Safety and acceptability of intravaginal rings releasing estradiol and progesterone

This study aimed to evaluate the safety and acceptability of two fixed-dose 28-day vaginal ring formulations of 17β-estradiol (E2) and progesterone (P4) to treat vasomotor symptoms (VMS) and the genitourinary syndrome of menopause.

DARE HRT1-001 was the first-in-woman study of 28-day exposure to two 28-day intravaginal rings (IVRs) designed to release 80 µg/day E2 + 4 mg/day P4 (IVR1) or 160 µg/day E2 + 8 mg/day P4 (IVR2) compared with oral E2 1 mg/day + oral P4 100 mg/day. To assess safety, participants completed a daily diary to record treatment emergent adverse events (TEAEs). To determine acceptability, at the end of treatment IVR users completed a questionnaire assessing tolerability and usability.

Enrolled women (n = 34) were randomized to use IVR1 (n = 10), IVR2 (n = 12) or oral (n = 12). Thirty-one participants (IVR1 = 10, IVR2 = 10, oral = 11) completed the study. The TEAE profile of those in the IVR groups were similar to the referent oral regimen. TEAEs related to the study product were more common with IVR2 use. Endometrial biopsies were not performed unless endometrial thickness was >4 mm or for clinically significant postmenopausal bleeding. One IVR1 participant had an endometrial stripe increase from 4 mm at screening to 8 mm at the end of treatment. The biopsy indicated no evidence of plasma cells or endometritis and no evidence of atypia, hyperplasia or malignancy. Two other endometrial biopsies were performed for postmenopausal bleeding with similar findings. There were no clinically meaningful laboratory or vital sign abnormalities or trends identified in observed values or changes from baseline. Pelvic speculum examination identified no clinically significant abnormalities in any participant at any visit. Tolerability and usability data demonstrated that both IVRs were generally highly acceptable.

Both IVR1 and IVR2 were safe and well tolerated in healthy postmenopausal women. TEAE profiles were comparable to the referent oral regimen.