恩诺沙星在大菱鲆(Scophthalmus maximus)、牙鲆(Paralichthys olivaceus)和半滑舌鳎(Cynoglossus semilaevis)体内的残留消除规律

本研究比较了在20℃水温条件下恩诺沙星(Enrofloxacin)在3种主要养殖鲆鲽鱼大菱鲆(Scophthalmus maximus)、牙鲆(Paralichthys olivaceus)和半滑舌鳎(Cynoglossus semilaevis)]体内的残留消除规律。选择体重为300–400 g 的健康2龄大菱鲆、牙鲆和半滑舌鳎，以10 mg/kg 的剂量连续3 d 通过灌胃的方式分别给予恩诺沙星后，于1、3、6、10、15、20、25、30、35、40 d 采集血浆、肝、鳃、肌肉和肾组织。利用高效液相色谱法检测血浆和各组织中的恩诺沙星浓度，拟合恩诺沙星在3种鲆鲽鱼体内的消除曲线，计算消除半衰期。结果显示，3种鲆鲽鱼的组织中，恩诺沙星在肾中残留浓度最高，其消除速度依次为牙鲆>大菱鲆>半滑舌鳎，其消除半衰期分别为3.75、6.54、7.37 d；恩诺沙星在大菱鲆、牙鲆和半滑舌鳎血浆中的消除比其代谢产物环丙沙星慢；综合比较恩诺沙星在3种鲆鲽鱼血浆和大多数组织中的消除规律，均呈现出牙鲆体内消除最快，大菱鲆次之，半滑舌鳎最慢的趋势。依据我国无公害水产品中恩诺沙星最高残留限量为50μg/kg 的标准，建议在20℃水温条件下使用恩诺沙星防治鲆鲽鱼细菌性疾病时的休药期为：大菱鲆44 d、牙鲆33 d、半滑舌鳎47 d 以上。

Residue Dynamics of Enrofloxacin in Scophthalmus maximus,Paralichthys olivaceus and Cynoglossus semilaevis

In this study we compared the elimination rates of enrofloxacin in 3 major aquacultured flatfish, turbot (Scophthalmus maximus), olive flounder (Paralichthys olivaceus) and tongue sole (Cynoglossus semilaevis), in 20℃ seawater after the oral drug administration. Healthy turbot, olive flounder and tongue sole weighing 300-400 g were selected and orally administered with enrofloxacin for 3 consecutive days. Plasma and various tissues, such as liver, gill, muscle and kidney, were sampled on 1, 3, 6, 10, 15, 20, 25, 30, 35, and 40 days post drug administration, and the enrofloxacin concentration in these tissues were determined using reversed-phase high performance liquid chromatography (HPLC). The elimination curves of enrofloxacin for 3 flatfish species were plotted as concentration versus time, and the half-lives of the drug were calculated. It was found that in all 3 species the concentration of enrofloxacin residue was higher in kidney than in other tissues. Elimination of enrofloxacin in kidney of olive flounder was the fastest among the 3 flatfish species, followed by turbot and then tongue sole. Half-lives in the 3 species were 3.75, 6.54 and 7.37 days respectively. As for drug elimination in plasma, enrofloxacin was removed slower than its metabolite ciprofloxacin. Overall, elimination of enrofloxacin was the fastest in olive flounder followed by turbot, and it was the slowest in tongue sole. In China, the maximum residue limit (MRL) of enrofloxacin in seafood was 50 μg/kg, therefore the withdrawal periods of enrofloxacin for farmed turbot, olive flounder and tongue sole should be at least 44, 33 and 47 days respectively.