Relugolix is an oral medicine that lowers the levels of sex hormones (testosterone in men, estrogen in women) by blocking signals from the brain to the reproductive glands. It belongs to a class of medicines called GnRH receptor antagonists, used for advanced prostate cancer in men and for heavy menstrual bleeding from uterine fibroids and pain from endometriosis in women. It is a prescription-only medicine.

• Therapeutic Class: Hormonal therapy (oncology use in men; gynecologic use in women).

• Pharmacological Class: Gonadotropin-releasing hormone (GnRH) receptor antagonist.

• Drug Family: Non-peptide, orally active GnRH antagonists.

• ATC Classification: L02BX04 (Relugolix, prostate cancer use) / G03XA (Relugolix combination, gynecologic use).

• Approved (men, Orgovyx): Advanced prostate cancer, as androgen deprivation therapy.

• Approved (women, Myfembree/Ryeqo): Management of heavy menstrual bleeding associated with uterine fibroids in premenopausal women, and management of moderate to severe pain associated with endometriosis.

• Commonly used for: Men with advanced prostate cancer needing testosterone suppression, and women with fibroid-related heavy bleeding or endometriosis pain not adequately controlled by other treatments.

● Oral tablets (Orgovyx, monotherapy): 120 mg, for once-daily use in men.

● Oral tablets (Myfembree/Ryeqo, combination): relugolix 40 mg / estradiol 1.0 mg / norethindrone acetate 0.5 mg, for once-daily use in women.

Relugolix blocks GnRH receptors in the pituitary gland, which normally trigger the release of hormones (LH and FSH) that stimulate the testes to produce testosterone or the ovaries to produce estrogen. By blocking this signal, relugolix rapidly and reversibly lowers testosterone levels in men (helping starve prostate cancer cells that depend on testosterone) or reduces estrogen-driven symptoms in women with uterine fibroids or endometriosis. In the combination product for women, low-dose estradiol and norethindrone acetate are added back to help offset the low-estrogen side effects that would otherwise result from full hormone suppression.

• Standard dose (Orgovyx, prostate cancer): A single 360 mg loading dose (three 120 mg tablets) on the first day, followed by 120 mg once daily thereafter.

• Standard dose (Myfembree/Ryeqo, uterine fibroids/endometriosis): One tablet (relugolix 40 mg/estradiol 1 mg/norethindrone acetate 0.5 mg) taken orally once daily; for uterine fibroids, treatment duration is currently approved for up to 24 months.

• Route: Oral, once daily, at approximately the same time each day, with or without food.

• Missed dose: Take as soon as remembered on the same day; if a full day is missed, resume the regular schedule the next day without doubling up.

• Overdose: May intensify known hormone-related side effects; requires medical attention.

• Common (men, Orgovyx): Hot flashes, fatigue, musculoskeletal pain, and elevated blood glucose/lipids.

• Common (women, Myfembree): Hot flashes, irregular bleeding patterns (especially early in treatment), headache, and nausea.

• Serious: Increased risk of cardiovascular events (particularly noted in men with pre-existing cardiovascular risk factors), and, for the combination product, risks associated with the estrogen/progestin component (blood clots, stroke, and other estrogen-related risks).

• Emergency symptoms: Chest pain, sudden weakness or numbness, sudden shortness of breath, leg swelling or pain (possible blood clot), or severe headache.

• Recovery advice: Hot flashes are common with hormone-suppressing therapy and often ease over the course of treatment; any new chest pain, leg swelling, or neurological symptoms should be reported immediately given the cardiovascular/clotting considerations.

• Pregnancy: Contraindicated in women who are pregnant or may become pregnant (relevant to the Myfembree/Ryeqo combination product); not applicable to Orgovyx, used only in men.

• Breastfeeding: Not recommended during treatment with the combination product; relugolix has been detected in breast milk in lactation studies.

• Liver disease: The combination product (with estrogen) is generally avoided in significant liver impairment; Orgovyx is used with routine monitoring.

• Kidney disease: Used with routine monitoring; no specific major dose adjustment established.

• Elderly: Orgovyx is commonly used in this age group, as prostate cancer is more common with age, with attention to cardiovascular risk factors.

• Children: Not approved for use in children.

● P-glycoprotein inhibitors (e.g., certain antifungals, some antibiotics): can increase relugolix levels; use with caution or adjust dosing timing.

● Strong CYP3A4 inducers: may reduce estradiol/norethindrone levels in the combination product, potentially reducing effectiveness.

● Other hormone-based therapies: not typically combined with additional hormonal treatments outside the specific approved combination formulation.

● Anticoagulants: relevant primarily to the estrogen-containing combination product, given its own associated clotting risk considerations.

● Testosterone levels periodically (men, Orgovyx) to confirm adequate suppression.

● Cardiovascular risk assessment, particularly in men with pre-existing heart disease risk factors.

● Bone mineral density assessment with longer-term use, given hormone suppression's effect on bone health.

● Bleeding pattern monitoring (women, Myfembree/Ryeqo) and blood pressure checks given the estrogen/progestin component.

Leuprolide, Goserelin (GnRH agonists, injectable, different administration route, men); Elagolix (another oral GnRH antagonist combination, women).

Orgovyx is used as monotherapy for prostate cancer, sometimes alongside other prostate cancer treatments as directed by the oncologist. Myfembree/Ryeqo is itself a fixed combination of relugolix with estradiol and norethindrone acetate, specifically formulated as add-back hormone therapy to reduce low-estrogen side effects.

● Prostate Cancer Medicines

● Uterine Fibroid & Endometriosis Treatments

● GnRH Receptor Antagonists

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1. https://www.pfizer.com/news/press-release/press-release-detail/myovant-sciences-and-pfizer-announce-fda-acceptance

2. https://www.fertstertreports.org/article/S2666-3341(22)00121-0/fulltext

The information on this page is for educational purposes only and is not a substitute for medical advice. Please consult your doctor to know if this treatment is appropriate for your condition.