Open-Label Extension Study of UT-15C in Subjects With Pulmonary Arterial Hypertension- A Long-Term Follow-Up to Protocol TDE-PH-310

This study is an international, multi-center, open-label study designed to provide oral treprostinil (UT-15C) to eligible subjects with pulmonary arterial hypertension who have completed the TDE-PH-310 study. The purpose of this study is to assess the long-term safety of UT-15C and to assess the effects of long-term treatment with UT-15C on exercise capacity.