Milestone Pharmaceuticals Inc.’s (MIST) resubmitted New Drug Application, seeking approval, for its nasal spray CARDAMYST, awaits the FDA decision on December 13, 2025.CARDAMYST, a novel calcium channel blocker nasal spray, is proposed for the management of paroxysmal supraventricular tachycardia, a type of arrhythmia or abnormal heart rhythm.The FDA refused to approve CARDAMYST in March of this year, citing two chemistry, manufacturing and control (CMC) issues – one involving nitrosamine impurities and another concerning a facility that performs “release testing” for the drug.Paroxysmal supraventricular tachycardia (PSVT) is characterized by episodes of sudden onset, rapid heartbeats often exceeding 150 to 200 beats per minute. The heart rate spike is unpredictable and may last several hours. The rapid heart rate often causes disabling, severe palpitations, shortness of breath, chest discomfort, dizziness or lightheadedness, and distress, forcing patients to limit their daily activities.While there are approved treatments for PSVT, they all necessitate intervention in a monitored, acute care environment, like an emergency department. Currently, there are no FDA-approved therapies for the acute termination of PSVT in an at-home setting.CARDAMYST is designed as a self-administered rapid-response therapy for patients, thereby bypassing the need for immediate medical oversight.If approved, the drug could achieve peak sales of over $700 million, according to analysts at HC Wainwright.MIST closed Wednesday’s (November 26, 2025) trading at $2.61, up 5.67%.