Dear Editor, Parkinson's disease (PD) is characterized by gradual neural degeneration in the substantia nigra, a region of the midbrain, which results in motor abnormalities, e.g., bradykinesia, resting tremor, cogwheel rigidity, and postural instability. The neuropsychiatric symptoms can include depression, dementia, apathy, hallucinations, and delusions (1). Some 20% to 50% of PD patients develop psychosis, with hallucinations and/ or delusions being the most prevalent symptoms (2). Pimavanserin (Nuplazid; Acadia Pharmaceuticals Inc., San Diego, CA, USA) is a 5-HT2A receptor antagonist. It differs from other antipsychotic medications commonly used in Parkinson’s disease psychosis (PDP) due to the selectivity for 5-HT2 receptors, a lower binding-affinity at the serotonin-2C receptor and the sigma 1 receptor, and because it spares dopamine post-synaptic receptors. It was approved by the US Federal Drug Administration in 2016 to treat Parkinson’s-related delusions and hallucinations (1). Development of the drug as a treatment for schizophrenia was attracted researchers and pimavanserin is currently in phase 3 clinical trials for the treatment of schizophrenia (2,3).
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