Milestone Pharmaceuticals' CARDAMYST Nasal Spray Gains Express Scripts Formulary Access
Express Scripts has added Milestone Pharmaceuticals' CARDAMYST nasal spray to its national formularies, improving access to the first FDA-approved self-administered treatment for PSVT in 30 years. The drug was approved in December 2025 and clinical studies show it converts PSVT episodes twice as likely and three times faster than placebo. The company has also submitted a marketing application to European regulators.
Milestone Pharmaceuticals Inc. announced that Express Scripts, one of the nation's largest pharmacy benefit managers, has added CARDAMYST™ (etripamil) nasal spray to its commercial national formularies, effective March 27, 2026. This inclusion makes CARDAMYST broadly accessible and affordable for their commercially insured lives across the United States, representing the first contracted formulary acceptance of CARDAMYST by a major payor.
CARDAMYST is the first and only self-administered nasal spray approved by the U.S. Food and Drug Administration (FDA) for the conversion of acute symptomatic episodes of paroxysmal supraventricular tachycardia (PSVT) to sinus rhythm in adults. The FDA approved the product on December 12, 2025, marking the first new treatment for this condition in 30 years, benefiting over two million Americans. The product became available in retail pharmacies in January 2026.
Clinical studies indicated that participants using CARDAMYST were twice as likely to convert PSVT to sinus rhythm and did so over three times faster compared to a placebo. The successful Phase 3 RAPID trial, published in The Lancet in 2023, achieved its primary endpoint with 64% of those who self-administered CARDAMYST converting from supraventricular tachycardia to sinus rhythm within 30 minutes compared to 31% on placebo. At one hour, the benefit was demonstrated in 73% of participants.
The FDA approval of CARDAMYST is supported by a robust clinical trial program based on safety data from more than 1,800 participants and more than 2,000 episodes of PSVT. The most frequent adverse events occurring in ≥5% of participants in randomized clinical trials were mild-to-moderate and transient in nature, including local-site nasal discomfort, nasal congestion, rhinorrhea, throat irritation, and epistaxis. Less than 2% of trial participants discontinued therapy due to adverse events.
Currently, etripamil is in Phase 2 development for treatment of PSVT in pediatric patients and Phase 3 development for control of acute atrial fibrillation with rapid ventricular rate (AFib-RVR) in adults. The company has also submitted a marketing authorization application to the European Medicines Agency for the same treatment, with a decision expected by mid-2027.
An estimated two million people in the United States are currently diagnosed with PSVT, which is characterized by episodes of sudden onset rapid heartbeats often exceeding 150 to 200 beats per minute. 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.