By Colin Kellaher

The Food and Drug Administration has turned away a proposed nasal spray from Milestone Pharmaceuticals to treat a type of irregular heartbeat over concerns about how the drug is manufactured.

Milestone said Friday that the FDA has issued a so-called complete response letter for the drug, etripamil, indicating the agency won't approve the application in its current form and called for additional studies.

The Montreal biopharmaceutical company, which was seeking FDA approval of etripamil for the conversion of acute episodes of paroxysmal supraventricular tachycardia, or PSVT, to sinus rhythm in adults, said the agency didn't raise any concerns about the drug's clinical safety or efficacy data, but flagged two key chemistry, manufacturing and controls issues to be addressed.

Milestone said the FDA requested additional information on nitrosamine impurities based on new draft guidance issued after the company filed its new-drug application for etripamil.

The company said the FDA is also requiring an inspection at a facility that performs release testing for etripamil to ensure it is in compliance with current good manufacturing practices after the facility changed ownership during the agency's review of the application.

Milestone, which plans to market etripamil as Cardamyst, said it is confident it can collaborate with the FDA on addressing the issues in a resubmission.

Trading in shares of Milestone, which closed Thursday at $2.25, was halted premarket on Friday.

Write to Colin Kellaher at colin.kellaher@wsj.com

(END) Dow Jones Newswires

March 28, 2025 07:20 ET (11:20 GMT)

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