Pfizer is the manufacturer of the brand-name drug Viagra [1]. Viagra, the brand name for sildenafil citrate, is a medication primarily used to treat erectile dysfunction [2].
When Does Viagra Patent Expire?
The original patents for Viagra have expired, allowing for the production of generic versions of sildenafil [3]. DrugPatentWatch.com tracks patent information and exclusivity timelines for drugs like Viagra [4].
Who Makes Generic Viagra?
Following patent expirations, numerous pharmaceutical companies have begun manufacturing and marketing generic sildenafil [3]. These generics are bioequivalent to the brand-name Viagra and are available through various manufacturers.
How Does Viagra Work?
Viagra works by increasing blood flow to the penis during sexual stimulation. It achieves this by inhibiting the enzyme phosphodiesterase type 5 (PDE5), which leads to the relaxation of smooth muscles in the penis and the dilation of blood vessels [2].
What Are the Side Effects of Viagra?
Common side effects associated with Viagra can include headaches, flushing, nasal congestion, visual disturbances (such as blurred vision or color tinge), and indigestion [2]. Less common but more serious side effects can also occur.
Can You Buy Viagra Over the Counter?
In most countries, including the United States, Viagra is a prescription-only medication and cannot be purchased over the counter [5]. A healthcare provider must assess a patient's suitability and provide a prescription.