Viagra (Sildenafil)

It was originally designed for use in hypertension and angina pectoris. The first clinical trials were conducted in Morriston Hospital in Swansea (Wales) .1 During the Phase I, conducted under the direction of Ian Osterloh suggested that the drug had little effect on angina, but could notable induce erections pene.2 3 Pfizer therefore decided to market it for erectile dysfunction, rather than for angina. The drug was patented in 1996, and approved for use in erectile dysfunction by the Food and Drug Administration of USA (FDA) on March 27, 1998. He thus became the first pill approved to treat erectile dysfunction in the United States, and there offered to sell the same year.4 immediately became a great success: annual sales of Viagra in the period 1999-2001 exceeded one billion dollars. [citation needed]