Vimizim (elosulfase alfa)
An approved treatment for Mucopolysaccharidosis Type IVA.
Drug facts
The same compound appears under different names depending on the context. Here is how to identify Elosulfase alfa wherever you encounter it, plus the key facts at a glance.
- Generic name
- Elosulfase alfa
- Brand name
- Vimizim
- Development code
- BMN 110
- Drug class
- Enzyme replacement therapy
- Manufacturer
- BioMarin Pharmaceutical
- How it's taken
- Intravenous infusion, once a week
The only FDA-approved treatment for MPS IVA (Morquio A syndrome).
Vimizim is a weekly intravenous infusion of the missing enzyme, approved in 2014, that improved 6-minute walking distance in its pivotal trial. Its label carries a boxed warning for anaphylaxis and for serious breathing complications during an acute respiratory illness.
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Where Elosulfase alfa fits
Vimizim is the only FDA-approved treatment for MPS IVA, a weekly enzyme infusion available since 2014[2].
- The label notes that the every-other-week dose did no better than placebo and that walking did not improve further after the first 24 weeks of treatment, through 48 more weeks in the extension study[1].
- Families can ask a metabolic genetics specialist how a child's neck stability and breathing will be checked during treatment.
How Elosulfase alfa works
In MPS IVA, changes in the GALNS gene leave the body short of an enzyme called N-acetylgalactosamine-6-sulfatase. That enzyme breaks down keratan sulfate and chondroitin-6-sulfate, long sugar chains called glycosaminoglycans, inside the lysosomes, the recycling compartments of cells. Without it, they build up mostly in cartilage and bone, which shapes the short stature, skeletal changes, unstable neck joints and narrow airways of Morquio A syndrome.
Vimizim is a manufactured copy of the enzyme, infused into a vein each week, that cells take up and use to clear the buildup.
Side effects and safety
- Anaphylaxis. in premarketing trials, 18 of 235 patients (7.7%) had anaphylaxis, from 30 minutes into the infusion to 3 hours after it, and as late as the 47th infusion
- Hypersensitivity reactions. hypersensitivity reactions affected 44 of 235 patients (18.7%), some as late as 6 days after an infusion
- Acute respiratory complications. a fever or respiratory illness raises the risk, and delaying an infusion is an option; sleep apnea is common, so the label says patients who use oxygen or CPAP during sleep should have it available during infusions
- Spinal cord compression. part of MPS IVA itself, seen on both Vimizim and placebo; the label asks that patients be watched for signs of it
- Infusions started in a healthcare setting with monitoring and resuscitation equipment
- Extra monitoring for patients with an acute respiratory illness
- Watching for signs of spinal or neck cord compression
Vimizim carries a boxed warning for hypersensitivity reactions including anaphylaxis, which can happen at any time during treatment, and for serious worsening of breathing in patients who have an acute respiratory illness when a reaction occurs[1]. In premarketing trials, 18 of 235 patients (7.7%) had anaphylaxis, from 30 minutes into an infusion to 3 hours after it and as late as the 47th infusion, and 44 of 235 (18.7%) had hypersensitivity reactions, some as late as 6 days after an infusion[1].
The label says treatment should start in a healthcare setting with monitoring and resuscitation equipment[1]. In the placebo-controlled trial, reactions more common on weekly Vimizim than placebo were fever (33% vs 14%), vomiting (31% vs 7%), headache (26% vs 15%), nausea (24% vs 7%), abdominal pain (21% vs 2%), chills (10% vs 2%) and tiredness (10% vs 3%)[1]. All patients on weekly Vimizim developed antibodies to the drug by week 4[1].
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 Elosulfase alfa
A weekly intravenous infusion of 2mg per kilogram of body weight[1]. Patients under 25kg get it in a 100mL bag over at least 3.5 hours, and patients 25kg or more in a 250mL bag over at least 4.5 hours, starting slowly and speeding up every 15 minutes[1]. The dosing section says to consider antihistamines, with or without fever reducers, 30 to 60 minutes before the infusion[1]. Supplied as 5mg/5mL single-dose vials[1].
Availability and cost
Only available as the brand-name product.
A weekly, lifelong enzyme replacement biologic for an ultra-rare disease. The label gives no price. BioMarin RareConnections offers benefits checks, prior authorization help and a co-pay program for eligible commercially insured patients.
