Ambrisentan is a propanoic acid??based, orally-available, endothelin receptor type A-receptor antagonist for the once-daily treatment of pulmonary arterial hypertension (PAH). It has >4000-fold selectivity for the type A receptor over type B receptor. Studies indicate that Ambrisentan has a low potential for drug interactions and at therapeutic concentrations does not inhibit UDP-glucuronosyltransferases or CYPs, or induce MDR protein 2 or P-gp. (1)

In contrast with other similar therapies, Ambrisentan has been shown to have a lower potential for increase of serum-level concentrations of aminotransferases. (2)