Myfembree is a once-daily oral tablet approved to treat heavy menstrual bleeding due to uterine fibroids and moderate to severe pain from endometriosis. According to studies, people who took Myfembree for fibroids had less menstrual blood loss and showed improvements in anemia. The majority of people taking Myfembree for endometriosis had less pain and were able to stop opioid pain medicine.
How Does It Work?
Myfembree contains three medicines:
- Relugolix
- Estradiol
- Norethindrone acetate
Relugolix lowers hormones in your body called estrogen and progesterone. The decrease in hormones helps to lower the bleeding associated with uterine fibroids and decrease the pain from endometriosis.
Estradiol is a form of estrogen that is included to help reduce the negative effect of relugolix on your bones. Estrogen helps to keep your bones strong and prevent osteoporosis. Replacing estrogen lost from relugolix may help reduce bone loss.
Norethindrone is a form of progesterone. It is included to help protect against endometrial cancer. Taking estradiol alone without progesterone raises the risk of this cancer.
Why Is a Pregnancy Test Necessary Before Starting Myfembree?
Myfembree is not safe to take during pregnancy. Taking Myfembree while pregnant or trying to get pregnant can cause early pregnancy loss. Although Myfembree contains hormones, it does not prevent pregnancy. Non-hormonal contraception (condoms, spermicides, diaphragm, etc) should be used while taking Myfembree and for at least 1 week after stopping Myfembree.
How Was It Studied?
The effect of Myfembree on blood loss during periods among people with uterine fibroids was determined in two studies. People in these studies were between 18 and 50 years old and had heavy bleeding during their periods. About half (53%) were Black, 41% were White, and 6% were of other races. The impact of the medicine on anemia among people with anemia was assessed, as well as pain from fibroids.
The effect of Myfembree on endometriosis pain was determined in two studies. People in these studies were between 18 and 50 years old and had moderate to severe menstrual pain and pain between their periods. The majority were White (91%), 6% were Black, and 3% were of other races. The study also looked at the use of pain medicine during Myfembree treatment. At the beginning of the study, 48% of people used opioid pain medication for endometriosis pain.
What Are the Benefits of Myfembree?
Most people taking Myfembree for uterine fibroids reported less heavy bleeding versus placebo (a pill with no medicine). Myfembree decreased bleeding and pain from fibroids, and hemoglobin levels improved in those with anemia through 6 months of treatment. Results are provided in the tables below. Your results may be different than what was seen in the studies.
Percentage of people with reductions in heavy bleeding
Placebo | Myfembree | |
Liberty 1 Study | 19% | 73% |
Liberty 2 Study | 15% | 71% |
The average change in percentage of menstrual blood loss
Placebo | Myfembree | |
Liberty 1 Study | 23% | 84% |
Liberty 2 Study | 15% | 84% |
Percentage of people who had improvements in anemia
Placebo | Myfembree | |
Liberty 1 Study | 22% | 50% |
Liberty 2 Study | 5% | 61% |
Percentage of people with improvements in pain
Placebo | Myfembree | |
Liberty 1 Study | 10% | 43% |
Liberty 2 Study | 17% | 47% |
Long-term studies looked at safety and efficacy through 2 years of treatment. Results showed that improvements in bleeding and pain were maintained through 2 years of treatment. Of those that continued Myfembree, 70% had less bleeding for 2 years. Once Myfembree was stopped, heavy bleeding returned around week 6 in most people.
For endometriosis, most people had a decrease in both menstrual pain and pain between periods. Results are shown in the tables below. Your results may be different from what was seen in the clinical studies.
Percentage of people with less pain during periods
Placebo | Myfembree | |
Spirit 1 Study | 27% | 75% |
Spirit 2 Study | 31% | 75% |
Percentage of people with less pain between periods
Placebo | Myfembree | |
Spirit 1 Study | 40% | 59% |
Spirit 2 Study | 43% | 66% |
Pain relief started as early as 4 weeks. The greatest relief from menstrual pain occurred at 8 weeks and continued throughout the study. The greatest relief from pelvic pain between periods occurred at 12 weeks and continued throughout the study.
A long-term study looked at the effects through 2 years of treatment. After 2 years of treatment, 91% of people no longer needed opioid pain medicine and 75% of people did not need analgesic pain medicine.
How Long Until Full Effects Happen?
For heavy bleeding due to uterine fibroids, you may see improvement in symptoms within 4 weeks of starting treatment. The greatest improvement may occur around week 12 and should continue throughout treatment.
For endometriosis, pain may improve in about 4 weeks with the greatest improvement around
8 weeks for menstrual pain and 12 weeks for pelvic pain between periods. Pain relief should continue throughout treatment.
How Do I Know If It Is Working?
If you are taking Myfembree for heavy bleeding due to uterine fibroids, you may start to see a change in about 4 weeks. You should notice less bleeding and discomfort.
If you are taking Myfembree for endometriosis, you may have less pain starting within 4 weeks with full improvement at 8-12 weeks. If Myfembree does not relieve heavy bleeding and pain, notify your health care provider.
Is It Right for Me?
Myfembree may be right for you if you experience heavy bleeding due to uterine fibroids or you have moderate to severe pain associated with endometriosis. Myfembree is only approved for people over the age of 18 who have not gone through menopause yet. Talk with your health care provider for more information.
