16.4 h, respectively. The residual OTC was rapidly eliminated from muscle with the elimination half-life value of 22.0 h. The OTC levels in muscle fell below the MRL (0.2 mu g/g) at 120 h post-dosing. However, the OTC level in shell increased to a high level (6.27 mu g/g) at 10 h post-administration and had not decreased at the last sampling time (120 h). OTC residues were lower in all cooked samples than in corresponding raw samples. Residual OTC in muscle was reduced by 30-60% by boiling, baking and frying, whereas in shell, OTC was reduced by 20% in every cooking method. (c) 2005 Elsevier B.V. All rights reserved.