Safety, Tolerability, and Pharmacokinetics Study of Elpipodect (MK-8189) in Participants With Schizophrenia and Healthy Participants (MK-8189-011)

Inclusion Criteria: * Has a body mass index (BMI) ≤40 kg/m2 * Has no clinically significant abnormality on 12-lead safety electrocardiogram (ECG) performed at the prestudy (screening) visit and/or prior to randomization * Has a normal resting blood pressure (BP: systolic BP is ≥90 millimeter of mercury \[mmHg\] and ≤140 mmHg; diastolic BP is ≥60 mmHg and ≤90 mmHg) and normal resting heart rate (≥45 beats per minute \[bpm\] and ≤100 bpm) in the semirecumbent position at the prestudy (screening) visit and/or prior to randomization. Repeat evaluations may be done if the values for a participant are, per investigator discretion, minimally outside the designated range. Participants may be included if values are outside the normal range but considered not clinically significant per investigator discretion * Participants with schizophrenia only: Meets diagnostic criteria for schizophrenia or schizoaffective disorder according to the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) criteria with the onset of the first episode being no less than 2 years prior to screening and monotherapy with antipsychotics for treatment should be indicated * Participants with schizophrenia only: Has a total Brief Psychiatric Rating Scale (BPRS) score of \<48 with a BPRS score \<4 for #10 (hostility) and #14 (uncooperativeness) at the screening visit * Participants with schizophrenia only: Is in the nonacute phase of their illness and clinically stable for 3 months prior to …