Guidance for switching from off-label antipsychotics to pimavanserin for Parkinson’s disease psychosis: an expert consensus

Kevin J. Black, Henry Nasrallah, Stuart Isaacson, Mark Stacy, Rajesh Pahwa, Charles H. Adler, Gustavo Alva, Jeffrey W. Cooney, Daniel Kremens, Matthew A. Menza, Jonathan M. Meyer, Ashwin A. Patkar, Tanya Simuni, Debbi A. Morrissette, Stephen M. Stahl
  • CNS Spectrums, December 2018, Cambridge University Press
  • DOI: 10.1017/s1092852918001359

How to switch to pimavanserin from an older antipsychotic for psychosis in Parkinson's disease

What is it about?

In this report, movement disorders experts, neuropsychiatrists and clinical pharmacologists provide suggestions on how doctors can switch a patient from a dopamine-blocking antipsychotic to the novel medication, pimavanserin, to treat hallucinations or delusions in people with Parkinson disease. A read-only, full-text version of the article is provided by the publisher at the following URL: (capital letters are needed for the last 6 characters there).

Why is it important?

When a new medication becomes available on the market, it generally has been tested rigorously only in the absence of competing drugs. This is appropriate, but it means that physicians have little solid information on how to switch someone to the new medication from another drug that is not working or is causing side effects. That's the situation physicians found themselves in when the novel serotonin 2A inverse agonist, pimavanserin, became available for treating psychosis in Parkinson disease. Patients who were doing fine on another treatment were OK, but those whose symptoms were not adequately controlled, or who were having side effects on the previous drug, now had a new option. But did one stop cold turkey, or gradually stop the old drug after starting pimavanserin? Either choice had potential advantages and risks. In the absence of controlled trial information, a bunch of folks with relevant expertise wrote this article giving our recommendations on how to manage this situation. Note, nearly all the authors have had income from Acadia Pharmaceuticals via clinical trials, advisory boards or a speakers bureau.


Dr Kevin J. Black
Washington University in St. Louis

Consensus in a large group of expert, not to say opinionated, people is never instantaneous. But overall, working with this diverse group to address what we saw as a real clinical need was a real pleasure. (Dealing with the process of turning a draft into the published article? Less so.)

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The following have contributed to this page: Dr Kevin J. Black