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8/28/2003

Immunoglobulin Product Approved With New Protections From Viruses

Cheryl A. Thompson

Bayer HealthCare LLC announced this morning that the Food and Drug Administration (FDA) approved the license for Gamunex, an intravenous (i.v.) immunoglobulin product whose manufacturing process includes a unique purification method.

The new product, known by the generic name immune globulin i.v., 10 percent caprylate/chromatography purified, is prepared from a large pool of human plasma that, because of its source, may contain viruses that can cause infections in recipients. As is the case for all i.v. immunoglobulin products on the market, a series of purification steps is used to remove or inactivate viruses that may be in the plasma but were not detected during the initial screening of donors.

Bayer, in manufacturing Gamunex, uses a salt or ester of the fatty acid caprylic acid to precipitate enveloped viruses—which have an outer layer of lipoprotein and include such well-known pathogens as human immunodeficiency virus (HIV), West Nile virus, and hepatitis B and C viruses—and inactivate those not removed during the precipitation step. Column chromatography is also used to remove viruses during the manufacture of Gamunex.

The FDA-approved labeling for the new product states that it is indicated as replacement therapy in patients with a primary immunodeficiency whose capacity to make antibodies is severely impaired. Gamunex is also to be used to rapidly boost the platelet count in patients with idiopathic thrombocytopenia purpura (ITP).

Unlike the labeling for Gamimune N, Bayer's i.v. immunoglobulin product whose manufacture includes solvent and detergent treatments to remove or inactivate viruses, the labeling for Gamunex does not state that the product is indicated for use in patients who received a bone marrow transplant or in children infected with HIV.

Gamunex must not be used in patients who have had an anaphylactic or severe systemic response to any immunoglobulin product, the product's labeling states, and should be used "with utmost cautionary measures" in persons with certain severe deficiencies of immunoglobulin A.

The most common adverse effects associated with receipt of Gamunex during the clinical studies, Bayer said, were headache, vomiting, fever, nausea, rash, and back pain.

According to the product's labeling, the recommended dosage of Gamunex to prevent infections in patients with a primary immunodeficiency is 300–600 mg per kilogram of body weight, usually every three or four weeks, depending on a person's health status. To prevent bleeding in patients with ITP or enable them to undergo surgery, the recommended dosage is 2 g per kilogram of body weight, given as two doses of 1 g/kg on consecutive days or five doses of 0.4 g/kg on consecutive days.

The initial infusion rate, regardless of indication for use, should be 1 mg/kg per minute for the first 30 minutes; this rate may be gradually increased to 8 mg/kg per minute but should be reduced if adverse events occur.

Gamunex is a ready-to-use solution that will be available in vials containing 1, 2.5, 5, 10, or 20 g of protein.

The vials should be stored at 2–8 degrees C. During the first 18 months from the date of manufacture, the vials may be stored for up to five months at room temperatures not exceeding 25 degrees C, or 77 degrees F, but then must be used immediately or discarded.

A Bayer spokeswoman said the new product would be available later this fall and Gamimune N 10% would be "phased out over time."