ACADIA Pharmaceuticals Inc. (NASDAQ:ACAD) stock was falling hard today on an article about its drug Nuplazid.

Nuplazid is a drug that was given approval by the U.S. Food and Drug Administration (FDA) and started being sold to customers in June 2016. The drug was given fast-track approval by the FDA, despite concerns that it may not actually help those suffering from Parkinson’s disease.

Now that it’s been two years since the release of ACADIA Pharmaceuticals Inc.’s Nuplazid, some think the approval wasn’t worth the risk. According to the Institute for Safe Medication Practices, there have been 244 deaths reported to the FDA in adverse event reports as of November.

Now those numbers are up to 700 deaths and ACADIA Pharmaceuticals Inc.’s Nuplazid is listed as a suspect in at least 500 of these reports. These numbers have some health officials concerned about the safety of the drug.

“This is almost unheard of, to have this many deaths reported,” Diana Zuckerman, President of the National Center for Health Research, told CNN. “You just don’t see this with most new drugs — you don’t see all these reports — so you have to take it seriously.”

ACADIA Pharmaceuticals Inc. isn’t taking these claims sitting down. The company argues that the mortality rate for patients on the drug is 12.4/100 per year. This isn’t as high as the mortality rate of 28.2/100 a year for patients with Parkinson’s disease. The company also says that the data doesn’t show that its drug is responsible for the deaths.

ACAD stock was down 25% as of Monday afternoon.

As of this writing, William White did not hold a position in any of the aforementioned securities.