In the investigation 974 patients participated which were affected by another type of dementia, one that obeys to vascular cause. Donepezile was administered to one group and an inactive substance (placebo) was administered to the other. Among the first group, 11 deaths were registered. No deaths took place among the patients in the second group.

The American Medicine's agency, the 'Federal Drug Administration' (FDA) is analyzing the results of the study, although, according to what The New York Times 'informed', after reviewing previous tests carried out with the product, this organism (FDA) does not see reasons for alarm and assures the public that donepezile continues to be a safe option for the patients who use it.

Thousands of patients of Alzheimer worldwide is medicated with donepezile, commercialized by Pfizer companies as well as by the Japanese Pharmaceutical Eisai.

Nevertheless, the case has revived the controversy on the possible adverse effects at the cardiovascular level that this and other similar drugs could have. Especially considering that their therapeutic benefits are modest; it is considered that they only delay some months the signs of cognitive deterioration in the neurological ailment.

The number of deaths registered in the test was statistically significant, which implies that few probabilities existed that the cause of death was due to random events. Recently a similar problem took place during a study with galantamine (Reminyl), another similar anti-Alzheimer drug. In this case the drug effects were being studied in patients with a slight cognitive deterioration level; and as with the former study an excess in the number of deaths was reported, which also occurred in the group that received the product.

The manufacturers of donepezile ensure that the drug is safe and they do not recommend the inclusion of any warnings labels in the drug.