A Study With BPS-314d-MR-PAH-303 in Participants With Pulmonary Arterial Hypertension

Participants will sign an informed consent to continue treatment for pulmonary arterial hypertension (PAH) with esuberaprost sodium tablets in this OLE study. At the Enrollment Visit for this OLE study, participants will begin a blinded transition from the BPS-314d-MR-PAH-302 double-blind study to this study over 4 weeks. The first dose for all participants in this OLE study will be 2 tablets. During this blinded transition, those participants on active study drug in the BPS-314d-MR-PAH-302 study will continue with blinded active study drug 4-times daily (QID); those participants who were on placebo study drug will receive 1 active tablet and 1 placebo tablet QID (blinded) during the first 2 weeks and increase to 2 active tablets QID (blinded) thereafter. After the first dose, the Investigator may adjust the dose as medically warranted. The maximum dose for this study is 30 microgram (μg) QID with a minimum accepted dose as 15 μg QID. For the first 4 weeks, contact with the participant should occur weekly to ensure up-titration to the fixed dose is tolerated and assess adverse events (AEs). Participants will return to the clinic at Week 4 to be supplied open-label esuberaprost sodium tablets and complete protocol specified procedures. At the Week 4 Visit, participants will be dosed with two 15 μg tablets (30 μg total), administered orally QID (provided the target dose is tolerated), or follow the Investigator's (or designee's) directions if adjustment is needed. Following the Week 4 Visit, each participant will return to the clinic at Months 3, 6, 9, and 12, and quarterly thereafter for assessments. This study is expected to continue until the first of any of the following are reached: the study drug is commercially available, the Sponsor discontinues the study, or the Sponsor offers enrollment in another study (estimated to be up to 2 years). At the conclusion of the study or if a participant discontinues the study prematurely, participants will return to the clinic for an End-of-Study (EOS) Visit. Participants will be provided instructions about down titration off esuberaprost sodium tablets by the Investigator.