United Pharmaceuticals SAS

1. To continue to provide UT-15C medication to eligible subjects who were previously enrolled in the UT-15C TDE-PH-310 clinical trial protocol evaluating patients with pulmonary hypertension. 2. To evaluate the long-term safety of UT-15C in subjects taking UT-15C orally. 3. To evaluate the effect of continued UT-15C treatment on exercise tolerance in subjects who have been using UT-15C for a long time.

1. To evaluate the effect of oral UT-15C on the time to first clinical deterioration and exercise endurance in PAH subjects compared with the placebo group. 2. To evaluate the change in 6-minute walk distance from baseline at week 24 in PAH subjects compared with the placebo group.

The effects of UT-15C and placebo on exercise tolerance were compared in PAH subjects not receiving ERAs, PDE-5 inhibitors, prostacyclin therapy, or any concomitant therapy. The primary evaluation was the change in 6-minute walk distance in subjects receiving the 0.25 mg tablet at baseline and secondarily in the entire population.