Spinraza (nusinersen)
An approved treatment for Spinal Muscular Atrophy.
The same compound appears under different names depending on the context. Here is how to identify Nusinersen wherever you encounter it, plus the key facts at a glance.
- Generic name
- Nusinersen
- Brand name
- Spinraza
- Development code
- ISIS-396443
- Drug class
- Antisense oligonucleotide
- Manufacturer
- Biogen
- How it's taken
- Administered as an intrathecal injection (into the spinal fluid) by lumbar puncture.
The first FDA-approved treatment for spinal muscular atrophy. Spinraza is delivered directly into the spinal fluid and works by helping the body produce more of the SMN protein that SMA patients lack.
We'll email you when Spinraza's FDA label changes, when the FDA acts on it, and when new trials for Spinal Muscular Atrophy open. Unsubscribe anytime.
Where Nusinersen fits
First approved disease-modifying therapy for SMA across all types. Requires ongoing intrathecal injections but has extensive long-term safety and efficacy data across age groups.
How Nusinersen works
In SMA, the SMN1 gene is missing or broken, so the body cannot make enough SMN protein to keep motor neurons alive. Everyone also has a backup gene called SMN2, but it mostly produces a shortened, non-functional version of the protein. Nusinersen binds to SMN2's pre-mRNA and corrects the splicing so that SMN2 produces the full-length, working protein instead.
Mechanism: Antisense oligonucleotide that modifies SMN2 pre-mRNA splicing to increase production of functional SMN protein
Side effects and safety
Common side effects include upper and lower respiratory infections, constipation, headache, back pain, and post-lumbar puncture syndrome. There is a risk of kidney toxicity and of low platelets and blood clotting problems, so blood and urine tests are required before every dose. With the high dose regimen in infants, the most common side effects were pneumonia, COVID-19, aspiration pneumonia, and malnutrition.
This is not a complete list of side effects. Talk to your doctor or pharmacist about what to expect and when to seek medical attention.
Taking Nusinersen
Administered as an intrathecal injection (into the spinal fluid) by lumbar puncture. There are 2 approved dosing options. Standard (low) dose: 4 loading doses of 12 mg (3 doses 14 days apart, then a fourth 30 days later), then 12 mg every 4 months. High dose (FDA approved March 30, 2026): two 50 mg loading doses 14 days apart, then 28 mg every 4 months. Platelet count, blood clotting tests, and a urine protein test are done before each dose. Procedure is performed at specialized neuromuscular centers.
Availability and cost
Only available as the brand-name product.
First-in-class antisense oligonucleotide requiring intrathecal (spinal) injection every 4 months after a loading phase. Complex manufacturing and ultra-rare disease target drive specialty pricing.
Help paying for Spinraza
Pick your insurance to see which help fits. Drugmaker copay cards can't be used with Medicare, Medicaid or TRICARE; charity funds are the usual route there.
- Copay help
Biogen Copay Program for Spinraza: people with non-government insurance generally eligible regardless of income; no annual maximum. Medicare, Medicaid, VA/DoD, TRICARE may not be eligible.
For: private insurance · source - Infusion cost help
Separate procedure copay program helps with approved anesthesia, imaging and administration codes. Not for residents of MA, MI, MN or RI.
For: private insurance · source - Insurance and case manager help
Family Access Manager and Lead Case Manager help with insurance benefits, treatment coordination, denials, and referrals to charities.
The official page does not say who qualifies. Ask the program. · source
Good to know: Drug and procedure copay programs require separate enrollment. If not eligible for copay help, case managers can refer to independent charities.
- From a charity · TotalAssist (formerly PAN Foundation)Spinal Muscular Atrophy fundOpen
Pays for: Out-of-pocket costs for approved medications, up to $6,500 per year. Requires health insurance (any kind).
- From a charity · Cure SMAEquipment Pool and Travel Support Package fundApply directly
Pays for: Medical equipment loans (wheelchairs, car beds) and travel equipment.
The foundation says: “Status not shown on page” - From a charity · Muscular Dystrophy AssociationMDA Durable Medical Equipment (DME) Grant Program fundApply directly
Pays for: Medical equipment (wheelchairs, lifts, canes and other DME), up to $1,000 per year.
