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An October 2023 release stated that erectile dysfunction medicines were the most seized drugs by the Interpol[92] accounting for 22% of seizures.

other ED treatments

The US Food and Drug Administration (FDA) has banned numerous products claiming to be Eurycoma longifolia that, in fact, contain only analogs of sildenafil. [44][45][46] Sellers of such fake herbals typically respond by just changing the names of their products. Sildenafil and/or N-desmethylsildenafil, its major active metabolite, may be quantified in plasma, serum, or whole blood to assess pharmacokinetic status in those receiving the drug therapeutically, to confirm the diagnosis in potential poisoning victims, or to assist in the forensic investigation in a case of fatal overdose. Nitric oxide (NO) in the corpus cavernosum of the penis binds to guanylate cyclase receptors, which results in increased levels of cGMP, leading to smooth muscle relaxation (vasodilation) of the intimal cushions of the helicine arteries. This smooth muscle relaxation leads to vasodilation and increased inflow of blood into the spongy tissue of the penis, causing an erection.

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[49] Robert F. Furchgott, Ferid Murad, and Louis Ignarro won the Nobel Prize in Physiology or Medicine in 1998 for their independent study of the metabolic pathway of nitric oxide in smooth muscle vasodilation. The molecular mechanism of smooth muscle relaxation involves the enzyme CGMP-dependent protein kinase, also known as PKG. This kinase is activated by cGMP and it phosphorylates multiple targets in the smooth muscle cells, namely myosin light chain phosphatase, RhoA, IP3 receptor, phospholipase C, and others. [50] Overall, this results in a decrease in intracellular calcium and desensitizing proteins to the effects of calcium, engendering smooth muscle relaxation.

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The molecular structure of sildenafil is similar to that of cGMP and acts as a competitive binding agent of PDE5 in the corpus cavernosum, resulting in more cGMP and increased penile response to sexual stimulation. [49][51] Without sexual stimulation, and therefore lack of activation of the NO/cGMP system, sildenafil should not cause an erection. Other drugs that operate by the same mechanism include tadalafil (Cialis) and vardenafil (Levitra). Sildenafil is broken down in the liver by hepatic metabolism using cytochrome p450 enzymes, mainly CYP450 3A4 (major route), but also by CYP2C9 (minor route) hepatic isoenzymes. The major product of metabolisation by these enzymes is N-desmethylated sildenafil, which is metabolised further. In 1992, Pfizer filed a patent covering the substance sildenafil and its use to treat cardiovascular diseases.

• Sildenafil online sales are subject to Irish and European drug laws.
• Verify if an online pharmacy provides pharmacist consultation services.
• Use reputable sources to avoid counterfeit or substandard products.
• Sildenafil can promote harder and longer-lasting erections.
• Ensure any online purchases come with legitimate receipts and invoices.
• Learn about potential side effects before starting sildenafil.
• Sildenafil is usually taken 30-60 minutes before intimacy.
• Avoid combining sildenafil with recreational drugs like poppers.
• Confirm the dosage and frequency guidelines on your sildenafil package.
• Online pharmacies often offer customer testimonials and reviews.
• Take care to avoid drug interactions by discussing your health history online.

[96] This would be marketed as Revatio.

Dosage	Typical Use Cases	Onset Time	Duration of Effect	Common Side Effects	Notes
25 mg	Mild Erectile Dysfunction	30-60 min	4-6 hours	Headache, flushing	Start with lowest dose
50 mg	Moderate ED, occasional use	30-60 min	4-6 hours	Dizziness, nasal congestion	Adjust dose as needed
100 mg	Severe ED, experienced users	30-60 min	4-6 hours	Vision changes, priapism	Consult doctor before use
Timing Tips	Take on an empty stomach for faster absorption	-	-	-	Avoid high-fat meals

The patent was published in 1993 and expired in 2012.

Product	Dosage	Quantity + Bonus	Price
Kamagra Oral Jelly	100mg	21 Sachets	95.92€ 91.35€	Buy
Kamagra Polo	100mg	12 Pills	60.21€ 57.34€	Buy
Kamagra	100mg	60 + 4 Pills	201.34€ 191.75€	Buy
Kamagra Soft Tabs	100mg	12 Pills	57.55€ 54.81€	Buy
Viagra Generic	200mg	180 + 10 Pills	277.56€ 264.34€	Buy
Kamagra Oral Jelly	100mg	63 + 7 Sachets	224.18€ 213.50€	Buy
Kamagra	100mg	20 Pills	86.09€ 81.99€	Buy
Kamagra Oral Jelly	100mg	30 + 5 Sachets	136.20€ 129.71€	Buy
Kamagra Soft Tabs	100mg	120 + 6 Pills	311.78€ 296.93€	Buy
Viagra Generic	150mg	120 + 8 Pills	177.58€ 169.12€	Buy
Viagra Generic	25mg	360 + 10 Pills	213.68€ 203.50€	Buy
Kamagra Polo	100mg	20 Pills	83.56€ 79.58€	Buy
Viagra Generic	100mg	20 Pills	45.58€ 43.41€	Buy
Kamagra Soft Tabs	100mg	272 + 12 Pills	593.42€ 565.16€	Buy
Viagra Generic	200mg	90 + 6 Pills	170.79€ 162.66€	Buy

The patent on Revatio (indicated for pulmonary arterial hypertension rather than erectile dysfunction) expired in late 2012. Generic versions of this low-dose form of sildenafil have been available in the US from a number of manufacturers, including Greenstone, Mylan, and Watson, since early 2013.

