This clinical trial is focused on studying the long-term safety and tolerability of a medication called pimavanserin in children and adolescents who have Autism Spectrum Disorder (ASD) and experience irritability. The study involves taking pimavanserin in capsule form, with doses of 10 mg, 20 mg, or 34 mg, over a period of 52 weeks. The purpose of the study is to understand how well children and adolescents with ASD tolerate this medication over a long period.

Participants in the study will take the medication orally, which means swallowing the capsules. The study will monitor various health indicators, such as vital signs, weight, and heart function, to ensure the safety of the participants. Additionally, the study will assess any side effects that may arise during the treatment period. The goal is to gather information on how the medication affects the participants’ health and behavior over the course of a year.

Throughout the study, researchers will also evaluate changes in irritability levels using specific scales designed to measure behavior and improvement. This will help determine if pimavanserin is effective in reducing irritability in children and adolescents with ASD. The study aims to provide valuable insights into the long-term use of pimavanserin for managing irritability associated with ASD.