US regulators have issued a green light for Acadia Pharmaceuticals’ atypical antipsychotic Nuplazid, offering patients the potential to access the first treatment for Parkinson's disease psychosis (PDP).

The National Parkinson’s Foundation estimates that one million people in the US suffer from disease, and that an around 40 percent experience related psychosis, characterised by hallucinations and delusions, a diminished quality of life, and significant caregiver burden.

Nuplazid (pimavanserin) is the first in a new class of medicines called selective serotonin inverse agonists (SSIA targets),  which target 5-HT2A receptors, thought to play an important role in the development of the condition.

Approval came after findings of a Lancet-published Phase III clinical trial, in which the drug was associated with a -5.79 decrease in the Parkinson’s disease-adapted scale for positive assessment of symptoms (SAPS-PD) versus -2.73 for placebo.

Overall, it was also found to be well-tolerated, with no significant safety concerns or worsening of motor functions, although 10 patients from the group given Nuplazid discontinued the trial because of an adverse event (four due to psychotic disorder of hallucination) compared to two in the placebo arm.

“Today’s approval of Nuplazid represents a major paradigm shift in the treatment of Parkinson’s disease psychosis,” said Michael Okun, edical Director of The National Parkinson Foundation. “Through its novel and selective mechanism of action, Nuplazid is a breakthrough treatment that works in a whole new way - treating hallucinations and delusions without blocking dopamine receptors and, therefore, not impairing motor function in Parkinson’s psychosis patients.”