The objective of this study is to evaluate the safety and the pharmacokinetics of ASP2151 after multiple oral dosing of ASP2151 in healthy non-elderly male and elderly male Japanese subjects, and to compare the pharmacokinetics of ASP2151 in healthy non-elderly male and elderly male Japanese subjects.

Inclusion Criteria:

• Body weight: ≥50.0 kg and <85.0 kg
• Body mass index (BMI): ≥17.6 and <26.4 kg/m2

Exclusion Criteria:

• Subjects with a complication of any diseases
• Subjects with a history of hepatic disease
• Subjects with a history of heart disease
• Subjects with a history of respiratory disease
• Subjects with a history of alimentary disease
• Subjects with a history of renal disease
• Subjects with a history of cerebrovascular disorder
• Subjects with a history of malignant tumor
• Subjects with a history of drug allergies or allergies disorders excluding pollinosis
• Subjects with a history of drug dependency or alcohol dependence syndrome
• Subjects who developed genital herpes or herpes zoster within 90 days before the initial dosing
• Subjects who do not meet any of the criteria for laboratory tests
• Subjects who received medications within 14 days before the initial dosing.
• Subjects who received any investigational drugs in other clinical trials or post-marketing studies within 120 days before screening or the initial dosing
• Excessive alcohol drinking or smoking habit
• Subjects who previously received administration of ASP2151 (including placebo)
• Abnormalities detected on an ophthalmological examination
• Subjects who deviate from the normal range of standard 12-lead ECG at screening