April 11, 2011 -- A drug that is widely used, but not approved, for the treatment of mild Alzheimer’s disease shows little evidence of benefit in these early-stage patients, according to a new research analysis.
Memantine, sold as Namenda in the U.S., was approved by the FDA in 2003 for moderate to severe Alzheimer’s, but two years later agency officials rejected an application to expand its indication to include patients with mild disease.
Nevertheless, the drug is often prescribed for this indication, either alone or in combination with drugs that are approved for mild Alzheimer’s disease (AD), such as Aricept (donepezil), Exelon (rivastigmine), and Razadyne (galantamine).
In a nationally representative survey of neurologists published in 2010, 40% reported that they sometimes prescribed memantine to their Alzheimer’s patients with mild cognitive impairment. In clinical trials involving patients with mild to moderate AD from 2003 to 2009, as many as 63% of patients were taking the drug.
In the newly published analysis, Alzheimer’s disease specialist Lon S. Schneider, MD, and colleagues examined research reviews, registries, and other data on the use of memantine for mild to moderate AD from Forest Laboratories, which markets the drug in the U.S.
The researchers identified three placebo-controlled trials that included 431 patients with mild disease and almost 700 patients with moderate disease.
They analyzed the drug’s impact on four key Alzheimer’s outcomes and found no significant differences between the memantine- and placebo-treated patients with mild disease when the trial data were assessed alone or together.
Likewise, no significant differences in outcomes were seen in patients with moderate AD in individual trials. But a significant effect was seen when data from the three trials were combined.
The researchers conclude that their findings “provide insight into why the FDA did not approve the manufacturer’s application to market the drug for mild AD.”
Schneider says the findings do not mean the drug should never be used in patients with mild cognitive declines due to Alzheimer’s disease.
He says properly designed studies with longer follow-up are needed to determine if memantine is effective, either alone or with other AD drugs, for the treatment of mild to moderate disease.
Schneider directs the University of Southern California Alzheimer’s Disease Research and Clinical Center.
“These results point to the need for adequate and well-controlled trials,” he says. “And in view of the small effects seen in patients with moderate disease, questions remain about this drug’s use in these patients.”
Bill Thies, PhD, who is chief medical and science officer for the Alzheimer’s Association, says memantine probably has clinical meaningful benefits in some patients with mild Alzheimer’s.
“Unfortunately, we can’t say who these patients are ahead of time,” he tells WebMD. “I would say that trying any of the Alzheimer’s drugs in people with a new diagnosis is a reasonable thing to do. But clinicians need to be watching closely to see if the drugs are making a difference.”
Thies says none of the available AD drugs have more than a modest effect on AD symptoms, adding that researchers are working to identify the next generation of drugs with the aim of slowing disease progression.
When contacted by WebMD, a spokesman for Forest Labs declined to comment on the study.
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