Pronunciation: NUE-si-NER-sen
Generic name: nusinersen
Brand name: Spinraza
Dosage form: intrathecal injection (12 mg/5 mL)
Drug class: Miscellaneous uncategorized agents

Medically reviewed by Carmen Pope, BPharm. Last updated on May 20, 2025.

What is nusinersen?

Nusinersen is an intrathecal injection used to treat spinal muscular atrophy (SMA) in children and adults. It is administered by a healthcare provider every 4 months after an initial dosing period. The brand name is Spinraza.

SMA is an inherited muscle-weakening condition caused by mutations in the SMN1 gene, which normally produces a protein needed for healthy motor neurons. A backup gene (SMN2) also makes this protein, but it's usually defective because a critical part called "exon 7" gets skipped. Nusinersen’s mechanism ensures the missing piece of information from exon 7 is included when SMN2 produces protein, resulting in a properly functioning protein that helps keep motor neurons healthy. It belongs to the drug class called antisense oligonucleotides.

Nusinersen gained FDA approval on December 23, 2016, under the brand name Spinraza. There is no generic.

Nusinersen side effects

The most common side effects of nusinersen are:

• Lower respiratory tract infections (such as a cold or the flu)
• Constipation
• Fever
• Headache
• Vomiting
• Back pain
• Post-lumbar puncture syndrome.

Serious side effects and warnings

Nusinersen may cause the following serious side effects:

• Increased risk of bleeding. Complications linked to an increased risk of bleeding have been observed after administration of similar medicines. Your healthcare provider will perform blood tests before you start treatment with nusinersen and before each dose to monitor for signs of these risks. Seek medical attention if unexpected bleeding occurs.
• Increased risk of kidney damage, including potentially fatal acute inflammation of the kidney. An increased risk of kidney damage has been observed after administration of similar medicines. Your healthcare provider will perform urine testing before you start treatment with nusinersen and before each dose to monitor for signs of this risk.

These are not all of the possible side effects of nusinersen. Call your healthcare provider for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Related/similar drugs

Before receiving

Before you receive nusinersen, tell your healthcare provider about all of your medical conditions, including if you:

• have a bleeding disorder
• have a kidney disorder
• are pregnant or intend to become pregnant
• are breastfeeding or intend to breastfeed.

Pregnancy

Nusinersen may harm an unborn baby. You should not become pregnant while receiving nusinersen. Tell your doctor immediately if you become pregnant while receiving nusinersen.

Breastfeeding

There is no data about the presence of nusinersen in human milk. Talk to your doctor about the best way to feed your baby while receiving treatment with nusinersen.

How is nusinersen administered?

Nusinersen is administered by a qualified healthcare professional in a treatment center.

• Nusinersen is injected into the fluid of the spine (intrathecal injection) over 1 to 3 minutes.

Before you start treatment with nusinersen and before each dose, your doctor will order blood and urine testing to monitor for the potential risks of bleeding complications or kidney damage.

Dosing information

Recommended nusinersen dosage for SMA:

• 12 mg (5 mL) per administration.

You will receive 4 initial loading doses of nusinersen.

• The first 3 doses will be given at 14-day intervals, and the 4th dose will be given 30 days after the 3rd dose.
• After your 4 loading doses, you will receive a maintenance dose of nusinersen every 4 months (3 times per year).

Before administering

• Allow nusinersen to warm up to room temperature before administering.
• Administer within 4 hours of removal from the vial.
• Before administration, remove 5 mL of cerebrospinal fluid.
• Administer as an intrathecal bolus injection over 1 to 3 minutes.
• See the full prescribing information for further dosing information.

What other drugs will affect nusinersen?

Tell your doctor about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.

What are the ingredients in nusinersen?

Active ingredient: nusinersen 12 mg

Inactive ingredients: monobasic dihydrate sodium phosphate, dibasic anhydrous sodium phosphate, sodium chloride, potassium chloride, calcium chloride, magnesium chloride, water.

Supplied as a 12 mg/5 mL (2.4 mg/mL) solution in a single-dose glass vial, free from preservatives.

Who makes nusinersen?

Nusinersen is manufactured by Biogen under the brand Spinraza. Biogen is located in Cambridge, MA.

Further information

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

Medical Disclaimer