Milestone Pharmaceuticals (MIST) said Friday that the US Food and Drug Administration has approved its Cardamyst nasal spray for the conversion of acute episodes of paroxysmal supraventricular tachycardia to sinus rhythm in adults.

This approval means 2 million Americans with paroxysmal supraventricular tachycardia can have access to the potentially self-administered treatment, the company said.

The drug will be available in pharmacies in Q1 2026.

The approval followed a clinical trial program involving 1,800 participants and 2,000 episodes of paroxysmal supraventricular tachycardia, which showed benefits for 73% of patients after 60 minutes, the company said.

Paroxysmal supraventricular tachycardia results in episodes of fast heart rates, the company said.

Shares of the company were down 18% in recent premarket activity.