Residues of Ampicillin and Amoxicillin in Olive Flounder Paralichthys olivaceus Following Oral Administration

Residues of ampicillin and amoxicillin in the muscles of olive fl ounder Paralichthys olivaceus were investigated after oral doses of 20 mg/kg body weight/day of ampicillin and 40 mg/kg body weight/day of amoxicillin in a fi rst examination and 40 mg/kg body weight/day of ampicillin and 80 mg/kg body weight/day of amoxicillin in a second examination for 5-6 days. The ranges of seawater temperatures in the 1 st and 2 nd examinations were 13.4-15.6 o C and 16.8-21.4 o C, respectively. Ampicillin and amoxicillin concentrations were analyzed by high performance liquid chromatography (HPLC). The average recovery rates of ampicillin and amoxicillin in fi sh samples ranged from 84.8- 95.2% and 100.8-103.8%, respectively. Residual concentrations in the olive flounder peaked on the 5 th day, with average concentrations of 0.075 mg/kg and 0.311 mg/kg in the 1 st examination, and 0.098 mg/kg and 0.630 mg/kg in the 2 nd examination for ampicillin and amoxicillin, respectively, with maximum concentrations in muscle. In the 1 st examination, ampicillin concentrations in olive fl ounder after withdrawals of 1 and 3 days were 0.041 mg/kg and 0.023 mg/kg, respectively, and amoxicillin concentrations after withdrawals of 1 day and 10 days were 0.172 mg/kg and 0.023 mg/kg, respectively. In the 2 nd examination, the ampicillin concentrations in olive fl ounder after withdrawals of 1 and 3 days were 0.041 mg/kg and 0.023 mg/kg, respectively, and amoxicillin concentration after withdrawals of 1 day and 10 days were 0.172 mg/kg and 0.023 mg/kg, respectively. We suggest that the recommended withdrawal periods should be 3 days for ampicillin and 10 days for amoxicillin in the olive fl ounder.