Sildenafil, commonly known by the trade name Viagra is an oral medication used for the treatment of erectile dysfunction (ED). Pfizer commercially released Viagra in 1996 officially making it the first drug ever approved by the FDA for the treatment of ED. Since its inception many other brands of Sildenafil have come to the market place taking the once held monopoly away from Pfizer as well as several other ED medications composed of different drugs, Cialis (Tadalafil) being the most notable and largest competition for Viagra.