Alglucosidase Alfa (Monograph)

Brand name: Myozyme
Drug class: Enzymes
Chemical name: [199-arginine,223-histidine]prepro-α-glucosidase (human)
Molecular formula: C₄₇₅₈H₇₂₆₂N₁₂₇₄O₁₃₆₉S₃₅
CAS number: 420794-05-0

Medically reviewed by Drugs.com on Mar 27, 2024. Written by ASHP.

Introduction

Biosynthetic (recombinant DNA origin) form of human acid α-glucosidase (GAA); enzyme that catalyzes the hydrolysis of α-1,4- and α-1,6-glycosidic linkages of lysosomal glycogen.

Uses for Alglucosidase Alfa

Pompe Disease

Management of infantile-onset Pompe disease (acid α-glucosidase [GAA] deficiency, glycogen storage disease type II [GSD II], glycogenosis type II, acid maltase deficiency); designated an orphan drug by the FDA for use in this condition.

Pompe disease is a rare progressively debilitating and often fatal inherited disorder of glycogen metabolism caused by the absence or marked deficiency of the lysosomal enzyme GAA.

In the infantile-onset form, Pompe disease results in intralysosomal accumulation of glycogen in various tissues, particularly cardiac and skeletal muscle and the liver, resulting in the development of cardiomyopathy, progressive muscle weakness, hepatomegaly, and impaired respiratory function; death secondary to cardiorespiratory failure usually occurs in the first year of life.

Alglucosidase alfa improves ventilator-free survival in patients with infantile-onset Pompe disease as compared with an untreated historical control group.

Safety and efficacy in patients with forms of Pompe disease other than infantile-onset not established.

Appears to have strongest and most consistent therapeutic effect on the cardiorespiratory manifestations of Pompe disease; effects on motor function appear highly dependent on patient’s condition at start of treatment. Effect of treatment on motor function over time unknown.

Alglucosidase Alfa Dosage and Administration

General

• May administer antipyretics and/or antihistamines prior to alglucosidase alfa infusion.

• If a severe reaction occurs, consider immediate discontinuance of the infusion and initiate appropriate medical treatment.

• Use caution when readministering alglucosidase alfa in patients who have experienced infusion reactions.

Administration

Administer by IV infusion.

IV Administration

Administer by IV infusion using an infusion pump and a 0.2-µm low-protein-binding inline filter.

Alglucosidase alfa particles (typically less than 10 in a vial) may be present in reconstituted alglucosidase alfa solutions in the form of thin white strands or translucent fibers subsequent to the initial inspection or following dilution for infusion; studies have shown that these particles are removed via inline filtration and do not have a detectable effect on the purity or strength of alglucosidase alfa solutions. Do not use solution if opaque particles or discoloration are observed immediately following reconstitution of the drug.

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

Reconstitution

Allow vial containing 50 mg of alglucosidase alfa to reach room temperature (over about 30 minutes), then reconstitute by slowly injecting 10.3 mL of sterile water for injection to the inside wall of the vial to yield a final concentration of 5 mg/mL (total extractable amount per vial: 50 mg [10 mL]). To avoid forceful impact of the water for injection on the powder and to avoid foaming, inject the sterile water for injection slowly by drop-wise addition down the inside of the vial and not directly unto the lyophilized cake.

Gently roll and tilt vial until the lyophilized cake or powder has dissolved; do not invert, swirl, or shake vial.

Vials are for single use only; discard partially used vials of reconstituted solution.

Dilution

Immediately dilute reconstituted alglucosidase alfa in 0.9% sodium chloride injection to provide a final concentration of 0.5–4 mg/mL and a total volume of 50–1000 mL (depending on patient weight, see table below).

Slowly withdraw the appropriate dose of reconstituted solution from each vial avoiding foaming; remove airspace from infusion bag to minimize particle formation. Inject reconstituted alglucosidase alfa solution slowly and directly into the sodium chloride infusion solution, not into any remaining airspace within the infusion bag; avoid foaming.

Gently invert or massage bag containing final solution to mix contents; do not shake.

Rate of Administration

Administer by IV infusion over approximately 4 hours using an infusion pump. Initial infusion rate should not exceed 1 mg/kg per hour. May increase infusion rate in stepwise fashion in increments of 2 mg/kg per hour every 30 minutes after patient tolerance to the infusion rate is established, to a maximum rate of 7 mg/kg per hour. Obtain vital signs at the end of each stepwise increase in the infusion rate.

