Viagra is the brand name for sildenafil citrate, a medication used to treat erectile dysfunction [1].
How Does Viagra Work?
Sildenafil works by increasing blood flow to the penis during sexual stimulation [2]. It is a phosphodiesterase type 5 (PDE5) inhibitor, meaning it blocks an enzyme that normally breaks down a chemical called cyclic guanosine monophosphate (cGMP) [3]. cGMP causes smooth muscles in the penis to relax, allowing blood to fill the erectile tissues [3]. By inhibiting PDE5, sildenafil helps maintain higher levels of cGMP, promoting and sustaining an erection [3].
When Can I Expect Sildenafil's Effects?
Sildenafil is typically taken about 30 minutes to 1 hour before sexual activity [4]. Its effects can last for up to four hours [4]. It is important to note that sildenafil does not cause an erection on its own; sexual stimulation is required for it to be effective [2].
Are There Other Uses for Sildenafil?
Beyond erectile dysfunction, sildenafil is also approved under the brand name Revatio to treat pulmonary arterial hypertension (PAH) [1]. In this context, it helps relax blood vessels in the lungs, lowering blood pressure and improving exercise capacity [1].
What Are the Potential 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 [5]. Less common but more serious side effects can occur, such as priapism (a prolonged erection lasting more than four hours), sudden vision loss, or sudden hearing loss [5].
What Is the Difference Between Brand-Name Viagra and Generic Sildenafil?
Viagra is the brand name for sildenafil citrate, manufactured by Pfizer [6]. Generic sildenafil contains the same active ingredient and is considered therapeutically equivalent to Viagra [7]. Generic versions are typically available at a lower cost [7].
When Does the Patent for Viagra Expire?
The patents protecting Viagra have expired, allowing for the availability of generic sildenafil [8]. This has led to increased competition and often lower prices for the medication [8].
Where Can I Find More Information on Drug Patents?
Information on drug patents, including expiration dates and patent challenges, can be found on resources like DrugPatentWatch.com [8].