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Medically reviewed by Last updated on Oct 8, 2020.


(eye dur SUL fase)

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Solution, Intravenous [preservative free]:

Elaprase: 6 mg/3 mL (3 mL)

Brand Names: U.S.

  • Elaprase

Pharmacologic Category

  • Enzyme


Idursulfase is a recombinant form of iduronate-2-sulfatase, an enzyme needed to hydrolyze the mucopolysaccharides dermatan sulfate and heparan sulfate in various cells. Accumulation of these polysaccharides can lead to various manifestations of disease, including physical changes, CNS involvement, cardiac, respiratory, and mobility dysfunction. Replacement of this enzyme has been shown to improve walking capacity in patients with a deficiency.


Varies dependent upon age and presence of antibodies (particularly patients <7.5 years): Vss:

Children 16 months to <7.5 years: Week 1: 394 ± 423 mL/kg; Week 27: Antibody negative: 272 ± 112 mL/kg; antibody positive: 829 ± 636 mL/kg

Children ≥7.5 years, Adolescents, and Adults <27 years: Mean range: 213 to 254 mL/kg

Half-Life Elimination

Varies dependent upon age and presence of antibodies (particularly patients <7.5 years)

Children 16 months to <7.5 years: Week 1: 160 ± 69 minutes; Week 27: Antibody negative: 134 ± 19 minutes; antibody positive: 84 ±46 minutes

Children ≥7.5 years, Adolescents, and Adults <27 years: Mean range: 44 to 48 minutes

Use: Labeled Indications

Mucopolysaccharidosis II (Hunter syndrome): Enzyme replacement therapy in Hunter syndrome (mucopolysaccharidosis II; MPS II)


There are no contraindications listed in the manufacturer’s labeling.

Canadian labeling: Hypersensitivity to idursulfase or any component of the formulation

Dosing: Adult

Mucopolysaccharidosis II (Hunter syndrome): IV: 0.5 mg/kg once weekly

Dosing: Pediatric

Mucopolysaccharidosis type II (MPS II, Hunter syndrome): Note: Current consensus opinion recommends initiation of therapy as early as possible following diagnosis (Scarpa 2011):

Children 16 months to <5 years: Limited data available: IV: 0.5 mg/kg once weekly (Muenzer 2011; Scarpa 2011). A small, open-labeled evaluation of the safety and efficacy of 53 weeks of therapy in 28 pediatric patients ≤5 years of age showed enzyme replacement with idursulfase reduced splenic volume similar to older pediatric patients but data did not support improvement in other disease-related symptoms (which were undefined) or long-term clinical outcomes (which were undefined) (manufacturer's labeling). Proving clinical benefit of therapy for disease-related symptoms in this population is challenging due to age-related compliance with evaluation techniques (eg, walking capacity evaluations, FEV) (Muenzer 2011). A larger observation trial (n=124) of patients <6 years (including infants) showed weekly administration of idursulfase produced a significant decrease in hepatic volume and a reduction in urine glycosaminoglycans (GAG) levels similar to that in older pediatric patients (Muenzer 2011).

Children ≥5 years and Adolescents: IV: 0.5 mg/kg once weekly.


Allow vials to reach room temperature prior to preparation. Dilute dose in NS 100 mL. Mix gently, do not shake.


IV: Administer using an infusion set containing a 0.2 micron low protein-binding inline filter. Infuse at an initial rate of 8 mL/hour for the first 15 minutes. If tolerated, may increase rate by 8 mL/hour increments every 15 minutes; maximum infusion rate of up to 100 mL/hour. Rate may be decreased, temporarily stopped, or discontinued based on tolerance. Initial infusion should be over 3 hours; if tolerated, subsequent infusions may be gradually reduced to a 1-hour infusion. Total infusion time should not exceed 8 hours.


Store vials under refrigeration at 2°C to 8°C (36°F to 46°F). Protect from light, do not freeze or shake. Should be used immediately after dilution in NS. However, solution for infusion may be stored under refrigeration for up to 24 hours.

Drug Interactions

There are no known significant interactions.

Adverse Reactions

The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified.


