Additional effects of bosentan in patients with idiopathic pulmonary arterial hypertension already treated with high-dose epoprostenol

Background Combination therapy has been proposed in treatment algorithms for idiopathic pulmonary arterial hypertension (IPAH), so the additional effects of bosentan in IPAH patients already treated with high-dose cpoprostcnol (EPO) was evaluated in the present study. Methods and Results Bosentan (62.5 mg twice daily) was administered to 8 IPAH patients already being treated with high-dose EPO (average dose 99.6 ± 43.4 ng · kg^-1 · min^-1). Hemodynamics were assessed at baseline and at 2 days and then 1 year after the initiation of bosentan. Because a remarkable elevation of mixed venous oxygen saturation was observed at the initiation of bosentan, the dosage of EPO was reduced in 7 patients (from 99,6 ± 43.4 to 82.8 ± 31.3 ng · kg^-1 · min^l, p<0.05), There was a significant decrease from the baseline value for systolic pulmonary artery pressure (80.1 ± 19.3 to 66.8 ± 16.5 mmHg, p<0.05). These effects were maintained for I year without progression of PAH in 6 patients whose condition had been stabilized at baseline. Conclusions The additional use of bosentan for IPAH patients whose condition has been stabilized by high-dose EPO is safe and effective.