[{"from": "human", "value": "Provide a description of this molecule. [C][C][=C][C][=Branch2][Ring2][Branch2][=N][C][=Branch1][Ring2][=N][Ring1][=Branch1][O][C@H1][Branch1][=Branch1][C][=Branch1][C][=O][O][C][Branch1][=Branch2][C][=C][C][=C][C][=C][Ring1][=Branch1][Branch1][=Branch2][C][=C][C][=C][C][=C][Ring1][=Branch1][O][C][C]"}, {"from": "gpt", "value": "The molecule is an orally active selective type A endothelin receptor antagonist indicated for the treatment of pulmonary arterial hypertension. It is approved in Europe, Canada and the United States for use as a single agent to improve exercise ability and delay clinical worsening. In addition, it is approved in the United States for use in combination with tadalafil to reduce the risks of disease progression, hospitalization and to improve exercise ability. Studies establishing the efficacy of Ambrisentan included patients with both idiopathic or heritable pulmonary arterial hypertension and those with pulmonary arterial hypertension associated with connective tissue diseases. Patients studied displayed symptoms and etiologies predominantly of WHO Functional Class II-III. As an endothelin receptor antagonist, Ambrisentan prevents endogenous endothelin peptide from constricting the muscles in blood vessels, allowing them to relax and permit a reduction in blood pressure."}]