PULMOTEN 62.5 mg is a prescription medication containing Bosentan, an endothelin receptor antagonist used in the treatment of Pulmonary Arterial Hypertension (PAH)—a rare, progressive condition characterized by high blood pressure in the arteries of the lungs. Bosentan works by blocking endothelin-1, a substance that narrows blood vessels, helping to relax pulmonary arteries and improve blood flow. This reduces the heart's workload and enhances exercise capacity and quality of life.