Additional Effects of Bosentan in Patients With Idiopathic Pulmonary Arterial Hypertension Already Treated With High-Dose Epoprostenol

Abstract

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. (Circ J 2008; 72: 1142 - 1146)