Trial · NCT05523895

Pimavanserin for the Treatment of Irritability Associated With Autism Spectrum Disorder

NCT05523895, Phase 2, Phase 3, Completed, ACADIA Pharmaceuticals Inc.; results first posted 2025-08-24

3 sourcestrials-2026-11-12-0.5.0

Cite this record

ConductScience Library. Pimavanserin for the Treatment of Irritability Associated With Autism Spectrum Disorder. Trials, record NCT05523895. Release trials-2026-11-12-0.5.0, 12 Nov 2026. https://conductscience.org/library/trials/NCT05523895

On this page

Trial

As registered on ClinicalTrials.gov, in the graph's capture of the registry.

Title: Pimavanserin for the Treatment of Irritability Associated With Autism Spectrum Disorder
NCT number: NCT05523895
Status: Completed
Phases: Phase 2, Phase 3
Enrollment: 237 participants, actual
Lead sponsor: ACADIA Pharmaceuticals Inc.
Conditions: Irritability Associated With Autism Spectrum Disorder
Interventions: Pimavanserin, Placebo
First posted: 2022-08-31
Last updated: 2025-08-24
Results first posted: 2025-08-24

Source ClinicalTrials.gov

Registered outcomes1

Each outcome the trial registered, primary first, in ClinicalTrials.gov's words.

List	Outcome	Time frame	Description
Primary	Change From Baseline at Week 6 in Caregiver-rated Aberrant Behavior Checklist Irritability (ABC-I) Subscale Score	6 weeks	The Aberrant Behavior Checklist (ABC) is a caregiver-rated scale comprised of 5 empirically-derived subscales encompassing 58 items that describe various behavior problems. It measures domains of irritability, lethargy/social withdrawal, stereotypic behavior, hyperactivity/noncompliance, and inappropriate speech. ABC-I is one of the subscales and comprises of 15 items. Minimum score is 0, maximum is 45. A score for each item ranges from 0 indicating "not at all a problem" to 3 indicating "the problem is severe in degree". Subscale scores are calculated by summing the items within that subscale. Higher scores indicate greater impairment.

Source ClinicalTrials.gov

Outcomes1

Each outcome the trial posted results for, in ClinicalTrials.gov's words.

Type	Outcome	Time frame	Population	Units	Measured as
PRIMARY	Change From Baseline at Week 6 in Caregiver-rated Aberrant Behavior Checklist Irritability (ABC-I) Subscale Score	6 weeks	Full Analysis Set: all randomized patients who received at least one dose of study drug and have a baseline value and at least one post-baseline value for the ABC-I subscale score.	score on a scale	LEAST_SQUARES_MEAN

Source ClinicalTrials.gov

Results by group3

Each measurement the trial posted, group by group, in the words and numbers it posted.

Outcome	Group	Value	Spread	Units
Change From Baseline at Week 6 in Caregiver-rated Aberrant Behavior Checklist Irritability (ABC-I) Subscale Score	Placebo	-9.6	Standard Error 1.06	score on a scale
Change From Baseline at Week 6 in Caregiver-rated Aberrant Behavior Checklist Irritability (ABC-I) Subscale Score	Pimavanserin Low Dose	-11.2	Standard Error 1.09	score on a scale
Change From Baseline at Week 6 in Caregiver-rated Aberrant Behavior Checklist Irritability (ABC-I) Subscale Score	Pimavanserin High Dose	-11.2	Standard Error 1.05	score on a scale

Source ClinicalTrials.gov

Participant flow9

How many started, completed or left each group, period by period.

Period	Milestone	Group	Participants
Overall Study	STARTED	Placebo	78
Overall Study	STARTED	Pimavanserin Low Dose	78
Overall Study	STARTED	Pimavanserin High Dose	81
Overall Study	COMPLETED	Placebo	74
Overall Study	COMPLETED	Pimavanserin Low Dose	67
Overall Study	COMPLETED	Pimavanserin High Dose	75
Overall Study	NOT COMPLETED	Placebo	4
Overall Study	NOT COMPLETED	Pimavanserin Low Dose	11
Overall Study	NOT COMPLETED	Pimavanserin High Dose	6

Source ClinicalTrials.gov

Adverse events18

Each adverse event the trial posted, group by group: the participants affected out of those at risk.

