The primary purpose of the study is to evaluate the safety and tolerability of the long-term use of TPIP in participants with PAH from studies INS1009-201 (NCT04791514), INS1009-202 (NCT05147805) and other lead-in studies of TPIP in participants with PAH.

Inclusion Criteria:

• Male and female participants who completed end of treatment study visit in Study INS1009-201, INS1009-202, or any other lead-in PAH TPIP study. Participants for whom the OLE study was not available at the time of their completion of the lead-in study are eligible for enrolment within one year of their lead-in end of treatment visit.
• Complete baseline screening assessments to confirm eligibility to participate if more than 30 days have elapsed since the end of the study visit in Study INS1009-201, INS1009-202, or any other lead-in PAH TPIP study.

Exclusion Criteria:

• Initiation of parenteral administration of prostacyclin analogues (eg, TRE, epoprostenol) since the completion of studies INS1009-201, INS1009-202 or other TPIP studies. Initiation of inhaled prostacyclin analogues (eg, TRE [Tyvaso] or iloprost) and oral prostacyclin analogues (eg, TRE [Orenitram]) or receptor agonists (eg, selexipag) are permitted if stopped 24 hours prior to the start of study drug administration.
• Any new ventricular or supraventricular tachyarrhythmia except for paroxysmal atrial fibrillation and any new symptomatic bradycardia.
• New-onset of heart disease including left ventricular ejection fraction (LVEF) ≤40% or clinically significant valvular, constrictive, or symptomatic atherosclerotic heart disease (eg, stable angina, myocardial infarction, etc).
• New evidence of thromboembolic disease as assessed by ventilation/perfusion (VQ) scan, pulmonary angiography, or pulmonary computed tomography (CT) scan.
• Active and current symptomatic coronavirus disease 2019 (COVID-19) or previous severe disease and/or hospitalization due to COVID-19.
• Interval organ transplantation.
• New active liver disease or hepatic dysfunction.
• Interval malignancy with exception of completely treated in situ carcinoma of the cervix and completely treated non-metastatic squamous or basal cell carcinoma of the skin.
• Use of any investigational drug/device or participation in any investigational study within 30 days prior to screening, not including TPIP of the lead-in study.
• Current use of cigarettes (as defined by Centers for Disease Control and Prevention [CDC]) or e-cigarettes: An adult who has smoked at least 100 cigarettes in his or her lifetime, who smokes either every day or some days.
• Participants who currently inhale marijuana (recreational or medical).

Note: Other inclusion/exclusion criteria may apply.