Treating Endometriosis-Related Pain With Ethinylestradiol/Drospirenone Regimen

Researchers examined the efficacy of FlexibleMIB (ethinylestradiol/drospirenone) vs placebo as therapy for endometriosis-related pain.

A flexible extended regimen of 20 mg ethinylestradiol and 3 mg drospirenone (FlexibleMIB) was shown to be superior to placebo for reducing endometriosis-related pain in a randomized, phase 3, double-blind study published in Fertility and Sterility.1

In this trial (Comparative Study of BAY86-5300 With an Extended Flexible Regimen for Endometriosis; Identifier NCT01697111), patients with endometriosis were assigned to receive FlexibleMIB (n=130), placebo (n=129), or dienogest (n=53). Patients receiving FlexibleMIB or placebo were provided 1 tablet a day for 12 days. At week 24, the study participants receiving placebo were given FlexibleMIB. Participants in the dienogest group received 2 mg of the drug per day for a total of 52 weeks as a blinded reference. Investigators assessed the change in endometriosis-associated pelvic pain from baseline to the end of treatment.

FlexibleMIB led to greater relief in daily severe endometriosis-associated pelvic pain, assessed using a visual analog scale at 24 weeks compared with placebo (least squares mean difference, −26.3 mm; 95% CI, −31.6 to −20.9 mm; P <.0001). In addition, participants receiving FlexibleMIB also reported greater improvement in average pain, pelvic tenderness, limitations in uterine mobility, and other gynecologic findings. FlexibleMIB was also associated with a reduction in the size of endometriomas.

Overall, treatment-emergent adverse events were higher in the FlexibleMIB group than the placebo group (56.9% vs 21.9%, respectively), but many of these adverse events were categorized as mild in intensity (72.3% and 60.2%, respectively).

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The investigators suggest that the patients’ menstrual pattern could have given them an indication about the treatment they were receiving, thus “unblinding” the patients and limiting the validity of the findings. In addition, considering that this study did not perform a statistical analysis of the data, researchers believe the significance of the effect of FlexibleMIB has yet to be established.

Despite the proposed limitations, the researchers found that FlexibleMIB is associated with high treatment satisfaction among patients with endometriosis-associated pelvic pain and may potentially “provide a new alternative for managing endometriosis.”


Harada T, Kosaka S, Elliesen J, et al. Ethinylestradiol 20 μg/drospirenone 3 mg in a flexible extended regimen for the management of endometriosis-associated pelvic pain: a randomized controlled trial [published online September 11, 2017]. Fertil Steril. doi:10.1016/j.fertnstert.2017.07.1165

This article originally appeared on Clinical Pain Advisor