Drug interactions between Flomax and Levitra

ADJUST DOSE: Vardenafil may potentiate the hypotensive effect of alpha blockers, resulting in symptomatic hypotension in some patients. Vardenafil inhibits phosphodiesterase-5-mediated degradation of cyclic guanosine monophosphate (cGMP), which in vascular smooth muscles can cause peripheral vasodilation that may be additive with that induced by alpha blockers. In healthy volunteers, vardenafil (10 or 20 mg) administered simultaneously or 6 hours after a 10 mg dose of terazosin resulted in significant hypotension (standing systolic blood pressure below 85 mmHg) in a substantial number of subjects. In a similar study using tamsulosin 0.4 mg, 2 of 16 subjects given vardenafil 10 mg simultaneously with tamsulosin and 1 of 24 subjects given vardenafil 20 mg six hours after the tamsulosin dose experienced significant hypotension.

MANAGEMENT: Caution is advised if vardenafil is used in combination with alpha blockers. Patients who demonstrate hemodynamic instability on alpha blocker therapy alone are at increased risk of symptomatic hypotension with concomitant use of vardenafil. Therefore, patients should be stable on alpha blocker therapy prior to initiating vardenafil, and vardenafil should be initiated at the lowest recommended dosage (i.e., 5 mg). In those patients already on an optimized dosage of vardenafil, alpha blocker therapy should be initiated at the lowest dosage. The safety of vardenafil in combination with alpha blockers may be affected by other variables such as intravascular volume depletion and use of other antihypertensive medications.