Acute hemodynamic effects of single oral dose of bosentan in patients with pulmonary arterial hypertension related to congenital heart disease.

Background: Endothelin-1 is a potent endogenous vasoconstrictor and an important remodeling factor in the pathogenesis of pulmonary arterial hypertension (PAH). Bosentan, a nonselective and active dual endothelin receptor antagonist, is used as a vasodilator in treatment of such patients. This study aimed to evaluate acute response to a single oral dose of bosentan as a vasodilator agent in comparison with nasal oxygen (O2) in patients with PAH related to congenital heart disease (CHD).

Materials And Methods: We enrolled 20 patients with PAH-CHD, with a mean age of 5.45 ± 4.5 years. Hemodynamic variables were measured at baseline state, after administration of nasal O2 (5 L/min) for 20 minutes, and then when hemodynamic variables returned to the baseline, the measurements were repeated for the third time 3 hours after administration of a single oral dose of bosentan (2 mg/kg).

Results: Mean pulmonary vascular resistance was 9.92 ± 2.97 Wood units · m(2) at baseline and was lowered by O2 to 6.17 ± 2.71 Wood units · m(2) (P = .001) and by bosentan to 5.90 ± 2.69 Wood units · m(2) (P = .0001). Mean pulmonary artery pressure was 71.2 ± 15.4 mm Hg at baseline and was reduced to 62.6 ± 15.2 mm Hg (P = .001) by O2 and to 61.6 ± 14.8 mm Hg (P = .0003) by bosentan.

Conclusion: A single oral dose of bosentan has the same acute vasodilatory effect on the pulmonary vascular bed as nasal O2 in patients with PAH related to CHD. Such patients may benefit from long-term therapy with this novel medication.