Viagra is a drug patented by Pfizer company with a registered trademark. Because it is actually a brand name, the Pfizer company is the only producer who has the right to market a product called Viagra. The term «generic Viagra» denotes a group of drugs that are chemically identical to Viagra and have the same effects, but are sold under another brand names.
The chemical name of the famous «blue pill» is Sildenafil citrate. The Pfizer company was actually using it in clinical studies for treating angina and blood pressure in 1990’s. The clinical trials have shown that the drug had low effectiveness in what concerns angina or blood pressure, but many of the patients reported to have a very strong erection that was achieved with less stimulation than usually. On top of that, men who have been experiencing erectile dysfunction (impotence) have also shown some prominent results when taking Sildenafil citrate. Male impotence is the inability to maintain a durable erection that would last until ejaculation.
Having these effects Pfizer decided to run a study on the effects of sildenafil citrate for treating erectile dysfunction, which have shown outstanding results. Viagra was patented in 1996, and in 1998 it was approved by the F.D.A. as a drug to treat male impotence. The standard Viagra dose is 50 milligrams of sildenafil but there are also 100 milligram doses for some users.
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