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Treatment for Rare Enzyme Disorder Approved

Cheryl A. Thompson

Laronidase, a recombinant protein having the same amino acid sequence as a variant of an essential enzyme, was approved last week by the Food and Drug Administration for use in patients with certain forms of mucopolysaccharidosis.

The drug, known by the brand name Aldurazyme (PDF), is intended for use in patients with the Hurler or Hurler-Scheie form of mucopolysaccharidosis I, a rare genetic disease caused by the absence or malfunctioning of L-iduronidase. This enzyme breaks down certain polysaccharides that, if left to accumulate in tissues, progressively damage various organs and can alter mental function. Laronidase is also for use in patients with the Scheie form of the disease, the disorder's mildest type, is accompanied by moderate to severe symptoms.

Treatment with laronidase during the major clinical study was found to improve patients' pulmonary function and ability to walk for short periods.

The recommended initial dosage of laronidase is 0.58 mg per kilogram of body weight administered by intravenous infusion once weekly at a rate of 10 mcg/kg/hr. This rate may be increased in increments every 15 minutes during the first hour, so long as the patient's vital signs remain stable, to a maximum of 200 mcg/kg/hr, with the total volume to be administered over three to four hours.

According to the product's labeling, an antipyretic or antihistamine or both should be administered 60 minutes before the infusion starts.

As yet, there are no contraindications to laronidase therapy. The most commonly reported adverse reactions during the clinical studies were upper-respiratory-tract infection, rash, and injection-site reaction.

Aldurazyme will be available in single-dose glass vials containing 2.9 mg of enzyme in 5 mL of solution and requiring strorage at 2–8 degrees C. Once diluted with 100 or 250 mL of 0.9 percent sodium chloride injection containing 0.1 percent albumin, the medication should be completely administered within 36 hours and not stored at room temperature. The product's labeling states that the medication must be prepared in a container made of polyvinyl chloride (PVC) and administered via a PVC infusion set equipped with an inline low-protein-binding 0.2-micrometer filter.

Genzyme Corp., which will distribute Aldurazyme on behalf of BioMarin Pharmaceutical Inc., said the product would be available "in the coming weeks." Accredo Health Inc. announced Monday that it was one of the two specialty pharmacy providers handling the product. Genzyme has not revealed the identity of the other company.