Elaprase treatment, price and cost, expensive medication
September 6 2016 by Ray Sahelian, M.D.


Elaprase (idursulfase) is the first prescription medication prescribed for the treatment of Hunter syndrome (Mucopolysaccharidosis II, or MPS II), a rare inherited disease which can lead to premature death. Elaprase is a new molecular entity, which is an active ingredient never before marketed in the United States. Elaprase was designated as an orphan product by FDA. Orphan products, such as Elaprase, are generally developed to treat rare diseases or conditions that affect fewer than 200,000 people in the U.S. The Orphan Drug Act provides a seven-year period of exclusive marketing to the first sponsor who obtains marketing approval for a designated orphan product.

Elaprase and Hunter Syndrome

Hunter Syndrome, which usually becomes apparent in children one to three years of age, is a disease in which the person's body is defective in producing the chemical iduronate-2-sulfatase, which is needed to adequately breakdown complex sugars produced in the body. Symptoms include growth delay, joint stiffness, and coarsening of facial features. In severe cases, patients experience respiratory and cardiac problems, enlargement of the liver and spleen, neurological deficits, and death. Hunter syndrome is diagnosed in approximately one out of 65,000 to 132,000 births.


Elaprase was approved after a randomized, double-blind, placebo-controlled study of 96 patients with Hunter syndrome showed that the treated participants had an improved capacity to walk. At the end of the 53–week trial, patients who received Elaprase infusions experienced on average a 38-yard greater increase in the distance walked in six minutes compared to the patients on placebo.

Elaprase side effects

The most serious Elaprase side effects reported during the trial were hypersensitivity reactions to Elaprase that could be life-threatening. They included respiratory distress, drop in blood pressure, and seizure. Other frequent, but less serious adverse events included fever, headache and joint pain. Because of the potential for severe hypersensitivity reactions, appropriate medical support should be readily available when Elaprase is administered. Patients and their physicians are encouraged to participate in a voluntary Hunter Outcome Survey which has been established to monitor and evaluate the safety and effects of long-term treatment with Elaprase.


Allergy. 2013. IgE-mediated anaphylaxis and allergic reactions to idursulfase in patients with Hunter syndrome. Enzyme replacement therapy (ERT) with recombinant human idursulfase is effective for the treatment of Hunter syndrome, mucopolysaccharidosis (MPS) type II. However, various adverse events can occur by the infusion of idursulfase. The purpose was to evaluate the occurrence of infusion-related allergic reactions, including anaphylaxis, to idursulfase in patients with MPS II receiving ERT and to elucidate its possible mechanism. A total of 34 patients with MPS II were enrolled to receive ERT with Elaprase(®) at a dose of 0.5 mg/kg intravenously once a week. Information regarding the symptoms, frequency, and timing of anaphylaxis during treatment was analyzed. Presence of anti-idursulfase IgE antibody was assessed by skin prick test (SPT) and enzyme-linked immunosorbent assay (ELISA). Western blotting was performed to confirm the reaction between idursulfase and specific IgE. Three patients (8.8%) showed anaphylaxis by infusion of idursulfase. No deaths occurred during the study. Anti-idursulfase IgE antibody was detected by SPT and ELISA. Immunoblotting with patients' sera and Elaprase(®) showed a single band of specific IgE binding to the protein around 70 kD, and idursulfase did not display amino acid sequence homology to known allergens. SPT with idursulfase demonstrated positive results in all patients with anaphylaxis. However, we failed to reveal any risk factors for the development of infusion-related immediate-type allergic reactions. Anaphylaxis related to infusion of idursulfase is mediated by anti-idursulfase IgE antibody, which might be produced by de novo synthesis. SPT is useful in predicting the occurrence of anti-idursulfase IgE-mediated anaphylaxis during infusion.

Elaprase is manufactured by Shire Human Genetic Therapies, Inc., in Cambridge, MA.