Bosentan for pulmonary hypertension and other pulmonary diseases: emerging evidence

Endothelin-1 is a potent vasoconstrictor and mitogen that is primarily synthesized and released from vascular endothelial cells. Bosentan is a dual endothelin-receptor antagonist that initially received approval for treatment of WHO group I pulmonary arterial hypertension (PAH) for patients in functional classes III and IV. Analysis of a study conducted in functional class II patients (Endothelin Antagonist Trial in Mildly Symptomatic PAH Patients [EARLY] trial) suggest its efficacy for these less symptomatic patients. In addition, bosentan has demonstrated efficacy in patients with congenital heart disease and Eisenmengers syndrome with right to left shunting and in HIV-related PAH. Studies of bosentan in inoperable or residual chronic thromboembolic pulmonary hypertension suggest possible efficacy. Bosentan appears promising in patients with idiopathic pulmonary fibrosis who do not have pulmonary hypertension. Combinations of bosentan with other PAH therapies such as iloprost and sildenafil may have incremental benefit over monotherapy.