Alzheimer's drug side effects can be reduced

By David Douglas

NEW YORK (Reuters Health) - Although rivastigmine improves cognitive symptoms in patients with Alzheimer's disease whether it is given twice or three times a day, the three times a day dosing schedule tends to produce fewer side effects and thus increase tolerability, researchers report in the Journal of Neurology, Neurosurgery and Psychiatry.

"This study," lead investigator Dr. Howard H. Feldman told Reuters Health, "suggests that for mild-to-moderate Alzheimer's disease, rivastigmine treatment delivered in three times a day dosing -- with smaller individual doses -- may provide better efficacy and safety."

Rivastigmine is the generic name; it is sold under the trade name Exelon.

Feldman of the University of British Columbia, Vancouver, and colleagues came to this conclusion after a study of 678 patients with probable Alzheimer's disease. The patients were randomly assigned to receive a placebo (sugar pill) or rivastigmine at 2 mg to 12 mg a day in two or three doses.

After 26 weeks, the average rivastigmine dose was 8.9 mg per day in the twice-daily group and 9.6 mg per day in the thrice-daily group.

Patient scores on a test for disease progression showed a drop of 0.2 in the thrice-daily group, an increase of 1.2 in the twice-daily group and an increase of 2.8 in the placebo group.

Side effects, which were mainly gastrointestinal, occurred in 17 percent of the twice-daily group, 11 percent of the thrice-daily group and 9 percent of placebo patients.

These findings, concluded Feldman, "support the development of a more uniform delivery of this medication as might be achieved through a once-a-day patch, a formulation that will be forthcoming." This approach would permit continuous delivery of the medication at a very slow rate.

SOURCE: Journal of Neurology, Neurosurgery and Psychiatry, October 2007.