Sildenafil, sold under the brand name Viagra, Revatio and others, is a drug used to treat erectile dysfunction and pulmonary arterial hypertension. It was originally developed by British scientists and then brought to market by the pharmaceutical company Pfizer. It acts by inhibiting cyclic GMP-specific phosphodiesterase type 5, an enzyme that promotes the degradation of cGMP, which regulates blood flow in the penis.


Therefore, Pfizer decided to market the drug as a treatment for erectile dysfunction rather than angina pectoris.

The drug was patented in 1996 and was approved for use in erectile dysfunction by the US Food and Drug Administration on March 27, 1998.

Thus, it became the first drug approved for the treatment of erectile dysfunction in the U.S. and went on sale in the same year. Annual sales of Viagra between 1999 and 2001 exceeded one billion dollars.

Numerous internet sites sell Viagra after online consultation. The name “Viagra” has become so well known that many fake aphrodisiacs now claim to be herbal Viagra or are sold in blue pills that mimic the shape and color of Pfizer’s product.

Viagra is also known unofficially as the blue pill or vitamin supplement.

In 2000, Viagra sales accounted for 92% of the prescription erectile dysfunction drug market, but by 2007, due to competition from other drugs such as tadalafil and vardenafil, imitations and copies of its own products, and testimonials from patients suffering from vision loss when using PDE-5 inhibitors, Viagra sales of Viagra declined by 50% in 2007.

It has also been confirmed that Pfizer was prevented from using the name Viagra in Argentina because the Argentine laboratory had a drug called VIAGRA, which has almost the same name as Viagra; in Argentina it is called Sidenafil.