What most people don't know about Viagra is the fact that it was discovered by accident.

At the beginning of the 1990s Pfizer, one of the world leading pharmaceutical companies was testing a drug for the treatment of a heart disease called angina pectoris. The medicine failed to reduce arterial blood pressure but triggered an interesting side effect with most male patients: erection. Researchers realized then they discovered something of great importance and after further studying they turned the side effect of the first drug into a prime effect thus creating Viagra.

In 1996 Viagra was patented with the intent of developing a treatment for erectile dysfunction. At the end of the 1998 it received approval from The Food and Drug Administration being quickly accepted and used world wide.

Viagra acts based on the existence of nitric oxide (NO) an important signaling molecule present in human body. Its existence was discovered in 1987 by Louise Ignarro an American pharmacologist at California University and his assistant Georgeta Buga a research biologist. They managed to prove that once released in the blood vessel NO can trigger the relaxation of downstream vessels. Therefore it can also act as a vasodilator in the penile erection.

The World Health Organization recommends Viagra as first aid when it comes to erectile dysfunctions and admits its efficiency. Sidenafil (the common name of the active substance in Viagra, one by which the medicine gets classified in pharmacies) has proven its effectiveness regardless the etiology of the erectile dysfunctions.