[{"from": "human", "value": "Provide a brief overview 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 bioavailable, selective antagonist of the endothelin type-A (ETA) receptor that may be used for the treatment of pulmonary arterial hypertension (PAH). Upon administration, ambrisentan targets and binds to ETA receptor, which prevents the binding of endothelin-1 (ET-1) to the ETA receptor and ET-1/ETA-mediated vasoconstriction and cell proliferation. This may lead to vasodilation. ET-1 concentrations are increased in plasma as well as lung tissue in PAH, and ET-1 may play a key role in the pathogenesis of PAH."}]