Aldurazyme (laronidase)
An approved treatment for Mucopolysaccharidosis Type I.
Drug facts
The same compound appears under different names depending on the context. Here is how to identify Laronidase wherever you encounter it, plus the key facts at a glance.
- Generic name
- Laronidase
- Brand name
- Aldurazyme
- Drug class
- Enzyme replacement therapy
- Manufacturer
- BioMarin Pharmaceutical (manufacturer) and Genzyme, a Sanofi company (distributor)
- How it's taken
- Intravenous infusion, once a week
The only FDA-approved enzyme replacement therapy for MPS I. Aldurazyme is a weekly intravenous infusion of the missing enzyme, approved in 2003 for the Hurler and Hurler-Scheie forms and for the Scheie form with moderate to severe symptoms.
It improved breathing capacity in its pivotal trial, and the label states its effect on the brain has not been determined.
We'll email you when Aldurazyme's FDA label changes, when the FDA acts on it, and when new trials for Mucopolysaccharidosis Type I open. Unsubscribe anytime.
- Trial Alerts, when a new trial opens or a trial changes
- Disease Updates, FDA decisions and condition news, usually 1 or 2 emails a month
We never share your email. Unsubscribe anytime. Privacy policy · Check any health site
Where Laronidase fits
Aldurazyme is the only FDA-approved enzyme replacement therapy for MPS I, a weekly infusion available since 2003[2].
- The label states that its effect on the brain and nervous system has not been determined[1].
- Families can ask a metabolic genetics specialist which form of MPS I a child has and how that shapes the choice of treatment.
How Laronidase works
In MPS I, changes in the IDUA gene leave the body short of alpha-L-iduronidase, an enzyme that breaks down dermatan sulfate and heparan sulfate, long sugar chains called glycosaminoglycans, inside the lysosomes, the recycling compartments of cells. Without it, these build up in organs and tissues, which enlarges the liver and spleen, stiffens joints, clouds the corneas, narrows the airway and strains the heart.
MPS I runs from the severe Hurler form to the milder Scheie form, with Hurler-Scheie in between. Aldurazyme 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 that its effect on the brain and nervous system has not been determined[1].
Side effects and safety
- Hypersensitivity and anaphylaxis. reactions can happen during or up to 3 hours after an infusion; about 1% of patients had severe or serious reactions, and the label urges caution with epinephrine because heart artery disease is more common in MPS I
- Acute respiratory complications. a patient with bronchitis and low oxygen had a respiratory arrest and died about 6 hours after a first infusion; sleep apnea is common, so the label says patients who use CPAP or oxygen should have it available during infusions, and delaying an infusion during a fever or respiratory illness is an option
- Acute heart and lung failure. reported after marketing; patients prone to fluid overload may need a smaller volume and slower rate
- Infusion reactions. can still occur after premedication
- Resuscitation equipment available during infusions
- Watching for reactions during and after infusions, which have occurred up to 3 hours later
- Extra monitoring for patients with weak lung function or an acute respiratory illness
Aldurazyme carries a boxed warning for life-threatening hypersensitivity reactions including anaphylaxis, and for serious worsening of breathing from infusion reactions in patients with weak lung function or an acute respiratory illness[1]. The label says about 1% of patients had severe or serious hypersensitivity reactions, which can happen during or up to 3 hours after an infusion, and 1 patient with bronchitis and low oxygen died of respiratory arrest about 6 hours after a first infusion[1].
In the placebo-controlled trial, infusion reactions occurred in 32% of patients on Aldurazyme, and reactions more common than on placebo included rash (36% vs 22%), upper respiratory infection (32% vs 17%), injection site reaction (18% vs 9%), overactive reflexes (14% vs 0), tingling (14% vs 4%) and poor vein access (14% vs 0)[1]. In children aged 6 months to 5 years, infusion reactions occurred in 35%, most often fever (30%) and chills (20%)[1]. Of 73 patients tested, 96% developed antibodies to the drug[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 Laronidase
A weekly intravenous infusion of 0.58mg per kilogram of body weight, diluted to 50mL, 100mL or 250mL depending on weight[1]. The rate starts slowly and steps up every 15 minutes, and the whole infusion takes about 3 to 4 hours[1]. The label says to consider antihistamines, with or without fever reducers, 60 minutes before the infusion[1]. Supplied as 2.9mg/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. Sanofi's CareConnect Personalized Support Services offers insurance help and a copay program for eligible commercially insured patients.
