Exondys 51 is a brand-name prescription medication. It’s FDA-approved to treat Duchenne muscular dystrophy (DMD) in people who have a certain gene mutation. “Gene mutation” means that a specific gene isn’t working the way it should.

To use Exondys 51, a person must have a mutation in the DMD gene that can be treated by “skipping” exon 51. An exon is a part of a gene. In this case, exon 51 refers to a specific exon in the DMD gene. For more information on how Exondys 51 works, including an explanation of exon skipping, see the “How Exondys 51 works” section below.

Exondys 51 comes as a clear solution that’s given as an intravenous infusion by a healthcare provider. (An intravenous infusion is an injection into a vein that’s given over a period of time.) You may receive this infusion at a doctor’s office or an infusion clinic. Or a healthcare provider may give you this infusion at home.

Exondys 51 is available in one strength: 50 milligrams per milliliter (mg/mL).

The active drug in Exondys 51 is eteplirsen. Eteplirsen belongs to a class of medications known as antisense oligonucleotides.

Accelerated approval

In 2016, the Food and Drug Administration (FDA) gave Exondys 51 accelerated approval. This type of approval is based on information the FDA reviewed from early clinical trials of the medication. The FDA won’t make a decision on full approval of Exondys 51 until after additional clinical trials have been completed.

Usually, medications receive approval from the FDA after extensive studies are completed. But for some drugs, approval may be granted before all studies have been finished. Accelerated approval is reserved for certain drugs designed to treat conditions that don’t have a lot of successful treatment options.

Exondys 51 is the first medication that’s FDA-approved to treat DMD. More trials are being conducted to confirm the FDA’s approval of Exondys 51 for this condition.

Effectiveness

For information about the effectiveness of Exondys 51, see the “Exondys 51 uses” section below.

Exondys 51 is available only as a brand-name medication. It’s not currently available in generic form.

A generic drug is an exact copy of the active drug in a brand-name medication. Generics usually cost less than brand-name drugs.

Exondys 51 contains the active drug eteplirsen.

Exondys 51 is approved by the Food and Drug Administration (FDA) to treat Duchenne muscular dystrophy (DMD) in people who have a certain gene mutation. “Gene mutation” means that a specific gene isn’t working the way it should.

DMD is the most common form of muscular dystrophy. This term refers to a group of genetic (inherited) disorders that cause loss of muscle mass over time. (For more information about DMD, see “About DMD” in the “Exondys 51 uses” section below.)

People with DMD lack a certain protein called dystrophin that muscles need to work properly. This is due to a mutation in the dystrophin (DMD) gene.

The most common DMD mutation involves one or more missing exons. An exon is a part of a gene. A missing exon causes errors in the DMD gene’s instructions for making dystrophin. This leads to not having enough dystrophin in the body.

Exondys 51 has a unique mechanism of action. It requires the presence of a specific exon, called exon 51, that’s part of the DMD gene.* The drug works by helping the body “skip” exon 51 while reading the genetic instructions for making dystrophin.† In the process, the missing exons are also skipped. This allows the body to make a shorter form of dystrophin that still works.

* Before prescribing Exondys 51, a doctor needs to confirm that exon 51 is present in a person’s DMD gene. They’ll do this through genetic testing.
† For more on how exon 51 skipping works, the manufacturer’s website features a video that details the process.

How long does it take to work?

Exondys 51 reaches its highest levels in your body right after you receive it. But because of how the drug works, you aren’t likely to feel it working.

Also, it isn’t known how soon Exondys 51 starts increasing the amount of dystrophin in the body. In clinical studies, the dystrophin levels of people using Exondys 51 weren’t measured until after 48 weeks.

In addition, the researchers didn’t monitor how soon symptoms lessened in those who saw their symptoms decrease. This is because the researchers didn’t watch for improvements in symptoms in these trials.

If you have additional questions about how Exondys 51 works, talk with your doctor.

The Exondys 51 dosage your doctor prescribes will depend on several factors. These include:

  • your body weight
  • any reactions you might have to an Exondys 51 infusion

The following information describes dosages that are commonly used or recommended. Your doctor will determine the best dosage to fit your needs.

