Conditions: Alzheimer Disease
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 526
Healthy volunteers: no

Brief summary:
The study will evaluate the efficacy and safety of an investigational drug called SAM-531 at three dosage levels. Subjects will receive either one of the 3 dosage levels of SAM-531, donepezil or placebo for the first 24 weeks of the study (period I). Subjects who receive placebo for period I will be assigned to receive the highest dose of SAM-531 SAM-531 for the remaining 28 weeks of the study, while subjects who received one of the three SAM-531 dosage levels or donepezil in period I will continue with the same study drug (period II).

Detailed description:
The study was stopped (date of termination was 13April2011) due to a 6 month interim analysis: all of the 3 SAM-531 dosage levels were declared futile. There were no safety concerns.

Arms:
arm 1: Placebo arm 2: SAM-531 1.5 mg arm 3: SAM-531 3.0 mg arm 4: SAM-531 5.0 mg arm 5: Donepezil

Interventions: intervention 1: Placebo intervention 2: SAM-531 1.5 mg intervention 3: SAM-531 3.0 mg intervention 4: SAM-531 5.0 mg intervention 5: Donepezil
Intervention descriptions: intervention 1: Capsules SAM-531 placebo and 5 mg tablet encapsulated Donepezil placebo capsules, once a day during 24 weeks. intervention 2: Capsules SAM-531 1.5 mg, once a day during 52 weeks. intervention 3: Capsules SAM-531 3.0 mg, once a day during 52 weeks. intervention 4: Capsules SAM-531 5.0 mg, once a day during 24 weeks or 52 weeks. intervention 5: Encapsulated Donepezil 5 mg tablets, once a day during 52 weeks. After Day 42, the dose can up titrated up to 10 mg of Donepezil.

Protocol document: