Gamunex wins orphan-drug approval from FDA for treatment of CIDP

December 15, 2008

FDA approves Gamunex for treatment of neurologic disease.

Key Points

Patients with chronic inflammatory demyelinating polyneuropathy (CIDP) finally have a treatment option that has been recognized by the U.S. Food and Drug Administration (FDA). Gamunex, an intravenous immune globulin (IVIG) pooled from human blood, recently received FDA approval for the treatment of CIDP.

The product was previously approved for primary humoral immunodeficiency disease (PI) and idiopathic thrombocytopenic purpura (ITP). Although various immune globulins have been used over the years to treat CIDP on an off-label basis, Gamunex is the first product to receive FDA approval as an orphan drug for this indication. The orphan-drug designation provides manufacturers with financial incentives to develop treatments for rare diseases, defined as those affecting fewer than 200,000 people in the United States.

CIDP is a rare autoimmune disorder characterized by progressive weakness and impaired sensory function in the legs and arms. The disorder, also known as chronic relapsing polyneuropathy, is caused by damage to the myelin sheath (the fatty covering that protects nerve fibers) of the peripheral nerves. CIDP is closely related to Guillain-Barré syndrome and is considered the chronic counterpart of that acute disease. Although it is typically more prevalent in young adults and in men, it can strike at any age and in either gender. The course of CIDP varies widely among patients, but many patients are left with residual numbness, weakness, fatigue, and other symptoms which can lead to reduced quality of life.

Gamunex was approved for administration as a total loading dose of 2 g/kg, given in divided doses over two to four consecutive days. For maintenance infusions, Gamunex may be administered either over one day at a dose of 1 g/kg or divided into two doses of 0.5 g/kg over two consecutive days. The dose is typically repeated every three weeks. Gamunex, which is available as a 10 percent liquid, is incompatible with saline but can be diluted with 5 percent dextrose in water (D5W).

Side effects reported most frequently by patients were headache, fever, increased blood pressure, rash, joint pain, chills, back pain, nausea, and lightheadedness. Similar to other licensed IGIV products, Gamunex holds a black box warning about renal dysfunction, acute renal failure, osmotic nephrosis, and death in predisposed patients. Therefore, blood urea nitrogen, serum creatinine, and urine output should be closely monitored in patients at risk of developing renal failure. Renal dysfunction and acute renal failure have been reported more frequently in patients receiving IGIV products containing sucrose, which is typically used as a stabilizer.

MONA NASHED is a writer and hospital pharmacist in New Jersey.