This clinical trial is focused on studying the long-term effects of a medication called Ralinepag in patients with a condition known as pulmonary arterial hypertension (PAH). PAH is a type of high blood pressure that affects the arteries in the lungs and the right side of the heart. The medication being tested, Ralinepag, is taken as a prolonged-release tablet, which means it is designed to release the drug slowly over time after being taken orally.

The purpose of this study is to evaluate the long-term safety and how well patients tolerate Ralinepag. Participants in this study have previously taken part in earlier phases of research involving Ralinepag. During the study, participants will continue to take the medication and attend regular visits to monitor their health and the effects of the treatment. The study will assess various health indicators, such as levels of a specific protein in the blood, the distance a patient can walk in six minutes, and overall quality of life. These assessments help researchers understand how the medication impacts the condition over an extended period.

This study is an open-label extension, meaning that all participants will receive Ralinepag, and there is no placebo group. The study aims to provide valuable information on the long-term use of Ralinepag for managing pulmonary arterial hypertension, contributing to a better understanding of its safety and effectiveness for patients with this condition.