Help paying for Vimizim
With private insurance, the drugmaker's copay card can lower what you pay for Vimizim. Drugmaker copay cards can't be used with Medicare, Medicaid or TRICARE, but charity funds often can. Of the 5 charity funds for Mucopolysaccharidosis Type IVA, 2 were open on October 26, 2026. Pick your insurance below to see which offers fit you.
- Copay help
Eligible commercially insured patients may pay as little as $0 for Vimizim. Not valid with Medicare, Medicare Advantage, Medigap, Medicaid, VA, DoD or TRICARE, or for cash-paying patients. Eligibility is reconfirmed every year; no annual maximum is published.
For: private insurance · source - Insurance and case manager help
Benefits verification, prior authorization and appeals support, and coordination of shipment and delivery.
The official page does not say who qualifies. Ask the program. · source
Good to know: Phone hours are Monday to Friday, 8 AM to 8 PM ET. BioMarin says RareConnections can help patients unable to afford treatment, but no free-drug program terms are published.
Charity funds for Mucopolysaccharidosis Type IVA
- From a charity · NORD RareCareMorquio A Syndrome Medical Assistance fundOpen
Pays for: Medical and medication costs.
The foundation says: “Accepting new applications and re-enrollments for next year” - From a charity · NORD RareCareMorquio A Syndrome Premium Copay Assistance fundOpen
Pays for: Insurance premiums and copays.
The foundation says: “Accepting new applications and re-enrollments for next year” - From a charity · National MPS SocietyFamily Assistance Program fundApply directly
Pays for: Specialized equipment and medical aids not covered by insurance (requires insurance denial and 10% family copay), up to $3,000 per year.
The foundation says: “Status not shown on page” - From a charity · National MPS SocietyMedical Travel Assistance Program fundApply directly
Pays for: Travel to out-of-town medical appointments more than 125 miles away (per year), up to $550 per year.
The foundation says: “Status not shown on page” - From a charity · National MPS SocietyJourney Assistance Program fundApply directly
Pays for: Items that ease daily life (40% of purchase price), up to $500 per year.
The foundation says: “Status not shown on page”
Every program and charity fund for Mucopolysaccharidosis Type IVA →
Access and eligibility
Approved for patients with MPS IVA (Morquio A syndrome)[1]. The label states safety and effectiveness are established in children 5 and older and not established below age 5, and no patients 65 or older were studied[1].
Source: FDA Drugs@FDA (BLA 125460)
Access program details are provided for informational purposes and may vary based on insurance coverage, geographic location, and individual circumstances. Confirm current eligibility directly with the manufacturer or your specialty pharmacy.
Clinical trial results
The pivotal trial, MOR-004 (NCT01275066), was a 24-week randomized, double-blind, placebo-controlled study of 176 patients aged 5 to 57 who could walk more than 30 but less than 325 meters in 6 minutes[1][3]. It compared Vimizim 2mg/kg weekly, the same dose every other week, and placebo[1]. On weekly Vimizim, 6-minute walking distance rose by 36.5 meters against 13.5 meters on placebo, a model-based difference of 22.5 meters (p=0.0174)[1].
Stair climbing did not differ from placebo, and the every-other-week dose did no better than placebo[1]. In the extension study (NCT01415427), patients who stayed on weekly dosing for 48 more weeks showed no further improvement in walking beyond the first 24 weeks[1][4].
Development history
Developed by BioMarin as BMN 110 and approved by the FDA on February 14, 2014 under BLA 125460 after priority review[2]. The label updated in October 2025 renamed the boxed warning and added that treatment should start in a healthcare setting with monitoring and resuscitation equipment; the warning about patients with an acute respiratory illness was already in the box[1].
Explore Mucopolysaccharidosis Type IVA trials
Common questions about Elosulfase alfa
▸What is Elosulfase alfa (Vimizim)?
The only FDA-approved treatment for MPS IVA (Morquio A syndrome). Vimizim is a weekly intravenous infusion of the missing enzyme, approved in 2014, that improved 6-minute walking distance in its pivotal trial. Its label carries a boxed warning for anaphylaxis and for serious breathing complications during an acute respiratory illness.
▸How does Elosulfase alfa work?
In MPS IVA, changes in the GALNS gene leave the body short of an enzyme called N-acetylgalactosamine-6-sulfatase. That enzyme breaks down keratan sulfate and chondroitin-6-sulfate, long sugar chains called glycosaminoglycans, inside the lysosomes, the recycling compartments of cells. Without it, they build up mostly in cartilage and bone, which shapes the short stature, skeletal changes, unstable neck joints and narrow airways of Morquio A syndrome. Vimizim is a manufactured copy of the enzyme, infused into a vein each week, that cells take up and use to clear the buildup.
