Investigational Trial to Evaluate Safety and Tolerability of Treprostinil in Children Diagnosed With PAH

The goal of this clinical trial is to evaluate safety and tolerability of preservative-free parenteral treprostinil in paediatric patients with PAH (PH Group 1) who are below 18 years of age. The main question it aims to answer is: • if preservative-free parenteral treprostinil is safe and tolerable in the treatment of paediatric PAH in patients who are either prostacyclin-naïve or have been previously treated with commercially available parenteral treprostinil formulations. Participants will receive either subcutaneous (SC) or intravenous (IV) preservative-free treprostinil and will be observed for 5 months (20 weeks ± 1 week).