Remodulin as Add-on Therapy for the Treatment of Persistent Pulmonary Hypertension of the Newborn

Inclusion Criteria: * Parent(s) or legal guardian provided consent for the subject to participate * Weight at least 2 kg at Screening * Gestational age of ≥34 weeks and ≤14 days old at Screening * Diagnosis of PPHN, which was either idiopathic in nature or associated with the following: meconium aspiration syndrome, pneumonia, respiratory distress syndrome, sepsis, birth hypoxia, perinatal encephalopathy, or unilateral congenital diaphragmatic hernia * Currently requiring ventilator support * Two consecutive oxygenation index (OI) of 15 or greater separated by at least 30 minutes, after receiving iNO for at least 3 hours * Echocardiographic (ECHO) evidence of pulmonary hypertension with elevated right ventricle pressure * Dedicated venous access for the administration of study drug (central line or peripherally inserted central venous catheter) Exclusion Criteria: * Previous or concurrent use of a phosphodiesterase-5 inhibitor, endothelin receptor antagonist, or prostanoid * Significant congenital heart disease as detected by ECHO, minor valvular abnormalities, or expected transitional findings such as a patent foramen ovale, or patent ductus arteriosus. * Clinically significant, untreated active pneumothorax at Screening * Evidence of clinically significant bleeding at Screening * Necrotizing enterocolitis (≥Bells stage II at Screening) * Uncontrolled hypotension (mean systemic pressures ≤35 mmHg at Screening) * Uncontrolled coagulopathy and / or untreated thrombocytopenia (\<50,000 platelets/µL at Screening) * History of severe (Grade 3 or 4) intracranial hemorrhage at Screening * Currently receiving extracorporeal mechanical oxygenation (ECMO) or had immediate plans to initiate ECMO * Expected duration on mechanical ventilation of \<48 hours * Life expectancy was less than 2 months or had a lethal chromosomal anomaly * Contraindication to ECMO * Bilateral congenital diaphragmatic hernia * Active seizures at Screening * Currently participating in another clinical drug study