Idursulfase (Monograph)

Brand name: Elaprase
Drug class: Enzymes
Chemical name: α-L-iduronate sulfate sulfatase
Molecular formula: C₂₆₈₉H₄₀₅₇N₆₉₉O₇₉₂S₁₄
CAS number: 50936-59-9

Introduction

Biosynthetic (recombinant DNA origin) form of human iduronate-2-sulfatase; lysosomal enzyme that catalyzes the hydrolysis of the 2-sulfate esters of terminal iduronate sulfate residues from the glycosaminoglycans dermatan sulfate and heparan sulfate.

Uses for Idursulfase

Hunter Syndrome

Management of Hunter syndrome (mucopolysaccharidosis II, MPS II); designated an orphan drug by FDA for use in this condition.

Hunter syndrome is an X-linked recessive disease characterized by a deficiency of the lysosomal enzyme iduronate-2-sulfatase.

In patients with Hunter disease, reduced or absent iduronate-2-sulfatase activity results in progressive accumulation of glycosaminoglycans in the lysosomes of various cells, leading to cellular engorgement, organomegaly, tissue destruction, and organ system dysfunction.

Idursulfase improves endurance (measured by increases in walking distance) in patients with Hunter syndrome.

Idursulfase Dosage and Administration

Administration

Administer by IV infusion.

IV Administration

For solution compatibility and storage information, see Stability.

Administer by IV infusion using a 0.2-µm filter.

Do not infuse idursulfase infusions simultaneously through the same IV line with other drugs.

Dilution

Prior to infusion, dilute the appropriate dose of commercially available idursulfase concentrated solution (2 mg of the drug per mL) in 100 mL of 0.9% sodium chloride for injection according to the manufacturer’s instructions. Vials are for single use only; discard partially used vials of idursulfase solution.

Withdraw the calculated volume providing the appropriate dose of idursulfase from the appropriate number of vials and dilute in 100 mL of 0.9% sodium chloride injection. Gently mix the solution in the infusion bag; do not shake. Consult the manufacturer’s labeling for additional information on dilution and administration of idursulfase.

Rate of Administration

Administer by IV infusion at an initial infusion rate of 8 mL/hour for the first 15 minutes. May increase infusion rate in increments of 8 mL/hour every 15 minutes in order to administer the entire volume within the desired time, up to a maximum rate of 100 mL/hour. May administer the total volume of infusion in 1–3 hours; do not exceed 8 hours. May decrease infusion rate, temporarily discontinue infusion, or stop the infusion for the particular visit if infusion-related reactions occur.

Dosage

The specific activity of idursulfase is 41–77 units/mg, with 1 unit defined as the amount of activity that results in the hydrolysis of 1 µmol of heparin disaccharide substrate per hour under specified assay conditions.

Pediatric Patients

Hunter Syndrome

IV

Children ≥5 years of age: 0.5 mg/kg by IV infusion once weekly.

Adults

Hunter Syndrome

IV

0.5 mg/kg by IV infusion once weekly.

Prescribing Limits

Pediatric Patients

Hunter Syndrome

IV

Maximum infusion rate: 100 mL/hour.

Adults

Hunter Syndrome

IV

Maximum infusion rate: 100 mL/hour.

Special Populations

No special population dosage recommendations at this time.

Cautions for Idursulfase

Contraindications

• The manufacturer states that there are no known contraindications to the use of idursulfase.

Warnings/Precautions

Sensitivity Reactions

Hypersensitivity Reactions

Life-threatening hypersensitivity reactions (e.g., anaphylaxis, respiratory distress, hypoxia, hypotension, seizure, loss of consciousness, urticaria, angioedema of the throat and tongue) reported during and after idursulfase infusion in patients receiving the drug. Ensure that appropriate medical support measures are readily available during administration.

Consider prolonged observation in patients who experience initial severe or refractory reactions, since biphasic anaphylactic reactions occurring up to approximately 24 hours after treatment and recovery from an initial anaphylactic reaction have been reported.

