Updated May 2026 · ClinicalTrials.gov
Pimavanserin vs. Quetiapine for Treatment of Parkinson's Psychosis
CSP #2015 - Multicenter, Randomized, Double-blind Comparator Study of Antipsychotics Pimavanserin and Quetiapine for Parkinson''s Disease Psychosis (C-SAPP)
Pimavanserin vs. Quetiapine for Treatment of Parkinson's Psychosis (NCT04373317) is a Phase 4 interventional studying Parkinson's Disease Psychosis, sponsored by VA Office of Research and Development. RECRUITING as of the most recent ClinicalTrials.gov update. Talk to your doctor before contacting the trial site.
About This Trial
Patients with Parkinson's disease (PD) sometimes experience symptoms affecting their movement, such as slowness, tremor, stiffness, and balance or walking problems. Many patients also have other symptoms not related to movement, called non-motor symptoms, which may affect one's mood or emotions, memory or thinking, or cause one to see or hear things that aren't real (hallucinations) or believe things that aren't true (delusions). Hallucinations or delusions, together called psychosis, occur in up to 60% of PD patients at some point in time. Parkinson's disease psychosis can sometimes be associated with decreased quality of life, increased nursing home placement, increased rate of death, and greater caregiver burden. There are approximately 50,000 Veterans with Parkinson's disease receiving care in the VA, and up to 30,000 (60%) of them will experience psychosis at some point in time. Quetiapine is an antipsychotic drug approved by the Food and Drug Administration (FDA) that is the most commonly used medication to treat PD psychosis, but more studies are needed to determine if it works for this condition and is also well tolerated and safe. Pimavanserin is a newer antipsychotic drug approved by the Food and Drug Administration (FDA) specifically to treat PD psychosis, but more studies are needed to determine if it works and its safety. The purpose of this research is to gather additional information on the safety and effectiveness of both Quetiapine and Pimavanserin. By doing this study, the investigators hope to learn which of these medications is the most effective course of treatment for people with PD psychosis. Enrollment is open to Veterans nationwide, see your VA provider about the possibility of being referred to one of the study's Hub sites. This can be done through contact from your provider to the study's NSC (Tamara Boney at 267-303-9829).
What Stage of Research Is This?
Phase 4 studies happen after a treatment has been approved by the FDA. They monitor long-term safety, real-world effectiveness, and any rare side effects that only emerge in larger populations over longer periods. Phase 4 results sometimes lead to label changes, additional warnings, or — rarely — withdrawal of approval.
This trial is currently recruiting participants. The sponsor has registered the study with ClinicalTrials.gov as actively enrolling, which means new applicants who meet the eligibility criteria can be considered for screening. Trial status can change between updates — confirm current recruiting status with the study contact before traveling for a screening visit.
A target enrollment of 358 participants makes this a sizable late-stage trial. Studies in this range typically have enough power to detect clinically meaningful differences from a comparator and to characterize less-common side effects.
Who May Be Eligible (Plain English)
These are translations of the protocol\'s inclusion and exclusion criteria, simplified for patients and caregivers. The original clinical text appears below. Eligibility is ultimately confirmed by the trial site\'s screening process — this summary is a starting point for a conversation with your doctor, not a final determination.
Original Eligibility Criteria
View original clinical language
Treatments Being Tested
Pimavanserin
Fixed-dose Pimavanserin - Pimavanserin is a new antipsychotic agent, and pure 5HT-2A inverse agonist, that was approved by the FDA recently (2016) for the treatment of PDP. It is the only FDA-approved medication for PDP, but is still not the first-line AP used in PD. All participants assigned to pimavanserin will receive the FDA-approved dose of 34 mg (equivalent to 40 mg pimavanserin tartrate) daily without titration up or down; however, because pimavanserin is blinded to quetiapine, participants will undergo sham titration based on tolerability (i.e., overall adverse event profile) and efficacy (i.e., improvement in severity of psychosis).