May decrease (or temporarily discontinue) infusion rate, if infusion-related reactions occur. (See Infusion Reactions under Cautions.)

Dosage

Dosage of alglucosidase alfa is expressed in mg. The specific activity of alglucosidase alfa is 3–5 U/mg, with 1 unit defined as the amount of activity that results in the hydrolysis of 1 µmol of a synthetic substrate per minute under specified assay conditions.

Pediatric Patients

Pompe Disease

Infantile-onset Pompe Disease

IV

Infants and children 1 month to 3.5 years of age: 20 mg/kg by IV infusion once every 2 weeks.

Prescribing Limits

Pediatric Patients

Pompe Disease

Infantile-onset Pompe Disease

IV

Maximum infusion rate: 7 mg/kg per hour.

Special Populations

No special population dosage recommendations at this time.

Cautions for Alglucosidase Alfa

Contraindications

• The manufacturer states that there are no known contraindications.

Warnings/Precautions

Warnings

Respiratory Effects

Acute cardiorespiratory failure requiring intubation and inotropic support has been observed up to 72 hours after alglucosidase alfa infusion in patients with infantile-onset Pompe disease and underlying cardiac hypertrophy; may be associated with fluid overload secondary to IV infusion of alglucosidase alfa.

Possible increased risk of acute cardiorespiratory failure in patients with underlying acute illness at time of alglucosidase alfa infusion. Ensure that appropriate medical support and monitoring measures are readily available during the infusion. Infants with cardiac dysfunction may require prolonged observation times, individualized based on the needs of the patient.

Cardiac Effects

Risk of cardiac arrhythmias (e.g., ventricular fibrillation, ventricular tachycardia, bradycardia); potentially fatal and may require cardiac resuscitation or defibrillation. Such arrhythmias have been associated with use of general anesthesia for placement of central venous catheter intended for IV infusion of the drug in patients with infantile-onset Pompe disease and cardiac hypertrophy. Use caution when administering general anesthesia in such patients.

Infusion Reactions

Infusion reactions, sometimes severe, reported; manifestations include rash, flushing, urticaria, fever, cough, tachycardia, decreased oxygen saturation, vomiting, tachypnea, agitation, cyanosis, hypertension, irritability, pallor, pruritus, retching, rigors, tremor, hypotension, bronchospasm, erythema, facial edema, hot sensation, headache, hyperhidrosis, increased lacrimation, livedo reticularis, nausea, periorbital edema, restlessness, and wheezing. In some cases, infusion reactions occurred in patients who received prophylactic treatment with antihistamines, antipyretic agents, and/or corticosteroids. Infusion reactions are more likely to occur with higher infusion rates, but may occur at any time during or up to 2 hours after IV infusion of the drug.

Possible increased risk of severe complications from infusion reactions in patients with advanced Pompe disease and compromised cardiac and respiratory functions. Additional monitoring required in such patients during administration of alglucosidase alfa.

Possible increased risk of infusion reactions in patients with underlying acute illness at time of alglucosidase alfa infusion. Carefully consider patient’s clinical status prior to administration of the drug.

May administer antipyretics and/or antihistamines prior to alglucosidase alfa infusion. If an infusion reaction occurs regardless of pretreatment, decreasing rate of infusion, temporarily discontinuing infusion, and/or administering antihistamines and/or antipyretic agents may ameliorate symptoms. If a severe reaction occurs, consider immediate discontinuance of alglucosidase alfa infusion and initiate appropriate medical treatment. Use caution when readministering alglucosidase alfa in patients who have experienced infusion reactions.

Sensitivity Reactions

Hypersensitivity Reactions

Severe and potentially life-threatening hypersensitivity reactions (e.g., anaphylactic shock, cardiac arrest, respiratory distress, hypotension, bradycardia, hypoxia, bronchospasm, throat tightness, dyspnea, angioedema, urticaria) reported during and within 3 hours after alglucosidase alfa infusion. Anaphylactic shock and/or cardiac arrest reported in approximately 1% of patients receiving alglucosidase alfa in clinical trials and postmarketing experience.

Ensure that appropriate medical support measures, including CPR equipment, are readily available.

If anaphylactic or other severe allergic reaction occurs, consider immediate discontinuance of alglucosidase alfa and institute appropriate therapy as indicated. Treatment has included cardiopulmonary resuscitation, mechanical ventilatory support, oxygen supplementation, IV fluids, hospitalization, inhaled β-adrenergic agonists, epinephrine, and IV corticosteroids.

