Two six-month, Phase 3 studies in patients with mild to moderate AD showed modest treatment benefits for memantine over placebo. The other trial, conducted in patients in Europe, showed benefits of memantine only at interim time points, and fell short of statistical significance at study completion.
In Forest Laboratories filed for FDA approval of memantine as a treatment for mild AD, but in the agency issued a non-approvable letter, requiring a confirmatory study. The drug was never formally approved for the early stages of AD, but is frequently prescribed at this stage.
Whether memantine is clinically useful in mild AD is controversial, as meta-analyses have reported conflicting conclusions Doody et al. Memantine was studied in combination therapy with the cholinesterase inhibitor donepezil. The first U. This is the first combination drug trial for AD to yield positive results Tariot et al.
Pharmacoeconomic studies have been largely positive. The U. Other authors reported that memantine treatment reduced caregiver time and other societal costs, as did combination memantine-cholesterol inhibitor treatment. Memantine has been prescribed off-label for frontotemporal dementia, and an open-label trial had suggested a possible benefit for the disease's psychiatric aspects. However, in a subsequent randomized controlled trial of 20 mg memantine daily in 81 patients, the drug had no benefit on neuropsychiatric symptoms while worsening cognition in some patients Boxer et al.
Two Phase 3 studies tested this drug in more than 2, patients with glaucoma, but the results reportedly fell short of being able to support a marketing application for this disease see clinicaltrials. Memantine was studied unsuccessfully for neuropathic pain and diabetic neuropathy Rogers et al. At least one early clinical trial of memantine in patients with vascular dementia appears to have shown cognitive improvement, but no further studies on this indication have been reported in the past 10 years Wilcock et al, Trials of memantine in adults with Down's syndrome were negative see Jan news story on Hanney et al.
For a listing of clinical trials of memantine, see clinicaltrials. To make a comment you must login or register. Improvement in behavioural symptoms in patients with moderate to severe Alzheimer's disease by memantine: a pooled data analysis.
Int J Geriatr Psychiatry. Memantine in moderate to severe Alzheimer's disease: a meta-analysis of randomised clinical trials. Dement Geriatr Cogn Disord. Epub May 10 PubMed. Memantine in moderate-to-severe Alzheimer's disease.
N Engl J Med. A week open-label extension study of memantine in moderate to severe Alzheimer disease. Arch Neurol. Meta-analysis of six-month memantine trials in Alzheimer's disease. Alzheimers Dement. Lack of evidence for the efficacy of memantine in mild Alzheimer disease. Mechanism of action of memantine. Curr Opin Pharmacol.
Epub Dec 20 PubMed. Cost effectiveness of memantine in Alzheimer's disease: an analysis based on a probabilistic Markov model from a UK perspective. Drugs Aging. Hunt L. Memantine improves outlook, cuts healthcare costs in AD. Alzheimer's dementia: budget impact and cost-utility analysis of a combination treatment of a cholinesterase inhibitor and memantine in Switzerland.
The recommended starting dose of Namenda is 5 mg once daily. The product was approved in Europe in May of for the Alzheimer's indication. There it is marketed there under the name Ebixa by Merz Pharmaceuticals. The average age of the study subjects was 76 ranging from 50 to 93 years old. Treatment efficacy was determined using both overall function through caregiver-related assessment, and an instrument that measures cognition.
Results from both studies showed that that patients taking Namenda experienced significant improvement on both measures compared to placebo. All Subjects had been treated with donepezil for at least 6 months and had been on a stable dose of donepezil for the last 3 months prior to the study. Adverse events associated with the use of Namenda may include but are not limited to the following:. Namenda, a low to moderate affinity NMDA N-methyl-D-aspartate receptor antagonist is thought to selectively block the effects associated with abnormal transmission of the neurotransmitter glutamate, while allowing for the physiological transmission associated with normal cell functioning.
The overexcitation of NMDA receptors by the neurotransmitter glutamate may facilitate Alzheimer's disease since glutamate is found in the neural pathways associated with learning and memory. Abnormal levels of glutamate may be responsible for neuronal cell dysfunction and the eventual cell death observed in Alzheimer's disease. Ruther E, et al.
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