An Open-Label Extension Trial of UT-15C SR in Subjects With Pulmonary Arterial Hypertension

This is an open-label study. Each subject's visit schedule will allow assessments after
defined periods of exposure to UT-15C SR (3, 6, 12, 24 and 36 months total exposure). The
study will continue with yearly visits beyond 36 months until either UT-15C SR is approved by
the appropriate regulatory authorities or the study is discontinued by the sponsor.
Therefore, the actual date of each visit will be determined by the date on which the subject
first received UT-15C SR (e.g., the date of study drug initiation in TDE-PH- 301, TDE-PH-302,
or TDE-PH-308 for subjects who were randomized to active therapy in those trials,and the date
of UT-15C SR initiation in this study for subjects who were randomized to placebo in the
previous controlled trial). Note that the TDE-PH-202, TDE-PH-203, TDE-PH-205 studies are
open-label design and therefore will follow the regimen for subjects receiving UT-15C SR.

Participation in study TDE-PH-202, TDE-PH-203, TDE-PH-205, TDE-PH-301,
TDE-PH-302,TDE-PH-308 or any additional UT-15C SR clinical protocol is required. Subjects
must complete all assessments in one of these studies to be eligible.