Drug forms and strengths

Exondys 51 comes as a clear solution that’s given as an intravenous infusion by a healthcare provider. (An intravenous infusion is an injection into a vein that’s given over a period of time.) You may receive this infusion at a doctor’s office or an infusion clinic. Or a healthcare provider may give you an infusion at home.

Exondys 51 is available in one strength: 50 milligrams per milliliter (mg/mL).

Dosage for Duchenne muscular dystrophy

For treating Duchenne muscular dystrophy (DMD), the recommended dose of Exondys 51 is based on a person’s body weight. Exondys 51 is given in a dose of 30 milligrams (mg) per kilogram (kg) of body weight. One kg is equal to about 2.2 pounds (lb).

As an example, a person weighing 50 kg (about 110 lb) would receive an Exondys 51 dose of 1,500 mg.

The dose is given once weekly over the course of 35 to 60 minutes. Your infusion time may be longer if you have an allergic reaction to the infusion. For more information on allergic reactions, see the “Exondys 51 side effects” section below.

Children’s dosage

The dosage of Exondys 51 for treating DMD in children is the same as it is for adults. See the “Dosage for Duchenne muscular dystrophy” section just above.

What if I miss a dose?

If you miss an appointment for your Exondys 51 dose, call your doctor as soon as you can. They’ll work to reschedule your infusion as soon as possible. They’ll also give you instructions on rescheduling future doses.

To help make sure that you don’t miss an appointment to get a dose, try setting a reminder on your phone.

Will I need to use this drug long term?

Exondys 51 is meant to be used as a long-term treatment. If you and your doctor determine that Exondys 51 is safe and effective for you, you’ll likely use it long term.

As with all medications, the cost of Exondys 51 can vary. To find current prices for Exondys 51 in your area, check out WellRx.com.

The cost you find on WellRx.com is what you may pay without insurance. The actual price you’ll pay depends on your insurance plan, your location, and the pharmacy you use.

It’s important to note that you’ll have to get Exondys 51 at a specialty pharmacy. This type of pharmacy is authorized to carry specialty medications. These are drugs that may be expensive or require help from healthcare professionals to be used safely and effectively.

Before approving coverage for Exondys 51, your insurance company may require you to get prior authorization. This means that your doctor and insurance company will need to communicate about your prescription before the insurance company will cover the drug. The insurance company will review the prior authorization request and decide if the drug will be covered.

If you’re not sure if you’ll need to get prior authorization for Exondys 51, contact your insurance company.

Financial and insurance assistance

If you need financial support to pay for Exondys 51, or if you need help understanding your insurance coverage, help is available.

Sarepta Therapeutics, Inc., the manufacturer of Exondys 51, offers a program called SareptAssist that may help lower the cost of this drug. The program also offers assistance to help you coordinate care when using Exondys 51. For more information and to find out if you’re eligible for support, call 888-SAREPTA (888-727-3782) or visit the program website.

Generic version

Exondys 51 isn’t available in a generic form. A generic drug is an exact copy of the active drug in a brand-name medication. Generics tend to cost less than brand-name drugs.

Exondys 51 can cause mild or serious side effects. The following lists contain some of the key side effects that may occur while using Exondys 51. These lists don’t include all possible side effects.

For more information about the possible side effects of Exondys 51, talk with your doctor or pharmacist. They can give you tips on how to deal with any side effects that may be bothersome.

Note: The Food and Drug Administration (FDA) tracks side effects of drugs it has approved. If you’d like to notify the FDA about a side effect you’ve had with Exondys 51, you can do so through MedWatch.

Mild side effects

Mild side effects* of Exondys 51 can include:

For more information on each of these side effects, see the “Side effect details” section below.

Most of these side effects may go away within a few days or a couple of weeks. But if they become more severe or don’t go away, talk with your doctor or pharmacist.

* This is a partial list of mild side effects from Exondys 51. To learn about other mild side effects, talk with your doctor or pharmacist or view Exondys 51’s prescribing information.

Serious side effects

Serious side effects from Exondys 51 aren’t common, but they can occur. Call your doctor right away if you have serious side effects. Call 911 or your local emergency number if your symptoms feel life threatening or you think you’re having a medical emergency.

Serious side effects include:

For more information on allergic reaction, see the “Side effect details” section below.

Side effects in children

Side effects in children aren’t expected to be different from those in adults.

