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Generic name: vestronidase alfaves-TRON-i-dase-AL-fa ]
Drug class: Lysosomal enzymes

Medically reviewed by on Apr 12, 2021. Written by Cerner Multum.

What is Mepsevii?

Mepsevii contains an enzyme that occurs naturally in the body in healthy people. Some people lack this enzyme because of a genetic disorder. This medicine helps replace this missing enzyme in such people.

Mepsevii is used to treat some of the symptoms of a genetic condition called mucopolysaccharidosis VII (MYOO-koe-pol-ee-SAK-a-rye-DOE-sis Seven) or MPS VII, also called Sly syndrome.

MPS VII is a metabolic disorder in which the body lacks the enzyme needed to break down certain natural substances. These substances can build up in the body, causing enlarged organs, abnormal bone structure, changes in facial features, breathing problems, heart problems, vision or hearing loss, and changes in mental or physical abilities.

Mepsevii may improve walking ability in people with this condition. However, this medication is not a cure for MPS VII.

Mepsevii may also be used for purposes not listed in this medication guide.


An allergic reaction may occur during or shortly after infusion of Mepsevii. Tell your caregivers or get emergency medical help right away if you have any signs of a severe allergic reaction, such as sweating, trouble breathing, pale skin, blue lips or fingernails, and feeling like you might pass out.

Before taking this medicine

Tell your doctor if you have ever had:

  • a lung disease or breathing problems.

Tell your doctor if you are pregnant or breastfeeding.

How is Mepsevii given?

Mepsevii is given as an infusion into a vein. A healthcare provider will give you this injection.

Mepsevii is usually given once every 2 weeks. Mepsevii must be given slowly, and the infusion can take about 4 hours to complete.

About 30 to 60 minutes before each injection, you will be given other medications to help prevent a serious allergic reaction.

Tell your caregivers if you feel any burning, pain, or swelling around the IV needle when Mepsevii is injected.

You will be watched closely for at least 60 minutes after receiving Mepsevii, to make sure you do not have an allergic reaction.

Mepsevii doses are based on weight. Your dose needs may change if you gain or lose weight.

What happens if I miss a dose?

Call your doctor for instructions if you miss an appointment for your Mepsevii.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while receiving Mepsevii?

Follow your doctor's instructions about any restrictions on food, beverages, or activity.

Mepsevii side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

An allergic reaction may occur during or shortly after infusion of Mepsevii. Tell your caregivers or get emergency medical help right away if you have any signs of a severe allergic reaction, such as:

  • feeling like you might pass out, even while lying down;

  • sweating, cold or clammy skin;

  • feeling short of breath;

  • pale skin; or

  • blue lips or fingernails.

Common side effects of Mepsevii may include:

  • diarrhea;

  • swelling in your hands or feet;

  • rash, itching; or

  • swelling or irritation around the IV needle.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect Mepsevii?

Other drugs may affect Mepsevii, 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.

Frequently asked questions

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

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