Alpha-Blockers: Caution is advised when PDE5 inhibitors are co-administered with alpha-blockers. PDE5 inhibitors, including LEVITRA 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. Clinical pharmacology studies have been conducted with co-administration of vardenafil with alfuzosin, terazosin or tamsulosin. [See Dosage and Administration (2.4), Warnings and Precautions (5.6), and Clinical Pharmacology (12.2).] 

 

Antihypertensives: LEVITRA may add to the blood pressure lowering effects of antihypertensive agents. In a clinical pharmacology study of patients with erectile dysfunction, single doses of vardenafil 20 mg caused a mean maximum decrease in supine blood pressure of 7 mmHg systolic and 8 mmHg diastolic (compared to placebo), accompanied by a mean maximum increase of heart rate of 4 beats per minute. The maximum decrease in blood pressure occurred between 1 and 4 hours after dosing. Following multiple dosing for 31 days, similar blood pressure responses were observed on Day 31 as on Day 1. 

 

Alcohol: LEVITRA (20 mg) did not potentiate the hypotensive effects of alcohol during the 4-hour observation period in healthy volunteers when administered with alcohol (0.5 g/kg body weight, approximately 40 mL of absolute alcohol in a 70 kg person). Alcohol and vardenafil plasma levels were not altered when dosed simultaneously. 

 

7.2 Effect of Other Drugs on Vardenafil

 

In vitro studies

 

Studies in human liver microsomes showed that vardenafil is metabolized primarily by cytochrome P450 (CYP) isoforms 3A4/5, and to a lesser degree by CYP2C9. Therefore, inhibitors of these enzymes are expected to reduce vardenafil clearance [see Dosage and Administration (2.4) and Warnings and Precautions (5.2)].

 

In vivo studies 

 

Potent CYP3A4 inhibitors  

 

Ketoconazole (200 mg once daily) produced a 10-fold increase in vardenafil AUC and a 4-fold increase in maximum concentration (Cmax) when co-administered with LEVITRA (5 mg) in healthy volunteers. A 5-mg LEVITRA dose should not be exceeded in a 24-hour period when used in combination with 200 mg once daily ketoconazole. Since higher doses of ketoconazole (400 mg daily) may result in higher increases in Cmax and AUC, a single 2.5 mg dose of LEVITRA should not be exceeded in a 24-hour period when used in combination with ketoconazole 400 mg daily. [See Dosage and Administration (2.4) and Warnings and Precautions (5).] 

 

Indinavir (800 mg t.i.d.) co-administered with LEVITRA 10 mg resulted in a 16-fold increase in vardenafil AUC, a 7-fold increase in vardenafil Cmax and a 2-fold increase in vardenafil half-life. It is recommended not to exceed a single 2.5 mg LEVITRA dose in a 24-hour period when used in combination with indinavir. [See Dosage and Administration (2.4) and Warnings and Precautions (5.2).]