Help paying for Aldurazyme
With private insurance, the drugmaker's copay card can lower what you pay for Aldurazyme. 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 I, 3 were open on October 26, 2026. Pick your insurance below to see which offers fit you.
- Copay help
The CareConnect Personalized Support Services Copay Assistance Program can cover copays, coinsurance and deductibles for US residents with commercial insurance. Not valid with Medicaid, Medicare, VA, DoD, TRICARE or other government programs. No annual maximum is published; full terms are given on registration.
For: private insurance · source - Infusion cost help
The copay program also covers certain infusion costs, such as mixing, administration, saline and IV tubing.
For: private insurance · source - Insurance and case manager help
Disease education, insurance navigation and help connecting with specialists and appointments.
The official page does not say who qualifies. Ask the program. · source
Good to know: Sanofi's copay page says uninsured patients or those denied coverage can call 1-800-745-4447, option 3, about its Patient Assistance Program; its terms were not confirmed on a Sanofi page. The support pages are marked for US healthcare professionals.
Charity funds for Mucopolysaccharidosis Type I
- From a charity · NORD RareCareMPS I (Hurler 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 RareCareMPS I (Hurler 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 · The Assistance FundMPS I - Hurler Syndrome (Hurler-Scheie, Scheie) fundOpen
Pays for: Copays, coinsurance, deductibles and other health-related expenses.
- 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 I →
Access and eligibility
Approved for adults and children with the Hurler and Hurler-Scheie forms of MPS I, and for the Scheie form when symptoms are moderate to severe[1]. The label says safety and effectiveness in mildly affected Scheie patients are not established, and that its effect on the brain and nervous system has not been determined[1]. It has been studied in children as young as 6 months; no patients 65 or older were studied[1].
Source: FDA Drugs@FDA (BLA 125058)
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 (NCT00912925) was a 26-week randomized, double-blind, placebo-controlled study of 45 patients aged 6 to 43, mostly with the Hurler-Scheie form, whose lung capacity (forced vital capacity, FVC) was 77% of predicted or lower[1][3]. Percent predicted FVC rose by 1 point on Aldurazyme and fell by 3 on placebo, a median difference of 2 points that was statistically significant (p=0.02)[1].
The 6-minute walk improved by 20 meters on Aldurazyme and fell by 18 on placebo, a median difference of 39 meters that did not reach statistical significance (p=0.07)[1]. Liver size and urinary glycosaminoglycans fell more on Aldurazyme, though no treated patient reached normal urinary levels[1]. A 52-week open-label study (NCT00146757) in 20 children aged 6 months to 5 years, mostly with the Hurler form, found urinary glycosaminoglycans fell by week 13 and stayed down[1][4].
Development history
Developed through a 50/50 joint venture between BioMarin and Genzyme, and approved by the FDA on April 30, 2003 under BLA 125058 after priority review[2][5]. The current label lists BioMarin as manufacturer and Genzyme, a Sanofi company, as distributor, with the trademark held by BioMarin/Genzyme LLC[1]. The label was revised in July 2026[1].
Explore Mucopolysaccharidosis Type I trials
Common questions about Laronidase
▸What is Laronidase (Aldurazyme)?
The only FDA-approved enzyme replacement therapy for MPS I. Aldurazyme is a weekly intravenous infusion of the missing enzyme, approved in 2003 for the Hurler and Hurler-Scheie forms and for the Scheie form with moderate to severe symptoms. It improved breathing capacity in its pivotal trial, and the label states its effect on the brain has not been determined.
▸How does Laronidase work?
In MPS I, changes in the IDUA gene leave the body short of alpha-L-iduronidase, an enzyme that breaks down dermatan sulfate and heparan sulfate, long sugar chains called glycosaminoglycans, inside the lysosomes, the recycling compartments of cells. Without it, these build up in organs and tissues, which enlarges the liver and spleen, stiffens joints, clouds the corneas, narrows the airway and strains the heart. MPS I runs from the severe Hurler form to the milder Scheie form, with Hurler-Scheie in between. Aldurazyme 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 that its effect on the brain and nervous system has not been determined[1].