In clinical studies of Exondys 51, the people enrolled were all male and between 4 and 19 years old. The most common side effects reported in those who took Exondys 51 are listed in the “Mild side effects” section above.

Side effect details

You may wonder how often certain side effects occur with this drug. Here’s some detail on certain side effects this drug may cause.

Allergic reaction

As with most drugs, some people can have an allergic reaction after receiving Exondys 51. It isn’t known how often this occurred in people receiving the drug in clinical studies.

Symptoms of a mild allergic reaction can include:

  • rash
  • itchiness
  • flushing (warmth, swelling, or redness in your skin)

A more severe allergic reaction is rare but possible. Symptoms of a severe allergic reaction can include:

  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your tongue, mouth, or throat
  • cough, wheezing, or trouble breathing
  • hypotension (low blood pressure)

If an allergic reaction occurs while you’re getting your Exondys 51 infusion,* your healthcare provider will treat your reaction. They may decide to try giving your next infusion over a longer period of time. Or they may decide to stop treatment with Exondys 51.

Call your doctor right away if you have an allergic reaction to Exondys 51 after getting your infusion, as the reaction could become severe. Call 911 or your local emergency number if your symptoms feel life threatening or you think you’re having a medical emergency.

* Exondys 51 is given as an intravenous infusion by a healthcare provider. (An intravenous infusion is an injection into a vein that’s given over a period of time.) You may receive this infusion at a doctor’s office or an infusion clinic. Or a healthcare provider may give you an infusion at home.

Problems with balance

Problems with balance was a side effect reported in clinical studies of Exondys 51. In these studies, 38% of people receiving Exondys 51 reported problems with balance. No one who received a placebo (a treatment with no active drug) reported this side effect.

It’s important to note that Exondys 51 studies involved only about 100 males ages 4 to 19 years. And some people received a higher Exondys 51 dose than the recommended 30 milligrams per kilogram (mg/kg) of body weight, which could have affected their risk for balance problems.

It isn’t known how often balance problems have happened in people receiving Exondys 51 since the drug was approved.

If you experience problems with balance while using Exondys 51, talk with your doctor.

Vomiting

Some people may experience vomiting as a side effect of Exondys 51. In clinical studies, 38% of people receiving Exondys 51 reported vomiting. No one who received a placebo (a treatment with no active drug) reported this side effect.

It’s important to note that these Exondys 51 studies involved only about 100 males ages 4 to 19 years. And some people received a higher Exondys 51 dose than the recommended 30 mg/kg of body weight, which could have affected their risk for vomiting.

If you experience vomiting while using Exondys 51, talk with your doctor.

Contact dermatitis

Contact dermatitis (irritated skin) is a possible side effect of Exondys 51.

In clinical studies, 25% of people receiving Exondys 51 reported contact dermatitis. No one who received a placebo (a treatment with no active drug) reported this side effect.

It’s important to note that Exondys 51 studies involved only about 100 males aged 4 to 19 years old. And some people received a higher Exondys 51 dose than the recommended 30 mg/kg of body weight, which could have affected their risk for contact dermatitis.

It isn’t known how often this side effect has occurred with Exondys 51 treatment since the drug was approved.

If you experience contact dermatitis while using Exondys 51, talk with your doctor.

The Food and Drug Administration (FDA) approves prescription drugs such as Exondys 51 to treat certain conditions. Exondys 51 may also be used off-label for other conditions. Off-label drug use means using a drug for a purpose other than what it’s been approved for by the FDA.

Exondys 51 for Duchenne muscular dystrophy

Exondys 51 is FDA-approved to treat Duchenne muscular dystrophy (DMD) in people who have a certain gene mutation. “Gene mutation” means that a specific gene isn’t working the way it should.

About DMD

DMD is the most common form of muscular dystrophy. This term refers to a group of genetic (inherited) disorders that cause loss of muscle mass over time. A person with a family history of muscular dystrophy has a greater risk for developing this condition.

Your body makes proteins that your muscles need to grow and function properly. In muscular dystrophy, genetic mutations interfere with protein production. As a result, muscles can’t form correctly. This loss of muscle leads to a loss of strength.

People with DMD lack a specific protein called dystrophin. This causes muscle weakness and loss over time.

DMD most commonly affects male children between the ages of 2 and 3 years. Rarely, it can affect female children as well.

