This study consists of a double-blind, double-dummy, parallel-group comparison of 23 mg donepezil SR with the currently marketed donepezil formulation (10 mg donepezil IR) in patients with moderate to severe Alzheimer's disease. Patients must have been taking 10 mg IR (or a bioequivalent generic) for at least 3 months prior to Screening. The study will consist of 24 weeks of daily administration of study medication, with clinic visits at Screening, Baseline, 3 weeks (safety only), 6 weeks, 12 weeks, 18 weeks and 24 weeks or early termination. Patients will receive either 10 mg donepezil IR in combination with the placebo corresponding to 23 mg donepezil SR, or 23 mg donepezil SR in combination with the placebo corresponding to 10 mg donepezil IR.~A total of approximately 1600 patients will be enrolled to obtain complete data from approximately 1200 completed patients (Revised per Amendment 02). During the Baseline visit, patients will be randomized in a 2:1 ratio (23 mg donepezil SR to 10 mg donepezil IR). The study will be performed at approximately 200 global sites (Asia, Oceania, Europe, India, Israel, North America, South Africa, and South America) (Revised per Amendments 01 and 02). An Independent Data Monitoring Committee (IDMC) will be established to review safety aspects of the study and to evaluate the results of a planned interim analysis.~Patients who complete the study may be eligible to undergo evaluation for enrollment into the open-label extension study, E2020-G000-328.
The purpose of this study is to compare 23 mg donepezil sustained release (SR) to the currently marketed formulation of 10 mg donepezil immediate release (IR) in patients with moderate to severe Alzheimer's disease.