title: Hemodynamic effects of Bosentan, an endothelin receptor antagonist, in patients with pulmonary hypertension.
abstract: BACKGROUND
  Few treatments are available for isolated pulmonary hypertension (PHT), which has a high morbidity and mortality. This trial was designed to assess the hemodynamic effects of bosentan, an endothelin receptor antagonist, in patients with PHT, in which local overproduction of endothelin-1 (ET-1) is thought to play a pathogenic role.
  
  
  RESULTS
  An open-label, dose-ranging study was performed in 7 female patients with primary PHT (n=5) or isolated PHT associated with limited scleroderma (n=2). Infusions of 50, 150, and 300 mg were administered at 2-hour intervals, and the hemodynamic responses were measured. Bosentan caused a dose-dependent fall in total pulmonary resistance (-20.0+/-11.0%, P=0.01) and mean pulmonary artery pressure (-10.6+/-11.0%, P>0.05). However, there was also a fall in the systemic vascular resistance (-26.2+/-12.8%, P<0.005) and mean arterial pressure (-19.8+/-14.4%, P<0.001). There was a slight increase in cardiac index (15+/-12%, P>0.05) and a dose-dependent rise in ET-1 but no significant change in other hemodynamic variables, gas exchange, or other vasoactive mediators.
  
  
  CONCLUSIONS
  Intravenous bosentan is a potent but nonselective pulmonary vasodilator at the doses tested, even in patients resistant to inhaled nitric oxide. Transient increases in plasma ET-1 were observed, consistent with a blockade of endothelial ET(B) receptors. Systemic hypotension and other significant events during the study indicate that its intravenous use in patients with severe PHT may be limited. Implications for future trial design and studies of chronic oral treatment are discussed.
authors.affiliation: Centre for Immunology, St Vincent's Hospital, Darlinghurst, USA. James.Williamson@health.wa.gov.au
authors.forename: D J
authors.initials: DJ
authors.lastname: Williamson
authors.forename: L L
authors.initials: LL
authors.lastname: Wallman
authors.forename: R
authors.initials: R
authors.lastname: Jones
authors.forename: A M
authors.initials: AM
authors.lastname: Keogh
authors.forename: F
authors.initials: F
authors.lastname: Scroope
authors.forename: R
authors.initials: R
authors.lastname: Penny
authors.forename: C
authors.initials: C
authors.lastname: Weber
authors.forename: P S
authors.initials: PS
authors.lastname: Macdonald
mesh_terms: D000328:Adult; D000368:Aged; D000959:Antihypertensive Agents / Q000008:administration & dosage* / Q000009:adverse effects; D000077300:Bosentan; D065128:Endothelin Receptor Antagonists; D005260:Female; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D006976:Hypertension, Pulmonary / Q000188:drug therapy* / Q000503:physiopathology*; D007262:Infusions, Intravenous; D008875:Middle Aged; D013449:Sulfonamides / Q000008:administration & dosage* / Q000009:adverse effects
chemical_list: D000959:Antihypertensive Agents; D065128:Endothelin Receptor Antagonists; D013449:Sulfonamides; D000077300:Bosentan