Sildenafil is also used in both men and women to treat the symptoms of pulmonary arterial hypertension. This, in my view, is the key issue in this appeal. The patent was published in and expired in These medicines prevent an enzyme called phosphodiesterase type-5 from working too quickly. The patent on Revatio indicated for pulmonary arterial hypertension rather than erectile dysfunction expired in late 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.  · Description and Brand Names. Drug information provided by: Merative, Micromedex ®. US Brand Name. Revatio. Viagra. Descriptions. Sildenafil is used to treat men who have erectile dysfunction (also called sexual impotence). Sildenafil belongs to a group of medicines called phosphodiesterase 5 (PDE5) inhibitors. Sildenafil is used to treat male sexual function problems (impotence or erectile dysfunction-ED). In combination with sexual stimulation, sildenafil works by increasing blood flow to the penis.