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Study on the Long-Term Safety of Pimavanserin for Treating Irritability in Children and Adolescents with Autism Spectrum Disorder

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What is this trial about?

A plain-language summary of the goals, design and what participants do

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.

The research process

The trial runs in 6 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Joining the study

    Participation begins after completing a previous study. Consent is required from both the participant and their parent or legal representative.

    The participant must be stable in terms of health and behavior, as assessed by the study investigator.

  2. Step 2

    Medication administration

    The study involves taking pimavanserin capsules orally. The available dosages are 10 mg, 20 mg, and 34 mg.

    The specific dosage and frequency will be determined by the study team based on individual needs and responses.

  3. Step 3

    Treatment duration

    The treatment period lasts for 52 weeks.

    Regular assessments will be conducted to monitor safety and effectiveness.

  4. Step 4

    Safety assessments

    Safety is evaluated through various measures, including monitoring vital signs, weight, and body mass index (BMI).

    Additional tests include electrocardiograms (ECGs), physical examinations, laboratory tests, and assessments for any adverse effects.

  5. Step 5

    Effectiveness evaluation

    The study aims to assess improvements in irritability associated with autism spectrum disorder (ASD).

    Effectiveness is measured by changes in behavior checklists and clinical impressions over the course of the study.

  6. Step 6

    Completion of the study

    The study concludes after 52 weeks of treatment.

    Final assessments are conducted to evaluate long-term safety and tolerability of the medication.

Who can join the trial?

8 criteria

  • The child or adolescent must have completed the treatment period of the previous study.
  • Before any study procedures, the child or adolescent must give their agreement to participate if they are able to do so. This is called "assent."
  • The parent or legal guardian must provide written permission for the child or adolescent to participate. They must be reliable, able to complete assessments about the child's development and behavior, and help ensure the child follows the study requirements.
  • If someone other than the parent or legal guardian is helping with the study, they must also provide written permission. This person should be a responsible adult, living with or in frequent contact with the child, and committed to helping with the study.
  • The child or adolescent, their parent or legal guardian, and any designated caregiver must understand the study, follow the study rules, and be willing to comply with taking the study medication.
  • The child or adolescent must be considered stable and not at risk of harming themselves or others, according to the study doctor.
  • The child or adolescent must be medically stable when joining the study, according to the study doctor.
  • Female participants who can become pregnant must agree to use two acceptable methods of birth control during the study and for at least 45 days after the last dose of the study medication. They must also have a negative pregnancy test at the start and during the study. Females who have started menstruating are considered of childbearing potential.

Who cannot join the trial?

8 criteria

  • Children and adolescents who do not have irritability associated with autistic disorder.
  • Individuals who are not within the age range specified for the study.
  • Participants who have any medical condition that might interfere with the study.
  • Individuals who are currently taking medications that could affect the study results.
  • Participants who have a history of severe allergic reactions to similar medications.
  • Individuals who are unable to follow the study procedures or instructions.
  • Participants who have been part of another clinical trial recently.
  • Individuals with any condition that the study doctors believe would make participation unsafe.
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Investigated drugs

Pimavanserin is being studied for its long-term safety and tolerability in children and adolescents with irritability associated with Autism Spectrum Disorder (ASD). This medication is being tested over a period of 52 weeks to see how well it can be tolerated and how safe it is for young patients with ASD.

What is already known about the treatment

Pimavanserin – Pimavanserin is administered orally, typically in tablet form. It is currently being studied in clinical trials for its long-term safety and tolerability in treating irritability associated with autism spectrum disorder (ASD) in children and adolescents. The medication is primarily used for its antipsychotic properties, and it works by selectively targeting serotonin receptors in the brain, which can help manage symptoms of irritability. Pimavanserin is classified as an atypical antipsychotic, and it is already approved for use in other conditions, such as Parkinson's disease psychosis.

Investigated diseases

Autistic Disorder – Autistic disorder, also known as autism spectrum disorder (ASD), is a developmental condition that affects communication and behavior. It is characterized by challenges with social skills, repetitive behaviors, and speech and nonverbal communication. The symptoms can vary widely in severity and may include difficulties in understanding social cues, forming relationships, and expressing emotions. Individuals with ASD may also exhibit restricted interests and repetitive patterns of behavior. The condition is typically diagnosed in early childhood, and its progression can vary significantly from person to person. Some individuals may experience improvements in symptoms over time, while others may continue to face challenges throughout their lives.
Trial detailsLast updated 2 Oct 2026
Age0-17PhasePhase IITrial ID2024-512202-25-00Protocol codeACP-103-070Estimated enrolment228 patientsSponsorAcadia Pharmaceuticals Inc.

sourced from the EU Clinical Trials Register and site verification

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On this site, “treatment” means an investigational medicine being studied in a clinical trial. Its safety and efficacy for the use being studied have not yet been confirmed, some participants may receive a placebo or a comparator medicine, and taking part does not guarantee any health benefit. The decision to take part is made by the doctor at the research site. This site is for information only and does not replace medical advice.

This service is not affiliated with the European Commission, the EMA, or the official CTIS system. Most information comes from publicly available international clinical-trial registries, supplemented by data from academic sites, national regulators and commercial sponsors. On this site, “treatment” and “therapy” mean a medicine being tested in a clinical trial. Its safety and effectiveness in the use being studied are not yet confirmed, some participants may receive a placebo or a comparator, and taking part does not guarantee a health benefit. The doctor at the research site decides who can take part. This site provides information, not medical advice. Certain content and visual elements on this website have been generated or enhanced using artificial intelligence (AI).