A 3-Part, Open-Label, Drug-Drug Interaction Study of Concomitant Administration of E2609 With Itraconazole, Rifampin, Digoxin, or Donepezil

Inclusion Criteria 1. Healthy male or female subjects aged 18-55 years inclusive at the time of informed consent 2. Provide written informed consent 3. Willing and able to comply with all aspects of the protocol Exclusion Criteria 1. Any history of seizures or epilepsy (not including a history of simple febrile seizures in childhood) or disturbance of consciousness likely to be due to seizures 2. A prolonged QT/QTc interval (QTc greater than 450 ms) as demonstrated by the mean of triplicate electrocardiograms (ECGs), recorded at least 1 min apart, at Screening or Baseline Periods 3. Evidence of clinically significant disease (eg, psychiatric disorders and disorders of the gastrointestinal tract, liver, kidney, respiratory system, endocrine system, hematological system, neurological system, or cardiovascular system) that in the opinion of the investigator(s) could affect the subject's safety or interfere with the study assessments or subjects who have a congenital abnormality in metabolism within 4 weeks before dosing. 4. Any laboratory abnormalities considered clinically significant by the investigator, which may require further investigations or treatment 5. Clinically significant illness which required medical treatment within 8 weeks or a clinically significant infection within 4 weeks of dosing