Indication
ELAPRASE^® (idursulfase) is indicated for patients with Hunter syndrome (Mucopolysaccharidosis II, MPS II). ELAPRASE has been shown to improve walking capacity in these patients.

Important Safety Considerations

Some patients in the clinical trials experienced life-threatening immediate allergic reactions to ELAPRASE (idursulfase) infusion. Patients who have experienced severe allergic reactions may experience another allergic reaction approximately 24 hours after the initial reaction and may require prolonged observation. Patients with compromised respiratory function or acute respiratory disease may have a higher risk of life-threatening reactions to ELAPRASE infusion and require additional monitoring.

Life-threatening allergic reactions have been seen in some patients during ELAPRASE infusions. Reactions included difficulty breathing, lack of oxygen, seizure or loss of consciousness, hives, and/or swelling of the throat or tongue. Patients received an antihistamine to reverse the allergic reaction or corticosteroid to decrease inflammation prior to or during later infusions. ELAPRASE was given more slowly or was stopped early if patients had serious reactions. With these measures, no patients stopped treatment permanently due to an infusion reaction.

Because of the potential for life-threatening complications, the ELAPRASE infusion may have to be delayed for patients who have respiratory illness and/or fever.

The most common side effects that required intervention had to do with infusions. These included headache, fever, rash, hives, itching and increased blood pressure. These side effects decreased over time with continued ELAPRASE treatment.

In clinical trials, patients given ELAPRASE once a week for 52 weeks had the following side effects at a rate greater than placebo and at least 10%. Approximately:

• 2 out of 3 patients had a fever or headache.
• 1 out of 3 patients had joint pain.
• 1 out of 4 patients had itching or high blood pressure.
• 1 out of 5 patients had general discomfort or disturbed vision or wheezing.
• 1 out of 6 patients had abscess or muscle/bone pain or chest wall pain or hives.
• 1 out of 7 patients had anxiety/irritability or irregular heart rhythm or stomach upset or swelling at the infusion site or a skin disorder or itchy rash or slight injury or a side effect from injury.

About half of the patients in clinical studies produced antibodies to treatment with ELAPRASE and these patients had an increase in infusion reactions. The presence of antibodies on the effectiveness of ELAPRASE is unknown.