The FDA’s Psychopharmacologic Drugs Advisory Committee has recommended the approval of pimavanserin (Nuplazid, Acadia Pharmaceuticals) for the treatment of psychosis related to Parkinson’s disease (PD). The panel voted 12 to 2 that the drug’s benefits outweigh its risks.
Currently, no drugs are approved in the U.S. specifically for PD psychosis, and common antipsychotic treatments, including quetiapine (Seroquel, AstraZeneca), clozapine (Clozaril, Novartis), risperidone (Risperdal, Janssen), and olanzapine (Zyprexa, Eli Lilly), are used for these patients. However, these drugs have limited effectiveness for PD psychosis, and they also carry a boxed warning regarding an increased mortality risk in elderly patients.
A new drug application for pimavanserin was submitted to the FDA for the treatment of PD psychosis in September 2015.
Pimavanserin is a selective inverse agonist of the 5-hydroxytryptamine 2A (5-HT2A) receptor. The drug preferentially targets the 5-HT2A receptor subtype, has low activity at the 5-HT2C receptor, and shows no measurable activity at other serotonergic, dopaminergic, histaminergic, adrenergic, or muscarinic receptors.
The efficacy of pimavanserin for the treatment of PD psychosis was established in a pivotal phase 3 outpatient study in which pimavanserin 34 mg or placebo was administered once daily for up to six weeks. A total of 176 patients completed the final visit.
In the primary efficacy analysis, the change from baseline in the total Scale for the Assessment of Positive Symptoms in Parkinson’s Disease (SAPS-PD) score was compared between the two treatment arms. At week 6, an improvement of 5.79 points in the SAPS-PD total score was observed in the pimavanserin arm compared with a 2.73-point improvement in the placebo arm (P = 0.001).
The most frequent treatment-emergent adverse events experienced by subjects in the pimavanserin group compared with the placebo group were fall (6.4% vs. 9.1%, respectively), urinary tract infection (7.4% vs. 6.9%), confusional state (5.9% vs. 2.6%), and nausea (6.9% vs. 4.3%).