This study will look at safety and tolerability of LIQ861 (treprostinil) inhalation powder in adults with pulmonary arterial hypertension (PAH, WHO Group 1) who switch from selexipag, a medicine taken by mouth, to treprostinil, a medicine breathed into the lungs.
Everyone who takes part will receive LIQ861. On the first study day, participants will stop taking selexipag and begin taking LIQ861 four times a day using a small handheld dry powder inhaler. The dose may be increased over time based on how well it is tolerated. Participants will take LIQ861 for 16 weeks.
The study will also look at whether switching to LIQ861 affects walking distance, a blood marker of heart strain, and symptoms reported by participants.