A recent double-blind, randomized clinical trial conducted in China has explored the potential of weekly mifepristone administration as a contraceptive method. The study, which involved 83 women across three centers, investigated the efficacy and safety of two different weekly doses of mifepristone, 25mg and 50mg. The results indicate promising contraceptive effects with no pregnancies reported across 456 women-months of use.
The trial, designed to assess contraceptive efficacy, changes in menstrual patterns, and side effects, assigned women to either the 25mg or 50mg mifepristone group. Each study cycle was defined as 28 days, and bleeding data were meticulously collected using menstrual cards. Of the 83 women enrolled, outcomes were known for 76, with 39 in the 25mg group and 37 in the 50mg group.
The primary finding of the study was the absence of pregnancies in both groups throughout the trial period. Further analysis revealed notable differences in menstrual patterns between the two dosage groups. In the later cycles (cycles 4, 5, and 6), the 50mg group exhibited significantly fewer mean bleeding days (0.86, 1.05, and 0.62 days, respectively) compared to the 25mg group (3.5, 2.87, and 2.4 days, respectively). Conversely, the 50mg group had significantly more mean no bleeding days (26.07, 25.95, and 26.11 days, respectively) than the 25mg group (22.93, 23.23, and 23.51 days, respectively).
Notably, the percentage of women experiencing no bleeding in a 28-day cycle was also significantly higher in the 50mg group (22.3%, 25%, and 21.1% for cycles 4, 5, and 6, respectively) compared to the 25mg group (2.6%, 3.9%, and 3.9%, respectively). These findings suggest a dose-dependent effect of mifepristone on menstrual bleeding patterns.
Regarding safety and tolerability, the study reported that side effects such as nausea and breast distension were uncommon and generally mild in both groups. This favorable safety profile adds to the appeal of mifepristone as a potential contraceptive option.
While these initial results are encouraging, further research is warranted to fully elucidate the long-term efficacy and safety of weekly mifepristone as a contraceptive. Larger, more diverse populations should be studied, and the potential impact on endometrial health should be carefully evaluated. Nevertheless, this study provides a promising foundation for the development of a novel, non-invasive contraceptive method.
