Pronunciation: ex-on-deez
Generic name: eteplirsen
Dosage form: injection for intravenous infusion
Drug class: Miscellaneous uncategorized agents

Medically reviewed by Carmen Pope, BPharm. Last updated on Mar 24, 2025.

What is Exondys 51?

Exondys 51 is used to treat patients with Duchenne Muscular Dystrophy (DMD) who have a confirmed mutation in the dystrophin gene amenable to exon 51 skipping. It is given as an intravenous infusion 1 time a week.

• Exondys 51 is not a cure for DMD, but may lessen muscle weakness and muscle wasting caused by this disease.

Exondys 51 (eteplirsen) gained FDA approval on September 19, 2016, under the accelerated approval designation. There is no generic.

• Continued approval may be contingent upon a clinical benefit being shown in further clinical trials.

How does Exondys 51 work?

Exondys 51 uses exon-skipping technology to help patients with Duchenne muscular dystrophy (DMD) produce a modified dystrophin protein. In DMD, a genetic mutation prevents the body from making functional dystrophin, a protein essential for muscle cell integrity.

Exondys 51’s mechanism allows the genetic machinery to skip over exon 51, which enables the creation of a shorter but partially functional dystrophin protein. This provides some protein support for muscle cells.

Exondys 51 belongs to the antisense oligonucleotide class of medications.

How effective is Exondys?

The following has been reported after weekly infusions of Exondys 51:

• Exon skipping in the dystrophin gene occurred in all 36 boys in one clinical study
• Dystrophin levels in 12 boys were an average 2.8 times higher than the baseline level after 48 weeks of treatment, but remained at a level much lower than that produced by people without Duchenne. Only one boy failed to show any increase at all.

Side effects

The most common side effects of Exondys 51 are:

• Problems with balance
• Vomiting
• Skin rash or irritation where the medicine was injected
• Headache
• Cough
• Rash.

Serious side effects and warning

Exondys 51 may cause the following serious side effects:

• Hypersensitivity reactions. Allergic reactions, including wheezing, chest pain, cough, rapid heart rate, and hives have occurred in patients who were treated with Exondys 51. Seek immediate medical care if you have any signs and symptoms of allergic reactions such as wheezing, chest pain, cough, rapid heart rate, or hives.

Ask your healthcare provider for advice about any side effects that concern you. The information provided here does not include all that is known about Exondys 51. To learn more, talk with your healthcare provider.

Report any negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch or call 1-800-FDA-1088. You may also report side effects to Sarepta Therapeutics at 1-888-SAREPTA (1-888-727-3782).

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Before taking

Before your child receives Exondys 51, tell the doctor about all your child's medical conditions or allergies, and all the medicines the child uses, including if they:

• Have ever had an allergic reaction to Exondys 51 or any other DMD treatment
• Have kidney problems
• Are pregnant or intending to become pregnant
• Are breastfeeding.

Although Exondys 51 has been used mainly in children, it is not known whether Exondys 51 could be harmful if used during pregnancy or while nursing.

How is Exondys 51 administered?

Exondys 51 is administered 1 time a week into a vein (intravenously) by a healthcare provider.

• The infusion takes 35 to 60 minutes.
• A topical anesthetic cream may be applied to the site prior to administration of the infusion.
• Tell your caregivers if you feel itchy, warm, light-headed, or have chest tightness or trouble breathing when Exondys 51 is injected.

Dosing information

• Dosage of Exondys 51 for DMD: 30 milligrams per kg body weight once weekly.

Tell your doctor if your child has any weight changes. Exondys 51 doses are based on weight, and any changes may affect the dose.

What other drugs will affect Exondys 51?

Other drugs may affect Exondys 51, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

Ingredients

Active: eteplirsen

Inactive: potassium chloride, potassium phosphate monobasic, sodium chloride, and sodium phosphate dibasic, anhydrous, in water for injection.

The product may contain hydrochloric acid or sodium hydroxide to adjust pH.

Available as:

• 100 mg/2 mL (50 mg/mL) in a single-dose vial
• 500 mg/10 mL (50 mg/mL) in a single-dose vial.

Manufacturer

Exondys 51 (eteplirsen) is manufactured by Sarepta Therapeutics, a biotechnology company based in Cambridge, Massachusetts.

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Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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