Safety and Efficacy of Inhaled Treprostinil in Patients With PAH

Eligible subjects must: * Be between 18 and 75 years of age at Screening (as defined by date of informed consent is signed), * Have a diagnosis of idiopathic or heritable PAH, PAH associated with connective tissue disease (CTD), PAH associated with repaired congenital systemic-to-pulmonary shunts (at least 1 year since repair) or human immunodeficiency virus (HIV) infection, or PAH associated with appetite suppressant or toxin use. * Be treatment naïve, or receiving background PAH therapies (e.g., phosphodiesterase type-5 inhibitor (PDE-5i)and / or endothelin receptor antagonist (ERA)) for less than 1 year prior to Screening. * Have a 6MWD at Baseline (as measured by the mean value of two 6MWT separated by at least 24 hours, but no more than 14 days) that is between 150 - 500 meters, inclusive.