Enrofloxacin (ENR) is widely used in aquaculture practice, but little is known about its pharmacokinetic, withdrawal period and dietary risk in fish via bath administration. The purpose of this study was to provide data support for the use of ENR bath therapy in the northern snakehead (Channa argus). The pilot study was carried out to evaluate the therapy concentrations of ENR in northern snakehead with immersion concentrations ranged from 5 to 40 mg/L for 6 h. Based on results of the pilot study, an ENR immersion concentration of 20 mg/L was used for the formal experiment. At this dose, the peak concentrations of ENR in plasma, muscle plus skin, liver and kidney were 4.85, 4.55, 3.87 and 7.42 μg/mL (or g), respectively. According to the AUC_0-∞ values, the distribution of ENR in northern snakehead followed the order of kidney > plasma > liver > muscle + skin. The elimination of ENR in northern snakehead was very slow, the half-lives (T_1/2λz) were up to 90.31, 85.5, 104.56 and 120.9 h in plasma, muscle plus skin, liver and kidney, respectively. Ciprofloxacin (CIP) was not detected in any samples in the pilot study and was only occasionally detected in muscle plus skin and liver samples in formal experiment. Based on the calculated PK/PD index AUC/MIC and C_max/MIC, the current bath treatment regimen will have a good therapeutic effect on infections caused by bacteria with MIC below 0.6 μg/mL. The dietary risk assessment suggested that there was a dietary risk (Hazard Quotients > 10%) until day 6 after bath treatment. It is mandatory for ENR to maintain a withdrawal period of at least 450°C-day in northern snakehead after bath treatment ceased.

中文翻译：

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恩诺沙星在乌鳢浴后的药代动力学、停药期及风险评估

恩诺沙星（ENR）广泛用于水产养殖实践，但对其药代动力学、停药期和通过浴液给药对鱼类的饮食风险知之甚少。本研究的目的是为乌鳢（Channa argus）使用ENR浴疗法提供数据支持。进行了初步研究，以评估 ENR 在北方黑鱼中的治疗浓度，浸泡浓度范围为 5 至 40 mg/L，持续 6 小时。根据预研究的结果，正式实验使用的 ENR 浸泡浓度为 20 mg/L。在此剂量下，血浆、肌肉加皮肤、肝脏和肾脏中 ENR 的峰值浓度分别为 4.85、4.55、3.87 和 7.42 μg/mL（或 g）。根据AUC _0-∞值，黑鱼ENR的分布顺序为肾脏>血浆>肝脏>肌肉+皮肤。ENR在黑鱼体内的消除非常缓慢，在血浆、肌肉加皮肤、肝脏和肾脏中的半衰期（T _{1/2λ z}）分别高达90.31、85.5、104.56和120.9 h。在初步研究中，没有在任何样本中检测到环丙沙星（CIP），在正式实验中，仅在肌肉、皮肤和肝脏样本中偶尔检测到。根据计算的PK/PD指数AUC/MIC和C _max /MIC，目前的浴浴治疗方案对于MIC低于0.6 μg/mL的细菌引起的感染将具有良好的治疗效果。饮食风险评估表明，直到沐浴治疗后第 6 天都存在饮食风险（危险商数 > 10%）。ENR 强制规定，在停止浴处理后，北方黑鱼必须保持每天至少 450°C 的戒断期。