A Study of Ralinepag in Healthy Chinese Adult Subjects

This is a single center, open-label, fixed sequence, non-randomized study of healthy subjects. The study is planned to enroll 15 subjects to ensure data for 8 evaluable subjects.

Subjects will visit the clinical unit for a screening visit up to 28 days before dosing. Eligible subjects will be admitted to the clinical unit prior to investigational medicinal product (IMP) administration (Day -1) and will remain onsite through the study discharge on Day 19. Following an overnight fast of at least 8 hours, subjects will receive Regimen A (single dose of ralinepag 50 mcg) in the morning of Day 1 and pharmacokinetic assessments will be conducted pre-dose and over the 96 hours post-dose. There will be a washout period of 7 days between each IMP administration. Regimens B and C (single dose of ralinepag 100 mcg and ralinepag 150 mcg) will be administered following an overnight fast on Day 8 and 15, respectively, with 96 hours of pharmacokinetic assessments as performed with Regimen A. A Follow-up phone call will take place 10±1 days post-last dose to ensure the ongoing well-being of the subjects. Ralinepag (APD811) will be supplied as 50 mcg round, orange, XR tablets for oral administration.

It is planned that every subject will receive each of the following regimens in the fasted state:

* Regimen A (50 mcg): 1 × 50 mcg ralinepag XR tablet * Regimen B (100 mcg): 2 × 50 mcg ralinepag XR tablets * Regimen C (150 mcg): 3 × 50 mcg ralinepag XR tablets Subjects will receive Regimens A, B and C in a sequential manner in consecutive treatment periods. Subjects who have tolerated the IMP in all prior regimens will continue in the study to receive each subsequent dose.