Pharmacy Name	Website URL	Price per 100mg	Delivery Time	Ratings (out of 5)	Verified Certificates
IrishMedOnline	www.irishmedonline.ie	€15	2-3 days	4.5	GMP, ISO-certified
Meds2U	www.meds2u.ie	€14	3-5 days	4.2	Verified seller
PharmaIreland	www.pharmaireland.ie	€16	2-4 days	4.0	Legitimate licenses
OnlineMedicines	www.onlinemedicines.ie	€13	4-6 days	4.3	Verified pharmacy

[97] Health care providers may prescribe generic sildenafil for erectile dysfunction. [98] For a time, the generic was not available in the same dosages as branded Viagra, so using dosages typically required for treating ED required patients to take multiple pills.

How Viagra Access and Prescription Rules Work Across Europe

Viagra and other products for sexual dysfunction, termed sexuopharmaceuticals, proliferated new types of specialised marketing for such products. [66] Viagra and similar prescription pharmaceuticals were promoted by images in media to the extent of becoming a cultural icon, at the time a relatively new phenomenon known to be permitted only in the United States and New Zealand and which is believed to have significantly contributed to norms regarding male sexuality. [67] One author notes that although sildenafil 100mg blue pill the effect of Viagra is only limited to penile blood vessels, advertisements routinely use imagery of couples hugging, smiling and dancing, with the author claiming that pharmaceutical companies were deceptive in the use of such advertisements. In 2000, Viagra sales accounted for 92% of the global market for prescribed erectile dysfunction pills. [69] By 2007, Viagra's global share had plunged to about 50%[70] due to several factors, including the entry of Cialis and Levitra, along with several counterfeits and clones, and reports of vision loss in people taking PDE5 inhibitors.

Understanding Erectile Dysfunction:

[71][72] In 2008, the FDA forced Pfizer to remove Viva Cruiser, an advergame for Viagra, from appearing on Forbes, after the game failed to disclose risk information about the drug. In February 2007, it was announced that Boots, the UK pharmacy chain, would try over-the-counter sales of Viagra in stores in Manchester, England. Males between the ages of 30 and 65 would be eligible to buy four tablets after a consultation with a pharmacist. [75] In 2017, the Medicines and Healthcare products Regulatory Agency (MHRA) enacted legislation that expanded this nationwide,[76] allowing a particular branded formulation of Sildenafil, Viagra Connect (50 mg), to be sold over the counter and without a prescription throughout the UK from early 2018. While the sale remains subject to a consultation with a pharmacist, the other restrictions from the trial have been removed, allowing customers over the age of 18 to purchase an unlimited number of pills.

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In May 2013, Pfizer, which manufactures Viagra, told the Associated Press they will begin selling the drug directly to people on its website. Pfizer's patents on Viagra expired outside the US in 2012; in the US they were set to expire, but Pfizer settled litigation with each of Mylan and Teva which agreed that both companies could introduce generics in the US in December 2017. [79][80] In December 2017, Pfizer released its own generic version of Viagra. As of 2018[update], the US Food and Drug Administration has approved fifteen drug manufacturers to market generic sildenafil in the United States. Seven of these companies are based in India. In 1994, Pfizer filed a patent covering the use of sildenafil to treat erectile dysfunction. [99] This would be marketed as Viagra.

• Cost of sildenafil online varies depending on dosage and brand.
• Generic sildenafil offers a more affordable alternative to brand-name Viagra.
• Look for licensed Irish online pharmacies for safe sildenafil purchase.
• Sildenafil may interact with medications like nitrates or antihypertensives.
• Purchase sildenafil online with secure payment options for privacy.
• Avoid buying sildenafil from suspicious websites that lack contact info.
• Delivery times for online sildenafil orders in Ireland typically range from 1-7 days.
• Keep a record of your sildenafil purchase for future reference.
• Sildenafil effectiveness can be enhanced with a healthy lifestyle.
• Read customer reviews before choosing an online sildenafil supplier.
• Regular health check-ups are recommended when using sildenafil long-term.

This patent was published in 2002 and expired in 2019.

