Viagra™

The much-publicized properties of Viagra were discovered in much the same fashion. It was also being used as a treatment for high blood pressure, as well as angina (heart pain), when its side effect was reported. In fact, it has been said that male patients refused to return the unused portion of their medications during clinical trials. 

Both serendipitous discoveries have spawned multimillion-dollar industries and made countless men and women very happy. They re growing industries, for sure. 

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Approved for sale in March, 1998, Viagra has been used by more than 16 million men. It is currently undergoing study as a treatment for preeclampsia, a complication of pregnancy that is responsible for as many as 70,000 deaths each year. 

A heterocycle is a cyclic compound that contains atoms of two or more elements in its ring, usually carbon along with nitrogen, oxygen, or sulfur. Heterocyclic amines are particularly common, and many have important biological properties. Pyridoxal phosphate, a coenzyme sildenafil (Viagra),... 

Preeclampsia, Viagra and, 164 Prelog, Vladimir, 181 Prepolymer, epoxy resins and, 673 Priestley, Joseph, 245 Primary alcohol, 600 Primary amine, 916 Primary carbon. 84 Primary hydrogen, 85 Primary structure (protein), 1038 Primer strand (DNA), 1108 pro-R prochiralitv center, 316 pro-S prochirality center, 316 Problems, how to work, 27 Procaine, structure of, 32 Prochirality, 315-317 assignment of, 315-316 naturally occurring molecules and, 316-317... 

Viagra, preeclampsia and, 164 structure of, 1 Vicinal, 261, 662 Vinyl group, 178 Vinyl monomer, 241 Vinylcyclopropane, rearrangement of, 1202... 

Beyond Viagra, there are a number of other PDE inhibitors that are used clinically. In fact, the classic drugs papaverine and dipyridamole were used clinically before their effects on PDEs were known. Caffeine and theophylline (a compound found in tea) are also PDE inhibitors. However, all of these drugs most likely have multiple targets, making conclusions regarding the roles of PDEs in processes that are sensitive to these agents difficult to interpret. Certainly, some of their effects are due to their actions on adenosine receptors. 

Involved in penile erection sildenafil citrate (Viagra) affects this process by inhibiting a cGMP phosphodiesterase... 

During the twentieth century chemistry changed for ever the way we live. Perhaps the greatest perceived benefits, to the general public, have come from the pharmaceuticals industry with developments of painkillers, antibiotics, heart drugs and, more recently, Viagra. However, it is difficult to think of an important facet of modem life which has not been transformed by products of the chemical and related industries, for example ... 

In Malaysia, interference from the outside, political or otherwise, regarding decisions of the regulatory authority is rare. A recent exception was the debate over the registration of sildenafil (Viagra ), for the treatment of erectile dysfianction. 

Khan KM et al. (2005) A facile and improved synthesis of sildenafil (Viagra) analogs through solid support microwave irradiation possessing tyrosinase inhibitory potential, their conformational analysis and molecular dynamics simulation studies. Mol Divers 9(l-3) 15-26... 

Oral Sildenafil Viagra 25-100 mg 1 hour prior to intercourse Once daily... 

Sildenafil (Viagra ), tadalafil (Cialis ), and vardenafil (Levitra ) act by selectively inhibiting phosphodiesterase (PDE) type 5, an enzyme that breaks down cGMP. By inhibiting the breakdown of cGMP, smooth muscle relaxation is... 

Sildenafil (Viagra ) Tadalafil (Cialis ) Vardenafil (Levitra )... 

An efficient one-pot synthesis of some novel azolo[l,5-a]pyrimidines, via enaminonitriles, has been described <00SC1985>. The utility of 3-aminocinnamonitrile in the synthesis of new pyrazolo[l,5-a]pyrimidines has been reported <00ZN(B)321>. The synthesis of novel arylaminopyrazolo[3,4-d]pyrimidin-4-ones has been described <99IJC(B)1075>. The synthesis and properties of a-Thiagra, a substituted 5-(2-thienyl)pyrazolo[4,3-d]pyrimidin-7-one bioisostere of Viagra, have been described <00H(53)2643>. Imidazo[4,5-b]pyrazines are obtained by the reaction of 4-amino- 5-imino-imidazole derivatives with acetophenone dimethylacetal . 

Viagra 25-100 mg (sildenafil citrate) One tab qd, one hour before sexual activity... 

Laties, A.M., Ellis, P, and Mollon, J.D., The effects of sildenafil citrate (Viagra ) on color discrimination in volunteers and patients with erectile dysfunction, Inv. Ophthalmol. Vis. Sci., 40, S693, 1999. 

Very often, drugs are discovered through persistent work and continual optimization and many tests and trials. This is exemplified by the history behind the discovery of sildenafil (Viagra, Pfizer), a drug for the treatment of erectile dysfunction, and the AIDS drug zidovidine (Retrovir, GlaxoSmithKline) (Exhibits 3.18 and 3.19). 

The long, tortuous path from drug discovery to commercialization is amply demonstrated by the sildenafil (Viagra) story. 

Hence, we can see how the focus of treatment for sildenafil changed from antihypertensive to angina treatment to overcoming erectile dysfunction, giving rise to the drug called Viagra. 

Viagra (sildenafil) Phosphodiesterase type 5 inhibitor Mort and Brigitte Harris Foundation Phase I... 

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