Avanafilinteractions

Avanafil can potentiate the hypotensive effect of nitrates, alpha-blockers, antihypertensives, and alcohol

CYP3A4 inhibitors (e.g., ketoconazole, ritonavir, erythromycin) increase avanafil exposure

7.1 Potential for

Pharmacodynamic Interactions with Avanafil Nitrates Administration of avanafil to patients who are using any form of organic nitrate, is contraindicated. In a clinical pharmacology trial, avanafil was shown to potentiate the hypotensive effect of nitrates. In a patient who has taken avanafil, where nitrate administration is deemed medically necessary in a life-threatening situation, at least 12 hours should elapse after the last dose of avanafil before nitrate administration is considered. In such circumstances, nitrates should only be administered under close medical supervision with appropriate hemodynamic monitoring. Alpha-Blockers Caution is advised when PDE5 inhibitors are co-administered with alpha-blockers. PDE5 inhibitors, including avanafil, and alpha-adrenergic blocking agents are both vasodilators with blood pressure-lowering effects. When vasodilators are used in combination, an additive effect on blood pressure may be anticipated. In some patients, concomitant use of these two drug classes can lower blood pressure significantly leading to symptomatic hypotension (e.g., dizziness, lightheadedness, fainting). Antihypertensives PDE5 inhibitors, including avanafil, are mild systemic vasodilators. A clinical pharmacology trial was conducted to assess the effect of avanafil on the potentiation of the blood pressure-lowering effects of selected antihypertensive medications (amlodipine and enalapril). Additional reductions in blood pressure of 3 to 5 mmHg occurred following co-administration of a single 200 mg dose of avanafil with these agents compared with placebo. Alcohol Both alcohol and PDE5 inhibitors, including avanafil, act as vasodilators. When vasodilators are taken in combination, blood pressure-lowering effects of each individual compound may be increased. Substantial consumption of alcohol (e.g., greater than 3 units) in combination with avanafil can increase the potential for orthostatic signs and symptoms, including increase in heart rate, decrease in standing blood pressure, dizziness, and headache.

7.2 Potential for

Other Drugs to Affect Avanafil Avanafil is a substrate of and predominantly metabolized by CYP3A4. Studies have shown that drugs that inhibit CYP3A4 can increase avanafil exposure. Strong CYP3A4 Inhibitors Ketoconazole (400 mg daily), a selective and strong inhibitor of CYP3A4, increased avanafil 50 mg single-dose systemic exposure (AUC) and maximum concentration (C max) equal to 13-fold and 3-fold, respectively, and prolonged the half-life of avanafil to approximately 9 hours. Other potent inhibitors of CYP3A4 (e.g., itraconazole, clarithromycin, nefazadone, ritonavir, saquinavir, nelfinavir, indinavir, atanazavir and telithromycin) would be expected to have similar effects. Do not use avanafil in patients taking strong CYP3A4 inhibitors. HIV Protease inhibitor — Ritonavir (600 mg twice daily), a strong CYP3A4 inhibitor, which also inhibits CYP2C9, increased avanafil 50 mg single-dose C max and AUC equal to approximately 2-fold and 13-fold, and prolonged the half-life of avanafil to approximately 9 hours in healthy volunteers. Do not use avanafil in patients taking ritonavir. Moderate CYP3A4 Inhibitors Erythromycin (500 mg twice daily) increased avanafil 200 mg single-dose C max and AUC equal to approximately 2-fold and 3-fold, respectively, and prolonged the half-life of avanafil to approximately 8 hours in healthy volunteers. Moderate CYP3A4 inhibitors (e.g., erythromycin, amprenavir, aprepitant, diltiazem, fluconazole, fosamprenavir, and verapamil) would be expected to have similar effects. Consequently, the maximum recommended dose of avanafil is 50 mg, not to exceed once every 24 hours for patients taking concomitant moderate CYP3A4 inhibitors. Although specific interactions have not been studied, other CYP3A4 inhibitors, including grapefruit juice are likely to increase avanafil exposure. Weak CYP3A4 Inhibitors No in vivo drug-drug interaction studies with weak CYP3A4 inhibitors were conducted. CYP3A4 Substrate When administered with avanafil 200 mg, amlodipine (5 mg daily) increased the C max and AUC of avanafil by approximately 22% and 70%, respectively. The half-life of avanafil was prolonged to approximately 10 hrs. The C max and AUC of amlodipine decreased by approximately 9% and 4%, respectively. Cytochrome P450 Inducers The potential effect of CYP inducers on the pharmacokinetics of avanafil was not evaluated. The concomitant use of avanafil and CYP inducers is not recommended.