A 7-Day, Open
Label, Multicenter, Pharmacokinetic Study (Part 1) Followed by A 7-Day,
Randomized, Multicenter, Double-Blind, Placebo-Controlled, Dose-Ranging,
Parallel Group Study (Part 2) of IV Sildenafil in the Treatment of
Neonates with Persistent Pulmonary Hypertension of the Newborn (PPHN) or
Hypoxic Respiratory Failure and at Risk for PPHN” (Protocol A1481157
Pfizer, Inc)