Cardiovascular: Flushing (7% to 16%)

Central nervous system: Headache (28%), fatigue (13%)

Dermatologic: Skin rash (19% to 32%), pruritus (25%), urticaria (16%)

Gastrointestinal: Vomiting (5% to 14%)

Hypersensitivity: Hypersensitivity reaction (57% to 69%)

Immunologic: Antibody development (neutralizing: 41% to 79%), development of IgG antibodies (51% to 68%)

Neuromuscular & skeletal: Musculoskeletal pain (13%)

Otic: Otitis (children: 11%)

Respiratory: Pneumonia (children: 18%)

Miscellaneous: Fever (9% to 36%)

1% to 10%:

Cardiovascular: Tachycardia (9%), hypotension (5%)

Central nervous system: Chills (9%), dizziness (5%)

Dermatologic: Erythema (7%)

Gastrointestinal: Diarrhea (9%), nausea (5%)

Respiratory: Cough (9%)

Frequency not defined:

Cardiovascular: Cardiac arrhythmia, pulmonary embolism

Hypersensitivity: Angioedema

Infection: Infection

<1%, postmarketing, and/or case reports: Anaphylaxis, cyanosis, loss of consciousness, respiratory distress, respiratory failure, seizure

ALERT: U.S. Boxed Warning

Hypersensitivity reactions:

Life-threatening anaphylactic reactions have occurred in some patients during and up to 24 hours after idursulfase infusions. Anaphylaxis, presenting as respiratory distress, hypoxia, hypotension, urticaria, and/or angioedema of throat or tongue, has been reported to occur during and after idursulfase infusions, regardless of duration of the course of treatment. Closely observe patients during and after administration and be prepared to manage anaphylaxis. Inform patients of the signs and symptoms of anaphylaxis and have them seek immediate medical care should symptoms occur. Patients with compromised respiratory function or acute respiratory disease may be at risk of serious acute exacerbation of their respiratory compromise due to hypersensitivity reactions, and require additional monitoring.


Concerns related to adverse effects:

• Hypersensitivity/anaphylactoid reactions: [US Boxed Warning]: Serious hypersensitivity reactions, including fatal life-threatening anaphylactic reactions, have been reported during and within 24 hours after infusion. Anaphylaxis may present as respiratory distress, hypoxia, hypotension, urticaria, and/or tongue/throat angioedema. Monitor closely during and after infusion. Appropriate medical support should be readily available. Patients with compromised respiratory function or acute respiratory disease are at risk of respiratory disease exacerbation due to hypersensitivity; additional monitoring may be required. Discontinue immediately if anaphylactic or acute reaction occurs. Patients experiencing initial severe or refractory reactions may need prolonged monitoring. Antihistamines, corticosteroids and/or decreased infusion rates may be used to manage subsequent infusions.

• Antibody formation: Development of anti-idursulfase IgG antibodies has been reported in 51% of patients; may increase incidence of hypersensitivity reactions.

Disease-related concerns:

• Acute febrile/respiratory illness: Hypersensitivity reactions may occur. Use caution and consider delaying treatment in patients with compromised respiratory function or acute febrile or respiratory illness; may be at increased risk for life-threatening complications from hypersensitivity reactions.

• Fluid overload: Use with caution in patients at risk for fluid overload or in conditions where fluid restriction is indicated (eg, acute underlying respiratory illness, compromised cardiac and/or respiratory function); conditions may be exacerbated during infusion. Extended observation may be necessary for some patients.

• Genetic mutations: Use with caution in patients with severe genetic mutations (eg, complete gene deletion, large gene rearrangement, nonsense, frameshift or splice site mutations); may increase risk of hypersensitivity reactions, serious adverse reactions, and antibody development.

Other warnings/precautions:

• Registry: Patients and healthcare providers are encouraged to participate in the Hunter Outcome Survey, intended to monitor disease progression, patient outcomes, and long-term effects of therapy. For more information, refer to or call OnePathsm at 1-866-888-0660.

Monitoring Parameters

Monitor for infusion-related and hypersensitivity reactions; pulmonary function, oxygen saturation; blood pressure

Pregnancy Considerations

Adverse events were not observed in animal reproduction studies.

Patient Education

What is this drug used for?

• It is used to treat Hunter syndrome.

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

• Loss of strength and energy

• Headache

• Diarrhea

• Muscle pain

• Cough

• Itching

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Infusion reaction

• Severe dizziness

• Passing out

• Blue/gray skin discoloration

• Shortness of breath

• Severe nausea

• Vomiting

• Seizures

• Chills

• Flushing

• Fast heartbeat

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.

Note: This is not a comprehensive list of all side effects. Talk to your doctor if you have questions.

Consumer Information Use and Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a limited summary of general information about the medicine's uses from the patient education leaflet and is not intended to be comprehensive. This limited summary does NOT include all information available about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not intended to provide medical advice, diagnosis or treatment and does not replace information you receive from the healthcare provider. For a more detailed summary of information about the risks and benefits of using this medicine, please speak with your healthcare provider and review the entire patient education leaflet.

Further information

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