RAHWAY, N.J.--(BUSINESS WIRE)--Merck (NYSE: MRK), known as MSD outside the United States and Canada, today announced that the U.S. Food and Drug Administration (FDA) has approved an update to the U.S. product label based on the Phase 3 ZENITH trial for WINREVAIRâ"¢ (sotatercept-csrk) for injection, 45mg, 60mg. WINREVAIR, an activin signaling inhibitor, is now FDA-approved for the treatment of adults with pulmonary arterial hypertension (PAH, WHO Group 1 pulmonary hypertension) to improve exercise. ...