This medication is a phosphodiesterase type 5 (PDE5) inhibitor, prescribed for erectile dysfunction (impotence). Erectile dysfunction is the inability to achieve or maintain an erection long enough to perform sexual intercourse. It relaxes the blood vessels in the penis, allowing more blood to enter to achieve an erection. It can also be used in pulmonary arterial hypertension.

Sildenafil helps response to stimulation. It calms lung vessels.

It comes as a tablet to take by mouth and injection to be administered through a vein. To treat pulmonary arterial hypertension it is usually taken three times a day. PO- 50 mg about 1 hour before sexual intercourse. Adjust dose based on response. Max: 100 mgdose and not more than once in 24 hour. Pulmonary Arterial Hypertension- 20 mg 3 times daily. IV- 10 mg (12.5 mL) administered as a bolus injection 3 times daily.