▸What are the side effects of Elosulfase alfa?
Vimizim carries a boxed warning for hypersensitivity reactions including anaphylaxis, which can happen at any time during treatment, and for serious worsening of breathing in patients who have an acute respiratory illness when a reaction occurs[1]. In premarketing trials, 18 of 235 patients (7.7%) had anaphylaxis, from 30 minutes into an infusion to 3 hours after it and as late as the 47th infusion, and 44 of 235 (18.7%) had hypersensitivity reactions, some as late as 6 days after an infusion[1]. The label says treatment should start in a healthcare setting with monitoring and resuscitation equipment[1]. In the placebo-controlled trial, reactions more common on weekly Vimizim than placebo were fever (33% vs 14%), vomiting (31% vs 7%), headache (26% vs 15%), nausea (24% vs 7%), abdominal pain (21% vs 2%), chills (10% vs 2%) and tiredness (10% vs 3%)[1]. All patients on weekly Vimizim developed antibodies to the drug by week 4[1].
▸How is Elosulfase alfa taken?
A weekly intravenous infusion of 2mg per kilogram of body weight[1]. Patients under 25kg get it in a 100mL bag over at least 3.5 hours, and patients 25kg or more in a 250mL bag over at least 4.5 hours, starting slowly and speeding up every 15 minutes[1]. The dosing section says to consider antihistamines, with or without fever reducers, 30 to 60 minutes before the infusion[1]. Supplied as 5mg/5mL single-dose vials[1].
▸Is Elosulfase alfa FDA approved?
Yes, Elosulfase alfa (Vimizim) is FDA approved (2014) for the treatment of Mucopolysaccharidosis Type IVA.
▸What is the boxed warning on Vimizim?
Vimizim's boxed warning covers anaphylaxis and serious breathing complications in patients with an acute respiratory illness.
How often: 7.7% of patients in premarketing trials had anaphylaxis.
Setting: The label says to start treatment where monitoring and resuscitation equipment are available.
Source: Vimizim prescribing information
▸How long does a Vimizim infusion take?
A Vimizim infusion takes at least 3.5 hours for patients under 25kg and at least 4.5 hours for patients 25kg or more.
Dose: 2mg/kg once a week.
Rate: The infusion starts slowly and speeds up every 15 minutes.
Source: Vimizim prescribing information
▸Can children under 5 get Vimizim?
The Vimizim label says safety and effectiveness have not been established in children younger than 5.
Studied: The pivotal trial enrolled patients aged 5 to 57.
Ask: A metabolic genetics specialist can explain what is known for younger children.
Source: Vimizim prescribing information
▸Is there help paying for Vimizim?
BioMarin RareConnections helps with insurance and offers a co-pay program for eligible commercially insured patients.
Services: Benefits checks, prior authorization and appeals help, and delivery coordination.
Who qualifies: Only commercially insured patients, and the program terms exclude Medicare, Medicaid, VA, DoD and TRICARE.
Phone: 1-866-906-6100, Monday to Friday, 8AM to 8PM ET.
Source: BioMarin RareConnections and program terms
Sources and references
Every factual claim on this page is drawn from the public sources listed below. Click any reference to open the original document.
- U.S. National Library of Medicine, DailyMed (BioMarin Pharmaceutical Inc.) · 2025-10. VIMIZIM (elosulfase alfa) injection, for intravenous use: prescribing information. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=0caa2565-12b2-0ad0-1f9a-273e81c3d4cc
- U.S. Food and Drug Administration · 2014-02-14. VIMIZIM approval history, BLA 125460. https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&ApplNo=125460
- ClinicalTrials.gov. A Double-Blind Study to Evaluate the Efficacy and Safety of BMN 110 in Patients With Mucopolysaccharidosis IVA (Morquio A Syndrome). https://clinicaltrials.gov/study/NCT01275066
- ClinicalTrials.gov. Long-Term Efficacy and Safety Extension Study of BMN 110 in Patients With Mucopolysaccharidosis IVA (Morquio A Syndrome). https://clinicaltrials.gov/study/NCT01415427
- BioMarin Pharmaceutical. Real support for the VIMIZIM® (elosulfase alfa) journey | BioMarin RareConnections™. https://www.biomarin-rareconnections.com/hcp/vimizim/