Sorry something went wrong with your subscription Please, try again in a couple of minutes Retry. By controlling the enzyme, sildenafil helps to maintain an erection after the penis is stroked. This development was credited largely “due to the introduction of generic products. It added further: “As a matter of policy and sound statutory interpretation, patentees cannot be allowed to ‘game’ the system in this way. These medicines prevent an enzyme called phosphodiesterase type-5 from working too quickly. Food and Drug Administration has approved fifteen drug manufacturers to market generic sildenafil in the United States. On 6 May , Pfizer , which manufactures Viagra, told the Associated Press they will begin selling the drug directly to people on its site. · Generic name: sildenafil (oral) [ sil-DEN-a-fil ] Brand names: Revatio, Viagra. Drug classes: Agents for pulmonary hypertension, Impotence agents. Medically reviewed by Kaci Durbin, MD. Last updated on Uses. Warnings. Before taking. Dosage. Side effects. Interactions. FAQ. What is sildenafil? Pfizer Viagra tablet in the trademark blue diamond shape “the blue pill”, or “blue diamond”, as well as various other nicknames. the branded 50 mg pill cost is between and US$ In the United States, Pfizer received two patents for sildenafil: one for its indication to treat cardiovascular disease (marketed as Revatio) and. Sildenafil oral tablet is available as a brand-name drug and as a generic drug. Brand names: Viagra, Revatio. Sildenafil comes in three forms: an oral tablet, an oral suspension (liquid), and an.