This is a clinical research study for an investigational drug called RAP-219 in participants with bipolar I disorder. This study is being conducted to determine if RAP-219 is safe and effective in participants experiencing mania associated with bipolar I disorder.

This is a Phase 2, proof-of-concept, multi-center, randomized, double blind, placebo-controlled study designed to evaluate the efficacy, safety and tolerability of RAP-219 in adult participants experiencing mania associated with bipolar I disorder. This is a 3-week inpatient clinical trial.

Inclusion Criteria:

• Meets the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) diagnosis of bipolar I disorder, with or without psychotic symptoms, as confirmed by the Structured Clinical Interview for DSM-5, Clinical Trials Version (SCID-5-CT). Episode may contain mixed features, as confirmed by Montgomery-Åsberg Depression Rating Scale (MADRS).
• Had at least one prior documented manic episode (with or without psychotic symptoms) that required treatment, within 5 years prior to Visit 1

Exclusion Criteria:

• History of any of the following diagnoses: a. schizophrenia; schizoaffective disorder; major depressive disorder; moderate or severe substance or alcohol use disorder; as assessed by the SCID-5-CT b. delirium, dementia, amnestic, or other cognitive disorders; borderline, paranoid, histrionic, schizotypal, schizoid, or antisocial personality disorders; by medical history and/or Investigator opinion Note: Any other current diagnoses must be discussed with the Medical Monitor.
• Rapid cycler, defined as experiencing ≥4 distinct mood episodes (ie, manic or depressive) each meeting full DSM-5 criteria in the previous 12 months, and each separated by ≥2 months of full or partial remission, or a switch to an episode of the opposite polarity, as assessed by the SCID-5-CT