For business reasons

This is a single-center, randomized, double-blind, placebo-controlled study to evaluate the safety, tolerability, and pharmacokinetics (PK) of repeated IV doses of TD-8954 in healthy adults 18 to 45 years of age and healthy elderly subjects 65 to 85 years old. A healthy elderly subject population is included to evaluate the safety, tolerability, and PK of TD-8954 IV. Pharmacodynamic effects on bowel movements will also be evaluated. Screening for all cohorts will be conducted within 21 days before the first dose.

Inclusion Criteria:

1. For Cohorts 1: adult males and females age 18 to 45 years, inclusive; for Cohorts 2 and 3, adult males and females 65 to 85 years of age, inclusive; for Cohort 4, adult males and females 18 to 45 or 65 to 85 years of age, inclusive.
2. Body mass index (BMI)between 18 to 36 kg/m2, inclusive.
3. Average frequency of ≥ 3 bowel movements per week.

Exclusion Criteria:

1. Persistent symptoms of functional GI disorder (such as irritable bowel syndrome, functional constipation, functional dyspepsia, or other symptom-based GI disorders unexplained by a pathologically based disorder) during the 6 months prior to screening, including a history of major surgery of the GI tract, excluding cholecystectomy and appendectomy.
2. History or presence of clinically significant respiratory, GI, 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 the condition is well controlled and not anticipated to interfere with the objectives of the study.

The PI may communicate the trial results generated by the PI, but only after the first publication or presentation of the combined study results generated by all participating sites. The Sponsor can then review trial results communications prior to public release and can embargo communications regarding trial results for a period that is more than 60 days but less than or equal to 180 days. The Sponsor cannot require changes to the communication and cannot extend the embargo.