Pharmacokinetics and Pharmacdynamics of Sildenafil

The Pharmacokinetics and Pharmacodynamics of Sildenafil in Pediatric and Adult Patients

The study is being done to investigate what happens to sildenafil in the body and how long it takes to get rid of this drug. Understanding how long the drug stays in the body and how it is changed by the body will help doctors determine the best dose. We also want to learn how well the medicine works based on the size of the dose or amount in the bloodstream.

There is no data regarding sildenafil drug disposition in infants and children with pulmonary hypertension. Sildenafil is used at The Children's Hospital of Philadelphia for the treatment of pulmonary hypertension. Patients receiving sildenafil as standard of care will be approached for consent.

Inclusion Criteria:

• Receive enteral sildenafil as standard of care
• > 28 days to >18 years of age
• Informed consent/assent

Exclusion Criteria:

• Parents/guardians and/or subjects who, in the opinion of the investigator, may be noncompliant with study schedules or procedures.