为寻求米非司酮用于紧急避孕的最低有效剂量 ,在全国 11个省市的计划生育技术指导站及综合医院妇产科观察了 112 4例紧急避孕临床效果。对避孕失败或无保护性生活后 72 h内就诊并符合条件的健康妇女随机分为两组 :组 1(n=5 79)为单次口服米非司酮 2 5 mg,组 2 (n=5 45 )单次口服米非司酮 10 mg。组 1失败 5例 ,组 2失败 12例 ,按Dixon法计算两组避孕有效率分别为 91.2 5 %和 77.99% ,经检验 P<0 .0 1,两组间有显著差异 ;两组受试者的月经周期无明显改变且未出现明显副作用。该试验结果与单次服用米非司酮 6 0 0 mg、15 0 mg、5 0 mg、10 mg、5 mg临床研究报告相比较 ,就其避孕效果、对月经周期的影响和药物副作用而言 ,米非司酮 2 5 mg单次口服用于紧急避孕最为理想。 In order to seek the lowest effective dose of mifepristone for emergency contraception, 112 4 emergency contraception clinical effects were observed in the family planning technical guidance stations and general hospital obstetrics and gynecology departments in 11 provinces and cities nationwide. Healthy women eligible for treatment within 72 hours after contraception failure or unprotected life were randomly assigned to two groups: Group 1 (n = 5 79) received single oral mifepristone 25 mg, Group 2 (n = 5 45) Single oral mifepristone 10 mg. Group 1 failed in 5 cases, group 2 failed in 12 cases, according to Dixon method, the two groups contraceptive effective rates were 91.2 5% and 77.99%, respectively, after testing P <0 01, significant differences between the two groups; two groups of subjects Menstrual cycle no significant change and no obvious side effects. The test results and a single dose of mifepristone 600 mg, 150 mg, 50 mg, 10 mg, 5 mg clinical study compared to its contraceptive effect, the impact on the menstrual cycle and drug side effects , Mifepristone 25mg single orally for emergency contraception is the best.