Comparison of Yuzpe regimen, danazol, and mifepristone (RU486) in oral postcoital contraception.
Authors: A. M. Webb, J. Russell, M. Elstein
Journal: BMJ (1992)

To compare the effectiveness and acceptability of three regimens of postcoital contraception.Randomised group comparison of ethinyloestradiol 100 micrograms plus levonorgestrel 500 micrograms repeated after 12 hours (Yuzpe method); danazol 600 mg repeated after 12 hours; and mifepristone 600 mg single dose.Community family planning clinic.616 consecutive women with regular cycles aged 16 to 45 years.Number of pregnancies, incidence of side effects, and timing of next period.The raw pregnancy rates (with 95% confidence intervals) for the Yuzpe, danazol, and mifepristone groups were 2.62% (0.86% to 6.00%), 4.66% (2.15% to 8.67%), and 0% (0% to 1.87%) respectively. Overall, these rates differed significantly (chi 2 = 8.988, df = 2; p = 0.011). The differences between the mifepristone and Yuzpe groups and between the mifepristone and danazol groups were also significant. Side effects were more common and more severe in the Yuzpe group (133 women (70%)) than in either the danazol group (58 (30%)) or the mifepristone group (72 (37%)). The Yuzpe regimen tended to induce bleeding early but mifepristone prolonged the cycle. Three women bled more than seven days late in the Yuzpe group compared with 49 in the mifepristone group.Mifepristone was effective in reducing expected pregnancy rates and the Yuzpe method also had a clinical effect. Danazol had little or no effect. A further multicentre trial is needed.In Manchester, England, a physician administered 3 different oral postcoital contraceptives to 616 16-45 year old women who came to the Palatine Centre obstetrics and gynecology clinic within 72 hours after intercourse, most of whom were 25 years old and primigravidae, to compare the effectiveness and acceptability of the 3 different postcoital methods. 66% were using a barrier method when they became pregnant. The probability of pregnancy was 34.7 pregnancies, but only 14 actually occurred. The researchers estimated 11.3 pregnancies for the women who followed the Yuzpe regimen (100 mcg ethinyl estradiol and 500 mcg levonorgestrel every 12 hours), but only 5 resulted for a pregnancy rate of 2.62%. 2 women continued their pregnancies and vaginally delivered full-term infants. They predicted 11.7 pregnancies for the women who took 600 mg danazol every 12 hours, but only 9 happened for a pregnancy rate of 4.66%. Only 1 woman continued her pregnancy and delivered a full term infant. They predicted 11.7 pregnancies for the women who took 1 dose of 600 mg mifepristone (RU-486) and no one became pregnant. There was a significant difference between the pregnancy rates of RU-486 and danazol (p=.004), but not between those of RU-486 and the Yuzpe regimen. The difference between the observed pregnancies and expected number of pregnancies had the women received no treatment was significant for RU-486 (p.001) and the Yuzpe regimen (p=.061). Women who followed the Yuzpe regimen were more likely to have nausea and vomiting (70% and 22%, respectively ) than those in the danazol (30% and 4%, respectively) and RU-486 groups (37% and 3%, respectively). The Yuzpe regimen was less likely to disrupt the regular menstrual cycle than the other 2 methods, however. For example, bleeding occurred 3 days late in only 6% of cases compared with 39% for RU-486 and 9% for danazol. RU-486 was the most effective method and was also acceptable due to minimal side effects.