VIAGRA

VIAGRA is rapidly absorbed after oral administration, with a mean absolute bioavailability of 41% (range 25–63%). The pharmacokinetics of sildenafil are dose-proportional over the recommended dose range. It is eliminated predominantly by hepatic metabolism (mainly CYP3A4) and is converted to an active metabolite with properties similar to the parent, sildenafil. Both sildenafil and the metabolite have terminal half lives of about 4 hours. Mean sildenafil plasma concentrations measured after the ...

In clinical studies, VIAGRA was assessed for its effect on the ability of men with erectile dysfunction (ED) to engage in sexual activity and in many cases specifically on the ability to achieve and maintain an erection sufficient for satisfactory sexual activity. VIAGRA was evaluated primarily at doses of 25 mg, 50 mg and 100 mg in 21 randomized, double-blind, placebo-controlled trials of up to 6 months in duration, using a variety of study designs (fixed dose, titration, parallel, crossover). VIAGRA was administered to more than 3,000 patients aged 19 to 87 years, with ED of various etiologi...

The following are discussed in more detail in other sections of the labeling:

• Cardiovascular [see Warnings and Precautions (5.1) ]
• Prolonged Erection and Priapism [see Warnings and Precautions (5.2) ]
• Effects on the Eye [see Warnings and Precautions (5.3) ]
• Hearing Loss [see Warnings and Precautions (5.4) ]
• Hypotension when Co-administered with Alpha-blockers or Anti-hypertensives [see Warnings and Precautions (5.5) ]
• Adverse Reactions with the Concomitant Use of Ritonavir [ see...

• Administration of VIAGRA to patients using nitric oxide donors, such as organic nitrates or organic nitrites in any form. VIAGRA was shown to potentiate the hypotensive effect of nitrates ( 4.1 , 7.1 , 12.2 )
• Known hypersensitivity to sildenafil or any component of tablet ( 4.2 )
• Administration with guanylate cyclase (GC) stimulators, such as riociguat ( 4.3 ) 4.1 Nitrates Consistent with it...

• Patients should not use VIAGRA if sexual activity is inadvisable due to cardiovascular status ( 5.1 )
• Patients should seek emergency treatment if an erection lasts >4 hours. Use VIAGRA with caution in patients predisposed to priapism ( 5.2 )
• Patients should stop VIAGRA and seek medical care if a sudden loss of vision occurs in one or both eyes, which could be a sign of non arteritic anterior ischemic optic neuropathy (NAION). VIAGRA should be used with caution, and only when the anticipate...

7 DRUG INTERACTIONS

• VIAGRA can potentiate the hypotensive effects of nitrates, alpha blockers, and anti-hypertensives ( 4.1 , 5.5 , 7.1 , 7.2 , 7.3 , 12.2 )
• With concomitant use of alpha blockers, initiate VIAGRA at 25 mg dose ( 2.3 )
• CYP3A4 inhibitors (e.g., ritonavir, ketoconazole, itraconazole, erythromycin): Increase VIAGRA exposure ( 2.4 , 7.4 , 12.3 )
• Ritonavir: Do not exceed a maxim...