Shares in Acadia Pharmaceuticals have dropped by 22% after the news that the US Food and Drugs Administration (FDA) has begun a review of Parkinson’s drug Nuplazid.

This follows a recent article by CNN that highlighted a report by the Institute for Safe Medication Practices, which claimed that 244 deaths connected to Nuplazid had been reported to the FDA between the drug’s launch and March 2017. The article claims that some experts involved in the approval of the drug voiced concerns about possible side-effects.

Nuplazid is the only medication approved in the US to treat hallucinations and delusions associated with Parkinson’s disease psychosis. ACADIA has denied that the drug is responsible for the deaths.

In a statement, Acadia said: “We are confident in Nuplazid’s efficacy and positive benefit/risk profile and stand firmly behind it. Acadia’s top priority has been, and continues to be, patient safety. Nuplazid was approved and launched in 2016.

“As the manufacturer of a newly launched drug, we are routinely in contact with the FDA regarding requests for additional information on Nuplazid, including post-marketing safety surveillance information as part of the FDA’s ongoing safety monitoring.”

The FDA has been conducting a review of the available information about the drug for several weeks after FDA Commissioner Scott Gottlieb told members of Congress that the agency would ‘take another look’ at it. However, the FDA has stated that its evaluation does not mean that it has determined the medicine to have a new risk or that patients should stop taking it. The agency has a duty to investigate reports of ‘adverse events’ but this does not mean that the drug being investigated is the cause.

In a statement, the FDA said: “The FDA continues to monitor adverse events reported with Nuplazid that are submitted to the FDA Adverse Event Reporting System.

“We have noted that the cases typically involve geriatric patients with advanced-stage Parkinson’s disease, as well as numerous medical conditions, who are frequently taking concomitant medications with risks for serious adverse events, including death.

“Based on these data, the FDA has, at this time, not identified a specific safety issue that is not already adequately described in the product labelling.”

Psychosis is a common symptom of Parkison’s that affects 40% of patients.  Nuplazid was approved as a ‘breakthrough therapy’, meaning that it treats a serious or life-threatening condition more effectively than other drugs on the market and subsequently can gain approval faster. The drug gained approval based on data from a six-week study involving 200 subjects.

Acadia has recently announced that clinical experience data for Nuplazid will be presented at the 2018 American Academy of Neurology Annual Meeting.