Vardenafil

PDE5 5A 3 GAF/activation PKA, PKG cGMP Sildenafil, Vardenafil, Tadalafil,... 

Recent use (within 24 h of sildenafil or vardenafil or within 48 h of tadalafil) of a phosphodiesterase-5 inhibitor for erectile dysfunction (or pulmonary hypertension)... 

Phosphodiesterase type 5 inhibitors are commonly prescribed for erectile dysfunction and include sildenafil, vardenafil,... 

Nitroglycerin should not be used within 24 hours of taking sildenafil or vardenafil or within 48 hours of taking tadalafil because of the potential for life-threatening hypotension. 

Sildenafil or vardenafil within 24 hours or tadalafil within... 

Vardenafil Levitra 5-20 mg 1 hour prior to intercourse Once daily... 

Sildenafil (Viagra ), tadalafil (Cialis ), and vardenafil (Levitra ) act by selectively inhibiting phosphodiesterase (PDE) type 5, an enzyme that breaks down cGMP. By inhibiting the breakdown of cGMP, smooth muscle relaxation is... 

The most dramatic difference between the three agents is tadalahl s extended duration of action, earning it the nickname the weekender drug. While sildenafil and vardenafil have average half-lives of 3 to 4 hours, tadalafil s half life is approximately 18 hours.18 The extended half-life allows for more spontaneous sexual activity over a couple of days, but may increase the duration of adverse effects and liklihood of drug interactions or sildenafil. 

Sildenafil (Viagra ) Tadalafil (Cialis ) Vardenafil (Levitra )... 

Vardenafil can cause QT-interval prolongation this effect in combination with certain anti-arrhythmic agents can lead to life-threatening arrhythmias. CYP, cytochrome P-450 isoenzyme. 

Gresser U, Gleiter CH. Erectile dysfunction comparison of efficacy and side effects of the PDE-5 inhibitors sildenafil, vardenafil and tadalafil review of the literature. Eur J Med Res 2002 7 435-446. 

Erectile dysfunction is common, and initial treatment should include one of the oral medications currently available (e.g., sildenafil, vardenafil,tadalafil). 

Unless otherwise stated, general information applies to the entire class of phosphodiesterase inhibitors. Sildenafil is highlighted because it was the first to be marketed and is the most thoroughly studied. The newer agents tadalafil and vardenafil have different pharmacokinetic profiles (Table 83-3), drug-food interactions, and adverse effects. 

For maximal absorption, patients should avoid taking sildenafil or vardenafil with a fatty meal. A fatty meal does not affect absorption of tadalafil. / If the first dose is not effective, patients should continue trying for five to eight doses. Some patients benefit from titration up to 100 mg of sildenafil, 20 mg of vardenafil, or 20 mg of tadalafil. 

Sildenafil doses should be decreased when any potent cytochrome P450 3A4 inhibitor is used (e g., cimetidine, erythromycin, clarithromycin, ketoconazole, itraconazole, ritonavir, and saquinavir). Vardenafil doses vary accordingto which agent is used (2.5 mg q 72 h for ritonavir, 2.5 mg q 24 h for indinavir, ketoconazole 400 mg daily, and itraconazole 400 mg daily and 5 mg q 24 h for ketoconazole 200 mg daily, itraconazole200 mg daily, and erythromycin). Tadalafil doses are reduced only when it is used with the most potent cytochrome P450 3A4 inhibitors (e g., ketoconazole or ritonavir). 

Sildenafil and vardenafil decrease systolic/diastolic blood pressure by 8 to 10/5 to 6 mm Hg for 1 to 4 hours after a dose. Although most patients are asymptomatic, multiple antihypertensives, nitrates, and baseline hypotension increase the risk of developing adverse effects. Although tadalafil does not decrease blood pressure, it should be used with caution in patients with cardiovascular disease because of the inherent risk associated with sexual activity. 

Drugs that may interact with nitrates include alcohol, alteplase, aspirin, beta-blockers, calcium channel blockers, dihydroergotamine, heparin, nondepolarizing muscle relaxants, phenothiazines, phosphodiesterase inhibitors (eg, sildenafil, tadalafil, vardenafil), and vasodilators. 

VARDENAFIL HYDROCHLORIDE 10 mg taken orally approximately 60 minutes before sexual activity. The dose may be increased to a maximum recommended dose of 20 mg or decreased to 5 mg based on efficacy and side effects. The maximum recommended dosing frequency is once daily. Vardenafil can be taken with or without food. 

Hepatic function impairment- A starting dose of 5 mg is recommended in patients with moderate hepatic impairment (Child-Pugh B). The maximum dose should not exceed 10 mg. Vardenafil has not been evaluated in patients with severe hepatic impairment (Child-Pugh C). 

Concomitant mecf/caf/ons - The dosage of vardenafil may require adjustment in patients receiving certain CYP3A4 inhibitors. For ritonavir, do not exceed a single dose of 2.5 mg vardenafil in a 72-hour period. For indinavir, ketoconazole 400 mg/day, and itraconazole 400 mg/day, do not exceed a single dose of 2.5 mg vardenafil in a 24-hour period. For ketoconazole 200 mg/day, itraconazole 200 mg/day, and erythromycin, do not exceed a single dose of 5 mg vardenafil in a 24-hour period. 

Pharmacology Sildenafil, tadalafil, and vardenafil are selective inhibitors of... 

Accounts for approximately 20% of sildenafil s pharmacologic activity. Accounts for approximately 7% of vardenafil s pharmacologic activity. 

MefaboZ/sm/Excref/on-Sildenafil, tadalafil, and vardenafil are cleared predominantly by the CYP3A4 (major route), 3A5 (major route vardenafil), and CYP2C9 (minor route) hepatic isoenzymes. 

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