The purpose of this study is to evaluate the effects of multiple doses of verapamil on the plasma concentration of a single dose of SAM-531 in healthy young adult subjects and to assess the safety and tolerability of co-administration of SAM-531 and verapamil.

Inclusion criteria :

1. Body mass index in the range of 18 to 30 kg/m2 and body weight greater than 50 kg.
2. Healthy as determined by the investigator on the basis of medical history, physical examination findings, clinical laboratory test results, vital sign measurements, and digital 12-lead ECG readings.

Exclusion criteria :

1. Presence or history of any disorder that may prevent the successful completion of the study.
2. Any significant cardiovascular, hepatic, renal, respiratory, gastrointestinal (GI), endocrine, immunologic, dermatologic, hematologic, neurologic, or psychiatric disease.