To assess the safety and tolerability of ascending single oral doses of SAM-531 in healthy subjects.To obtain preliminary pharmacokinetic (PK) and pharmacodynamic (PD) profiles of SAM-531, an investigational drug, in healthy subjects and to evaluate the effect of a high-fat meal on the PK of SAM-531 administered to healthy subjects.

Inclusion criteria

1. Men or women of nonchildbearing potential aged 18 to 45 years
2. Elderly men or women aged 65 years and above as of study day 1.
3. Body mass index in the range of 18 to 30 kg/m2 and body weight ≥50 kg. Body weight for elderly subjects must be ≥45 kg.

Exclusion criteria

1. Any significant cardiovascular, hepatic, renal, respiratory, gastrointestinal, endocrine, immunologic, dermatologic, hematologic, neurologic, or psychiatric disease
2. Any clinically important deviation from normal limits in physical examination, vital signs, digital 12-lead ECGs, or clinical laboratory test results.
3. Tobacco use or the consumption of any caffeine-containing products (e.g., coffee, tea, chocolate, or soda) or alcoholic beverages within 48 hours before study day 1, or grapefruit or grapefruit-containing products 72 hours before study day 1, and until the end of the inpatient confinement period.