Clozapine: Efficacy for Parkinson Disease psychosis in patients refractory to pimavanserin

Beatriz H. Thames, William G. Ondo

Research output: Contribution to journalArticlepeer-review


Pimavanserin is the only approved drug for Parkinson's disease psychosis (PDP) and is an increasingly used therapy where available. Clozapine has proven efficacy for PDP but is much less commonly used secondary to frequent blood tests to monitor for agranulocytopenia. We identified 27 patients with PDP (72 ± 7.3 years, 11 (41%) female), with an inadequate response to pimavanserin, who subsequently started clozapine. The final mean daily dose of clozapine was 49.5 mg [range 25–100] at night, and mean duration of follow-up was 17 months [range: 2–50 months]. Patients reported clozapine to be markedly effective in 11 (41%), moderately effective in 6 (22%), somewhat effective in 5 (18%). No patient reported that it was ineffective, but 5 (19%) had inadequate follow-up. Clozapine should be considered in pimavanserin refractory psychosis.

Original languageEnglish (US)
Article number105356
Pages (from-to)105356
JournalParkinsonism and Related Disorders
StatePublished - Apr 2023


  • Clozapine
  • Parkinson disease psychosis
  • Pimavanserin
  • Clozapine/therapeutic use
  • Humans
  • Parkinson Disease/complications
  • Female
  • Male
  • Psychotic Disorders/etiology
  • Antipsychotic Agents/therapeutic use

ASJC Scopus subject areas

  • Geriatrics and Gerontology
  • Clinical Neurology
  • Neurology


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