Elpipodect (MK-8189) Multiple Dose Study in Healthy Volunteers and Schizophrenia Participants (MK-8189-003)

This 3-part dose titration study will assess elpipodect safety, tolerability, pharmacokinetics (PK), and central nervous system activity. Part 1 (Panels A and B) will assess elpipodect administered as monotherapy in participants with schizophrenia. Part 2 (Panel C) will assess elpipodect administered as add-on to atypical antipsychotic treatment in participants with schizophrenia. Part 3 (Panel D) will assess monotherapy with elpipodect in healthy participants, including those of Japanese descent. The primary hypothesis is that there is at least one dose of elpipodect that is generally safe and well-tolerated which will have the desired PK parameters in participants with schizophrenia.