FDA Approves Myfembree to Treat Heavy Monthly Bleeding

Posted on June 28, 2021

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Key takeaways:

• Myfembree (relugolix/estradiol/norethindrone acetate) was recently FDA-approved to treat heavy monthly bleeding due to uterine fibroids — the first once-daily oral medication to treat this condition.
• Myfembree was very effective in clinical trials and helped lighten bleeding for over 70% of people taking it.
• Myfembree can cause bone loss, so you should only take it for a total of two years to avoid serious bone problems like osteoporosis.
• Myfembree is currently available at pharmacies, and the manufacturer offers various copay assistance programs to help with the cost of this medication.

Heavy monthly bleeding is a very common problem, affecting roughly 1 out of every 5 Americans who menstruate. This could mean your bleeding lasts for more than 7 days at a time, you have to change your pad or tampon more often than every 2 hours, or you pass clots larger than the size of a quarter. There are multiple causes for this, but one possible explanation for heavy monthly bleeding is uterine fibroids.

Uterine fibroids — often referred to as fibroids — are non-cancerous tumors that grow in or around the uterus. They can be experienced by anyone with internal reproductive organs and are estimated to affect between 20% and 80% of people who menstruate before age 50. Besides heavy bleeding, fibroids can also cause lower back pain, a feeling of fullness around your hips and genitals, and problems during pregnancy.

There are multiple ways to treat heavy bleeding due to fibroids, but recently Pfizer and Myovant Sciences announced the FDA approval of Myfembree (relugolix/estradiol/norethindrone acetate), the first once-daily medication approved to treat this fibroid symptom in people who menstruate. Since everyone responds uniquely to medications for heavy bleeding, having another option available is great news.

Here, we’ll discuss how Myfembree works, the side effects you can expect if you take this medication, and when you can expect it to be available.

What is Myfembree?

Myfembree is a combination of three medications: relugolix, estradiol, and norethindrone acetate. It comes available as a once-daily oral tablet that you can take with or without food.

You should begin your very first Myfembree prescription within 7 days of the start of your monthly bleeding. Once you start taking it, you will take it every day until your provider tells you to stop.

How does Myfembree work?

Relugolix belongs to a group of medications called gonadotropin-releasing hormone (GnRH) antagonists. It attaches to an area of your brain that signals the body to produce estrogen and progesterone — the two hormones responsible for a person’s monthly bleeding cycle. Once relugolix starts working, your body produces less of these hormones, and you experience less monthly bleeding.

Estradiol is a synthetic (lab-made) estrogen. While it may seem like taking an estrogen along with relugolix would cause opposite effects, estradiol actually plays an important role. Because relugolix lowers your natural estrogen a lot, you are at a higher risk for bone loss (more details on that later). Estradiol helps to prevent that side effect by providing your body with some of the estrogen it needs to keep your bones healthy.

Norethindrone acetate is a type of progestin — synthetic progesterone. Again, taking a progestin may seem like it would counteract relugolix’s effects, but it doesn’t. If you have a uterus and take a form of estrogen, such as estradiol, it is important to also take a progestin. Taking estrogen by itself raises your risk of developing endometrial cancer and progestins help lower that risk.

How effective is Myfembree?

In its phase 3 clinical trials — the last step before manufacturers can seek FDA approval — Myfembree helped relieve heavy bleeding for over 70% of people who took it. On average, people reported 84% less monthly bleeding while taking Myfembree. In fact, 50% of participants taking the medication stopped experiencing monthly bleeding altogether.

Is Myfembree safe?

Like all hormonal treatments, Myfembree does come with risks. One of the biggest warnings is that this medication can cause bone loss, so it shouldn’t be taken if you have osteoporosis. As mentioned earlier, the relugolix in Myfembree lowers your body’s natural estrogen, which plays a major role in keeping your bones healthy. Because of this serious side effect, you should only take Myfembree for a total of 2 years, and you will need to have your bone density checked before and while taking it.

Another serious side effect of Myfembree is a higher risk of blood clots. All medications that contain a form of estrogen carry this risk. Thankfully, clinical trials for Myfembree suggest the risk is low with this medication.

Of the more than 1,000 people who took the medication during studies, only 1 person developed blood clots. This person also had other risk factors for blood clots, which is why you should discuss your blood clot risk with your provider before taking Myfembree.

