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# Myfembree Wins OK for Endometriosis Pain
- URL: https://www.fdaweb.com/myfembree-wins-ok-for-endometriosis-pain/
- Published: 2022-08-08T12:00:00.000Z
- Updated: 2026-09-14T17:54:58.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5152461

FDA has approved Myovant Sciences/Pfizer’s Myfembree (relugolix 40 mg, estradiol 1 mg, and norethindrone acetate 0.5 mg) as a one-pill, once-a-day therapy (treatment duration up to 24 months) for managing moderate to severe pain associated with endometriosis in pre-menopausal women. Previously, the drug was approved for managing heavy menstrual bleeding associated with uterine fibroids in premenopausal women.

The approval is based on data from the Phase 3 SPIRIT program, which included two 24-week multi-national clinical studies (SPIRIT 1 and SPIRIT 2) in more than 1,200 women with pain associated with endometriosis, as well as the first 28 weeks of an open-label extension study to assess its longer-term use. “Overall, these studies showed Myfembree reduced menstrual pain and non-menstrual pelvic pain with a loss of mean bone mineral density of less than 1% from baseline through one year of treatment,” the companies say.

SPIRIT 1 and 2 each met their co-primary endpoints with 75% of women taking Myfembree achieving a clinically meaningful reduction in dysmenorrhea compared with 27-30% of women in the placebo groups at Week 24\. “For non-menstrual pelvic pain, treatment with Myfembree demonstrated a clinically meaningful reduction in pain in 59% and 66% of women, compared with 40% and 43% of women in the placebo groups,” they say.

Adverse reactions occurring in at least 3% of women treated with the drug and greater than placebo were: headache, vasomotor symptoms, mood disorders, abnormal uterine bleeding, nausea, toothache, back pain, decreased sexual desire and arousal, arthralgia, fatigue, and dizziness, according to the companies.