The Aberrant Behavior Checklist (ABC) - Community version is a 58-item, caregiver-rated scale designed to measure inappropriate and maladaptive behavior of people with developmental disabilities (including intellectual disability and ASD). The ABC has 5 subscales (Irritability, Social Withdrawal, Stereotypic Behavior, Hyperactivity and Inappropriate Speech). The caregiver rates the child's behavior from 0=not at all a problem to 3= the problem is severe in degree. The range for Irritability is 0 to 45. Higher scores indicate greater severity.

An adverse event (AE) is defined as any untoward medical occurrence in a patient or clinical investigation participant administered a pharmaceutical product which does not necessarily have a casual relationship with this treatment. The investigator assesses the relationship of each event to the use of the study. A serious adverse event (SAE) is an event that results in death, is life threatening, requires or prolongs hospitalization, results in a congenital anomaly, persistent or significant disability/incapacity or is an important medical event, that based on medical judgment, may jeopardize the participant and may require medical or surgical intervention to prevent any of the outcomes listed above. Treatment-emergent adverse events/ treatment emergent serious adverse events (TEAEs/TESAEs) are defined as any event that began or worsened in severity on or after the first dose of the study drug.

Change in vital signs like systolic and diastolic blood pressure will be assessed.

Number of participants with incidence of abnormal clinical laboratory test results like hematology will be assessed.

12 -lead resting ECGs will be recorded. Parameters include RR interval, PR interval, QT interval, and QRS duration.

SAS is a 10-item rating scale for assessment of antipsychotic-induced parkinsonism in both clinical practice and research settings. Each item ranges from 0 (normal) to 4 (extreme symptoms). The scale consists of 1 item measuring gait (hypokinesia), 6 items measuring rigidity, and 3 items measuring glabella tap, tremor, and salivation, respectively.

The C-SSRS is a clinician-rated instrument that reports the severity of both suicidal ideation and behavior, with a higher score denoting more severe suicidal ideation and behavior.

BARS is a 4-item rating scale used to assess drug-induced akathisia. The scale comprises items for rating the observable restless movements that characterize the condition, the subjective awareness of restlessness, and any distress associated with the akathisia (each on a 4-point scale from normal \[0\] to severe \[3\]). In addition, there is a global severity for akathisia rated on a 6-point scale (absent \[0\] to severe akathisia \[5\]).

AIMS assesses abnormal involuntary movements, such as tardive dyskinesia, associated with antipsychotic drugs; it measures facial, oral, extremities, and trunk movements, as well as the participant's awareness of abnormal movements. The first 10 items are rated on a none (0) to severe (4) scale. There are an additional 2 items on dental status that are answered yes or no.

The CDRS-R is a 17-item clinician-administered scale specifically developed for the assessment of depressive symptoms in children and adolescents. Total scores range from 17 to 113. In general, scores below 20 indicate an absence of depression, scores of 20 to 30 indicate borderline depression, and scores of 40 to 60 indicate moderate depression. The CDRS-R will be administered by a clinician with extensive professional training in mental illness.

The MADRS is a 10-item, clinician-rated scale that evaluates the participant's depressive symptomatology during the past week. Participants were rated on items assessing feelings of sadness, lassitude, pessimism, inner tension, suicidality, reduced sleep or appetite, difficulty in concentration, and lack of interest. Each item was scored on a 7-point scale with a score of 0 reflecting no symptoms and a score of 6 reflecting symptoms of maximum severity. The total score ranges from 0 to 60 with a higher score indicating more depression. A negative change from Baseline indicates improvement. Mixed-effects Model for Repeated Measures (MMRM) was used for analyses.

The MADRS is a 10-item, clinician-rated scale that evaluates the patient's depressive symptomatology during the past week. Patients are rated on items assessing feelings of sadness, lassitude, pessimism, inner tension, suicidality, reduced sleep or appetite, difficulty in concentration, and lack of interest. Each item is scored on a 7-point scale with a score of 0 reflecting no symptoms and a score of 6 reflecting symptoms of maximum severity. mITT Population included all randomized participants who had ≥1 postbaseline assessment of the MADRS total score. Number of subjects analyzed are the number of participants with data available for analyses.

Relapse was defined as the occurrence of any 1 of the following: * Young Mania Rating Score (YMRS) total score ≥ 17 (range 0-60; higher score indicates a worse outcome); * Montgomery Asberg Depression Rating Scale; (MADRS) total score ≥ 20 (range 0-60; higher score indicates more depressive symptoms); * Clinical Global Impression-Improvement scale (CGI-S) ≥ 4 (range from 1 \[normal, not at all ill\] to 7 \[extremely ill\]); * Initiation of additional psychiatric medication; * Psychiatric hospitalization; * Exacerbation of illness as judged by clinical impression of the Investigator. Time to first relapse (days) was calculated as the date of the first relapse - the date of randomization + 1. Participants who did not meet the relapse criteria were considered censored at the time of completion or discontinuation from the Double-Blind Treatment Period (DBTP) of the study. Percentiles (95% Confidence Intervals \[CI\]) are based on Kaplan-Meier estimates.