This study will consist of 2 Parts. Part 1 will include healthy participants who will be assigned to a dose group. Participants will then be randomized to receive a single oral administration of S-309309 or placebo in a fasted state. Administration will be initiated in the lowest dose group, and administration in the next dose group will not occur until a review of safety and tolerability has been completed for the preceding group.~Part 2 will include 2 groups. Healthy participants and obese but otherwise healthy participants will receive multiple oral administrations of S-309309 or placebo in a fed state.
The primary aim of the study is to assess the safety and tolerability of S-309309 after oral administration in healthy adult or obese but otherwise healthy adult participants. The secondary aim of the study is to assess the pharmacokinetics of S-309309 and the effects on ECG parameters after oral administration in healthy or obese but otherwise healthy participants.