A Study of Elpipodect (MK-8189) in Participants With Schizophrenia (MK-8189-014)

The main inclusion and exclusion criteria include but are not limited to the following: Inclusion Criteria: * Meets diagnostic criteria for schizophrenia or schizoaffective disorder according to the Diagnostic and Statistical Manual of Mental Disorders (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. * Is in the non-acute phase of their illness and clinically stable for 3 months prior to screening as demonstrated by: 1) no clinically significant change in dose of prescribed antipsychotic medication, or clinically significant change in antipsychotic medication to treat symptoms of schizophrenia for two months prior to screening; 2) no increase in level of psychiatric care due to worsening of symptoms of schizophrenia for three months prior to screening. * Has a history of receiving and tolerating antipsychotic medication within the usual dose range employed for schizophrenia. * Is able to discontinue the use of all antipsychotic medication at least 5 days or 3 half-lives (whichever is longer) prior to Day -1 and during the study period. Exclusion Criteria: * Is at imminent risk of self-harm. * Has a history of cancer (malignancy). Exceptions: 1) adequately treated nonmelanomatous skin carcinoma or carcinoma in situ of the cervix; 2) malignancies which have been successfully treated ≥10 years prior to the prestudy (screening) visit; 3) highly unlikely to …