Information about the Alzheimer's Disease Medication Memantine (Namenda)
In 2003, the FDA approved memantine (Namenda) for the treatment of moderate to severe Alzheimer's disease. The drug has been the mainstay of Alzheimer's treatment in Germany for years, and the European Union approved it for Alzheimer's disease in 2002.
The medication helps block the activity of the neurotransmitter glutamate by binding to N-methyl-D-aspartate (NMDA) receptors on the surface of brain cells. Glutamate, at appropriate levels, plays an important role in learning and memory. If glutamate levels are too low, cognitive problems develop. If levels are too high, glutamate overstimulates nerve cells, leading to cell death.
Because Namenda has been on the market in the United States for much less time than the cholinesterase inhibitors, less information is available about its long-term cognitive effects. However, in one 28-week study comparing Namenda with a placebo, people taking the drug showed significantly less cognitive decline during that time period. By the study's end, about 20% of the patients taking Namenda showed some improvement in cognition and/or activities of daily living.
Another study found that people taking Namenda plus Aricept averaged less cognitive decline over 24 weeks than those taking a placebo plus Aricept. About 40% of people in the Namenda plus Aricept group experienced cognitive improvements, and 30% showed improvements in daily functioning.
Some people who take Namenda may experience improvements over the short term, but most can expect to see only a modest delay in the deterioration of memory and in the ability to perform activities of daily living. The medication may extend the time patients can spend at home before requiring assisted living. However, Namenda does not reverse or halt the degeneration that occurs in the brain.
Physician-prescribing patterns in the United States have not caught up to those in Europe, where cholinesterase inhibitors and Namenda have been available longer. In Europe, the two drug types are often prescribed together early in the disease.
In the United States, Namenda is FDA approved only for the later stages of Alzheimer's disease. That said, physicians are allowed to prescribe approved drugs "off-label" (in ways not covered in the drug's initial approval), so some doctors do prescribe both types of drugs early in the disease.