Quetiapine
Flexible-dose Quetiapine - Quetiapine, which is a mixed serotonin and dopamine receptor antagonist, is by far the most commonly used AP for PDP. However, scientific evidence for the efficacy of quetiapine in PDP is almost non-existent as most of the studies were underpowered, had high drop-out rates, and possibly underdosed quetiapine. Quetiapine immediate and extended release will be titrated as shown: Baseline visit Quetiapine: 25 mg IR QHS, All participants must be up-titrated to 50 mg/day Week 1 call Quetiapine: 50 mg XR QHS, Up-titration to 50 mg Week 3 visit Quetiapine: 100 mg XR QHS, Up-titration as appropriate Week 5 visit Quetiapine: 150 mg XR QHS, Up- or down-titration as appropriate Week 6 call Quetiapine: 200 mg XR QHS, Up- or down-titration as appropriate
Locations (20)
Trial sites listed on ClinicalTrials.gov for this study. Site activation status can vary — confirm with the specific site before traveling for a screening visit.
How to Talk to Your Doctor About This Trial
Bring the printable summary of this trial — including the NCT ID (NCT04373317), the sponsor (VA Office of Research and Development), and the key eligibility criteria — to your next appointment. Your doctor can review the inclusion and exclusion criteria against your medical history, lab values, and current treatments to assess whether you are likely to qualify. They can also help you weigh whether trial participation makes sense alongside your existing care plan.
Useful questions to walk through together: What does the trial protocol require beyond standard care? How long is the active treatment phase, and how long is follow-up? Are there study visits at sites I can reach? Who pays for the trial-specific procedures, and who pays for standard-of-care portions? See our 25 questions to ask about clinical trials guide for a more complete checklist.
Authoritative Sources
The official record for this trial lives on ClinicalTrials.gov — the federal registry maintained by the National Library of Medicine at NIH. For background on how this trial fits into the FDA approval pathway, see the FDA drug approval process. For oncology-specific guidance for patients considering trials, the National Cancer Institute publishes patient-oriented overviews. International trial registries are aggregated by the WHO ICTRP.
Frequently Asked Questions
What is the NCT04373317 clinical trial studying?
Patients with Parkinson's disease (PD) sometimes experience symptoms affecting their movement, such as slowness, tremor, stiffness, and balance or walking problems. Many patients also have other symptoms not related to movement, called non-motor symptoms, which may affect one's mood or emotions, memory or thinking, or cause one to see or hear things that aren't real (hallucinations) or believe things that aren't true (delusions). Hallucinations or delusions, together called psychosis, occur in up to 60% of PD patients at some point in time. Parkinson's disease psychosis can sometimes be associ… The full protocol is registered on ClinicalTrials.gov and includes the primary outcome measures, eligibility criteria, and study endpoints.
Who can participate in NCT04373317?
Eligibility for this trial depends on the specific inclusion and exclusion criteria set by the sponsor. The plain-English summary above translates the most important criteria into accessible language; the official clinical text is preserved in the collapsible section underneath. Whether you fit any specific trial is a medical decision your doctor needs to confirm — bring the trial information to your treating physician for a full review against your medical history.
How do I contact the trial site for NCT04373317?
Contact information registered with ClinicalTrials.gov is shown in the sidebar of this page. Before reaching out, confirm with your treating physician that this trial is appropriate for your situation. The trial site will then walk you through the screening process to determine final eligibility.
Is participating in a clinical trial safe?
Clinical trials in the United States are regulated by the FDA and overseen by Institutional Review Boards (IRBs) that review the protocol for safety. Risk varies by trial — Phase 1 studies test new treatments in humans for the first time, while Phase 3 trials use treatments that have already passed earlier safety screening. The informed consent document for any specific trial details the known risks and what to expect. Discuss those risks with your physician before deciding whether to participate.
Where can I verify the data on this page?
Every detail on this page comes directly from the ClinicalTrials.gov API. Click "View on ClinicalTrials.gov" in the sidebar to see the official, unmodified record. The federal record is always authoritative; this page is a structured presentation with a plain-English eligibility translation. For background on how clinical trials are regulated, see the FDA drug approval process documentation.
How This Page Is Built
Every field on this page is pulled directly from the ClinicalTrials.gov API v2 — no estimates, no proxies. The plain-English eligibility translation is generated from the original protocol text and reviewed for fidelity to the underlying clinical criteria. The original clinical text remains visible in the collapsible section above so users and clinicians can verify the translation. Read the full methodology for the data pipeline and known limitations.
Source: ClinicalTrials.gov API v2 record for NCT04373317. Maintained by the National Library of Medicine at NIH. Public domain. Cite as: "TrialFinderData. NCT04373317. Data: ClinicalTrials.gov."
Medical disclaimer: This page is informational, not medical advice. Talk to your doctor about whether a clinical trial is right for you.
Last updated 2026-05-08 · Data from ClinicalTrials.gov.