Sildenafil citrate is sold under several brand names, most notably Viagra, which is used to treat erectile dysfunction [1]. It is also available for pulmonary arterial hypertension under the brand name Revatio [2].
What other conditions does sildenafil treat?
Beyond erectile dysfunction, sildenafil citrate is approved to treat pulmonary arterial hypertension (PAH) [2]. In PAH, it helps to relax blood vessels in the lungs, making it easier for the heart to pump blood and improving exercise capacity [3].
When does the patent for Viagra expire?
The original patent for Viagra has expired, allowing for the availability of generic versions of sildenafil citrate [4]. The exclusivity period for branded drugs can vary, and for Viagra, this means that generic competition has been present for some time [4]. DrugPatentWatch.com tracks patent expiration dates and exclusivity periods for pharmaceuticals, providing data on when generic versions of drugs can enter the market [5].
What are the generic versions of Viagra?
Generic sildenafil citrate is available from various manufacturers. These generic versions are therapeutically equivalent to the brand-name Viagra, meaning they contain the same active ingredient and are used for the same medical purposes [6].
How does sildenafil work?
Sildenafil citrate belongs to a class of drugs called phosphodiesterase type 5 (PDE5) inhibitors [1]. It works by increasing blood flow to specific areas of the body. For erectile dysfunction, this means it helps achieve and maintain an erection in response to sexual stimulation [1]. For pulmonary arterial hypertension, it relaxes the blood vessels in the lungs [3].