One-third to one-half of the subjects in these studies reported successful intercourse at least once during a 4-week, treatment-free run-in period. Therefore, inhibitors of these isoenzymes may reduce sildenafil clearance and inducers of these isoenzymes may increase sildenafil clearance. Protein binding is independent of total drug concentrations. Population pharmacokinetic data from patients in clinical trials also indicated a reduction in sildenafil clearance when it was co-administered with CYP3A4 inhibitors such as ketoconazole, erythromycin, or cimetidine [see Dosage and Administration 2. If you are taking sildenafil for erectile dysfunction, your doctor will probably start you on an average dose of sildenafil and increase or decrease your dose depending on your response to the medication. In pulmonary hypertension it works by relaxing blood vessels in the chest.Sildenafil oral tablet is available as a brand-name drug and as a generic drug. Brand names: Viagra, Revatio. Sildenafil comes in three forms: an oral tablet, an oral suspension (liquid), and an. El sildenafilo (Viagra) se usa para tratar la disfunción eréctil en los hombres (impotencia; incapacidad para tener una erección o mantenerla). El sildenafilo (Liqrev, Revatio) se usa para mejorar la capacidad para hacer ejercicio en adultos (Liqrev, Revatio) y en niños a partir de 1 año (Revatio) con hipertensión arterial pulmonar (HAP. About sildenafil (Viagra) Sildenafil is a medicine used to treat erection problems (erectile dysfunction). Sildenafil is also sometimes used to treat pulmonary hypertension (high blood pressure in the blood vessels that supply the lungs). If you have erection problems sildenafil works by temporarily increasing blood flow to your penis when.