Viagra, a drug discovered by chance
It is small, with a rhombus and blue shape. Recognizable almost by anyone, although some do it dissembling and without wanting to name it out loud, Viagra supposed almost 20 years ago a radical change in the sexual life of many people suffering from punctual or chronic erectile dysfunction.
And that was not born with that intention. What we know as Viagra (this is one of their commercial names) is actually called sildenafil, or sildenafil citrate, a compound developed by British scientists who had no intention of treating erection problems in principle.
Viagra against angina
It was the mid-90s and his name was an insipid UK92480. The authors of the compound wanted to use it to treat hypertension and angina pectoris, a disease in which the vessels that carry blood to the heart contract, making circulation difficult. The idea was that sildenafil citrate would help relax those blood vessels and improve the health of patients.
The first clinical trials were carried out at the Morriston Hospital, in Wales, by the pharmaceutical company Pfizer. And the results were disappointing. There were no significant effects on angina pectoris.
The scientists considered discarding the compound and moving on to other studies. But the trial volunteers began reporting an unexpected side effect: penile erections right after taking the medication, something that by then there was no effective oral treatment and that it was a succulent business opportunity.
Erections in the laboratory
So the pharmaceutical company put one of its researchers, Chris Wayman, to analyze this effect. Wayman recreated in his laboratory a model of the blood circulation around the male penis: he arranged a series of test tubes filled with an inert liquid and in each one he placed a piece of tissue from the cavernous bodies of the penis of men with impotence problems .
Each piece of tissue was then connected to an electrical system that would send light electrical signals, imitating the moment when a man feels sexually aroused.
When Wayman activated these signals, the response was non-existent at first. Nothing changed in the fabric. But after adding sildenafil citrate, the blood vessels relaxed, as in the normal process of an erection. Then the liquid could enter and the tissue expanded and hardened.
How Viagra works
The sildenafil citrate inhibits the action of an enzyme (called phosphodiesterase type 5) which is responsible for degrading another compound, called GMP (cyclic guanosine monophosphate). When the levels of GMP increase, this causes the arteries of the penis to dilate and the corpus cavernosum to relax. The vasodilation of the penis increases its blood supply, which is what causes the erection.
When Viagra began to be commercialized in 1998 and 1999, there was no other oral treatment for erectile dysfunction. All that there were were uncomfortable (and frightening) injections or cumbersome prosthetics, both problematic and not very discreet methods with a problem often sensitive as is impotence.
Side effects
That made this medicine a great commercial success. In 2000 Viagra accounted for 92% of sales in the male impotence solutions market. In 2007, the quota had dropped to 50% due to competitors, counterfeits and testimonies from some patients who had suffered some side effects.
Like any medication, Viagra can produce some side effects. One of them, for example, is priapism, in which the patient suffers a continuous and painful erection that does not disappear and remains even without sexual arousal. If an erection of this type lasts more than four hours, it is time to go to a medical consultation.
Other effects are related to vision, such as bluish vision (cyanpsia), blurred vision, or loss of peripheral vision. In the year 2005, the American authority for medicines (DFA), analyzed a hundred reports that linked the consumption of Viagra with severe vision problems in exceptional situations, and other studies relate it to cases of optic neuropathy, although the conclusions do not without signs at the moment.
