TOP HAT

Trial of Ondansetron as a Parkinson’s Hallucinations Treatment

TOP HAT is a multi-centre, double blind, randomized, placebo-controlled, parallel group trial of flexibly dosed ondansetron, as a treatment for Parkinson’s hallucinations, with a 12-week primary outcome and follow-up to 24 weeks. The primary objective of the trial is to establish whether flexibly dosed ondansetron will effectively treat visual hallucinations in people with Parkinson’s disease, evidenced by clinically meaningful superiority over placebo at 12 weeks. In addition to testing the effectiveness of ondansetron, the study aims to answer several other important questions. These include whether ondansetron can reduce delusions, establishing safety and tolerability, cost-effectiveness and ability to improve quality of life in people with PD. The Lewy Body dementia (DLB) sub-study will consider whether there is an indication that ondansetron can be used for treatment of hallucinations for those with DLB and will provide initial information about tolerability and safety in this population.