In 2008, Pfizer's Viagra (sildenafil citrate) was a leading medication for erectile dysfunction, generating substantial sales. While specific sales figures for 2008 are not readily available in the provided context, the drug's market presence was significant during that period.
When Did Viagra's Primary Patent Expire?
The primary U.S. patent for Viagra expired in 2013 [1]. This expiration allowed for the introduction of generic versions of sildenafil citrate to the market.
What Happened After Viagra's Patent Expired?
Following the patent expiration in 2013, generic versions of sildenafil citrate became available. This typically leads to a significant decrease in the market share and sales of the branded drug as lower-cost alternatives enter the market.
How Does Viagra Work?
Viagra works by increasing blood flow to the penis during sexual stimulation. It does this by inhibiting an enzyme called phosphodiesterase type 5 (PDE5). By inhibiting PDE5, sildenafil helps to relax and widen blood vessels, allowing for an erection [2].
What Are the Side Effects of Viagra?
Common side effects of Viagra include headache, flushing, indigestion, nasal congestion, visual disturbances, and diarrhea [3]. Less common but more serious side effects can occur, and individuals should seek medical attention if they experience persistent or concerning symptoms [3].
Who Manufactures Viagra?
Viagra is manufactured by Pfizer [1]. Generic versions of sildenafil citrate are produced by various pharmaceutical companies.
Where Can I Find Information on Drug Patents?
Resources like DrugPatentWatch.com provide comprehensive information on drug patents, including expiration dates and patent litigation for various medications [1].