Inclusion Criteria:  Inclusion Criteria:  Male or female participants must be 6 to 17 years of age (inclusive) Participants must have completed study intervention in their lead-in study  Exclusion Criteria:  Participant has an unresolved AE or a clinically significant finding on a physical examination, vital sign assessment, or neurological assessment along with an ECG or clinical laboratory tests (if results are available by the time of enrollment) that; in the opinion of the investigator, could represent a safety concern or a condition that would be exclusionary, could prevent the participant from performing any protocol assessments, or could confound study assessments. Participant has known allergies or hypersensitivity to opioids Female participants who are currently pregnant or nursing, or plan to become pregnant or nurse during the clinical study. Participant has no gallbladder, (ie, agenesis of the gallbladder or cholecystectomy). Participant has known or suspected biliary duct obstruction, or sphincter of Oddi disease or dysfunction Participant has a history of pancreatitis; structural diseases of the pancreas, known or suspected pancreatic duct obstruction Participant has a history of chronic or severe constipation, or sequelae from constipation, or known or suspected mechanical GI obstruction or pseudo obstruction Participant has renal impairment or an unstable hepatic, metabolic, or hematologic condition. Participant is a current regular alcohol drinker and/or binge drinker*, and/or has a history of alcoholism, alcohol abuse (eg, binge-drinking*), or alcohol addiction, and/or intends to consume alcohol during the study