Relugolix/Estradiol/Norethisterone Acetate: A Review in Endometriosis-Associated Pain

An oral fixed-dose combination of relugolix/estradiol/norethisterone (also known as norethindrone) acetate [Myfembree® (USA); Ryeqo® (EU)] (hereafter referred to as relugolix combination therapy) has been approved in the USA for the management of moderate to severe pain associated with endometriosis in premenopausal women and in the EU for the symptomatic treatment of endometriosis in adult women of reproductive age with a history of previous medical or surgical treatment for their endometriosis. The gonadotropin-releasing hormone (GnRH) receptor antagonist relugolix decreases estradiol and progesterone levels, while the addition of estradiol/norethisterone acetate mitigates hypoestrogenic effects including bone mineral density (BMD) loss and vasomotor symptoms. In two pivotal phase III trials, relugolix combination therapy significantly improved dysmenorrhoea and non-menstrual pelvic pain in premenopausal women with moderate to severe endometriosis. The combination also reduced overall pelvic pain and dyspareunia, reduced analgesic and opioid use, and improved health-related quality of life. The efficacy of relugolix combination therapy was sustained over the longer term (up to 2 years). Relugolix combination therapy was generally well tolerated and BMD loss over time was minimal. With the convenience of a once daily oral dosing regimen, relugolix combination therapy is a valuable addition to the options currently available for the management of endometriosis-associated pain. Endometriosis is a disease where tissue similar to the lining of the uterus grows outside the uterus and may reach other organs. This causes chronic pain as a result of increased inflammation and scar tissue. Women with endometriosis may experience painful menstrual periods, pelvic pain between periods, pain during sex, painful bowel movements and painful urination. Recently, a fixed-dose tablet comprising relugolix, estradiol and norethisterone (also known as norethindrone) acetate [Myfembree® (USA); Ryeqo® (EU)] (hereafter referred to as relugolix combination therapy) has been approved to treat endometriosis-associated pain. The treatment works by decreasing levels of ovarian hormones (estrogen and progesterone). In clinical trials, relugolix combination therapy improved period pain and pain between periods in women with moderate to severe pain associated with endometriosis. The treatment also improved other symptoms (overall pelvic pain and pain during sex), reduced the need for pain medications and improved health-related quality of life. Relugolix combination therapy was generally well tolerated and caused minimal bone loss, which is known to occur with some hormone therapies. With the convenience of a once daily oral pill, relugolix combination therapy is a valuable addition to the options currently available for women with endometriosis-associated pain.