";s:4:"text";s:4408:"Safety and effectiveness have not been established in pediatric patients.Healthy elderly volunteers (65 years or over) had a reduced clearance of sildenafil resulting in approximately 84% and 107% higher plasma AUC values of sildenafil and its active N-desmethyl metabolite, respectively, compared to those seen in healthy young volunteers (18–45 years) [Of the total number of subjects in clinical studies of Viagra, 18% were 65 years and older, while 2% were 75 years and older. The changes from baseline in scoring on the two end point questions (frequency of successful penetration during sexual activity and maintenance of erections after penetration) were highly statistically significantly in favor of ViagraA review of population subgroups demonstrated efficacy regardless of baseline severity, etiology, race and age. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse effects, nor should it be construed to indicate that use of particular drug is safe, appropriate or effective for you or anyone else. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse effects, nor should it be construed to indicate that use of particular drug is safe, appropriate or effective for you or anyone else. These effects on the metabolite are not expected to be of clinical consequence.Sildenafil is a weak inhibitor of the CYP isoforms 1A2, 2C9, 2C19, 2D6, 2E1 and 3A4 (IC50 >150 µM). Adults and children older than 12 years of age—The usual dose is 150 micrograms (mcg) (2 puffs) three to four times per day or 300 mcg (4 puffs) 2 times per day. NO then activates the enzyme guanylate cyclase, which results in increased levels of cyclic guanosine monophosphate (cGMP), producing smooth muscle relaxation in the corpus cavernosum and allowing inflow of blood.Sildenafil enhances the effect of NO by inhibiting phosphodiesterase type 5 (PDE5), which is responsible for degradation of cGMP in the corpus cavernosum. MedicineNet does not provide medical advice, diagnosis or treatment. The primary measure in the principal studies was a sexual function questionnaire (the International Index of Erectile Function - IIEF) administered during a 4-week treatment-free run-in period, at baseline, at follow-up visits, and at the end of double-blind, placebo-controlled, at-home treatment. When vasodilators are used in combination, an additive effect on blood pressure may occur. One patient discontinued the study prematurely due to an adverse event of hypotension following dosing with Viagra 50 mg. Visit the Selected from data included with permission and copyrighted by First Databank, Inc. Following at least 14 consecutive days of doxazosin, Viagra 50 mg or matching placebo was administered simultaneously with doxazosin 4 mg (17 subjects) or with doxazosin 8 mg (3 subjects). Sildenafil at recommended doses has no effect in the absence of sexual stimulation.In addition to human corpus cavernosum smooth muscle, PDE5 is also found in other tissues including platelets, vascular and visceral smooth muscle, and skeletal muscle, brain, heart, liver, kidney, lung, pancreas, prostate, bladder, testis, and seminal vesicle. Information is also available online at Do not let anyone else use your medication. Such combinations may further lower blood pressure. At doses above the recommended dose range, adverse reactions were similar to those detailed in Table 1 below but generally were reported more frequently.When Viagra was taken as recommended (on an as-needed basis) in flexible-dose, placebo-controlled clinical trials of two to twenty-six weeks duration, patients took Viagra at least once weekly, and the following adverse reactions were reported:The following events occurred in <2% of patients in controlled clinical trials; a causal relationship to Viagra is uncertain.