OBJECTIVE: To review the pharmacology, pharmacokinetics, efficacy, safety, and 
place in therapy of pimavanserin for the treatment of hallucinations and 
delusions of Parkinson's disease psychosis (PDP).
DATA SOURCES: A comprehensive PubMed search (1966 to January 2017) was conducted 
using the search terms Parkinson's disease psychosis, hallucinations, delusions, 
pimavanserin, and ACP-103. Additional data were obtained from references of 
identified articles, governmental sources, manufacturer product labeling and 
website, and Clinicaltrials.gov.
STUDY SELECTION AND DATA EXTRACTION: All English-language trials evaluating 
pimavanserin in PDP were included. Data from review articles were included if 
relevant to clinical practice. One phase II and 3 phase III trials are 
discussed.
DATA SYNTHESIS: Pimavanserin was approved in April 2016 for the treatment of 
delusions and hallucinations of PDP. One phase II and 2 phase III trials 
reported no difference for primary outcomes when pimavanserin was compared with 
placebo. The pivotal phase III ACP-103-020 trial adapted a scale to target more 
specific symptoms prevalent in PDP and showed that least-squares mean 
differences of the total PD-adapted Scale for the Assessment of Positive 
Symptoms score were significantly improved for pimavanserin-treated patients as 
compared with placebo-treated patients (difference = -3.06; 95% CI [-4.91 to 
-1.20]; P = 0.0014]). Pimavanserin's adverse effect profile includes urinary 
tract infections, falls, peripheral edema, hallucinations, confusion, nausea, 
and headaches.
CONCLUSION: Pimavanserin is a novel 5-HT2A inverse agonist that has shown 
promising results for managing hallucinations and delusions in patients with PDP 
without worsening motor effects or orthostasis. Yet its high cost and specialty 
pharmacy access may limit use in clinical practice.