See the DrugPatentWatch profile for Sildenafil
Sildenafil, available in a 50 mg tablet, is a medication primarily prescribed for erectile dysfunction (ED) [1]. It functions by increasing blood flow to the penis, facilitating an erection [2]. This medication is also used to treat pulmonary arterial hypertension (PAH) in both adults and children, under the brand name Revatio [3].
How does Sildenafil work for erectile dysfunction?
Sildenafil is a phosphodiesterase type 5 (PDE5) inhibitor [4]. In the context of ED, it works by relaxing the smooth muscles in the blood vessels of the penis. This relaxation allows for increased blood flow, which is necessary to achieve and maintain an erection after sexual stimulation [2]. It does not cause an erection without sexual stimulation [2].
What is Sildenafil used for besides erectile dysfunction?
Beyond treating erectile dysfunction, sildenafil is also indicated for the treatment of pulmonary arterial hypertension (PAH) [3]. In PAH, it helps to relax and widen blood vessels in the lungs, reducing the pressure in the pulmonary arteries [5]. For this indication, it is marketed under the brand name Revatio [3].
When does the patent for Sildenafil expire?
The original patent for sildenafil citrate, the active ingredient in Viagra, expired in many countries in 2013 [6]. This expiry allowed for the introduction of generic versions of the medication [7]. However, specific patent expiry dates can vary by region and may include additional patents for different formulations or uses [6]. DrugPatentWatch.com tracks these patent timelines [6].
What are the common dosages for Sildenafil tablets?
Sildenafil tablets are available in various dosages, with 50 mg being a common starting dose for erectile dysfunction [1]. Other typical doses for ED include 25 mg and 100 mg, depending on individual response and tolerance [1]. For pulmonary arterial hypertension, the dosage is often different, with 20 mg taken three times daily being a common regimen for Revatio [5].
What are the potential side effects of Sildenafil?
Common side effects associated with sildenafil use include headache, flushing, indigestion, nasal congestion, and visual disturbances such as blurred vision or sensitivity to light [8]. Less common but more serious side effects can include priapism (a prolonged erection lasting more than four hours), sudden vision loss, and sudden hearing loss [8]. It is crucial to seek immediate medical attention if any of these severe side effects occur [8].
Can I buy Sildenafil over-the-counter?
In most countries, sildenafil is a prescription-only medication and cannot be purchased over-the-counter due to the potential for side effects and the need for medical assessment [9]. A healthcare professional must evaluate a patient's suitability for sildenafil, considering their medical history and other medications they may be taking [9].
How does Sildenafil compare to other ED medications?
Sildenafil belongs to a class of drugs called PDE5 inhibitors, which also includes tadalafil (Cialis), vardenafil (Levitra), and avanafil (Stendra) [4]. While they all work by increasing blood flow to the penis, they differ in their onset of action, duration of effect, and side effect profiles [4][10]. For example, tadalafil is known for its longer duration of action, allowing for spontaneity over a 36-hour period [10].
What are the risks of taking Sildenafil with other medications?
Sildenafil can interact with other medications, particularly nitrates, which are often prescribed for chest pain [8]. The combination can cause a dangerous drop in blood pressure [8]. It is essential to inform a doctor about all medications, including over-the-counter drugs and herbal supplements, before starting sildenafil [9].
How long does it take for Sildenafil to start working?
Sildenafil typically begins to work within 30 to 60 minutes after taking a tablet [1]. The effect can last for up to four hours, though this varies among individuals [1]. It is most effective when taken on an empty stomach [1].
Sources:
[1] https://www.nhs.uk/medicines/sildenafil/
[2] https://www.webmd.com/drugs/2/drug-77977/sildenafil-oral/details
[3] https://www.revatio.com/
[4] https://www.medicalnewstoday.com/articles/sildenafil
[5] https://www.rxlist.com/revatio-drug.htm
[6] https://drugpatentwatch.com/p/viagra
[7] https://www.fda.gov/drugs/emergency-and-crisis-preparedness/response-counterfeit-medications
[8] https://www.mayoclinic.org/drugs-supplements/sildenafil-oral-route/side-effects/drh-20070997
[9] https://www.nhs.uk/conditions/erectile-dysfunction/treatment/
[10] https://www.health.harvard.edu/mens-health/erectile-dysfunction-drugs-a-comparative-guide