Other side effects of Myfembree

Myfembree was well-tolerated in studies. The most common side effects were:

• Hot flashes or night sweats
• High blood pressure
• Irregular monthly bleeding

Less common side effects included lower sex drive (low libido) and hair loss. Contact your provider if you notice anything unusual after starting Myfembree.

Because high blood pressure is a common side effect of Myfembree, you should not take it if you have untreated or uncontrolled hypertension (chronic high blood pressure). Myfembree could raise your blood pressure to unsafe levels or cause your hypertension to worsen.

Rarely, certain types of fibroids — called submucosal fibroids — can be pushed out of the uterus, leading to severe bleeding and pain. In clinical trials, this problem happened more often to people taking Myfembree than those taking a placebo (a pill with no medication in it). Contact your provider if you notice severe bleeding or cramping while taking Myfembree, as these can be signs of a fibroid that’s being pushed out of your body.

The estradiol in Myfembree can raise your risk for certain cancers, including breast cancer. Tell your provider if you have a personal or family history of any cancers, as this medication may not be the right choice for you. Be sure to discuss cancer warning signs to watch for and go to any cancer screening appointments with your provider while taking Myfembree.

Like all hormonal treatments, Myfembree can cause mood and behavior changes in some people. Let your provider know if you have a history of mental health conditions, and contact them right away if you notice any sudden mood swings or thoughts of suicide while taking this medication.

Myfembree cannot be taken if you’re pregnant, as it can cause a miscarriage. However, because Myfembree greatly lightens or completely stops monthly bleeding, it can make it difficult to tell if you are pregnant. Be sure to discuss which birth control method you should use with your provider before starting Myfembree, and contact them immediately if you become pregnant while taking this medication.

How does Myfembree compare to similar medications, such as Oriahnn?

Oriahnn (elagolix/estradiol/norethindrone acetate) is another medication used to treat heavy monthly bleeding due to fibroids. It is very similar to Myfembree and was the first oral medication of its kind to be FDA-approved for this condition. Like Myfembree, it contains a GnRH antagonist, an estrogen, and a progestin. While there are no published studies comparing Myfembree and Oriahnn, we can explain the differences between these competing medications.

How you take Oriahnn

Oriahnn is a twice-daily oral capsule you can take with or without food for up to 2 years total. The morning capsule has all three ingredients in it, but the evening dose only contains elagolix. This means you have to take the capsules in a certain order for them to work. Myfembree is simpler, as you only have to take one pill per day.

Oriahnn’s effectiveness

Oriahnn works well to help lessen monthly bleeding. Between 68% and 77% of people who took Oriahnn in studies experienced lighter bleeding, with about 50% reporting their monthly bleeding completely stopped while taking it. Although there are no studies comparing the two, Myfembree had similar results to Oriahnn in its clinical trials, so we can say they are both effective options for treating heavy bleeding.

Oriahnn’s side effects

Oriahnn carries the same rare but serious warnings as Myfembree (blood clots, bone loss, etc) and was also well-tolerated by people in studies. The most common side effects included hot flashes, headaches, tiredness, and unusual bleeding. You should expect a similar experience with both medications.

How much will Myfembree cost?

According to a recent U.S. Security and Exchange Commission (SEC) filing, a 28-day supply of Myfembree is expected to have a list price of about $975. While GoodRx will be able to offer you savings on this medication, it could still be pricey since it will have no generic version available for quite some time.

Myovant is offering savings through their Myfembree Support Program. They will offer a copay card for people with commercial insurance that should bring the price at the pharmacy down to $5 for most people. They will also have additional patient assistance programs available that will provide Myfembree free of charge for people who qualify. Check it out and see if you’re eligible for any of their savings programs today.

When will Myfembree be available?

Great news! Myfembree is already available. So if you have heavy monthly bleeding that’s caused by fibroids, talk to your provider at your next appointment to see if Myfembree is an option for you.

The bottom line

Myfembree is a combination medication that was recently FDA-approved to treat heavy monthly bleeding caused by uterine fibroids. In studies, it was very effective with few side effects, but it does carry some serious risks, including bone loss and a higher risk for blood clots. It’s best to discuss your medical history and risks for complications with your provider before taking this medication.

And be sure to check out Myfembree’s website for copay savings from Myovant before you head to the pharmacy to fill your first prescription.