Type	Event	Organ system	Group	Affected	At risk	Events
other	Nausea	Gastrointestinal disorders	Placebo	1	78	1
other	Nausea	Gastrointestinal disorders	Pimavanserin Low Dose	4	77	6
other	Nausea	Gastrointestinal disorders	Pimavanserin High Dose	1	81	1
other	Upper respiratory tract infection	Infections and infestations	Placebo	4	78	4
other	Upper respiratory tract infection	Infections and infestations	Pimavanserin Low Dose	7	77	7
other	Upper respiratory tract infection	Infections and infestations	Pimavanserin High Dose	5	81	6
other	Decreased appetite	Metabolism and nutrition disorders	Placebo	0	78	0
other	Decreased appetite	Metabolism and nutrition disorders	Pimavanserin Low Dose	4	77	4
other	Decreased appetite	Metabolism and nutrition disorders	Pimavanserin High Dose	2	81	2
other	Headache	Nervous system disorders	Placebo	4	78	4

1 to 10 of 18Source ClinicalTrials.gov

See all 18 adverse events

Adverse event totals9

The totals the trial posted for each group.

Total	Group	Affected	At risk
Total, all-cause mortality	Placebo	0	78
Total, all-cause mortality	Pimavanserin Low Dose	0	77
Total, all-cause mortality	Pimavanserin High Dose	0	81
Total, other adverse events	Placebo	11	78
Total, other adverse events	Pimavanserin Low Dose	17	77
Total, other adverse events	Pimavanserin High Dose	16	81
Total, serious adverse events	Placebo	1	78
Total, serious adverse events	Pimavanserin Low Dose	0	77
Total, serious adverse events	Pimavanserin High Dose	0	81

Source ClinicalTrials.gov

Papers1

The papers the trial lists on ClinicalTrials.gov.

PMID	Listed as
42162607	DERIVED

Source PubMed

Grants0

The grants NIH RePORTER links to the trial, newest funded first: NIH's, and some of AHRQ's, CDC's, FDA's and VA's. Each shows its title, principal investigators, organization and funder in its newest year.

None in this release.

Trial comparisons0

Comparisons of the trial's two groups, calculated by ConductScience from the counts it posted.

None in this release.

Tests0

The ConductCognition tests this trial's registered outcomes name, as ScienceGraph matched them in trial-tests-2026-11-12-0.2.1.

None in this release.

Data dates

The day each source was copied for this release.

ClinicalTrials.gov: 2026-11-12; ClinicalTrials.gov
Results, from AACT: 2026-03-23; AACT
NIH grant links: 2026-11-13; NIH RePORTER

Sources 3

ClinicalTrials.gov's posted results, through CTTI's AACTFreely available. Acknowledgement requested
ClinicalTrials.govNo license stated
NIH RePORTER's clinical studies and project filesPublic domain

Each source's terms

ClinicalTrials.gov's posted results, through CTTI's AACTClinicalTrials.gov data via Aggregate Analysis of ClinicalTrials.gov (AACT), CTTI. CTTI makes its materials freely available and requests acknowledgement. https://aact.ctti-clinicaltrials.org/documentation/299
ClinicalTrials.govnone stated
NIH RePORTER's clinical studies and project filesPublic domain (NIH RePORTER)

ClinicalTrials.gov's data carry an international copyright outside the United States: https://clinicaltrials.gov/about-site/terms-conditions.

For software

Read this trial from software.

The record and each of its lists are JSON, twenty rows a page. No key.

GET https://conductscience.org/api/trials/v1/NCT05523895

GET https://conductscience.org/api/trials/v1/NCT05523895/registered

API reference For AI assistants