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Rivastigmine, Donepezil Produce Sustained Benefit in Alzheimer's Patients: Presented at ANA

By Jill Stein
Special to DG News

NEW YORK CITY, NY -- October 14, 2002 -- Both rivastigmine and donepezil provide long-term cognitive benefits (for up to two years) in patients with Alzheimer's disease (AD), researchers report.

Findings of a study presented at the 127^th Annual Meeting of the American Neurological Association also show that the cognitive benefit resulting from rivastigmine use may be greater.

Dr. George Grossberg, with St. Louis University School of Medicine in St. Louis, Missouri, United States, compared the two most widely prescribed AD agents, donepezil and rivastigmine, with regard to their reported efficacy after two years.

Donepezil is an acetylcholinesterase (AChE)-selective inhibitor, while rivastigmine is a dual inhibitor of both AChE and butyrlcholinesterase. Both drugs are approved for the symptomatic treatment of AD.

"The long-term efficacy and safety-tolerability of these drugs has become a focus of major interest," Dr. Grossberg pointed out. "While placebo-controlled, long-term trials are scientifically optimal, they are considered ethically unacceptable. Open-label extensions of randomized, placebo-controlled trials are an alternative, provided there is adequate mathematical-statistical handling of the data."

Donepezil data were drawn from three published studies (n=888), while rivastigimine data came from one published meta-analysis of four studies (1,810).

After two years, a greater proportion of patients (55 percent) continued with rivastigmine treatment compared with those receiving donepezil (34.6 or 49 percent depending on the study).

In one donepezil study, treated patients showed an 11-point decline on the Alzheimer's Disease Assessment Scale-cognitive subscale. If left untreated, they would have declined by 14 points.

In another two studies, donepezil-treated patients declined by 7.4 and 10 points, however the data published were not sufficient to tabulate declines in untreated patients.

Rivastigmine-treated patients declined by 8.6 points, with a projected decline by 13.6 points if left untreated.

Overall, the results show that the two agents provide long-term benefits. Rivastigmine may provide greater cognitive benefit (5.0 points) than donepezil (about 4 points) following two years of treatment.

Dr. Grossberg said that the results of a large ongoing head-to-head study (EXCEED), assessing the efficacy and safety/tolerability of rivastigmine and donepezil will provide direct evidence of the comparative long-term efficacies of donepezil and rivastigmine.

The study was supported by Novartis Pharma AG in Basel, Switzerland.

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