Bosentan is a medication primarily used to treat the symptoms of pulmonary arterial hypertension (PAH), a progressive condition characterized by high blood pressure in the arteries of the lungs. PAH occurs when the blood vessels in the lungs become narrowed or blocked, making it difficult for the heart to pump blood efficiently. Bosentan belongs to a class of drugs known as endothelin receptor antagonists (ERAs), which work by blocking the effects of endothelin-1, a substance that causes blood vessels to constrict. By inhibiting endothelin-1, bosentan helps dilate the pulmonary arteries, reducing resistance in the blood vessels and lowering blood pressure. This improved circulation relieves strain on the heart, enhances oxygen delivery, and helps alleviate PAH symptoms such as shortness of breath, fatigue, dizziness, and chest pain.

In addition to improving symptoms, bosentan is also effective in slowing the progression of PAH and enhancing exercise capacity, thereby improving patients' overall quality of life. It is often prescribed for patients with WHO Functional Class II-IV PAH, where symptoms range from mild to severe limitations in physical activity. However, due to its potential to cause liver toxicity, regular liver function monitoring is required during treatment. Bosentan is also known to interact with certain medications and can reduce the effectiveness of hormonal contraceptives, necessitating additional precautions for women of childbearing potential. Despite these considerations, bosentan remains an essential therapy in PAH management, offering significant benefits in terms of symptom control, exercise tolerance, and delaying disease progression when used under proper medical supervision.