Myfembree was not studied in people with certain health conditions because it can increase the risk of serious side effects. You should not take Myfembree if you have a history of heart attacks, stroke, or blood clots, as Myfembree increases this risk. Your risk is also increased if you are over the age of 35 and smoke.
Myfembree contains hormones, which can cause hormone-sensitive cancers to spread or develop. Do not take Myfembree if you have a history of hormone-sensitive cancer. You should also avoid Myfembree if you are taking hormonal birth control.
Myfembree is only for people with pelvic pain and heavy bleeding from fibroids and endometriosis. If you have pelvic pain or bleeding from other causes, you should avoid Myfembree.
Myfembree may cause bone loss, so you should not take it if you have osteopenia or osteoporosis. Myfembree should not be taken longer than 24 months to limit the effect it has on your bones.
What Can I Do to Treat/Manage Side Effects?
The most common side effects of Myfembree are headaches, irregular menstrual bleeding, and hot flashes. Headaches and hot flashes occur because Myfembree lowers estrogen levels in your body.
To limit headaches, be sure you are getting enough sleep, staying hydrated, exercising, and not skipping meals. Hot or cold compresses, meditation, resting in a cool, dark room, and massage may also help.
To manage hot flashes, dress in layers so you can remove clothing if necessary. Avoid alcohol, spicy foods, and caffeinated beverages, as they can trigger hot flashes.
Myfembree can cause bone loss, which can lead to osteopenia or osteoporosis. Calcium and vitamin D are essential for healthy bones. Be sure you are getting enough calcium and vitamin D. Calcium can be found in dairy products, beans, seeds, broccoli, oranges, and green leafy vegetables.
Vitamin D helps your body absorb calcium. It can be found in fortified foods such as milk, cereal, and orange juice. Eggs and fatty fish, like salmon and sardines, also have small amounts of vitamin D. Your body also makes vitamin D when your skin is exposed to sunlight. Aim for 5 to 30 minutes a day of sun exposure without sunscreen. Those at risk for skin cancer should speak with their health care provider. Supplements are also available if you do not get enough calcium and vitamin through diet and sun exposure.
Myfembree can increase your risk of heart attack, stroke, or blood clots that can lead to death. Get emergency care right away if you experience any of the following symptoms:
- Chest pain or pressure
- Trouble breathing
- Leg pain or swelling that won’t go away
- Pain in your back, jaw, throat, or arm
- Sudden and severe headache
- Slurred speech or trouble speaking
- Weakness or numbness on one side of the body
- Sudden vision changes
You can minimize your risk of heart attacks and stroke by eating a healthy diet, exercising, lowering stress levels, and getting enough rest. You should also avoid smoking and limit alcohol use.
This is not a complete list of side effects of Myfembree. Speak with your health care provider if side effects don’t go away or become bothersome. You can report side effects to the Food and Drug Administration (FDA) at 800-FDA-1088.
How Do I Take It?
Myfembree is a tablet that is taken by mouth once daily. It can be taken with or without food and should be taken at the same time every day. It should be started as soon as you get your period or within 7 days.
If you miss a dose, take it as soon as you remember the same day, then resume your regular dosing schedule the next day. Do not take two doses in the same day.
What Types of Drug Interactions Can Happen and How Can I Tell if a Drug Interaction Is Happening?
Several medications can interact with Myfembree. This can decrease how well Myfembree works or increase your risk of side effects. Some medicines that inhibit a protein called P-glycoprotein (P-gp) should either not be taken with Myfembree or be taken 6 hours apart. Ask your health care provider if you are taking a P-gp inhibitor. If you take both Myfembree and a P-gp inhibitor 6 hours apart, tell your health care provider if you get any side effects.
Other medicines are called inducers of both P-gp and an enzyme called CYP3A4. These medicines may make Myfembree not work very well. Ideally, you will not take both Myfembree and a P-gp/3A4 inducer. Ask your health care provider if any of your medicines may cause this interaction. If you do, tell your health care provider if you feel that Myfembree is not working.
Tell your health care provider and pharmacist about all prescription, over-the-counter (OTC) medications, vitamins/minerals, herbal products, and supplements you take or have recently taken. This will help determine if there are any interactions with Myfembree.
How Long Does It Stay in Your System?
It takes about 10-12 days for Myfembree to be eliminated from the body after the last dose. This is why you should continue using a barrier birth control for at least 7 days after your last dose of Myfembree.
What Do I Need to Do to Get It?
Myfembree requires a prescription. Your primary care doctor or gynecologist can prescribe Myfembree. It is available at retail and mail-order pharmacies.
Is There Any Cost Assistance Available?
A copay assistance program is available from the manufacturer and may allow you to pay as little as $5 for your prescription each month. Eligibility depends on your current prescription insurance coverage.
Those without insurance or those whose insurance doesn't pay for Myfembree may be eligible to receive the medication at no cost through the Myovant Sciences Assistance Program. You can find out more information at www.myfembree.com/cost-and-support or by calling 833-MYFEMBREE (833-693-3627).
For questions about cost, insurance coverage, or any other questions related to Myfembree, you can call Myovant Sciences at 833-MYOVANT (833-696-8268).
