Viagra, a medication used to treat erectile dysfunction, is manufactured by Pfizer [1]. The active ingredient in Viagra is sildenafil citrate [2].
When does Viagra's patent expire?
The original patents for Viagra have expired in many countries, allowing for the production of generic versions. For instance, in the United States, the patent expired in 2013, leading to the introduction of generic sildenafil [3]. DrugPatentWatch.com tracks patent expiry dates for numerous drugs, including Viagra [4].
Who makes generic Viagra?
Following the patent expiry of brand-name Viagra, several pharmaceutical companies have begun manufacturing and marketing generic sildenafil citrate [3]. These generic versions are available from various manufacturers.
How does generic sildenafil work?
Sildenafil citrate, the active ingredient in both Viagra and its generic versions, is a phosphodiesterase type 5 (PDE5) inhibitor [2]. It works by increasing blood flow to the penis, helping to achieve and maintain an erection when sexually stimulated [2][5].
What are the side effects of Viagra and generic sildenafil?
Common side effects associated with sildenafil citrate include headache, flushing, indigestion, nasal congestion, and visual disturbances [5]. More serious, though less common, side effects can also occur [5].
Can Viagra be used for other conditions?
While Viagra is primarily known for treating erectile dysfunction, sildenafil citrate is also approved for treating pulmonary arterial hypertension under the brand name Revatio [6]. Its mechanism of action, to relax and widen blood vessels, is relevant to both conditions [6].
What is the difference between Viagra and Cialis?
Viagra and Cialis are both PDE5 inhibitors used to treat erectile dysfunction, but they contain different active ingredients: sildenafil citrate for Viagra and tadalafil for Cialis [7]. They also differ in their onset of action and duration of effect, with Cialis generally having a longer duration [7].
Where can I find information on drug patents?
DrugPatentWatch.com provides comprehensive information on drug patents, including expiry dates and patent litigation for a wide range of pharmaceuticals [4].
Sources:
1. https://www.pfizer.com/
2. https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/020895s036s039,021975s015s017lbl.pdf
3. https://www.fda.gov/
4. https://drugpatentwatch.com/
5. https://www.rxlist.com/viagra-side-effects-drug-center.htm
6. https://www.rxlist.com/revatio-side-effects-drug-center.htm
7. https://www.medicalnewstoday.com/articles/320008