• Buying sildenafil online in Ireland requires understanding of local laws.
• Use reputable review platforms to verify the credibility of online pharmacy sites.
• Never share personal or banking details on insecure websites.
• Online sildenafil orders can sometimes include additional health advice.
• Verify the authenticity of sildenafil packaging upon delivery.
• Store sildenafil in a secure, child-proof container.
• Some online pharmacies offer consultation with licensed doctors.
• Sildenafil can improve sexual performance but does not cure underlying issues.
• Monitor side effects closely when using sildenafil purchased online.
• Price comparisons online can help find the best deals on sildenafil.
• Always adhere to medical advice when using sildenafil for ED.

Teva sued to have the latter patent invalidated, but Pfizer prevailed in an August 2011 federal district court case. [100] An agreement with Pfizer allowed Teva to begin to provide the generic drug in December 2017.

Route of administration

This metabolite also has an affinity for the PDE receptors, about 40% of that of sildenafil. Thus, the metabolite is responsible for about 20% of sildenafil's action. Sildenafil is excreted as metabolites predominantly in the feces (about 80% of administered oral dose) and to a lesser extent in the urine (around 13% of the administered oral dose). If taken with a high-fat meal, absorption is reduced; the time taken to reach the maximum plasma concentration increases by around one hour, and the maximum concentration itself is decreased by nearly one-third. When taken orally, sildenafil for erectile dysfunction results in an average time to onset of erections of 27 minutes (ranging from 12 to 70 minutes).

Marketing and sales

Sublingual use of sildenafil for erectile dysfunction results in an average onset of action of 15 minutes and lasting for an average of 40 minutes. The preparation steps for synthesis of sildenafil are:[54] Methylation of 3-propylpyrazole-5-carboxylic acid ethyl ester with hot dimethyl sulfate Hydrolysis with aqueous sodium hydroxide (NaOH) to free acid Carboxamide formation with refluxing thionyl chloride/NH4OH Reduction of nitro group to amino group Sildenafil (compound UK-92,480) was synthesized by a group of pharmaceutical chemists led by Simon Campbell[55] working at Pfizer's Sandwich, Kent, research facility in England. It was initially studied for use in hypertension (high blood pressure) and angina pectoris (a symptom of ischaemic heart disease). [56] The first clinical trials were conducted in Morriston Hospital in Swansea. [57] Phase I clinical trials under the direction of Ian Osterloh suggested the drug had little effect on angina, but it could induce marked penile erections.

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[58][59] Pfizer therefore decided to market it for erectile dysfunction, rather than for angina; this decision became an often-cited example of drug repositioning. [60][61] The drug was patented in 1996, approved for use in erectile dysfunction by the FDA on 27 March 1998, becoming the first oral treatment approved to treat erectile dysfunction in the United States, and offered for sale in the United States later that year. [62] It soon became a great success: annual sales of Viagra peaked in 2008 at US$1.934 billion. In the US, even though sildenafil is available only by prescription from a doctor, it was advertised directly to consumers on TV (famously being endorsed by former United States Senator Bob Dole and football star Pelé). Numerous sites on the Internet offer Viagra for sale after an "online consultation", often a simple web questionnaire. In the United States, Pfizer received two patents for sildenafil: one for its indication to treat cardiovascular disease (marketed as Revatio) and another for its indication to treat erectile dysfunction (marketed as Viagra).

• Online Ireland pharmacies may require an online health questionnaire.
• Sildenafil's effects can last for 4-6 hours post-administration.
• Be cautious of pharmacies offering sildenafil without a proper prescription.
• Verify authenticity by checking for official pharmacy seals or licenses.
• Sildenafil can sometimes cause temporary vision changes.
• Patients should disclose all medications to their healthcare provider beforehand.
• Use appropriate storage to preserve sildenafil's efficacy.
• Consider consulting a doctor for underlying causes of erectile dysfunction.
• When bought online, check shipping policies and customer service support.
• Use sildenafil responsibly to avoid potential health risks.
• Keep a record of all online transactions for safety and reference.

The substance is the same under both brand names.

Chemical synthesis

The patent for Pfizer's Viagra sildenafil to treat erectile dysfunction expired in April 2020. In 2026 a chocolate syrup called Boner Bears from Lockout Supplements was recalled through the FDA because of it containing Sildenafil as an undisclosed ingredient. Counterfeit Viagra, despite generally being cheaper,[88] can contain harmful substances or substances that affect how Viagra works, such as blue printer ink, amphetamines, metronidazole, boric acid, and rat poison. Viagra is one of the world's most counterfeited medicines. [90][91] According to a 2012 Pfizer study, around 80% of sites claiming to sell Viagra were selling counterfeits. Sildenafil is available as a generic drug in the United States, labeled for pulmonary arterial hypertension,[98] and to treat erectile dysfunction, as the patent expired in April 2020.

Status	Description	Effective Date	Legal for Purchase	Restrictions
Prescription	Only available via prescription from a licensed doctor	N/A	Yes	Must have a medical prescription
Over-the-counter	Not available without prescription	N/A	No	Restricted by law
Import Regulations	Importing without proper authorization is illegal	N/A	No	Customs confiscation
Penalties	Fines or legal action for illegal purchase/shipment	N/A	N/A	Violations can lead to court