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