Children: Viagra Sildenafil is not intended for use by children or adolescents under 18 years of age. The patent was published in and expired in There were highly statistically significant improvements on the two principal IIEF questions frequency of successful penetration during sexual activity and maintenance of erections after penetration on VIAGRA compared to placebo. This medication is taken with or without food an hour before sex. These effects on the metabolite are not expected to be of clinical consequence. Teva sued to have the latter patent invalidated, but Pfizer prevailed in an August federal district court case. Its effects often last for 4 to 5 hours.AdFree Shipping Available. Buy Dysfunction Erectile Products on ebay. Money Back Guarantee!Daily Deals · Buyer Protection Program · Huge Savings · >80% Items Are NewService Catalog: Privacy, Sexual Wellness, Advanced, Affiliates, Learn More and more. Viagra (Sildenafil) belongs to a group of medications called phosphodiesterase type 5 inhibitors. It is used for the treatment of Erectile Dysfunction (male impotence). It helps to achieve and keep an erection sufficient for sexual activity. It does this by allowing a greater blood flow into the penis when a man is sexually aroused. Sildenafil citrate is a white to off-white crystalline powder with a solubility of mg/mL in water and a molecular weight of VIAGRA is formulated as blue, film-coated rounded-diamond-shaped tablets equivalent to 25 mg, 50 mg and mg of sildenafil for oral administration.