中文摘要：

[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法测定乳中思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思诺沙星长，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。

英文摘要：

[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.