Study Evaluating Safety, Tolerability and Pharmacokinetics of Single and Multiple Dose of SAM-531

Inclusion criteria: * Body mass index in the range of 18 to 30 kg/m2 and body weight greater than or equal to 50 kg. Body weight for elderly subjects must be greater than or equal to 45 kg. * history, physical examination findings, clinical laboratory test results, vital sign measurements, and digital 12-lead ECG readings. Exclusion criteria: * Presence or history of any disorder that may prevent the successful completion of the study. * Any significant cardiovascular, hepatic, renal, respiratory, gastrointestinal (GI), endocrine, immunologic, dermatologic, hematologic, neurologic or psychiatric disease.