Pharmacokinetics of Sildenafil in Premature Infants

Pharmacokinetics and safety of sildenafil will be studied in preterm infants who are
receiving sildenafil per standard of care or 1 dose prescribed for the study.

Inclusion Criteria:

Cohort 1:

- Gestational age 28 weeks or less receiving sildenafil as standard of care < 365
postnatal days

Cohort 2:

- Gestational age 28 weeks or less

- 7-28 postnatal days of age

- Mechanical ventilation or nasal continuous positive airway pressure (NCPAP) or
high-flow nasal cannula

- Intravenous line in place

Exclusion Criteria:

Cohort 1:

- Any condition that would make the participant, in the opinion of the investigator,
unsuitable for the study

Cohort 2:

- Previous exposure to sildenafil within 7 days prior to enrollment

- Any condition that would make the participant, in the opinion of the investigator,
unsuitable for the study

- History of allergic reactions to sildenafil

- AST > ULN or ALT > 3x ULN

- Currently on a vasopressor for hypotension

- Known sickle cell disease