A Study of KarXT + KarX-EC for Treatment of Irritability in Children and Adolescents With Autism

Inclusion Criteria * Participants must have a confirmed diagnosis of ASD, as defined by the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR) criteria, confirmed by the K-SADS-PL and must be experiencing symptoms of irritability. * Participants must have ABC-I ≥18 (C18 on the Irritability subscale of the ABC-I) and CGIS specific to irritability ≥4, at screening and baseline (Day 1). Exclusion Criteria * Participants must not have a current primary DSM-5 diagnosis of bipolar disorder, including bipolar II disorder, schizophrenia, schizoaffective disorder, major depressive episode as determined by clinical instrument, or post-traumatic stress disorder (PTSD). * Exception Include: Participants with comorbid ADHD, provided that attention deficit/hyperactivity disorder (ADHD) is not the primary disorder, the participant is adequately treated and based on the investigator judgment the disorder is clinically stable. * Participants must not have history/presence of clinically significant disease or disorder that would jeopardize participant safety or validity of study results. * Participants must not have a risk for suicidal behavior, and any clinically significant abnormal laboratory test. * Other protocol-defined Inclusion/Exclusion criteria may apply.