A Study of SB-742457, Added to Donepezil for the Treatment of Mild-to-moderate Alzheimer's Disease

Inclusion Criteria:

- Subjects and their caregivers must provide informed consent prior to study entry.

- Subjects must have a clinical diagnosis of probable mild-to-moderate Alzheimer's
disease with no evidence of disorders that are thought to be the cause of, or
contributing to the severity of the subject's dementia and a documented history of at
least 6 months of ongoing donepezil therapy with stable dosing for at least the last 2
months.

- Subjects must have a regular caregiver who is willing to attend visits, oversee the
subject's compliance with the study and report on the subject's status.

- Female subjects of child-bearing potential must agree to abstinence or an approved
form of birth control.

- Subjects must have adequate blood pressure and laboratory values.

Exclusion Criteria:

- Subjects with a diagnosis of possible, probable or definite vascular dementia may not
participate.

- Subjects with known hypersensitivity to sunlight or a history of seizures, previous
exposure to SB-742457, taking agents for which there is a theoretical risk of
interaction with SB-742457, or taking medication for Alzheimer's disease or centrally
acting agents which might impact study outcomes may not participate.