Naglazyme (galsulfase)
An approved treatment for Mucopolysaccharidosis Type VI.
Drug facts
The same compound appears under different names depending on the context. Here is how to identify Galsulfase wherever you encounter it, plus the key facts at a glance.
- Generic name
- Galsulfase
- Brand name
- Naglazyme
- Development code
- rhASB
- Drug class
- Enzyme replacement therapy
- Manufacturer
- BioMarin Pharmaceutical
- How it's taken
- Intravenous infusion, once a week
The only FDA-approved treatment for MPS VI (Maroteaux-Lamy syndrome).
- Naglazyme is a weekly intravenous infusion of the missing enzyme, approved in 2005, that improved walking distance in its pivotal trial.
- Since July 2024 the label carries a boxed warning for anaphylaxis.
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Where Galsulfase fits
Naglazyme is the only FDA-approved treatment for MPS VI, a weekly enzyme infusion approved in 2005[2].
- The label reports that it improved walking distance, while stair climbing did not improve significantly and urinary glycosaminoglycans stayed above normal[1].
- Families can ask a metabolic genetics specialist how a child's breathing, heart and spine will be checked during treatment.
How Galsulfase works
In MPS VI, a change in the ARSB gene leaves the body short of an enzyme called N-acetylgalactosamine 4-sulfatase, also known as arylsulfatase B. That enzyme breaks down dermatan sulfate, one of the long sugar chains called glycosaminoglycans, inside the lysosomes, the recycling compartments of cells. Without it, dermatan sulfate builds up in tissues across the body, which stiffens joints, thickens heart valves, narrows the airway and limits growth.
Naglazyme is a manufactured copy of the enzyme, infused into a vein each week, that cells take up and use to clear the buildup. The label states it has been shown to improve walking and stair-climbing capacity.
Side effects and safety
- Hypersensitivity and anaphylaxis. reactions can happen during the infusion and up to 24 hours after it
- Immune-mediated reactions. immune complex reactions, including a kidney condition called membranous glomerulonephritis, have been reported
- Acute heart and lung failure. patients prone to fluid overload, such as those weighing 20kg or less, with an acute respiratory illness or with weak heart or lung function, need extra monitoring
- Breathing complications. sleep apnea is common in MPS VI and antihistamine pretreatment may increase pauses in breathing, so the label says patients who use oxygen or CPAP during sleep should have it available during infusions; delaying an infusion during a fever or respiratory illness is an option
- Infusion reactions. infusion reactions, some severe, occurred in 33 of 59 patients (56%) in clinical studies despite antihistamine pretreatment
- Spinal cord compression. part of MPS VI itself; the label asks that patients be watched for signs of it
- Infusions started in a healthcare setting with monitoring and resuscitation equipment
- Watching for reactions during and after infusions, which have occurred up to 24 hours later
- Watching for signs of spinal or neck cord compression
Naglazyme carries a boxed warning, added in July 2024, for hypersensitivity reactions including anaphylaxis, which the label says have occurred both early in treatment and after long treatment[1]. The label says treatment should start in a healthcare setting with monitoring and resuscitation equipment[1]. In clinical studies, infusion reactions, some severe, occurred in 33 of 59 patients (56%) even with antihistamine pretreatment, appearing as early as week 1 and as late as week 146[1].
Patients who weigh 20kg or less, have an acute respiratory illness or have weak heart or lung function can have a serious worsening of heart or breathing status from the infusion volume, and because sleep apnea is common in MPS VI, the label says patients who use oxygen or CPAP during sleep should have it available during infusions[1].
Immune complex reactions, including membranous glomerulonephritis, a kidney condition, have been reported[1]. In the placebo-controlled trial, reactions more common on Naglazyme than placebo included abdominal pain (47% vs 35%), ear pain (42% vs 20%), joint pain (42% vs 25%), pain (32% vs 5%), conjunctivitis (21% vs 0), shortness of breath (21% vs 10%), rash (21% vs 10%) and chills (21% vs 0)[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 Galsulfase
A weekly intravenous infusion of 1mg per kilogram of body weight, diluted to 250mL, or 100mL for patients 20kg or less or prone to fluid overload[1]. The infusion lasts at least 4 hours: slowly for the first hour, then faster for the remaining 3, and it can be stretched to as long as 20 hours if reactions occur[1]. The label recommends antihistamines, with or without fever reducers, 30 to 60 minutes before each 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 Naglazyme
With private insurance, the drugmaker's copay card can lower what you pay for Naglazyme. Drugmaker copay cards can't be used with Medicare, Medicaid or TRICARE, but charity funds often can. Of the 6 charity funds for Mucopolysaccharidosis Type VI, 3 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 Naglazyme. 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 VI
- From a charity · NORD RareCareMPS VI Medical Assistance fundOpen
Pays for: Medical and medication costs.
The foundation says: “Accepting new applications and re-enrollments for current year” - From a charity · NORD RareCareMPS VI Premium Copay Assistance fundOpen
Pays for: Insurance premiums and copays.
The foundation says: “Accepting new applications and re-enrollments for current year” - From a charity · NORD RareCareMucopolysaccharidosis type VI (MPS VI) Emergency Relief fundOpen
Pays for: Emergency relief.
The foundation says: “Accepting Applications” - 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 VI →
Access and eligibility
Approved for patients with MPS VI (Maroteaux-Lamy syndrome), with no age limit in the indication[1]. Clinical studies covered patients aged 5 to 29, plus 4 infants under 13 months in a small open-label study, and no patients older than 29 were studied[1].
Source: FDA Drugs@FDA (BLA 125117)
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 (NCT00067470) was a 24-week randomized, double-blind, placebo-controlled study (NCT00067470) in patients aged 5 to 29 who could walk 5 to 400 meters in 12 minutes[1][3]. Patients on Naglazyme walked 109 meters farther in 12 minutes than at baseline, against 26 meters on placebo, a model-based difference of 92 meters (p=0.025)[1].
Stair climbing rose by 7.4 stairs a minute on Naglazyme and 2.7 on placebo, a difference that did not reach statistical significance (p=0.053)[1]. After 72 weeks of open-label treatment, 95% of patients had at least a 50% drop in urinary glycosaminoglycans, though none reached the normal range[1]. A small open-label study in 4 infants aged 3 to 12.7 months found safety consistent with older patients[1][4].
Development history
Explore Mucopolysaccharidosis Type VI trials
Common questions about Galsulfase
▸What is Galsulfase (Naglazyme)?
The only FDA-approved treatment for MPS VI (Maroteaux-Lamy syndrome). Naglazyme is a weekly intravenous infusion of the missing enzyme, approved in 2005, that improved walking distance in its pivotal trial. Since July 2024 the label carries a boxed warning for anaphylaxis.
▸How does Galsulfase work?
In MPS VI, a change in the ARSB gene leaves the body short of an enzyme called N-acetylgalactosamine 4-sulfatase, also known as arylsulfatase B. That enzyme breaks down dermatan sulfate, one of the long sugar chains called glycosaminoglycans, inside the lysosomes, the recycling compartments of cells. Without it, dermatan sulfate builds up in tissues across the body, which stiffens joints, thickens heart valves, narrows the airway and limits growth. Naglazyme is a manufactured copy of the enzyme, infused into a vein each week, that cells take up and use to clear the buildup. The label states it has been shown to improve walking and stair-climbing capacity.
▸What are the side effects of Galsulfase?
Naglazyme carries a boxed warning, added in July 2024, for hypersensitivity reactions including anaphylaxis, which the label says have occurred both early in treatment and after long treatment[1]. The label says treatment should start in a healthcare setting with monitoring and resuscitation equipment[1]. In clinical studies, infusion reactions, some severe, occurred in 33 of 59 patients (56%) even with antihistamine pretreatment, appearing as early as week 1 and as late as week 146[1]. Patients who weigh 20kg or less, have an acute respiratory illness or have weak heart or lung function can have a serious worsening of heart or breathing status from the infusion volume, and because sleep apnea is common in MPS VI, the label says patients who use oxygen or CPAP during sleep should have it available during infusions[1]. Immune complex reactions, including membranous glomerulonephritis, a kidney condition, have been reported[1]. In the placebo-controlled trial, reactions more common on Naglazyme than placebo included abdominal pain (47% vs 35%), ear pain (42% vs 20%), joint pain (42% vs 25%), pain (32% vs 5%), conjunctivitis (21% vs 0), shortness of breath (21% vs 10%), rash (21% vs 10%) and chills (21% vs 0)[1].
▸How is Galsulfase taken?
A weekly intravenous infusion of 1mg per kilogram of body weight, diluted to 250mL, or 100mL for patients 20kg or less or prone to fluid overload[1]. The infusion lasts at least 4 hours: slowly for the first hour, then faster for the remaining 3, and it can be stretched to as long as 20 hours if reactions occur[1]. The label recommends antihistamines, with or without fever reducers, 30 to 60 minutes before each infusion[1]. Supplied as 5mg/5mL single-dose vials[1].
▸Is Galsulfase FDA approved?
Yes, Galsulfase (Naglazyme) is FDA approved (2005) for the treatment of Mucopolysaccharidosis Type VI.
▸Does Naglazyme have a boxed warning?
Yes. Since July 2024 the Naglazyme label carries a boxed warning for hypersensitivity reactions including anaphylaxis.
When: Reactions have occurred early in treatment and after long treatment.
Setting: The label says to start treatment where monitoring and resuscitation equipment are available.
▸How is Naglazyme given for MPS VI?
Naglazyme is an intravenous infusion of 1mg/kg given once a week, lasting at least 4 hours.
Before: The label recommends antihistamines, with or without fever reducers, 30 to 60 minutes before each infusion.
Volume: 250mL, or 100mL for patients 20kg or less or prone to fluid overload.
▸How much did Naglazyme improve walking in MPS VI?
In the 24-week pivotal trial, patients on Naglazyme walked 109 meters farther in 12 minutes than at the start, against 26 meters on placebo.
Difference: 92 meters after adjusting for baseline, which was statistically significant.
Stairs: Stair climbing improved more on Naglazyme, but the difference was not statistically significant.
▸Is there help paying for Naglazyme?
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.) · 2024-09. NAGLAZYME (galsulfase) injection, for intravenous use: prescribing information. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=59341250-deac-ed71-3823-a4f5d64dbd77
- U.S. Food and Drug Administration · 2005-05-31. NAGLAZYME approval history, BLA 125117. https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&ApplNo=125117
- ClinicalTrials.gov. Study of Recombinant Human N-acetylgalactosamine 4-sulfatase (rhASB) in Patients With MPS VI. https://clinicaltrials.gov/study/NCT00067470
- ClinicalTrials.gov. A Phase 4 Two Dose Level Study of Naglazyme(TM) (Galsulfase) in Infants With MPS VI. https://clinicaltrials.gov/study/NCT00299000
- BioMarin Pharmaceutical. Real support for the NAGLAZYME® (galsulfase) journey | BioMarin RareConnections™. https://www.biomarin-rareconnections.com/hcp/naglazyme/naglazyme-enroll/