Sildenafil Citrate is the citrate salt form of sildenafil, an orally bioavailable pyrazolopyrimidinone derivative structurally related to zaprinast, with vasodilating and potential anti-inflammatory activities. Sildenafil is used to treat erectile dysfunction. It increases blood flow to the penis to help men get an erection. Sildenafil is also sometimes used to treat pulmonary hypertension (high blood pressure in the blood vessels that supply the lungs).