目的 从桂枝茯苓胶囊（Guizhi Fuling Capsules，GZFLC）临床用于治疗痛经的功效出发，探索建立基于子宫平滑肌收缩活性测定的GZFLC质量生物活性评价方法。方法 通过注射雌激素增加小鼠子宫敏感性，建立缩宫素诱导的小鼠离体子宫平滑肌收缩模型，采集给药前后小鼠子宫平滑肌的收缩频率、幅值和峰面积，以收缩峰面积为指标进行统计并对药效进行归一化处理。考察小鼠离体子宫平滑肌收缩模型的主要影响因素如雌激素注射方式与天数、缩宫素浓度、动物周龄和GZFLC前处理方法。建立GZFLC质量生物活性评价方法并进行方法学考察，测定10个批次GZFLC合格样品及2个GZFLC高温破坏样品的生物活性。结果 连续3 d ip雌激素10 mg/（kg·d）后小鼠子宫平滑肌收缩峰面积较高且收缩节律较好；最适缩宫素造模质量浓度为0.050 μg/mL；将GZFLC配制成质量浓度为0.125 g/mL的药液并超声溶解60 min有利于药效发挥；重复性考察RSD为11.298%，日内精密度RSD为12.452%，日间精密度RSD为10.438%；10批次GZFLC半数抑制浓度（half inhibitory concentration，IC50）为1.526～1.631 mg/mL，高温破坏后GZFLC的IC50明显增大。结论 基于子宫平滑肌收缩活性测定的GZFLC质量评价方法重复性和精密度较好，为后续GZFLC的综合质量评价标准建立提供了科学依据。
Objective To explore a method to evaluate the quality of Guizhi Fuling Capsules (桂枝茯苓胶囊, GZFLC) through its biological activity, which inhibits the contractile activity of uterine smooth muscle based on clinical anti-dysmenorrhea effect of GZFLC. Methods Uterine sensitivity in mice was increased by estrogen injection, and a contraction model of ex vivo uterine smooth muscle contraction in mice induced by oxytocin was established. The contraction frequency, amplitude and peak area of uterine smooth muscle before and after administration were recorded. Peak area was used as an indicator for normalized efficacy. The main influencing factors of the contraction model such as estrogen injection method and injection days, oxytocin concentration, animal age and GZFLC pretreatment methods were investigated. After the biological activity evaluation method of GZFLC was established, the methodology was investigated. A total of 10 batches of GZFLC qualified samples and two GZFLC high-temperature destruction samples were detected for biological activity. Results After ip 10 mg/(kg·d) estrogen for three consecutive days, the contraction peak area of smooth muscle was higher and the contraction rhythm was better; The optimal induction concentration of oxytocin was 0.050 μg/mL; The GZFLC was configured to a concentration of 0.125 g/mL and then dissolved ultrasonically for 60 min, which was conducive to the efficacy; The repeatability RSD was 11.298%, the intraday precision RSD was 12.452%, and the interday precision RSD was 10.438%; The half inhibitory concentration (IC50) of 10 batches of GZFLC was 1.526-1.631 mg/mL, and the IC50 of GZFLC was significantly increased after high temperature destruction. Conclusion The quality evaluation method of GZFLC based on anti-contractive activity of uterine smooth muscle is reproducible and precise, which provides a scientific basis for the establishment of comprehensive quality evaluation criteria for GZFLC.