Ethinylestradiol 20 μg/drospirenone 3 mg in a flexible extended regimen for the management of endometriosis-associated pelvic pain: a randomized controlled trial

To investigate the efficacy and safety of ethinylestradiol 20 μg/drospirenone 3 mg in a flexible extended regimen (FlexibleMIB) compared with placebo to treat endometriosis-associated pelvic pain (EAPP). A phase 3, randomized, double-blind, placebo-controlled, parallel-group study, consisting of a 24-week double-blind treatment phase followed by a 28-week open-label extension phase with an unblinded reference arm. Thirty-two centers. A total of 312 patients with endometriosis. Patients were randomized to FlexibleMIB, placebo, or dienogest. The FlexibleMIB and placebo arms received 1 tablet per day continuously for 120 days, with a 4-day tablet-free interval either after 120 days or after ≥3 consecutive days of spotting and/or bleeding on days 25–120. After 24 weeks, placebo recipients were changed to FlexibleMIB. Patients randomized to dienogest received 2 mg/d for 52 weeks in an unblinded reference arm. Absolute change in the most severe EAPP based on visual analog scale scores from the baseline observation phase to the end of the double-blind treatment phase. Compared with placebo, FlexibleMIB significantly reduced the most severe EAPP (mean difference in visual analog scale score: −26.3 mm). FlexibleMIB also improved other endometriosis-associated pain and gynecologic findings and reduced the size of endometriomas. FlexibleMIB improved EAPP and was well tolerated, suggesting it may be a new alternative for managing endometriosis. NCT01697111.