Evaluation of ovulation and safety outcomes in a multi-center randomized trial of three 84 day ulipristal acetate regimens

Abstract

Objectives: To describe ovulation inhibition and safety of daily oral ulipristal acetate (UPA) over 84 days.

Study design: This multi-center phase 1 and/or 2 trial randomized participants to use oral ulipristal 10 mg or 5 mg daily or a 3 cycle regimen of 5 mg for 24 days followed by four placebo days. We stratified randomization by body mass index (BMI) <32 or 32-40 kg/m². To estimate ovulation inhibition, the primary outcome, participants underwent transvaginal ultrasound and blood sampling twice weekly; we analyzed compliant participants who completed the 84 day study. Safety endpoints included 3 endometrial biopsies and liver chemistry tests.

Results: We enrolled 180 participants and included 137 in the ovulation inhibition analyses. Progesterone values that remained below 3ng/mL throughout treatment suggested consistent ovulation inhibition in 52 of 137 (38%) participants; 25 of 47(53%), 20 of 44(45%), and 7 of 46(15%) among participants randomized to the 10 mg, 5 mg, and cyclic treatments, respectively (p < 0.01). Progesterone values consistently <3 ng/mL were more frequent in participants with a BMI > 32kg/m² (25/50(50%) vs 27/87(31%), p = 0.01). Average ulipristal concentrations were higher among participants with low progesterone concentrations (p < 0.01). Endometrial biopsies during treatment showed progesterone-receptor-modulator-associated endometrial changes in 52 of 164 participants (32%); 22 of 49(40%), 16 of 48(29%), and 14 of 51(26%) in women randomized to the 10 mg, 5 mg, and the cyclic treatments, respectively (p = 0.07, test-for-trend); these changes resolved after treatment cessation. Liver transaminase changes were rare.

Conclusions: Oral ulipristal acetate over 12 weeks did not reliably suppress ovulation, particularly in the 5 mg cyclic-dose group. Ovulation inhibition and endometrial changes were dose dependent. Reversible endometrial changes occurred during treatment.

Implications: Progesterone-receptor modulators have been suggested for daily oral contraception. Since progesterone concentrations suggest that ovulation occurred during treatment, further studies would be necessary to assess whether these were functional ovulations and to evaluate other possible mechanisms of contraception.

Keywords: Endometrial safety; Ovulation suppression; Pharmacodynamics; Ulipristal acetate.