Marinus Pharmaceuticals of Radnor saw its stock price plunge by more than 80 percent Monday because of a setback in an experimental seizure drug, writes John George for Philadelphia Business Journal.

The company had a drug candidate in phase 3 testing that targets refractory status epilepticus, a rare condition that causes life-threatening, prolonged seizures in epilepsy patients.

But during trials, the drug candidate did not meet pre-defined criteria, and the study was stopped early.

An independent data monitoring committee recommended that Marinus continue late-stage testing of the drug candidate.

The recommendation raised questions about the effectiveness of the treatment, which uses an intravenous ganaxolone medicine. 

Ganaxolone is also the active ingredient in Ztalmy, the company’s flagship seizure disorder medicine.

Shares of Marinus closed at $1.30 per share following the news, down 83 percent from Friday’s closing price of $7.52. 

“While we are disappointed that [the phase 3 clinical trial] did not meet the early stopping criteria, we will only be able to determine the trial’s outcome once we unblind and analyze the full data set,” said Dr. Scott Braunstein, chairman and CEO of Marinus in a statement.

Read more about further drug studies and other treatments in development at Marinus Pharmaceuticals in the Philadelphia Business Journal.

Marinus CEO Scott Braunstein in an interview from three years ago shares his outlook for the company