Alzheimer's drugs donepezil, memantine show some benefits in study

A new study of patients with moderate-to-severe Alzheimer’s disease found that extended treatment with donepezil could improve cognition and function for even severe patients; however, experts caution that the benefits of the drug were modest.

The study, published in the New England Journal of Medicine, also found that memantine, another Alzheimer’s medication commonly given, improved cognition and functioning in patients who have moderate to severe progression of the disease.

The multicenter, double-blind, placebo-controlled clinical trial randomly assigned 295 patients, who had been treated with donepezil for at least 3 months and had moderate or severe Alzheimer’s disease, to 1 of 4 treatment regimens. Patients continued to receive donepezil, discontinued donepezil, discontinued donepezil and started memantine, or continued both donepezil and started memantine. At the end of 52 weeks, outcomes were assessed.

Taking both Alzheimer’s drugs together - a common practice in the United States - showed no additional benefit compared with donepezil alone.

Researchers assessed patient’s cognitive abilities using a Standardized Mini-Mental State Examination (SMMSE) and also recorded scores on the Bristol Activities of Daily Living Scale (BADLS) to measure daily functioning.

They found that those patients who had randomly been assigned to take donepezil for the study period had scores on the SMMSE that were 1.9 points higher on average than those patients taking a placebo. Their scores on the BADLS were on average of 3.0 points lower, showing less impairment, but this decrease was not significant enough to indicate a clinically important difference.

The difference in scores on the 2 exams for patients taking memantine were less pronounced and failed to meet the minimum requirements necessary to indicate a clinically important difference.

Jack Rosenberg, PharmD, PhD, a professor emeritus of pharmacy practice and pharmacology at Long Island University, told Drug Topics that while the study did show cognitive improvement for patients who were taking donepezil, it also showed that these benefits were more significant for patients in the moderate stages of the disease. The effect was minimized for those in more severe stages of Alzheimer’s.

Neither drug is a panacea, he said, and won’t stop the decline in Alzheimer’s patients and may only slow the progression of the fatal brain disease. Rosenberg did not participate in the study, which was done in London.