Eteplirsen (Intravenous)

Eteplirsen, marketed under the brand name Exondys 51, is an injectable medication used to help alleviate the symptoms of Duchenne muscular dystrophy.

Overview

Duchenne muscular dystrophy is a genetic disorder that usually becomes evident when a child is between the ages of three and five. The condition most often affects males, but there are some female patients born with the condition. Duchenne muscular dystrophy is caused by the lack of a substance in the body known as dystrophin. Dystrophin plays a role in helping the muscles of the body to function properly.

Duchenne muscular dystrophy begins with muscle weakness in the hips, thighs and shoulders. As the condition progresses, other muscles become affected including the heart muscle. Most patients do not live past early adulthood.

In 2016, researchers developed eteplirsen to help alleviate the symptoms of Duchenne muscular dystrophy. Since there were no other drugs on the market known to help those with the condition, the Food and Drug Administration in the United States gave eteplirsen accelerated approval so that it could start being used in patients as quickly as possible.

Eteplirsen is not a cure for Duchenne muscular dystrophy. There is not a cure for this genetic disorder. Since the drug has become available on the general market, some patients have benefited greatly from using the drug. The drug does not help all those to whom it is administered.

Eteplirsen works in the body by bonding with exon 51. This allows the body to skip over exon 51 when mRNA processing takes place in the body. When exon 51 is skipped, the body can produce a truncated form of dystorphin protein. This protein then helps the muscles to function better and helps to mitigate the muscle weakness associated with Duchenne muscular dystrophy.

There are several different types of muscular dystrophy that result from different types of genetic mutations. Eteplirsen is not effective in helping with these other forms of muscular dystrophy.

Those who receive the drug must take it on a regular basis for it to be effective. Normally, an injection of the drug is given to the patient on a weekly basis for as long as the drug is demonstrating that it is of some benefit in alleviating the patient's symptoms.

As with all medications, eteplirsen does have some side effects. Allergies to the drug have been reported. As many as 38 percent of those being treated with eteplirsen have reported side effects of varying degrees.

Since eteplirsen is an injectable form of medication, the patient will receive the drug in a physician's office or at another healthcare setting.

Conditions Treated

  • Duchenne Muscular Dystrophy

Type Of Medication

  • Morpholino Antisense Oligomer

Side Effects

There have been some reports of a generalized allergic reaction in those who have taken eteplirsen. This may result in breathing difficulties.

There are three very common side effects reported by those using eteplirsen. Balance disorders have been reported in as many as 38 percent of the patients who use eteplirsen. This type of side effect may manifest as dizziness when attempting to walk or in a disjointed manner of walking that makes the patient feel as if they are unsteady on their feet.

Another very common side effect for those on the drug is vomiting. This side effect has also been reported in up to 38 percent of those using the drug. This side effect does not usually cause the drug to have to be discontinued.

Contact dermatitis occurs in approximately 25 percent of those using the drug. This dermatitis may be limited to the area where the injection is placed into the body.

Confusion occurs in as many as 10 percent of those taking eteplirsen. This is usually a transitory side effect that does not necessitate that the drug be discontinued.

Treatment with eteplirsen has caused other side effects that are not as common as those already listed. However, they do appear in a number of patients using the drug. Transient erythema has been noticed for a period after the drug is first administered. This erythema goes away shortly and usually requires no treatment.

Also reported right after the drug is administered is facial flushing. This too normally goes away shortly after the drug is in the patient's body.

On the day when the drug is infused, patients sometimes report that they have a fever. The fever normally only lasts for one day and does not necessitate the drug having to be discontinued.

There are a host of skin side effects that have been reported at varying levels of severity. Some of these skin side effects are generalized in nature while others are more specific to the site where the drug is injected. Some of the more generalized skin side effects include generalized itching, hives, rash, redness, burning, discoloration of the skin, blistering and dryness. More localized skin side effects include swelling, soreness, pressure, discoloration, redness, pain and crusting.

There has been a report of a patient developing an upper respiratory infection while taking the drug. It is not certain if this was a direct result of the drug itself. There has also been a report of arthralgia when taking the drug.

Dosage

The dosasge of eteplirsen to be received is based upon the patient's weight. The normal dosage is 30 milligrams per kilogram. This is to be given to the patient once a week as an infusion that lasts from between 35 to 60 minutes. If a patient should miss a dose, the dose should be made up as quickly as possible as the drug needs to be taken on a regularly scheduled basis to be effective.

The manufacturer has some specific instructions as to how the eteplirsen infusion is to be prepared. Each vial of the medication needs to be brought to room temperature. Each vial should be inverted two to three times, but the vials should not be shaken. The medication is colorless. If the preparer notices any discoloration, the vial should not be used.

The drug should be drawn out of the vial using a 21 gauge needle. The contents are then injected into a solution of 0.9 percent sodium chloride to a volume of between 100 to 150 milliliters. The solution should be administered within four hours. It may be refrigerated between 36 to 46 degrees Fahrenheit for up to 24 hours if absolutely necessary.

Many of the patients receiving this drug are growing children. It is important to weigh patients on a regular basis while the drug is being used as the dosage of eteplirsen is based upon the patient's weight.

Interactions

There are no drugs that are known to interact with eteplirsen. It is still important to inform the healthcare provider of all prescription and non-prescription drugs that are being taken.

Warnings

Eteplirsen is only effective if it is used on an ongoing basis. It is important to never miss a dose of the drug if the best results are to be obtained.

This drug has not been tested on geriatic patients as those with Duchenne muscular dystrophy usually do not reach this age. If the drug is used in geriatic patients, caution is advised.

There has been no testing done on this drug in regard to its affect on pregnancy. There has been no testing as to whether this drug is excreted in breastmilk.

Patients should be advised that this drug had an accelerated acceptance by the FDA. The efficacy of this drug has not been fully established. Full acceptance of this drug by the FDA will be based upon the results that are observed as patients receive this drug in a clinical setting. This drug is not a cure for Duchenne muscular dystrophy and it is only designed to alleviate the symptoms and possibly the progression of the condition.

Storage

Eteplirsen should be refrigerated between 36 to 46 degrees Fahrenheit. The medication should not be exposed to light prior to use.

Summary

Eteplirsen is the first drug known to alleviate the symptoms of Duchenne muscular dystrophy. The drug received accelerated approval by the FDA, and it is not yet known how well the drug will work. This medication works by allowing the body to skip over exon 51 when the body is manufacturing dystrophin. If a truncated form of dystrophin is made, it helps the muscles work better and may keep the condition from progressing.

Eteplirsen is used intravenously and the dosage is determined based on a patient's weight. The drug should be administered once a week for as long as it is shown to be effective.

There are several side effects associated with the drug, but three are quiet common. Balance problems, vomiting and contact dermatitis are by far the most prevalent side effects. Most side effects with the drug are mild to moderate. Most patients do not need to discontinue treatment due to side effects.