Use extreme caution and ensure appropriate resuscitation measures are available if alglucosidase alfa is readministered in a patient who has experienced anaphylaxis or other severe allergic reaction.

General Precautions

Immunologic Reactions and Antibody Formation

Severe cutaneous and systemic immune-mediated reactions (e.g., ulcerative and necrotizing skin lesions, possible type III immune complex-mediated reactions, severe inflammatory arthropathy associated with fever and elevated erythrocyte sedimentation rate) reported. Reactions occurred several weeks to 3 years following initiation of alglucosidase alfa therapy. Monitor patients for the development of systemic immune complex-mediated reactions involving skin and other organs.

Possible formation of antibodies to alglucosidase alfa. Monitor patients for IgG antibody formation every 3 months; contact Genzyme Corporation at 800-745-4447 for information on testing and to obtain a sample collection box. The effect of antibody development on the long-term efficacy of alglucosidase alfa is not fully known; some patients who develop high and sustained anti-alglucosidase alfa antibody titers have experienced a poorer clinical response and/or reduced motor function. Infusion reactions to alglucosidase alfa appear to be more common in antibody-positive patients. (See Infusion Reactions under Cautions.)

Hepatic Effects

Hepatic accumulation of acid α-glucosidase (GAA) observed in preclinical studies of alglucosidase alfa. The manufacturer recommends measurement of hepatic enzyme concentrations before initiation of alglucosidase alfa and periodically thereafter. Caution recommended in interpretation of these measurements since increased ALT and AST concentrations may be associated with muscle pathology in patients with Pompe disease.

Specific Populations

Pregnancy

Category B.

Lactation

Not known whether alglucosidase alfa is distributed into milk. Caution if used in nursing women.

Pediatric Use

Patients 1 month to 3.5 years of age at time of first infusion have received alglucosidase alfa in clinical trials.

Older pediatric patients (2–16 years of age) also have received alglucosidase alfa in open-label clinical trials; however, safety and efficacy of alglucosidase alfa have not been established in patients with juvenile-onset Pompe disease.

Geriatric Use

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

Common Adverse Effects

Pyrexia, cough, decreased oxygen saturation, respiratory distress, respiratory failure, rhinorrhea, tachypnea, pneumonia, otitis media, upper respiratory tract infection, gastroenteritis, pharyngitis, ear infection, oral candidiasis, catheter-related infection, bronchiolitis, nasopharyngitis, diarrhea, vomiting, gastroesophageal reflux disease, constipation, rash, diaper dermatitis, urticaria, tachycardia, bradycardia, post-procedural pain, anemia, flushing.

Drug Interactions

No formal drug interaction studies to date.

Alglucosidase Alfa Pharmacokinetics

Absorption

Plasma Concentrations

Plasma concentrations increase approximately dose-proportionately between dosages of 20 and 40 mg/kg.

Distribution

Extent

Not known whether alglucosidase alfa is distributed into milk.

Elimination

Half-life

About 2 and 3 hours following single IV doses of 20 and 40 mg/kg, respectively.

Special Populations

Increased clearance (by about 50% [range: 5–90%]) observed in patients developing anti-alglucosidase alfa antibody titers of ≥12,800 at week 12 of treatment.

Stability

Storage

Parenteral

Powder for IV Infusion

2–8°C. Vials are for single use only; discard any unused product. Administer reconstituted and diluted solution without delay; if not used immediately, solution is stable for up to 24 hours at 2–8°C.

Protect reconstituted and diluted solutions from light; do not freeze, shake, or store at room temperature.

Actions

• Biosynthetic (recombinant DNA origin) form of acid α-glucosidase (GAA), a lysosomal enzyme that catalyzes the hydrolysis of α-1,4- and α-1,6-glycosidic linkages of lysosomal glycogen.

• Provides an exogenous source of GAA in patients with Pompe disease.

• Binds to mannose-6-phosphate receptors on the cell surface via carbohydrate groups on the alglucosidase alfa molecule, which is then internalized and transported into lysosomes.

• In the lysosomes, undergoes proteolytic cleavage resulting in increased enzymatic activity.

Advice to Patients

• Importance of encouraging caregivers and patients, including nursing women and women of childbearing potential, to participate in the Pompe disease registry ([Web] or 800-745-4447).

• 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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