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Paroxysmal supraventricular tachycardia, known as PSVT, is a heart rhythm disorder in which the heart suddenly races, sometimes past 150 beats per minute, for anywhere from a few minutes to several hours. An estimated two million people in the United States live with the condition, and for a long time the only real fix during an episode was a trip to the emergency room, where clinicians use physical maneuvers or intravenous medication to reset the heart’s rhythm. That works, but it is costly, disruptive, and often frightening for someone who never knows when the next episode will hit.
Over the past several years, the cardiovascular field has started shifting some of that burden away from the hospital and into the patient’s own hands. Self administered nasal sprays, wearable monitors, and at home diagnostics have all gained ground as ways to treat acute cardiac events without an ambulance ride. For a small biopharmaceutical company built around a single therapy, expanding that therapy beyond its home market is one of the clearest signs that the underlying science travels, and it can also unlock cash the company would not otherwise see for years.
Milestone Pharmaceuticals Inc. (NASDAQ: MIST) has spent years developing etripamil, a calcium channel blocker formulated as a nasal spray that patients can use on their own to stop a PSVT episode. In the United States the drug is sold under the brand name CARDAMYST, and it earned approval from the Food and Drug Administration in December 2025 as the first self administered option for adults with the condition.
Milestone announced today that China’s National Medical Products Administration, or NMPA, had approved etripamil nasal spray for PSVT, marking the first time the drug has been cleared anywhere outside the United States. The company’s partner in Greater China, Everest Medicines Limited (HKEX: 1952.HK), will lead commercialization across Mainland China, Hong Kong, Macau, and Taiwan, an area home to an estimated 3 million to 6 million people living with PSVT. The approval was supported by the global Phase 3 RAPID study along with a separate Phase 3 study conducted in China, which found etripamil significantly more effective than placebo at converting PSVT back to a normal heart rhythm within 30 minutes of treatment.
The China clearance triggers an immediate $2.0 million payment to Milestone, and under its licensing agreement the company remains eligible for up to $98.0 million in additional commercial and development milestones, plus royalties reaching as high as 18% on future etripamil sales in the region. For a company whose public story has centered almost entirely on the American launch of CARDAMYST, a paying customer base on the other side of the world changes the shape of that story. It is one thing to have a drug approved in a single country. It is another to prove a regulator in the world’s most populous nation reached the same conclusion, using its own clinical data, about the same medicine.
None of this guarantees how quickly Everest Medicines can build out prescribing and distribution across such a large and varied market, and the bulk of the $98.0 million in potential milestones still depends on commercial performance that has not yet happened. What the NMPA decision does confirm is that etripamil’s clinical profile holds up under a second, independent regulatory review, and that Milestone now has a funded partner actively working to bring the therapy to millions of patients who previously had no self-administered alternative to a hospital visit.