Currently, there’s no cure for DMD or any other type of muscular dystrophy. But certain treatments can slow muscle loss and improve symptoms.

Symptoms of DMD

Symptoms of DMD can change over time as the disease progresses. Early symptoms of DMD can include:

  • trouble walking, running, or jumping
  • learning disabilities, such as learning to speak later than usual
  • muscle weakness

As time goes on, the following symptoms may begin to appear:

  • breathing problems, including acute respiratory failure
  • lumbar lordosis (excessive inward curve of the lower spine)
  • not being able to walk

Accelerated approval

In 2016, the FDA gave Exondys 51 accelerated approval. This type of approval is based on information the FDA reviewed from early clinical trials of the medication. The FDA won’t make a decision on full approval of Exondys 51 until after additional clinical trials have been completed.

Usually, medications receive approval from the FDA after extensive studies are completed. But for some drugs, approval may be granted before all studies have been finished. Accelerated approval is reserved for certain drugs designed to treat conditions that don’t have a lot of successful treatment options.

Exondys 51 is the first medication that’s FDA-approved to treat DMD. More trials are still being conducted to confirm the FDA’s approval of Exondys 51 for this condition.

Effectiveness for DMD

Clinical studies have shown that Exondys 51 can improve dystrophin levels in people with DMD.

One study looked at muscle dystrophin levels in people before and after receiving Exondys 51 for 48 weeks. There wasn’t a group of people receiving a placebo (a treatment with no active drug) in this study.

Before the study, researchers measured muscle dystrophin levels and found that they were an average of 0.16% of the levels in people without DMD. After 48 weeks, researchers again measured muscle dystrophin levels in people receiving Exondys 51. They found that muscle dystrophin levels were now an average of 0.44% of those in people without DMD.

Another study looked at whether people receiving Exondys 51 scored better than people receiving a placebo on a 6-minute walk test. This test measures how far a person can walk on a flat, hard surface in 6 minutes. Researchers in this 24-week study didn’t find a difference in how well people who took Exondys 51 did compared with people who took a placebo.

Exondys 51 and children

Exondys 51 is approved to treat DMD in people who have a certain gene mutation, including children. Clinical studies didn’t distinguish results in adults and children.

For more information on Exondys 51’s effectiveness, see “Effectiveness for DMD” just above.

There aren’t any known interactions between Exondys 51 and alcohol.

Drinking a moderate amount of alcohol usually doesn’t cause harm to most people with a neuromuscular disease, such as Duchenne muscular dystrophy (DMD).

But consuming alcohol may cause problems with balance or coordination, as well as trouble breathing. These are also potential side effects of Exondys 51. Drinking alcohol while using Exondys 51 may increase your risk for these side effects.

Talk with your doctor before you consume alcohol while receiving Exondys 51. They’ll help determine how much is safe for you to drink.

Exondys 51 isn’t known to interact with other medications. And it isn’t known to interact with any supplements or foods.

Different interactions can cause different effects. For instance, some interactions can interfere with how well a drug works. Other interactions can increase the number of side effects or make them more severe.

Therefore, you should still talk with your doctor and pharmacist before using Exondys 51. Tell them about all prescription, over-the-counter, and other drugs you take. Also tell them about any vitamins, herbs, and supplements you use. Sharing this information can help you avoid potential interactions.

If you have questions about drug interactions that may affect you, ask your doctor or pharmacist.

Other drugs may be available that can treat Duchenne muscular dystrophy (DMD). Some may be a better fit for you than others. If you’re interested in finding an alternative to Exondys 51, talk with your doctor. They can tell you about other medications that may work well for you.

Note: Some of the drugs listed here are used off-label to treat these specific conditions. Off-label drug use is when an FDA-approved drug is used for a purpose other than what it’s approved for.

Examples of other drugs that may be used to treat DMD include:

Exondys 51 comes as a clear solution that’s given as an intravenous infusion by a healthcare provider. (An intravenous infusion is an injection into a vein that’s given over a period of time.)

You may receive this infusion at a doctor’s office or an infusion clinic. Or a healthcare provider may give you an infusion at home. Typically, the infusion will last between 35 and 60 minutes, and you’ll receive it once a week.

To help make sure that you don’t miss an appointment to get a dose, try setting a reminder on your phone.

