Sildenafil Citrate is a prescription drug that was developed originally as a means to treat pulmonary arterial hypertension. What the manufacturers discovered was that it also seemed to be a suitable remedy for erectile dysfunction. Discovered and manufactured by the pharmaceutical company Pfizer under the brand name Viagra, this unanticipated turn of events obviously had an impact on the marketing side of their product.

Through further study and testing this product became the go to treatment for erectile dysfunction in 1998. It works by reducing an enzyme [cGMP] found in the penis tissue that controls the blood flow. Since it hit the market a decade ago, sildenafil citrate has caused quite a stir. The discovery has even given way to an underground market for the drug, friends selling their prescriptions to friends! It also caused a flurry of activity among other drug manufacturers to develop competing brands. Tadalafil and Vardenafil are two competitors that are sold under the brand name Cialis and Levitra respectively