Yang Fan, Zhang Chao-Shuo, Wang Han, Yang Fang
College of Animal Science and Technology, Henan University of Science and Technology, Luoyang, China.
Henan Provincial Open Laboratory of Key Disciplines in Environmental and Animal Products Safety, Henan University of Science and Technology, Luoyang, China.
J Vet Pharmacol Ther. 2020 Jan;43(1):79-86. doi: 10.1111/jvp.12822. Epub 2019 Nov 6.
The previously adopted marker residue for florfenicol (FF) in China was only florfenicol amine (FFA); however, the marker residue has been changed to FF plus FFA since the end of 2017. The previous official withdrawal period determined based on the only concentration of FFA may no longer be suitable. Therefore, the present study aimed to determine the depletion profiles of FF and FFA and further calculate the withdrawal period in the crucian carp (Carassius auratus) based on the new marker residues. Florfenicol was intramuscularly administered at 10 mg/kg bodyweight daily for five consecutive days to crucian carps reared in freshwater at 10°C. After the last dose, plasma and tissue samples were randomly collected from 10 fish at different time points. The FF and FFA concentrations were simultaneously determined by high-performance liquid chromatography (HPLC) with a fluorescence detector and further subjected to noncompartmental analysis. The elimination half-life (h) of FF in different tissues decreased as follows: liver (39.1) > kidney (36.3) > skin plus muscle (34.6) > plasma (31.7), whereas that of FFA decreased as follows: kidney (41.4) > skin plus muscle (39.4) > liver (39.3) > plasma (35.7). Considering a maximum residue limit of 1 μg/g for the total concentration of FF and FFA in the skin plus muscle, a withdrawal period of 6 days was calculated based on the upper limit of the one-sided 95% confidence interval.
中国此前采用的氟苯尼考（FF）的标识残留物仅为氟苯尼考胺（FFA）；然而，自2017年底起，标识残留物已变更为FF加FFA。之前基于仅FFA浓度确定的官方休药期可能不再适用。因此，本研究旨在确定FF和FFA的消除情况，并基于新的标识残留物进一步计算鲫鱼（Carassius auratus）的休药期。以10mg/kg体重的剂量，每天对饲养在10°C淡水中的鲫鱼进行连续5天的肌肉注射氟苯尼考。最后一次给药后，在不同时间点从10条鱼中随机采集血浆和组织样本。采用配有荧光检测器的高效液相色谱法（HPLC）同时测定FF和FFA的浓度，并进一步进行非房室分析。FF在不同组织中的消除半衰期（h）如下降低：肝脏（39.1）＞肾脏（36.3）＞皮肤加肌肉（34.6）＞血浆（31.7），而FFA的消除半衰期降低情况如下：肾脏（41.4）＞皮肤加肌肉（39.4）＞肝脏（39.3）＞血浆（35.7）。考虑到皮肤加肌肉中FF和FFA总浓度的最大残留限量为1μg/g，基于单侧95%置信区间的上限计算出休药期为6天。
