Long-term ambrisentan therapy for the treatment of pulmonary arterial hypertension

J Am Coll Cardiol. 2009 Nov 17;54(21):1971-81. doi: 10.1016/j.jacc.2009.07.033.


Objectives: This study evaluated the safety and efficacy of ambrisentan for a period of 2 years in patients with pulmonary arterial hypertension (PAH).

Background: Ambrisentan is an oral, once-daily endothelin receptor antagonist that is selective for the endothelin type A receptor. The ARIES-1 (Ambrisentan in Pulmonary Arterial Hypertension, Randomized, Double-Blind, Placebo-Controlled, Multicenter, Efficacy Studies) and ARIES-2 trials were the pivotal 12-week, placebo-controlled studies that led to the regulatory approval of ambrisentan (5 and 10 mg) for the treatment of PAH.

Methods: In the ARIES-1 and -2 studies, and the subsequent long-term extension protocol, the ARIES-E study, 383 patients received ambrisentan (2.5, 5, or 10 mg). Efficacy and safety assessments are presented from the time of the first dose of ambrisentan for all patients with post-baseline data.

Results: After 2 years of ambrisentan exposure, the mean change from baseline in 6-min walk distance was improved for the 5-mg (+23 m; 95% confidence interval: 9 to 38 m) and 10-mg (+28 m; 95% confidence interval: 11 to 45 m) groups. Estimates of survival and freedom from clinical worsening for the combined dose group were 94% and 83%, respectively, at 1 year and 88% and 72%, respectively, at 2 years. The annualized risk of aminotransferase abnormalities >3x the upper limit of normal was approximately 2% per year; most of these events were mild and did not lead to discontinuation of drug.

Conclusions: Two years of ambrisentan treatment was associated with sustained improvements in exercise capacity and a low risk of clinical worsening and death in patients with PAH. Ambrisentan was generally well tolerated and had a low risk of aminotransferase abnormalities over the 2-year study period. (A Long Term Study of Ambrisentan in Pulmonary Arterial Hypertension Subjects Having Completed AMB-320 or AMB-321; NCT00578786).

Publication types

  • Comparative Study
  • Multicenter Study
  • Randomized Controlled Trial

MeSH terms

  • Administration, Oral
  • Dose-Response Relationship, Drug
  • Double-Blind Method
  • Exercise Tolerance / drug effects
  • Female
  • Follow-Up Studies
  • Humans
  • Hypertension, Pulmonary / drug therapy*
  • Hypertension, Pulmonary / mortality
  • Hypertension, Pulmonary / physiopathology
  • Male
  • Middle Aged
  • Phenylpropionates / administration & dosage*
  • Pulmonary Wedge Pressure / drug effects
  • Pyridazines / administration & dosage*
  • Survival Rate / trends
  • Time Factors
  • Treatment Outcome


  • Phenylpropionates
  • Pyridazines
  • ambrisentan

Associated data

  • ClinicalTrials.gov/NCT00578786