Study Overview: This study seeks to understand the safety and how the body processes a new injectable medicine, called lumateperone, for people with schizophrenia (a mental illness causing delusions and hallucinations) or schizoaffective disorder (a condition with mood disorder and schizophrenia symptoms). The study uses a single shot given in a muscle.

Key Points:

• This study lasts for a short time, as it focuses on just one injection.
• Participants must be clinically stable, meaning no severe symptoms for at least 3 months before the study.
• There are certain health checks needed, like a heart test (ECG) to ensure safety.

Eligibility: Adults between 18-55 years with stable schizophrenia or schizoaffective disorder can join. Participants should have a normal weight range and no serious health issues that could affect the study. Those with recent thoughts of self-harm or certain heart issues cannot participate.

This research helps find better treatments for mental health conditions, but it's important for volunteers to meet health requirements to ensure safety.