To assess the safety and tolerability of ascending multiple oral doses of SAM-531, an investigational drug, in healthy Japanese young male and elderly subjects.To provide the pharmacokinetics (PK) and pharmacodynamics (PD) profiles of multiple oral doses of SAM-531 in healthy Japanese young male and elderly subjects.

Inclusion criteria

• Men aged 20 to 45 years, inclusive, at screening.
• Elderly men or women aged 65 years and above as of screening.
• Body mass index (BMI) in the range of 17.6 to 26.4 kg/m2 and body weight ≥45 kg.

Exclusion critereia

• Any significant cardiovascular, hepatic, renal, respiratory, gastrointestinal, endocrine, immunologic, dermatologic, hematologic, neurologic, or psychiatric disease.
• Any clinically important deviation from normal limits in physical examination, vital signs, 12-lead ECGs, or clinical laboratory test results. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels should be below the upper limit of normal at screening.
• Tobacco use or consumption of any caffeine-containing products (e.g., coffee, tea, chocolate, or carbonated beverages) or alcoholic beverages within 48 hours before study day 1 until the end of the inpatient confinement period.