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10/20/2003

FDA Approves 1st Treatment for Severe Alzheimer's

Cheryl A. Thompson

Memantine hydrochloride on Friday became the first drug that can be marketed as a treatment for Alzheimer's disease in patients showing symptoms more serious than forgetfulness.

The drug, to be sold under the brand name Namenda by Forest Pharmaceuticals Inc., acts in a unique way to slow the disease's progressive deterioration of patients' mental powers, the Food and Drug Administration (FDA) said.

According to the product's labeling (PDF), memantine interferes with the actions of glutamate, a naturally occurring neurotransmitter whose persistent activation of N-methyl-D-aspartate receptors in the central nervous system is believed responsible for some of the symptoms of Alzheimer's disease.

Clinical studies of memantine hydrochloride found it useful in slowing, not preventing, the worsening of symptoms in patients whose Alzheimer's disease was considered moderate or severe.

The moderate stage of the disease, according to the Alzheimer's Association, is characterized by the emergence of major gaps in memory and deficits in cognitive function and a true need for help with day-to-day activities. After progressing through the moderately severe stage, patients reach the final stage, severe, in which they cannot respond appropriately to the world around them.

Patients with a hypersensitivity to memantine hydrochloride, lactose, or another ingredient in the tablets must not take Namenda, according to the product's labeling

FDA said the most frequently reported adverse events in study participants taking memantine hydrochloride were dizziness (7 percent), headache (6 percent), and constipation (6 percent).

A starting dosage of 5 mg of memantine hydrochloride per day is recommended in the product's labeling, with the goal of gradually increasing the dosage to a target of 20 mg/day. After at least one week of 5 mg taken once daily, the dosage is to be increased to 5 mg twice a day. The twice-daily 5-mg doses are to be given for at least one week, then the dosage increased to 15 mg/day, given as a 5-mg dose and a separate 10-mg dose. After at least one week of 15-mg/day doses, the dosage should be increased to 20 mg/day, given as 10 mg twice daily.

The product's labeling recommends that patients with moderate renal impairment receive a smaller dosage than usual, although no details are provided for this alternative regimen. Patients with severe renal impairment should not take the drug.

Namenda will be sold in bulk bottles and unit dose packages of 5- or 10-mg film-coated tablets. A "titration pak"—a blister pack containing sufficient 5- and 10-mg tablets to deliver the first four weeks of doses recommended in the product's labeling—will also be sold.

Forest announced that Namenda will be available in pharmacies in January 2004.