▸What are the side effects of Laronidase?
Aldurazyme carries a boxed warning for life-threatening hypersensitivity reactions including anaphylaxis, and for serious worsening of breathing from infusion reactions in patients with weak lung function or an acute respiratory illness[1]. The label says about 1% of patients had severe or serious hypersensitivity reactions, which can happen during or up to 3 hours after an infusion, and 1 patient with bronchitis and low oxygen died of respiratory arrest about 6 hours after a first infusion[1]. In the placebo-controlled trial, infusion reactions occurred in 32% of patients on Aldurazyme, and reactions more common than on placebo included rash (36% vs 22%), upper respiratory infection (32% vs 17%), injection site reaction (18% vs 9%), overactive reflexes (14% vs 0), tingling (14% vs 4%) and poor vein access (14% vs 0)[1]. In children aged 6 months to 5 years, infusion reactions occurred in 35%, most often fever (30%) and chills (20%)[1]. Of 73 patients tested, 96% developed antibodies to the drug[1].
▸How is Laronidase taken?
A weekly intravenous infusion of 0.58mg per kilogram of body weight, diluted to 50mL, 100mL or 250mL depending on weight[1]. The rate starts slowly and steps up every 15 minutes, and the whole infusion takes about 3 to 4 hours[1]. The label says to consider antihistamines, with or without fever reducers, 60 minutes before the infusion[1]. Supplied as 2.9mg/5mL single-dose vials[1].
▸Is Laronidase FDA approved?
Yes, Laronidase (Aldurazyme) is FDA approved (2003) for the treatment of Mucopolysaccharidosis Type I.
▸Does Aldurazyme treat the brain in Hurler syndrome?
The Aldurazyme label states that its effect on the brain and nervous system in MPS I has not been determined.
What it showed: Better breathing capacity and smaller liver size in its pivotal trial.
Ask: A metabolic genetics specialist can explain how this shapes treatment for the Hurler form.
▸What is the boxed warning on Aldurazyme?
Aldurazyme's boxed warning covers life-threatening allergic reactions including anaphylaxis, and serious breathing problems during infusions in people with weak lung function or a respiratory illness.
How often: About 1% of patients had severe or serious allergic reactions.
Setting: Resuscitation equipment should be available during infusions.
▸How is Aldurazyme given?
Aldurazyme is an intravenous infusion of 0.58mg/kg once a week, taking about 3 to 4 hours.
Rate: It starts slowly and steps up every 15 minutes.
Before: The label says to consider antihistamines, with or without fever reducers, 60 minutes before.
▸Is there help paying for Aldurazyme?
Sanofi's CareConnect Personalized Support Services offers insurance help and a copay program for eligible commercially insured patients.
Copay program: Can cover copays, coinsurance and deductibles, plus certain infusion costs, for US residents with commercial insurance.
Not covered: Medicare, Medicaid and other government insurance.
Phone: 1-800-745-4447, option 3.
Source: Aldurazyme copay program and CareConnect
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 (Genzyme Corporation) · 2026-07. ALDURAZYME- laronidase injection, solution, concentrate. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=a80ac249-cae4-41f3-88bb-344088b20e60
- U.S. Food and Drug Administration · 2003-04-30. ALDURAZYME approval history, BLA 125058. https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&ApplNo=125058
- ClinicalTrials.gov. Clinical Study of Aldurazyme in Patients With Mucopolysaccharidosis (MPS) I. https://clinicaltrials.gov/study/NCT00912925
- ClinicalTrials.gov. A Study Evaluating the Safety and Pharmacokinetics of Aldurazyme® (Laronidase) in MPS I Patients Less Than 5 Years Old. https://clinicaltrials.gov/study/NCT00146757
- BioMarin Pharmaceutical · 2008-04-29. BioMarin Announces First Quarter 2008 Financial Results. https://www.biomarin.com/news/press-releases/biomarin-announces-first-quarter-2008-financial-results/
- Sanofi. CareConnect Personalized Support | Aldurazyme® | For US HCPs. https://pro.campus.sanofi/us/products/aldurazyme/careconnect-personalized-support
- Sanofi. Aldurazyme® Copay Program | For US HCPs. https://pro.campus.sanofi/us/products/aldurazyme/copay-assistance