Viagra is the brand name for the drug sildenafil, used to treat erectile dysfunction [1]. Sildenafil citrate is the active ingredient in Viagra [2]. Pfizer originally developed and marketed Viagra [3].
How does sildenafil work?
Sildenafil works by increasing blood flow to the penis during sexual stimulation. It inhibits an enzyme called phosphodiesterase type 5 (PDE5), which normally breaks down a substance called cyclic guanosine monophosphate (cGMP). cGMP causes the smooth muscles in the blood vessels of the penis to relax, allowing more blood to enter and create an erection [4].
When did Viagra's patent expire?
Pfizer's primary patent for Viagra expired in the United States in 2013 [5]. This expiration opened the door for generic versions of sildenafil to enter the market [6].
Can you buy generic sildenafil?
Yes, generic versions of sildenafil are available. Once the patent protection expired, other pharmaceutical companies were able to manufacture and sell their own versions of the drug, typically at a lower cost than the brand-name Viagra [5][6].
Who makes generic sildenafil?
Numerous pharmaceutical companies produce generic sildenafil. These manufacturers include Teva Pharmaceuticals, Mylan, and Sandoz, among others [7].
What are the differences between Viagra and generic sildenafil?
The active ingredient in both Viagra and generic sildenafil is the same: sildenafil citrate. The primary differences are typically the inactive ingredients, the tablet shape and color, and the price. Generic versions are usually more affordable than the brand-name drug [2][6].
Are there other uses for sildenafil?
While widely known for treating erectile dysfunction, sildenafil is also prescribed under different brand names for other medical conditions. It is used to treat pulmonary arterial hypertension (PAH), a type of high blood pressure affecting the lungs. In this use, it is marketed as Revatio [8].