Memantine for Alzheimer’s Disease
The FDA has approved memantine (Namenda®, Forest Laboratories) for patients with moderate to severe Alzheimer’s disease (AD). The drug has long been sold in Germany. Previous treatments have been studied for less severe (mild to moderate) AD. Meman-tine appears to work by blocking the action of glutamate; the other approved drugs delay the breakdown of acetyl-choline, which is vital for nerve cells to communicate.
Approximately 4.5 million Americans have AD, a degenerative condition that affects memory, judgment, and the ability to reason. The drug is an ./V-methyl-D-asparate (NMDA) antagonist. Meman-tine helps to alleviate symptoms of AD in some patients, but there is no evidence that it modifies the underlying pathology of the disease.
The drug was studied in two double-blind trials involving about 650 patients. The first two studies, each about six months’ duration, were conducted in the U.S. The larger study was carried out in patients already taking generic donepezil (Aricept drug, Eisai, Pfizer), a drug approved previously for the treatment of AD. During both studies, patients taking meman-tine experienced less deterioration in functioning and fewer symptoms than did patients taking placebo. In the third study, conducted in nursing homes in Latvia, memantine also showed a statistically significant advantage over placebo in 166 patients with severe AD.
Measures used to evaluate the drug’s effectiveness included the Severe Impairment Battery to assess attention, orientation, language, memory, and social interactions, and the modified Alzheimer’s Disease Cooperative Study-Activities of Daily Living scale, which assessed the ability of patients to eat, dress, bathe, travel, shop, and perform household chores. The Behavioral Rating Scale for Geriatric Patients assessed day-to-day functioning, and the Clinical Global Impression of Change assessed the patients’ overall condition.
The most frequently reported adverse events were dizziness (7%), headache (6%), and constipation (6%). The drug should be available for sale by January.
