Reported adverse reactions with imiglucerase have generally not been considered serious or have usually not warranted medical intervention or discontinuation of therapy. Approximately 13.8% of patients report adverse events thought to be causally related to imiglucerase. Some of the adverse events are related to the route of administration. An injection site reaction may occur, presenting as discomfort, pruritus, burning, swelling, or sterile abscess; each of these reactions are reported in less than 1% of patients.[49245]

Roughly 15% of patients receiving imiglucerase develop IgG antibody formation to the medication. In most patients, the development of antibodies does not prohibit continued drug administration. Antibodies are most likely to develop within the first 6—12 months of treatment. While patients with IgG antibodies are at higher risk of developing imiglucerase hypersensitivity, the development of antibodies is not necessary for a hypersensitivity reaction to occur. Symptoms suggestive of hypersensitivity occur in roughly 6.6% of all patients treated. Hypersensitivity reactions manifest during or shortly after the completion of imiglucerase infusion as pruritus, flushing, chest pain (unspecified), dyspnea or other respiratory symptoms, cough, cyanosis, hypotension and, rarely, urticaria or angioedema. Serious symptoms occur in less than 1.5% of patients treated. Pretreatment with antihistamines and/or corticosteroids and a reduced rate of infusion has allowed for continued treatment in most patients. If a serious hypersensitivity reaction occurs, continued treatment with imiglucerase should be re-evaluated.[49245] Cross-sensitivity between alglucerase and imiglucerase may not always occur. In one case report, a patient exhibited anaphylactoid reactions to recombinant-derived imiglucerase but not to placental-derived alglucerase.[27607]

Approximately 6.5% of patients receiving imiglucerase reported nausea and vomiting, abdominal pain, diarrhea, rash (unspecified), fatigue, headache, fever or chills, dizziness, backache, transient peripheral edema, or sinus tachycardia. Each of these events individually occurs in less than 1.5% of the patient population treated. In some cases, these events are related to the infusion rate. Spontaneously reported post-marketing adverse reactions in children ages 2—12 years have included dyspnea, fever, nausea, vomiting, flushing, and cough; in adults (age > 16 years) and adolescents (age > 12—16 years), the most commonly reported post-marketing adverse effects included headache, pruritus, and rash.[49245]

The use of imiglucerase should be directed by a qualified health care professional knowledgeable in the management of Gaucher's disease. In < 1% of patients, pulmonary hypertension has been observed during treatment with imiglucerase. Pulmonary hypertension is a known complication of Gaucher's disease in patients receiving and not receiving imiglucerase. No causal relationship to imiglucerase has been established. Patients with respiratory symptoms should be evaluated for the presence of pulmonary hypertension.

Previously, the imiglucerase product may have contained small amounts of Haemaccel, a gelatin polypeptide, from the manufacturing process. Products that have an expiration date before April 2007 still contain Haemaccel, and should be use cautiously in patients with an immediate gelatin hypersensitivity. However, this warning is not applicable to products that have an expiration date of April 2007 or later as they do not contain Haemaccel.

Imiglucerase is classified in FDA pregnancy risk category C. Animal reproduction and human reproduction data are not available. According to the manufacturer, it should be used during pregnancy with caution and only when the benefit to the mother outweighs the potential, unknown risk to the fetus.[49245] However, a report from a panel of clinicians that treat Gaucher's disease indicated that treatment with enzyme replacement therapy during pregnancy led to a reduced risk of spontaneous abortion and a reduced risk of Gaucher-related complications during delivery and during the postpartum period. No adverse effects on the fetus have been reported secondary to imiglucerase therapy.[49246] Imiglucerase has thus been suggested, based on the data available, as an agent for consideration for the treatment of Gaucher's disease during pregnancy.[56701] There is also a published case report of the successful use of imiglucerase in a pregnant, and subsequently lactating, patient.[56702]

It is not known if imiglucerase is distributed into breast milk. According to the manufacturer, it should be used with caution in breast-feeding women.[49245] Enzymes such as imiglucerase are likely to be degraded by the infant's digestive sytem and unlikely to reach the systemic circulation of a nursing infant. Limited data in a report from a panel of clinicians that treat Gaucher's disease indicated that breast-feeding complications were reduced in women treated with enzyme replacement therapy postpartum. No adverse effects on the nursing infant were reported secondary to imiglucerase therapy. Consider reducing the duration of breast-feeding to avoid excessive bone loss in the mother.[49246] There are published reports of the successful use of imiglucerase in a pregnant, and subsequently lactating, patient. The case report stated a small amount of imiglucerase was found to be excreted into human breast milk, but only in the first milk produced after infusion, and the patient was able to successfully breast-feed the infant.[56702] Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition. If a breast-feeding infant experiences an adverse effect related to a maternally administered drug, healthcare providers are encouraged to report the adverse effect to the FDA.