Sildenafil to Repair Brain Injury Secondary to Birth Asphyxia

Cohort 1 of 3-6 neonates: 1st dose of 2mg/kg/dose, 2nd dose of 2.5 mg/kg/dose, and subsequent doses of 2.5mg/kg/dose q12h (= 5 mg/kg/day from dose #2) Cohort 2 of 3-6 neonates: 1st dose of 2mg/kg/dose, 2nd dose of 2.5 mg/kg/dose, 3rd dose of 3mg/kg/dose, and subsequent doses of 3mg/kg/dose q12h (= 6 mg/kg/day from dose #3) dose expansion phase in up to 5-15 asphyxiated neonates