Safety and Tolerability of Donepezil in Mild Cognitive Impairment: Open-Label Extension Study

Following a 48-week, double-blind, randomized, placebo-controlled trial of donepezil in 821 patients with amnestic mild cognitive impairment (aMCI), safety and tolerability of donepezil (10 mg) were further evaluated in a 28-week extension study. Of 499 participants who completed the double-blind phase, 145 enrolled in the open-label study. Adverse events (AEs) were recorded throughout. Overall, 57.4% of participants in the donepezil/donepezil group and 62.3% in the placebo/donepezil group experienced an AE, with the most frequent treatment-emergent AEs being diarrhea, muscle spasms, insomnia, and nausea. Most were mild to moderate in severity and were more common in the first several weeks after treatment initiation. More participants in the placebo/donepezil group (22.1%) discontinued donepezil due to an AE compared with the donepezil/donepezil group (10.3%). These findings support the safety of donepezil in patients with aMCI. When compared with other studies, however, the data suggest that patients with Alzheimer’s tolerate donepezil better than patients with MCI.