Daily use of oral mifepristone dosed at 10 mg can significantly decrease the size of uterine fibroids and improve anemia, without any notable adverse reactions. To study the safety and efficacy of mifepristone 10 mg as compared to placebo, M L Bian and researchers performed a randomized controlled trial comprising 132 patients with uterine fibroids.

These patients were stratified into (a) Study group (66 patients) with patients on a tablet of mifepristone 10 mg daily and, (b) Control group (66 patients) with patients on a once-daily placebo tablet for 3 months. The rate of change of maximum leiomyoma (fibroid) volume was regarded as the primary efficacy evaluation indicator. Amenorrhea rate, recovery of subjective symptoms, and anemia were regarded as secondary efficacy evaluation indicators. Adverse events and variations in laboratory biochemical indicators were regarded as safety evaluation indicators.

The maximum leiomyoma volume decreased by 25.97% and 1.51% in the study and control group after 3 months of therapy. As compared to the control group, the rate of change of maximum leiomyoma volume was considerably higher in the study group prior to and following the use of mifepristone with the difference in the change rate of the maximum leiomyoma volume between the two groups being -24.84%, much higher than the fixed 10% superiority threshold goal.

Complete amenorrhea rate, dysmenorrhea elimination rate, and rate of disappearance of menstrual blood loss were considerably higher in the study group than the control group after 3 months. Statistically significant differences were observed in the case of mean hemoglobin, red blood cell count, and hematocrit between the two groups.

Serum estradiol level considerably reduced in the study group than the control group. Between the two groups, no significant differences in follicle-stimulating hormone and cortisol levels were observed. No significant adverse events were noted. Thus, mifepristone appears to be a promising drug therapy for uterine fibroids patients prior to surgery.