Key Inclusion Criteria:  Medically confirmed diagnosis of dyskinesia (dystonia and/or choreoathetosis) due to Cerebral palsy (CP). The dyskinetic movements must cause disability and be of at least moderate severity. Medical conditions are stable and expected to remain stable throughout the study.  Key Exclusion Criteria:  Subjects will be excluded from the study if they meet any of the following criteria:  Are pregnant or breastfeeding. Have a clinical diagnosis or history of dyskinesia due to condition other than CP. Have inability to swallow soft solids, or requirement to take medications by gastro-enteral tube. Have any suicidal behavior or suicidal ideation in the year prior to screening or on Day 1. Is a substance abuser of any compound. Known history of long QT syndrome or cardiac tachyarrhythmia, or clinically significant ECG abnormalities.