The purpose of this study is to measure the way in which TD-1211 is absorbed and eliminated by the body and to evaluate whether it is safe and well tolerated.

Inclusion Criteria:

• For the elderly cohort, nonsmoking 65 to 85 years, inclusive. For the young cohort, nonsmoking 18 to 45 years, inclusive.
• Body mass index (BMI) should be 18 to 36 kg/m2, inclusive.
• At screening, sitting or supine heart rate of 50 to 100 beats per minute and sitting or supine systolic and diastolic blood pressure of 90 to 150 mm Hg and 50 to 90 mm Hg, respectively (2 of 3 measurements)
• Subjects with mild, chronic, stable disease (e.g., controlled hypertension, non-insulin-dependent diabetes, arthritis) may be enrolled if deemed medically acceptable by the investigator
• Negative for hepatitis B virus, hepatitis C virus, and human immunodeficiency virus antibody within the last 3 months
• No clinically relevant abnormalities in laboratory evaluations

Exclusion Criteria:

• History or presence of clinically significant respiratory, gastrointestinal, renal, hepatic, endocrine, hematological, neurological (including chronic headache, current or prior psychiatric disease/condition, stroke), cardiovascular, psychiatric, musculoskeletal, genitourinary, immunological, or dermatological disorders. Subjects with mild, chronic, stable disease (e.g., controlled hypertension, controlled hypercholesterolemia, non insulin-dependent diabetes, osteoarthritis) may be enrolled if condition is well controlled and not anticipated to interfere with the objectives of the study.
• Any clinically significant abnormal ECG (electrocardiogram).
• Participation in another clinical trial of an investigational drug or medical device within 60 days.
• Donation of ≥500 mL blood, or equivalent, within 8 weeks prior to admission day.
• Any other condition that, in the opinion of the investigator, would confound or interfere with evaluation of safety, tolerability, or PK of the investigational drug or prevent compliance with the study protocol.