Provide additional monitoring in patients with compromised respiratory function or acute respiratory disease, who may be at risk of serious acute exacerbation of their respiratory compromise secondary to infusion reactions. Consider delaying idursulfase infusion in patients with concomitant acute respiratory and/or febrile illness.

If anaphylactic reactions or other severe allergic reaction occurs, immediately discontinue administration of the drug, and initiate appropriate medical treatment. In clinical studies, treatment included hospitalization, epinephrine, inhaled β-adrenergic agonists, and corticosteroids. Consider resuming the infusion at a slower rate or discontinuing the idursulfase infusion for that visit. May consider use of antihistamines and/or corticosteroids prior to and during subsequent infusions in patients who have experienced severe infusion reactions.

General Precautions

Antibody Formation

Possible formation of antibodies to idursulfase. Increased incidence of infusion reactions, including allergic reactions, reported in patients who developed IgG antibodies to idursulfase; in addition, decreased reduction of urinary glycosaminoglycan excretion reported in patients who developed antibodies to idursulfase. The relationship between the development of antibodies to idursulfase and clinical efficacy outcome is not fully known.

Specific Populations

Pregnancy

Category C.

Lactation

Not known whether idursulfase is distributed into milk. Use with caution.

Pediatric Use

Patients ≥5 years of age have received idursulfase in clinical trials. Clinical response to idursulfase was similar in children, adolescents, and adults. Safety and efficacy of idursulfase in pediatric patients <5 years of age have not been established.

Geriatric Use

No experience in patients ≥65 years of age; unknown whether geriatric patients respond differently than younger individuals.

Common Adverse Effects

Pyrexia, headache, arthralgia, limb pain, pruritus, hypertension, malaise, visual disturbance, wheezing, abscess, chest wall musculoskeletal pain, musculoskeletal dysfunction, urticaria, anxiety/irritability, atrial abnormality, dyspepsia, infusion site edema, injury, pruritic rash, skin disorder, superficial injury.

In clinical studies, the most frequent serious adverse effects related to idursulfase were hypoxic episodes. The most common infusion-related reactions were headache, fever, cutaneous reactions, and hypertension.

Drug Interactions

No formal drug interaction studies to date.

Idursulfase Pharmacokinetics

Absorption

Plasma Concentrations

AUC values increased in a greater than dose proportional manner following single 1-hour IV infusion of idursulfase dosages ranging from 0.15–1.5 mg/kg.

Distribution

Extent

Not known whether idursulfase is distributed into milk.

Elimination

Half-life

44–48 minutes.

Stability

Storage

Parenteral

Solution for IV Infusion

2–8°C; protect from light and do not shake or freeze. Vials are for single use only; discard any unused product.

Administer diluted solution without delay; if not used immediately, diluted solution is stable at 2–8°C ≤48 hours. If held at room temperature, administer diluted solution within 8 hours.

Actions

• Biosynthetic (recombinant DNA origin) form of human iduronate-2-sulfatase, a lysosomal enzyme that catalyzes the hydrolysis of the 2-sulfate esters of terminal iduronate sulfate residues from the glycosaminoglycans dermatan sulfate and heparan sulfate in the lysosomes of various cell types.

• Provides an exogenous source of iduronate-2-sulfatase in patients with Hunter syndrome.

• Binds to mannose-6-phosphate receptors on the cell surface via mannose-6-phosphate residues on the oligosaccharide chains of the idursulfase molecule, which is then internalized and transported into lysosomes.

• Enzymatic activity of idursulfase, which results in catabolism of accumulated glycosaminoglycans, is dependent on the posttranslational modification of a specific cysteine to formylglycine.

Advice to Patients

• Importance of encouraging patients to participate in the Hunter Outcome Survey ([Web] or 866-888-0660) to understand the variability and progression of the disease and to continue to monitor and evaluate long-term treatment effects of idursulfase.

• Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs.

• Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.

• Importance of informing patients of other important precautionary information. (See Cautions.)

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

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Biological Products Related to idursulfase

Find detailed information on biosimilars for this medication.

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