Drug Therapy

Endometriosis: New Drug Improves Outcomes

Long-term use of the gonadotropin-releasing hormone antagonist elagolix is associated with improved outcomes in women with endometriosis, according to new findings.

Researchers reached this conclusion following a study of 569 women enrolled in 2 extension studies: Elaris Endometriosis (EM)-III and EM-IV. Each trial assessed participants for an additional 6 months of treatment after the completion of two 6-month, phase 3 trials.

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Two doses of elagolix—once-daily 150 mg and twice-daily 200 mg—were assessed. Primary efficacy endpoints included the proportion of responders who achieved clinically meaningful pain reduction and stable or decreased rescue analgesic use based on their average monthly dysmenorrhea and non-menstrual pelvic pain scores.

Responder rates to elagolix at 12 months were:

  • Dysmenorrhea: 52.1% with 150 mg once-daily and 78.1% with 200 mg twice-daily in Elaris EM-III participants, compared with 50.8% and 75.9%, respectively, in EM-IV participants.
  • Non-menstrual pelvic pain: 67.8% with 150 mg once-daily and 69.1% with 200 mg twice-daily in EM-III participants, compared with 66.4% and 67.2%, respectively, in EM-IV participants.
  • Dyspareunia: 45.2% with 150 mg once-daily and 60.0% with 200 mg twice-daily in EM-III participants, compared with 45.9% and 58.1%, respectively, in EM-IV participants.

The most commonly reported adverse event was hot flush, and no adverse endometrial findings were recorded. The researchers noted that 12-month treatment with elagolix was associated with decreased bone mineral density and increased lipids from baseline.

“Long-term elagolix treatment provided sustained reductions in dysmenorrhea, non-menstrual pelvic pain, and dyspareunia,” the researchers concluded. “The safety was consistent with reduced estrogen levels and no new safety concerns were associated with long-term elagolix use.”

—Christina Vogt


Surrey E, Taylor HS, Guidice L, et al. Long-term outcomes of elagolix in women with endometriosis: results from two extension studies. Obstet Gynecol. 2018;132(1):147-160. doi:10.1097/AOG.0000000000002675