It’s possible that you may experience an allergic reaction after your Exondys 51 infusion. It isn’t known exactly how many people may have had this reaction in clinical studies. (For information about allergic reaction symptoms, see “Allergic reaction” in the “Exondys 51 side effects” section above.)

Call your doctor right away if you think you’re having an allergic reaction to Exondys 51. Call 911 or your local emergency number if your symptoms feel life threatening or you think you’re having a medical emergency.

It isn’t known if Exondys 51 is safe to use while pregnant. This is because the active drug in Exondys 51, eteplirsen, hasn’t been studied during pregnancy.

If you have additional questions about Exondys 51 and pregnancy, talk with your doctor.

It’s not known if Exondys 51 is safe to use during pregnancy. If you’re sexually active and you or your partner can become pregnant, talk with your doctor about your birth control needs while you’re using Exondys 51.

For more information about using Exondys 51 during pregnancy, see the “Exondys 51 and pregnancy” section above.

It isn’t known if Exondys 51 is safe to use while breastfeeding. This is because the active drug in Exondys 51, eteplirsen, hasn’t been studied in anyone who’s breastfeeding. It also isn’t known if eteplirsen could cause side effects in a breastfed child.

If you have additional questions about Exondys 51 and breastfeeding, talk with your doctor.

Here are answers to some frequently asked questions about Exondys 51.

Does Exondys 51 cure Duchenne muscular dystrophy?

No, Exondys 51 doesn’t cure Duchenne muscular dystrophy (DMD). Currently, there isn’t a cure for DMD or any other type of muscular dystrophy.

People with DMD lack a specific protein called dystrophin that causes muscle weakness and loss over time. Clinical trials have shown that Exondys 51 can increase dystrophin levels in people with DMD.

If you have additional questions about treatment options for DMD, talk with your doctor.

If I have kidney problems, can I use Exondys 51?

Possibly. The active drug in Exondys 51, eteplirsen, passes from the body primarily through the kidneys. Clinical studies have shown that people with mild or moderate kidney problems had higher blood levels of eteplirsen than people without kidney problems. But this wasn’t found to increase the risk of side effects.

The manufacturer of Exondys 51 doesn’t make any recommendations for adjusting the dose for people with kidney problems. Also, Exondys 51 hasn’t been studied in people with severe kidney problems. Still, before receiving Exondys 51, you should tell your doctor about any medical conditions you may have, including kidney problems.

How do I know if Exondys 51 will work for me?

Exondys 51 is approved by the Food and Drug Administration (FDA) to treat DMD in people who have a certain gene mutation. “Gene mutation” means that a specific gene isn’t working the way it should.

To use Exondys 51, you must have a mutation in the DMD gene that can be treated by “skipping” exon 51. An exon is a part of a gene. In this case, exon 51 refers to a specific exon in the DMD gene. (For more information on how Exondys 51 works, including an explanation of exon skipping, see the “How Exondys 51 works” section above.)

Before receiving Exondys 51, your doctor will order a genetic test. The test will check whether you have a mutation in the DMD gene that can be treated by skipping exon 51. This will help make sure the drug is right for your condition.

Before using Exondys 51, talk with your doctor about your health history. Exondys 51 may not be right for you if you have certain medical conditions or other factors affecting your health. These include:

  • Kidney problems. The active drug in Exondys 51, eteplirsen, is passed from the body primarily through the kidneys. Clinical studies didn’t show an increased risk of side effects in people with mild or moderate kidney problems. But the drug hasn’t been studied in people with severe kidney problems. Be sure to tell your doctor about any history of kidney problems before you start using Exondys 51. Your doctor may choose to monitor your kidney function more closely while you’re receiving Exondys 51.
  • Allergic reaction. If you’ve had an allergic reaction to Exondys 51 or any of its ingredients, you shouldn’t use Exondys 51. Ask your doctor about which other medications are better options for you.
  • Pregnancy. It isn’t know if Exondys 51 is safe to take while pregnant. For more information, see the “Exondys 51 and pregnancy” section above.
  • Breastfeeding. It isn’t known if Exondys 51 is safe to use while breastfeeding. For more information, see the “Exondys 51 and breastfeeding” section above.

Note: For more information about the potential negative effects of Exondys 51, see the “Exondys 51 side effects” section above.

Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.