Memantine Officially Approved for Use in U.S.
(Updated October 17, 2003)
A Food and Drug Administration officially approved memantine (brand name Namenda) as a new treatment for Alzheimer's Disease in the U.S. The agency said that the drug is safe and effective for the treatment of moderate to severe Alzheimer's Disease. Forest Laboratories, the maker of the drug, said it expects Namenda to be available to physicians, patients, and pharmacies in January 2004.
FDA Commissioner Mark McClellan, M.D., Ph.D. said on October 17, 2003, "The approval of memantine is good news for Alzheimers Disease patients. This is the first drug shown to have an effect on the symptoms of moderate to severe Alzheimers Disease, and shows a low incidence of minor side effects."
Memantine is a new type of drug that works differently from currently available anti-cholinesterase inhibitors, which are generally only effective in milder forms of the disease. Memantine has been found to slow deterioration in individuals with moderately severe Alzheimers Disease, researchers reported in the April 3 issue of the New England Journal of Medicine.
According to Dr. Barry Reisberg M.D. at New York University, the results of the study showed that the experimental drug memantine can significantly reduce the worsening of Alzheimers Disease symptoms, even though it does not stop or reverse the progression of the disease. One of the things that makes memantine so promising is that it seems to be essentially free of harmful side effects, he added. The study showed that both patients who received memantine and those who received the placebo showed signs of decline, but, those who received memantine showed less decline than the patients who received the placebo treatment.
Memantine (also known by its brand name Axura in Germany and to be marketed under the brand name Nameda in the U.S.) is a new class of anti-Alzheimers drug that blocks the transmission of glutamate, a critical brain chemical involved in memory and learning. Clinicians believe that an overstimulation of the N-methyl-D-aspartate (NMDA) receptor by glutamate contributes to neurodegenerative disorders. Memantine blocks the overstimulation of the glutamate; it is also referred to as an antiglutamatergic treatment.
Existing treatments such as Cognex (tacrine), Aricept (donepezil hydrochloride), Exelon (rivastigmine tartrate), and Reminyl (galantamine hydrobromide) are categorized as acetylcholinesterase inhibitors. These drugs increase the concentration of acetylcholine, a brain chemical that helps nerve cells communicate. The longer acetylcholine remains in the brain, the longer those cells can call up memories. They have been found to be most helpful in earlier stages of the disease and do not cure or reverse the underlying dementing process.
Since memantine attacks Alzheimers Disease differently from the acetylcholinesterase inhibitors, researchers speculate they may be used concurrently to deliver a double punch to the disease. Researchers presented study results at the American Academy of Neurology Annual Meeting in Honolulu suggesting that memantine can provide additional benefits to patients already on these cholinesterase inhibitor therapies.
"The results of this memantine combination therapy study point the way towards a new standard of care in the treatment of moderate-to-severe Alzheimer's disease," said Martin Farlow, M.D., a lead investigator on the study and Professor of Neurology at the Indiana University School of Medicine. "The findings are encouraging since they suggest memantine's mechanism of action, which is unique and different from cholinesterase inhibitors, will really let us attack the disease on another front. Clearly, in this study, memantine provided additional cognitive and functional benefits in patients already taking donepezil. This is the first successful combination drug trial for Alzheimer's, and it is truly an exciting advance for patients and their loved ones."
The Clinical Studies
In the first study to determine memantine's effectiveness, over 250 individuals participated in the 28-week long drug study across 32 locations. According to Dr. Reisberg, patients who received memantine faired much better in the categories of cognition and activities of daily living than those who received the placebo. There was no significant change for either group in the area of behavior. The results were determined by assessing patients performance in three categories: cognitive function, behavioral symptoms, and the ability to carry out activities of daily living (e.g., dressing and bathing).
The study was funded in part by Merz & Co., the German company that makes memantine. It was conducted by researchers affiliated with Silberstein Aging & Dementia Research Center at the New York University School of Medicine.
In the second study, 402 patients with moderate-to-severe Alzheimer's disease at 37 U.S. sites took either a treatment regimen of memantine, an investigational drug, and donepezil (Aricept), a widely used acetylcholinesterase inhibitor, or a combination of donepezil and placebo. Researchers reported that patients treated with memantine and donepezil illustrated a sustained improvement in cognitive function. By comparison, cognitive function for patients on donepezil and placebo declined relative to their baseline status. Patients taking the combination therapy also showed significantly less decline in activities of daily living.
Additional placebo-controlled trials evaluating memantine as monotherapy and combination therapy are ongoing in patients with mild-to-moderate and moderate-to-severe Alzheimer's disease. Results from these investigations are expected to become available later in 2003, Forest Laboratories said in an announcement.
- NEJM Abstract: http://content.nejm.org/cgi/content/short/348/14/1333
- Participating in Clinical
Trials: What You Need to Know
- Memantine Information http://www.memantine.com
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