What is Viagra?

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Viagra (generic name sildenafil) is a medication used to treat men who have trouble getting an erection, a condition called erectile dysfunction or impotence. The U.S. Food and Drug Administration approved Viagra for erectile dysfunction, but not to prolong erections. Viagra will not help delay ejaculation.Viagra works by increasing blood flow to the penis. With sexual stimulation, this causes an erection. You won’t get an erection by simply taking a Viagra pill. Viagra improves the ability to have erections in about 80 percent of the men who take it.

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Viagra is available in doses of 25 to 100 mg. For best results, take it one hour before having sex. The drug can be effective anywhere from ten minutes to four hours after taking a dose. It works faster when you take it on an empty stomach. When the sexual experience is over, the erection goes away: Viagra doesn’t help you keep an erection. Don’t take more than one dose of Viagra per day because this greatly increases the risks of severely low blood pressure.




And according to Wikipedia:

Sildenafil citrate, sold under the names Viagra, Revatio and under various other names, is a drug used to treat male erectile dysfunction (impotence) and pulmonary arterial hypertension (PAH), developed by the pharmaceutical company Pfizer. Its primary competitors on the market are tadalafil (Cialis), and vardenafil (Levitra).

Sildenafil (compound UK-92,480) was synthesized by a group of pharmaceutical chemists working at Pfizer’s Sandwich, Kent research facility in England. It was initially studied for use in hypertension (high blood pressure) and angina pectoris (a symptom of ischaemic cardiovascular disease). The first clinical trials were conducted in Morriston Hospital in Swansea. Phase I clinical trials under the direction of Ian Osterloh suggested that the drug had little effect on angina, but that it could induce marked penile erections. Pfizer therefore decided to market it for erectile dysfunction, rather than for angina. The drug was patented in 1996, approved for use in erectile dysfunction by the Food and Drug Administration on March 27, 1998, becoming the first pill approved to treat erectile dysfunction in the United States, and offered for sale in the United States later that year. It soon became a great success: annual sales of Viagra in the period 1999–2001 exceeded $1 billion.

The British press portrayed Peter Dunn and Albert Wood as the inventors of the drug, a claim which Pfizer disputes. Their names are on the manufacturing patent application drug, but Pfizer claims this is only for convenience.

Even though sildenafil is available only by prescription from a doctor, it was advertised directly to consumers on U.S. TV (famously being endorsed by former United States Senator Bob Dole and football star Pelé). Numerous sites on the Internet offer Viagra for sale after an “online consultation,” often a simple web questionnaire. The “Viagra” name has become so well known that many fake aphrodisiacs now call themselves “herbal Viagra” or are presented as blue tablets imitating the shape and colour of Pfizer’s product. Viagra is also informally known as “Vitamin V”, “the Blue Pill”, as well as various other nicknames.

In February 2007, it was announced that Boots the Chemist would trial over the counter sales of Viagra in stores in Manchester, England. Men aged between 30 and 65 would be eligible to buy four tablets after a consultation with a pharmacist.

Pfizer’s worldwide patents on sildenafil citrate will expire in 2011–2013. The UK patent held by Pfizer on the use of PDE5 inhibitors (see below) as treatment of impotence was invalidated in 2000 because of obviousness; this decision was upheld on appeal in 2002.

See the rest of the wikipedia article here.

Sources:
Micromedex® Healthcare Series. Thomson Micromedex, 2006.
Viagra product information, Pfizer Labs, 2006.
Medina P. “Effects of sildenafil on human penile blood vessels.” Urology 56 (2000).
Drug Facts and Comparisons. Facts & Comparisons, 2006.

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