Efficacy Study of Ambrisentan in Chinese Patients With Pulmonary Arterial Hypertension (PAH)

Pulmonary arterial hypertension (PAH) consists of a group of progressive and incurable diseases of the pulmonary vasculature. These are characterised by profound vasoconstriction and abnormal proliferation of smooth muscle cells in the walls of the pulmonary arteries, which leads to a progressive increase in pulmonary vascular resistance (PVR) and sustained elevations in pulmonary artery pressure (PAP). A variety of drug classes have been used to treat PAH but no single compound has yet been shown to be effective in treating all patients with the disease. Three widely used treatment options are calcium channel blockers (CCBs), diuretics and anticoagulants but all have varying responses.There is a lack of clinical data on ambrisentan among the Chinese population,Ambrisentan is conditionally approved for the treatment of PAH in China.A clinical trial with a minimum of 100 patients in the ambrisentan arm was requested by SFDA.Several PAH medications have been approved in China, so a placebo-controlled study is not ethically appropriate while an active control non-inferiority design is unfeasible due to sample size requirements and inconsistency in indications.