Long-term trial of bosentan monotherapy for pulmonary arterial hypertension in Japanese patients.

OBJECTIVE

To determine the efficacy and safety of long-term bosentan monotherapy in Japanese patients with pulmonary arterial hypertension (PAH).

RESEARCH DESIGN AND METHODS

The present study was an extension to a 12-week open-label trial of bosentan in which 21 Japanese patients with PAH received bosentan, 125 mg twice daily. Of the 21 patients in the initial trial, 20 elected to participate in the long-term study and to continue to receive bosentan for up to 3 years.

MAIN OUTCOME MEASURES

The primary efficacy measure was comparison of World Health Organization (WHO) functional class for pulmonary arterial hypertension following long-term (> 2.5 years) therapy compared with baseline (prior to initiation of bosentan). Secondary outcomes included time from initiation of bosentan therapy to clinical worsening and safety assessments.

RESULTS

Bosentan treatment was continued for a median of 2.7 years (range 0.4-3.0 years); 12 patients received bosentan monotherapy for at least 2.5 years. Following long-term treatment, improvement of WHO functional class compared with baseline was observed in 9/12 patients (75.0%) and in 3/12 patients (25.0%) the functional class remained stable; no patient experienced a worsening of WHO functional class compared with baseline. Overall, long-term treatment with bosentan was well tolerated.

CONCLUSIONS

Long-term treatment with bosentan is well tolerated and is associated with sustained clinical improvement in Japanese patients with PAH. Bosentan, therefore, represents a valuable treatment option for Japanese patients with this devastating disease.