The foundation says: “Status not shown on page”
Clinical trial results
The ENDEAR trial in infantile-onset SMA showed 51% of treated infants achieved motor milestones versus 0% on placebo. The CHERISH trial in later-onset SMA demonstrated significant improvement in motor function scores. Long-term data shows sustained benefit over 5+ years.
Development history
Developed by Ionis Pharmaceuticals and licensed to Biogen. Approved by FDA in December 2016 as the first treatment ever for SMA, transforming a previously untreatable disease. Has since treated over 11,000 patients worldwide.
Explore Spinal Muscular Atrophy trials
Other Spinal Muscular Atrophy treatments
Nusinersen in Trial Friend News and Guides
- Isembyld Is Approved for SMA as the First Muscle-Targeted Add-On to Spinraza and EvrysdiSeptember 17, 2026
- The FDA's Plausible Mechanism Framework Could Unlock Gene Therapies for the Rarest DiseasesApril 24, 2026
- A Quiet Crisis in Rare Disease Research: Trial Enrollment Is Slowing Just as Treatments Start WorkingApril 13, 2026
Common questions about Nusinersen
▸What is Nusinersen (Spinraza)?
The first FDA-approved treatment for spinal muscular atrophy. Spinraza is delivered directly into the spinal fluid and works by helping the body produce more of the SMN protein that SMA patients lack.
▸How does Nusinersen work?
In SMA, the SMN1 gene is missing or broken, so the body cannot make enough SMN protein to keep motor neurons alive. Everyone also has a backup gene called SMN2, but it mostly produces a shortened, non-functional version of the protein. Nusinersen binds to SMN2's pre-mRNA and corrects the splicing so that SMN2 produces the full-length, working protein instead.
▸What are the side effects of Nusinersen?
Common side effects include upper and lower respiratory infections, constipation, headache, back pain, and post-lumbar puncture syndrome. There is a risk of kidney toxicity and of low platelets and blood clotting problems, so blood and urine tests are required before every dose. With the high dose regimen in infants, the most common side effects were pneumonia, COVID-19, aspiration pneumonia, and malnutrition.
▸How is Nusinersen taken?
Administered as an intrathecal injection (into the spinal fluid) by lumbar puncture. There are 2 approved dosing options. Standard (low) dose: 4 loading doses of 12 mg (3 doses 14 days apart, then a fourth 30 days later), then 12 mg every 4 months. High dose (FDA approved March 30, 2026): two 50 mg loading doses 14 days apart, then 28 mg every 4 months. Platelet count, blood clotting tests, and a urine protein test are done before each dose. Procedure is performed at specialized neuromuscular centers.
▸Is Nusinersen FDA approved?
Yes, Nusinersen (Spinraza) is FDA approved (2016) for the treatment of Spinal Muscular Atrophy.
▸How does nusinersen work for spinal muscular atrophy?
Nusinersen is an antisense oligonucleotide that modifies the splicing of SMN2 pre-mRNA, increasing production of functional SMN protein. SMA patients lack sufficient SMN1 gene function, and nusinersen helps the backup SMN2 gene produce more of the critical SMN protein needed for motor neuron survival.
▸How is nusinersen administered?
Nusinersen (Spinraza) is given by intrathecal injection (into the spinal fluid) every 4 months after initial loading doses. Administration requires a lumbar puncture procedure performed by a healthcare professional at a treatment center.
▸Was nusinersen the first approved treatment for SMA?
Yes. Nusinersen was approved in December 2016 as the first disease-modifying therapy for spinal muscular atrophy, transforming SMA from an untreatable condition to a manageable disease. It is approved for all SMA types across all ages.
▸How does nusinersen compare to risdiplam?
Both increase SMN protein production by modifying SMN2 splicing. Nusinersen requires intrathecal injection every 4 months, while risdiplam is taken as a daily oral liquid at home. Nusinersen acts directly in the central nervous system, while risdiplam distributes throughout the body.
▸How does nusinersen compare to gene therapy (Zolgensma)?
Nusinersen is an ongoing therapy requiring regular intrathecal injections that boost SMN2 output, while Zolgensma is a one-time IV gene therapy that delivers a functional SMN1 gene. Nusinersen can be used at any age, while Zolgensma IV is approved for children under 2.
▸What patient support is available for Spinraza?
Biogen provides patient support programs including insurance navigation, copay assistance, and treatment coordination for Spinraza patients through their dedicated SMA support resources.