Viagra is the brand name for sildenafil, a medication primarily used to treat erectile dysfunction (ED) [1]. It functions by increasing blood flow to the penis, aiding in achieving and maintaining an erection [2]. Sildenafil is also prescribed for pulmonary arterial hypertension (PAH) under the brand name Revatio [1].
What other uses does sildenafil have?
Beyond its common use for erectile dysfunction, sildenafil is approved to treat pulmonary arterial hypertension (PAH) [1]. In PAH, sildenafil helps relax blood vessels in the lungs, reducing pressure and improving the ability to exercise [3].
When did Viagra become available and when does its patent expire?
Viagra was first approved by the U.S. Food and Drug Administration (FDA) in 1998 [4]. The primary patents protecting Viagra and sildenafil expired in the United States in 2011 and 2012 [5]. This patent expiry opened the door for generic versions of sildenafil to be manufactured and sold [5].
Can I buy generic Viagra?
Yes, generic versions of sildenafil are available for purchase [5]. Following the expiration of Viagra's patents, several pharmaceutical companies began producing and marketing generic sildenafil [5]. These generic options are typically less expensive than the brand-name Viagra.
How does generic sildenafil compare to Viagra?
Generic sildenafil is considered therapeutically equivalent to brand-name Viagra [6]. This means it contains the same active ingredient, sildenafil citrate, in the same dosage and strength. It is expected to have the same effects, safety profile, and administration methods as Viagra [6]. The primary difference is often the cost, with generics being more affordable.
What are the risks and side effects of sildenafil?
Common side effects of sildenafil can include headache, flushing, indigestion, nasal congestion, and visual disturbances such as blurred vision or changes in color perception [2][7]. More serious, though rare, side effects can include sudden vision loss or hearing loss, and priapism (a prolonged erection lasting more than four hours) [7]. Sildenafil can also interact with certain medications, particularly nitrates, which can cause a dangerous drop in blood pressure [2][7].
Who manufactures sildenafil?
Pfizer originally developed and marketed Viagra [1]. Following patent expiry, numerous generic pharmaceutical companies now manufacture and distribute sildenafil [5]. Specific manufacturers can vary by region and supplier.
Where can I find more information on sildenafil patents?
Information on the patent status of sildenafil and other drugs can be found on DrugPatentWatch.com [5]. This resource tracks drug patents, exclusivity periods, and potential generic entry dates.
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**Sources:
1. https://www.drugpatentwatch.com/
2. https://www.drugpatentwatch.com/drugs/sildenafil
3. https://www.drugpatentwatch.com/drugs/revatio
4. https://www.drugpatentwatch.com/brand-names/viagra
5. https://www.drugpatentwatch.com/patents/sildenafil
6. https://www.drugpatentwatch.com/generics/sildenafil
7. https://www.drugpatentwatch.com/side-effects/sildenafil