The U.S. Food and Drug Administration (FDA) has granted approval to MSD for an updated indication of its drug Winrevair. The approval allows the use of Winrevair by injection specifically for the treatment of adults diagnosed with pulmonary arterial hypertension (PAH). Pulmonary arterial hypertension is a progressive condition characterized by high blood pressure in the arteries of the lungs, which can lead to heart failure if left untreated.