Volibris, known generically as ambrisentan, is a prescription medication used in the treatment of pulmonary arterial hypertension (PAH), a condition characterized by high blood pressure in the arteries that supply blood to the lungs. By blocking the effects of endothelin-1, a substance that causes blood vessels to narrow, Volibris helps relax and widen the blood vessels in the lungs. This action decreases the blood pressure within these vessels, improving symptoms such as shortness of breath and enhancing the ability of patients to exercise. Volibris is typically administered in tablet form and is part of a class of drugs known as endothelin receptor antagonists. It is important for patients to follow their healthcare provider's instructions closely when taking Volibris, as it can have significant interactions with other medications and is not suitable for everyone, including pregnant women due to potential risks to the fetus.