As per the studies conducted, this has been reported that erectile dysfunction is highly prevalent with What side effects can this medication cause? Both sildenafil and the metabolite have terminal half lives of about 4 hours. On 6 May , Pfizer , which manufactures Viagra, told the Associated Press they will begin selling the drug directly to people on its site. Below is a common prescription for an adult younger than Take 60mg no more than once a day. 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 VIAGRA.Sildenafil (Viagra, Revatio) is a moderately priced drug used to treat erection problems in men. It is also used to treat pulmonary arterial hypertension, a serious heart and lung condition. This drug is more popular than comparable drugs. It . Sildenafil citrate, USP is a white to off-white crystalline powder with a solubility of mg/mL in water and a molecular weight of Sildenafil Tablets USP: Sildenafil citrate is formulated as white, film-coated round tablets for oral administration. Each tablet contains sildenafil citrate equivalent to 20 mg of sildenafil. Sildenafil is used to treat erectile dysfunction (ED) and to reduce blood pressure in pulmonary arterial hypertension (PAH). It is taken when needed for ED and daily for PAH. A headache, stomach upsets, and flushing are the main side effects, and it should not be taken within 24 hours of a nitrate.