The US Food and Drug Administration's Perspective on the New Antipsychotic Pimavanserin

Objective: To summarize the US Food and Drug Administration’s (FDA’s ) review of the safety and effectiveness for pimavanserin, an atypical antipsychotic, for the treatment of hallucinations and delusions associated with Parkinson’s disease psychosis. We describe the regulatory and clinical issues important to the FDA’s approval of this New Drug Application, with special focus on the risk-benefit balance. We also describe a new labeling feature that presents additional efficacy data to clinicians.

Data Sources: Data sets for all relevant clinical trials of pimavanserin and the Applicant’s and FDA’s analyses of these data were considered in this review. Data were available from 616 patients with Parkinson’s disease with hallucinations and delusions who received at least 1 dose of pimavanserin, with a total exposure of 825 patient-years in the Parkinson’s disease psychosis population.

Results: Pimavanserin 34 mg/d was effective in treating hallucinations and delusions associated with Parkinson’s disease. In the Applicant’s single pivotal trial, 80.5% of pimavanserin patients experienced at least some improvement in symptoms compared to 58.1% of patients taking placebo. Pimavanserin did not worsen motor function, an adverse effect commonly observed with other antipsychotics, probably because of a lack of consequential dopamine binding.

Conclusions: Pimavanserin is the only FDA-approved treatment for the hallucinations and delusions seen in patients with psychosis of Parkinson’s disease. Although pimavanserin appears to have a pharmacologic mechanism that is different from other atypical antipsychotics, concern remained that the increased risk of death seen with antipsychotic use in elderly demented patients, and described in all approved antipsychotic labels, would also occur with pimavanserin. Pimavanserin bears the same boxed warning about the risk of death associated with antipsychotic use in elderly patients with dementia.