Phase 2 Study of Ambrisentan for Liver Function Test Rescue in Pulmonary Arterial Hypertension

A Phase 2, Open-label, Multicenter Study Evaluating Ambrisentan in Subjects With Pulmonary Arterial Hypertension Who Have Previously Discontinued Endothelin Receptor Antagonist Therapy Due to Serum Aminotransferase Abnormalities

This Phase 2 study was to determine the incidence of increased serum aminotransferase concentrations (alanine aminotransferase [ALT] and/or aspartate aminotransferase [AST]), as well as the overall safety and tolerability of ambrisentan, in participants with pulmonary arterial hypertension (PAH), idiopathic PAH (IPAH), or familial PAH (FPAH) who had previously discontinued ERA therapy (bosentan or sitaxsentan) due to increased serum ALT or AST concentrations.

Summary of Inclusion Criteria:

• Males and Females between 12 and 75 years of age
• Current diagnosis of IPAH, FPAH, or PAH associated with collagen vascular disease, congenital systemic-to-pulmonary shunts, anorexigen use, HIV infection
• Must have previously discontinued bosentan or sitaxsentan therapy due to serum aminotransferase (ALT and/or AST) concentrations > 3 x ULN
• Must have normal (< 1 x ULN) serum ALT and AST concentrations at screening
• Six-minute Walk distance of at least 150 meters at screening
• If receiving sildenafil or a clinically approved prostanoid for PAH, must have been on stable therapy for at least 4 weeks prior to screening
• Subjects with a diagnosis of HIV must have stable disease status during the screening period