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 epoprostenol (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(-1), 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 1 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.