恩诺沙星及其代谢产物在奶牛乳中的消除规律

Depletion of Enrofloxacin and Its Metabolite in the Milk of Lactating Cows

【目的】研究乳房炎奶牛单剂量乳房灌注1%恩诺沙星(50ml/头)后乳中药物浓度的变化规律。【方法】采用HPLC法测定乳中恩诺沙星及其代谢产物环丙沙星的浓度,用统计矩原理处理药物浓度—时间数据。【结果】在给药区恩诺沙星和代谢产物环丙沙星均于给药后2h左右乳中浓度达到最高值,分别为(13.16±3.10)μg·ml-1和(2.79±0.94)μg·ml-1,然后逐渐下降;12h后检测不到恩诺沙星,24h已检测不到环丙沙星。对于非给药区,恩诺沙星给药后1h左右乳中浓度达到最高值(0.19±0.02)μg·ml-1,然后逐渐下降;6h后检测不到恩诺沙星,而代谢产物环丙沙星于给药后4h乳药浓度可达最高峰(0.51±0.07)μg·ml-1,24h已检测不到乳药浓度。给药区代谢物环丙沙星的消除半衰期较恩诺沙星长,平均为(1.67±0.20)h,平均滞留时间(MRT)亦长。在本试验条件下,建议临床休药期不少于3d。【结论】恩诺沙星吸收较迅速,代谢较快、清除较快,表明恩诺沙星与环丙沙星在乳中不会形成残留。

[Objective] Depletion of enrofloxacin and its metabolite in the milk were studied in mastitis cows after a single intramammary dose of 500 mg per quarter. [Method] Concentration of enrofloxacin and its metabolite ciprofloxacin were determined by high-performance liquid chromatography with fluorescence detector and the concentration-time data were analyzed by statistical moment principle. [Result] Enrofloxacin and its metabolite ciprofloxacin were all at the peak after 2 hours in the administered quarter. The concentrations were （13.16±3.10） μg·ml^-1 and （2.79±0.94） μg·ml^-1, respectively. Enrofloxacin and its metabolite ciprofloxacin can not be detected after 12 hours and 24 hours. In the healthy quarter enrofloxacin was at the peak after 1 hour and the concentration was （0.19±0.02） μg·ml^-1. Enrofloxacin can not be detected after 6 hours. Ciprofloxacin was at the peak after 4 hours and the concentration was （0.51±0.07） μg·ml^-1. Ciprofloxacin can not be detected after 24 hours. In the administered quarter, ciprofloxacin showed longer t1/2β which is （1.67±0.20） h in milk and maintained longer period than enrofloxacin. Under the experiment condition, it is suggested that the clinical withdrawal time should not be less than three days. [Conclusion] The results showed that enrofloxacin in mastitis cows is of rapid absorption, metabolism and elimination . Enrofloxacin and its metabolite ciprofloxacin are not residuary in milk.