Viagra

Viagra was developed by a team of scientists working at Pfizer, a pharmaceutical company based in the United States. The team was led by Dr. Simon Campbell and Dr. David Roberts, who discovered sildenafil citrate, the active ingredient in Viagra, while researching a new treatment for angina (chest pain caused by reduced blood flow to the heart). The team found that sildenafil citrate had an unexpected side effect of improving erectile function, and Pfizer subsequently developed the drug as a treatment for erectile dysfunction. Viagra was approved by the US Food and Drug Administration (FDA) in 1998 and has since become one of the most widely prescribed medications in the world.