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"Viagra" redirects here. For the Russian/Ukrainian girl group also known as "Via Gra", see Nu Virgos
Sildenafil
Systematic (IUPAC) name
1-[4-ethoxy-3-(6,7-dihydro-1-methyl- 7-oxo-3-propyl-1H-pyrazolo[4,3-d]pyrimidin-5-yl) phenylsulfonyl]-4-methylpiperazine citrate Identifiers CAS number 139755-83-2 ATC code G04BE03 PubChem 5281023 DrugBank APRD00556 Chemical data Formula C22H30N6O4S Mol. mass base: 474.6 g/mol SMILES search in eMolecules, PubChem Pharmacokinetic data Bioavailability 40% Metabolism Hepatic Half life 3-4h Excretion CYP3A4 Therapeutic considerations Pregnancy cat. N/A Legal status℞ Prescription only Routes OralSildenafil 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). Contents 1 History 2 Mechanism of action 3 Dosage and price 4 Contraindications 5 Side effects 6 Other uses 6.1 Pulmonary hypertension 6.2 Raynaud's phenomenon 6.3 Altitude sickness 7 Non-medical use 7.1 Aphrodisiac 7.2 Recreational use 7.3 Prevention of plant wilting 7.4 Jet lag research 8 Chemical synthesis 9 See also 10 Notes 11 External links // HistorySildenafil (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 form of ischaemic cardiovascular disease). 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.[1][2] 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.[3] 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.[4] Their names are on the manufacturing patent application drug, but Pfizer claims this is only for convenience. Even though sildenafil is available by prescription from a doctor, it was advertised directly to consumers on US 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", a mere 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.[5] 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. Mechanism of actionPart of the physiological process of erection involves the parasympathetic nervous system causing the release of nitric oxide (NO) in the corpus cavernosum of the penis. NO binds to the receptors of the enzyme guany |