Background and objectives: The purpose of this study was to investigate 1) the beneficial effect of bosentan treatment (125 mg twice daily) on exercise capacity and echocardiographic variables and 2) the profiles and frequency of adverse events in Korean patients with World Health Organization (WHO) class III or IV pulmonary artery hypertension (PAH).
Subjects and methods: Twelve patients who received bosentan treatment were investigated in an open label manner. One patient was excluded in the final analyses due to a prohibited concomitant medication. A 6-minute walk test and echocardiography were performed at baseline and after 12 weeks of treatment.
Results: The administration of bosentan for 12 weeks resulted in a significant improvement in exercise capacity (measured with the 6-minute walking distance), WHO functional capacity, and in echocardiographic variables. Bosentan treatment was associated with a decrease in the maximal tricuspid regurgitation jet velocity {from 4.7 m/sec (95% confidence interval, 3.89-5.45) at baseline to 4.4 m/sec (95% confidence interval, 3.61-5.1) at 12 weeks, p=0.03} and systolic pulmonary arterial pressure {from 105 mmHg (95% confidence interval, 74.4-135.6) at baseline to 93 mmHg (95% confidence interval, 66.3-120.1) at 12 weeks, p=0.04}. Treatment with bosentan at a dose of 125 mg twice a day was not associated with life-threatening side effects, although a higher incidence of elevated liver enzymes compared to previous studies was noted.
Conclusion: Bosentan at a dose of 125 mg twice daily is considered a clinically optimal, safe dose and can be used as a valuable treatment option in Korean PAH patients with WHO functional capacity III or IV, though close monitoring of liver function is required.
Keywords: Adverse effects; Bosentan; Hypertension, pulmonary.