Edyfil Drug Interactions

Sildenafil metabolism is principally mediated by the cytochrome P-450 (CYP) isoforms 3A4 (major route) and 2C9 (minor route). Inhibitors of these isoenzymes may reduce sildenafil clearance. Co-administration of CYP3A4 inhibitors (e.g. ketoconazole, erythromycin, cimetidine) will reduce sildenafil clearance.
Co-administration of the HIV protease inhibitor, ritonavir, which is a highly potent P-450 inhibitor with sildenafil resulted in increase in sildenafil C_max and plasma AUC. Sildenafil had no effect on ritonavir pharmacokinetics.
Single doses of antacid (magnesium hydroxide/aluminium hydroxide) did not affect the bioavailability of sildenafil.
Sildenafil is a weak inhibitor of the cytochrome P-450 isoforms 1A2, 2C9, 2C19, 2D6, 2E1 and 3A4 (IC50 >150 micromole). Given sildenafil peak plasma concentrations of approximately 1 micromole after recommended dose, it is unlikely that will alter the clearance of substrates of these isoenzymes.
Sildenafil (50 mg) did not potentiate the increase in bleeding time caused by aspirin (150 mg).
Sildenafil (50 mg) did not potentiate the hypotensive effects of alcohol with maximum blood alcohol levels of 0.08% (80 mg/dL).
No interaction was seen when sildenafil (100 mg) was co-administered with amlodipine in hypertensive patients.
When the α-blocker doxazosin (4 mg) and sildenafil (25, 50 or 100 mg) were administered simultaneously to patients with benign prostatic hyperplasia (BPH), additional average reductions of supine blood pressure were observed. When higher doses of sildenafil and doxazosin (4 mg) were administered simultaneously, there were infrequent reports of patients who experienced symptomatic postural hypotension within 1-4 hrs of dosing. Simultaneous administration of sildenafil to patients taking α-blocker therapy may lead to symptomatic hypotension in some patients.