Memantine Does Not Help Mild Alzheimer's, Says Analysis

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Memantine, a drug often prescribed to treat patients who have moderate to severe Alzheimer’s disease, is also frequently administered off-label to treat mild Alzheimer’s disease and mild cognitive impairment. However, results of a new study that will appear in the August print issue of Archives of Neurology found no evidence that the drug is beneficial in patients who have mild Alzheimer’s disease.

Memantine may help moderate Alzheimer’s disease

Memantine (Namenda®) is the only member of a drug class called NMDA receptor antagonists. The drug reportedly works by reducing abnormal activity in the brain, specifically neurotransmission mediated by the neurotransmitter called glutamate.

Clinical studies have shown that memantine may help people with Alzheimer’s disease think more clearly as well as function more easily with activities of daily living, which can reduce their dependence on others. Memantine is not a cure for the disease, however, nor does it stop its progression.

The new study, conducted by investigators at the University of Southern California Keck School of Medicine, Los Angeles, involved an analysis of three randomized, placebo-controlled, parallel-group clinical trials that included patients who had mild (431 patients) or moderate (697 patients) Alzheimer’s disease. In each case, the researchers evaluated cognition, functional activities, patients’ behavior, and global change.

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Overall, the authors reported “there were no significant differences between memantine and placebo on any outcome for patients with mild AD, either within any trial or when data were combined.” When the investigators looked at the patients with moderate Alzheimer’s, they did not find a significant difference between memantine and placebo in any individual trial, but there was a significant effect when the three trials were statistically combined.

In July 2005, the Food and Drug Administration (FDA) turned down a supplemental new drug application by the manufacturer of memantine to extend its approval to include mild Alzheimer’s disease. The application referred to three placebo-controlled clinical trials that included patients with mild to moderate Alzheimer’s. However, because the trials included patients with mild and moderate Alzheimer’s, they did not provide specific proof of the drug’s efficacy in mild Alzheimer’s disease only, and the extended use was not approved.

The authors of the new analysis note that “evidence is lacking for a benefit of memantine in mild AD,” even though healthcare professionals frequently prescribe it for this patient population.

They also report “there is meager evidence for its efficacy in moderate AD,” pointing out that prospective trials should be conducted to determine memantine’s potential when given alone or when used along with cholinesterase inhibitors, such as donepezil (Aricept) and rivastigmine (Exelon), in individuals who have mild to moderate Alzheimer’s disease.

SOURCE:
Schneider LS et al. Archives of Neurology pub. online 2011 April 11; doi: 10.1001/archneurol.2011.69

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