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Trial of Ondansetron as a Parkinson's HAllucinations Treatment

Trial of Ondansetron as a Parkinson's HAllucinations Treatment

Status
Active, not recruiting
Phases
Phase 2
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT04167813
Acronym
TOP HAT
Enrollment
168
Registered
2019-11-19
Start date
2021-10-01
Completion date
2024-08-30
Last updated
2024-03-27

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Dementia With Lewy Bodies, Parkinson's Hallucinations

Brief summary

TOPHAT (Trial of Ondansetron as a Parkinson's HAllucinations Treatment) is a double blind, individually randomized, placebo-controlled, parallel group, flexible dose trial of ondansetron (8-24mg/day) as a treatment for Parkinson's hallucinations, with a 12-week primary outcome and follow-up to 24 weeks.

Detailed description

This study investigates whether ondansetron, a drug used to treat post-operative sickness, has a meaningful treatment effect on Parkinson's hallucinations, and whether the drug is safe and cost effective for use in the NHS. We will compare ondansetron to placebo (a tablet that looks identical but contains no drug) over 12 weeks treatment, with follow up (once treatment ends) for a further 12 weeks. Assessments of symptoms will be carried out during treatment (after 6 and 12 weeks), and once treatment ends (18, 24 weeks), to measure hallucinations, delusions (false beliefs), Parkinson's symptoms (tremor, anxiety, sleep disturbance), memory, quality of life, possible side-effects such as constipation and headache, and the proportion of people who drop out due to side effects, or require additional treatment for their hallucinations. Blood drug concentration (measured after 6 and 12 weeks) will provide information on how quickly the drug is cleared from the body, and how this relates to treatment effects and side-effects, to guide future prescribing in people with Parkinson's. Based on knowledge of the average hallucinations scores in previous Parkinson's treatment studies, 306 people will be needed for the study to detect a meaningful treatment effect. The study will run for 4 years and involves a series of linked stages: (1) Trial set up across 20-30 UK centres; (2) Recruitment over 2 years; (3) Completion of follow up; and analysis, publication and dissemination of results.

Interventions

DRUGOndansetron 8mg or matched placebo tablets

Participants will take one tablet daily in weeks 1 and 2, two tablets daily in weeks 3 and 4 and 3 tablets daily in weeks 5 and 6. Dose escalation will be guided by tolerability, through telephone safety monitoring prior to each dose increase

Sponsors

MODEPHARMA Limited
CollaboratorUNKNOWN
Parkinson's UK
CollaboratorOTHER
PRIMENT
CollaboratorUNKNOWN
SEALED ENVELOPE
CollaboratorUNKNOWN
Wasdell Packaging Ltd
CollaboratorUNKNOWN
Custom Pharmaceuticals Limited
CollaboratorUNKNOWN
University College, London
Lead SponsorOTHER

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)

Masking description

Double-blind

Intervention model description

TOPHAT is a double blind, individually randomized, placebo-controlled, parallel group, flexible dose trial

Eligibility

Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No

Inclusion criteria

1. Adults aged over 18 years. 2. Meet MDS criteria for Parkinson's disease or revised criteria for DLB. 3. Score of 3 or more on the SAPS-H visual hallucinations item, indicating the presence of visual hallucinations at least weekly in the previous month. 4. Score of 3 or more on SAPS-H global rating, indicating moderate symptom severity. 5. Score of 4 or more on CGI-S, indicating moderate symptom severity. 6. On a stable dose of anti-Parkinson's medication, cholinesterase inhibitor or memantine for at least 28 days. 7. Capacity to give informed consent or, if lacking, legal representative able to give consent. 8. Pre-menopausal women, and men whose partners are of child bearing potential will agree to use effective contraception. 9) If treated with an antipsychotic drug at the time of enrolment, can still participate, provided the drug is stopped the day before trial medication is commenced. \-

Exclusion criteria

1. Bradycardia (\<50 bpm) (rescreen if reversible). 2. Congenital long QTc syndrome or presence of clinically significant prolongation of QTc (\>460 ms for men or \>470 ms for women) on ECG screening. 3. Severe hepatic failure (bilirubin \>50 micromole/L) 4. Prescribed apomorphine (if apomorphine is discontinued, rescreen once stable on an alternative anti-Parkinson's treatment). 5. Prescribed tropisetron, granisetron, dolasetron. 6. History of hypersensitivity to ondansetron and its excipients (or those of placebo) or drugs listed in 5). 7. Participation in another Clinical Trial of an Investigational Medicinal Product (IMP) in the previous 28 days. \-

Design outcomes

Primary

MeasureTime frameDescription
Hallucinations12 weeksScale for Assessment of Positive Symptoms-Hallucinations (0-35 points, higher scores indicate greater severity of hallucinations

Secondary

MeasureTime frameDescription
Safety and tolerability2, 4, 6, 12, 18, 24 weeksNumber of Participants With Treatment-Related Adverse Events
Health related quality of life6, 12, 18, 24 weeksEQ-5D-5L
Cost effectiveness2, 4, 6, 12, 18, 24 weeksHealth and social service utilisation
Pharmacokinetics, plasma concentrations of the study drug6, 12 weeksMeasured using a validated HPLC/MS assay
Delusions2, 4, 6, 12, 18, 24 weeksScale for Assessment of Positive Symptoms-Delusions (0-65 points, higher scores indicate greater symptom severity
Global illness severity2, 4, 6, 12, 18, 24 weeksClinical Global Impression of Severity Scale (1-7, higher scores indicate greater severity)
Non-motor symptoms2,4,6,12,18,24 weeksNon-motor symptoms scale (0-120, higher scores indicate greater severity
Cognition12 weeksStandardised Mini-Mental State Examination (0-30, higher scores indicate better performance)
Feasibility and Acceptability of Video Consultationbaseline, 6 and 12 weeksThe feasibility of video consultation will be measured at baseline, 6 and 12 weeks by the proportion of participants who were able to successfully attend on at least one occasion, the proportion who successfully attended all three assessments, and a Satisfaction questionnaire that allows both quantitative and qualitative information to be collected.
Hallucinations2, 4, 6, 18, 24 weeksScale for Assessment of Positive Symptoms-Hallucinations (0-35 points, higher scores indicate greater severity of hallucinations

Countries

United Kingdom

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026