Viagra or Sildenafil Citrate
Sildenafil citrate, sold as Viagra , Revatio and under various other trade names, is a drug used to treat erectile dysfunction and pulmonary arterial hypertension (PAH). It was developed and is being marketed by the pharmaceutical company Pfizer. It acts by inhibiting cGMP-specific phosphodiesterase type 5, an enzyme that regulates blood flow in the penis. Since becoming available in 1998, sildenafil has been the prime treatment for erectile dysfunction; 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 heart 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 US Food and Drug Administration on March 27, 1998, becoming the first oral treatment 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 that 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 soccer 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 2000, Viagra sales accounted for 92 percent of the global market for prescribed erectile dysfunction pills. By 2007, Viagra’s global share had plunged to about 50 percent due to several factors, including the entry of Cialis and Levitra, along with several counterfeits and clones, and reports of vision loss in people taking PDE5 inhibitors.
The primary indication of sildenafil is treatment of erectile dysfunction (inability to sustain a satisfactory erection to complete intercourse).
Some say all good things come at a cost and viagra most definitely has a cost, in addition to the cost of the drug.
In clinical trials, the most common adverse effects of sildenafil use included headache, flushing, dyspepsia, nasal congestion and impaired vision, including photophobia and blurred vision. Some sildenafil users have complained of seeing everything tinted blue (cyanopsia). Some complained of blurriness and loss of peripheral vision. In July 2005, the U.S. Food and Drug Administration found that sildenafil could lead to vision impairment in rare cases and a number of studies have linked sildenafil use with nonarteritic anterior ischemic optic neuropathy.
Rare but serious adverse effects found through postmarketing surveillance include priapism, severe hypotension, myocardial infarction (heart attack), ventricular arrhythmias, stroke, increased intraocular pressure, and sudden hearing loss. As a result of these postmarketing reports, in October 2007, the FDA announced that the labeling for all PDE5 inhibitors, including sildenafil, required a more prominent warning of the potential risk of sudden hearing loss.
Viagra, like its competing drugs in levitra and cialis has obvious serious health risks for assistance to overcome erectile dysfunction. Yohimbine, a safe alternative with the same results for overcoming erectile dysfunction and libido is not a drug and therefore there is no need for a prescription or even a consultation. Ingesting yohimbine in a suspended gel strip provides highly effective bioavailability while eliminating the health risks associated with viagra, cialis and levitra.
Nano Business
