A phase 2b multicenter, randomized, double-blind, placebo-controlled clinical trial to evaluate the efficacy and safety of vaginal rings containing nomegestrol acetate or etonogestrel and 17β-estradiol in the treatment of women with primary dysmenorrhea.

<bold>Objective: </bold>To evaluate the effect of investigational vaginal rings containing nomegestrol acetate (NOMAC) plus 17β-estradiol (E2) or etonogestrel (ENG) plus E2 in women with moderate to severe primary dysmenorrhea.<bold>Study Design: </bold>This was a Phase 2b randomized, placebo-controlled, multicenter, double-blind study. We randomized participants to one of five treatment groups: four hormonal rings and one placebo ring. The investigational vaginal rings released 300 μg of E2 daily along with 700 μg or 900 μg of NOMAC or 100 μg or 125 μg of ENG. Each participant received 2 identical rings and was to insert each for 21 days followed by a 7-day ring-free period. The primary endpoint, as assessed by a daily electronic diary (e-Diary), was the change in menstrual pain score from baseline to the second in-treatment withdrawal bleeding episode (Cycle 2). The pain score was the mean of the three highest scores for menstrual cramping pain (0-4 point scale) recorded from the day before menses to the third day of bleeding. The primary hypothesis was that at least one investigational vaginal ring would demonstrate a statistically significant larger reduction from baseline in pain score compared to placebo. Secondary endpoints included total mean impact score (which assessed the negative impact on work/school, physical activities, leisure/social activities) and the amount and days of rescue medication (ibuprofen) used.<bold>Clinical Trial Registration Number: </bold>NCT01670656.<bold>Results: </bold>We randomized 439 participants. The mean pain score decreased from baseline to Cycle 2 in all groups; the decrease in all four treatment groups compared to placebo was statistically significant (p-values ≤0.002). All treatment groups had greater reductions than placebo in ibuprofen intake and greater improvement in impact scores; these differences were statistically significant for both endpoints for the ENG-E2 100/300 μg/day group, while the other groups were not statistically significant for one or both endpoints.<bold>Conclusion: </bold>All four investigational rings produced a statistically significantly larger reduction from baseline in mean menstrual pain score compared to placebo while pain medication use decreased.<bold>Implications: </bold>This placebo-controlled study provides evidence that vaginal contraceptive rings containing NOMAC-E2 or ENG-E2 improve moderate to severe dysmenorrhea, across all of doses studied. This adds to the evidence that hormonal contraceptives are effective treatments for dysmenorrhea. [ABSTRACT FROM AUTHOR]