An Extension Study of Treprostinil Palmitil Inhalation Powder (TPIP) for Pulmonary Arterial Hypertension (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.