Misplaced Pages

#448551

68-424: Sildenafil , sold under the brand name Viagra among others, is a medication used to treat erectile dysfunction and pulmonary arterial hypertension . It is also sometimes used off-label for the treatment of certain symptoms in secondary Raynaud's phenomenon . It is unclear if it is effective for treating sexual dysfunction in females. It can be taken orally (swallowed by mouth), intravenously (injection into

136-566: A 25 mg dose was shown to cause no significant change in erectile quality, but did reduce the postejaculatory refractory time . This study also noted a significant placebo effect in the control group. Unprescribed recreational use of sildenafil and other PDE5 inhibitors is noted as particularly high among users of illegal drugs. Sildenafil is sometimes used to counteract the effects of other substances, often illicit. Some users mix it with methylenedioxymethamphetamine ( MDMA , ecstasy), other stimulants, or opiates in an attempt to compensate for

204-435: A critical role, often then selling the rights to larger companies that have the resources to run the clinical trials. Drug discovery is different from Drug Development. Drug Discovery is often considered the process of identifying new medicine. At the same time, Drug development is delivering a new drug molecule into clinical practice. In its broad definition, this encompasses all steps from the basic research process of finding

272-511: 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. One author notes that although 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

340-417: A decrease in intracellular calcium and desensitizing proteins to the effects of calcium, engendering smooth muscle relaxation. Sildenafil is a potent and selective inhibitor of cGMP-specific phosphodiesterase type 5 (PDE5), which is responsible for degradation of cGMP in the corpus cavernosum . The molecular structure of sildenafil is similar to that of cGMP and acts as a competitive binding agent of PDE5 in

408-476: 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. The Viagra name has become so well known that many fake aphrodisiacs now call themselves " herbal viagra " or are presented as blue tablets imitating

476-575: A group of 2245 elderly Americans (average age of 71) surveyed over the period 2010 – 2011, those percentages were 88%, 38%, and 64%. One of the key classifications is between traditional small molecule drugs; usually derived from chemical synthesis and biological medical products ; which include recombinant proteins , vaccines , blood products used therapeutically (such as IVIG ), gene therapy , and cell therapy (for instance, stem cell therapies). Pharmaceuticals or drugs or medicines are classified into various other groups besides their origin on

544-490: 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. The preparation steps for synthesis of sildenafil are: Sildenafil (compound UK-92,480) was synthesized by a group of pharmaceutical chemists led by Simon Campbell working at Pfizer's Sandwich, Kent , research facility in England. It

612-483: A large number of patients, yields no evidence for an increased risk of non-arteritic anterior ischemic optic neuropathy or other adverse ocular events associated with PDE-5 inhibitor use. Rare but serious adverse effects found through postmarketing surveillance include prolonged erections , severe low blood pressure , myocardial infarction (heart attack), ventricular arrhythmias , stroke , increased intraocular pressure , and sudden hearing loss . In October 2007,

680-505: A list of essential medicines . A sampling of classes of medicine includes: Pharmaceuticals may also be described as "specialty", independent of other classifications, which is an ill-defined class of drugs that might be difficult to administer, require special handling during administration, require patient monitoring during and immediately after administration, have particular regulatory requirements restricting their use, and are generally expensive relative to other drugs. Drugs affecting

748-602: 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. The decision was made, in part, to reduce online sales of counterfeit and potentially dangerous erectile dysfunction treatments. In May 2013, Pfizer , which manufactures Viagra, told

SECTION 10

#1732881501449

816-718: A pharmacist dispenses only on the order of a physician, physician assistant , or qualified nurse ) from over-the-counter drugs (those that consumers can order for themselves). Another key distinction is between traditional small molecule drugs, usually derived from chemical synthesis , and biopharmaceuticals , which include recombinant proteins , vaccines , blood products used therapeutically (such as IVIG ), gene therapy , monoclonal antibodies and cell therapy (for instance, stem cell therapies). Other ways to classify medicines are by mode of action, route of administration , biological system affected, or therapeutic effects . An elaborate and widely used classification system

884-452: A process known as reverse pharmacology . Hits from these screens are then tested in cells and then in animals for efficacy . Even more recently, scientists have been able to understand the shape of biological molecules at the atomic level and to use that knowledge to design (see drug design ) drug candidates. Modern drug discovery involves the identification of screening hits, medicinal chemistry , and optimization of those hits to increase

952-411: A process of identifying a new medicine. Development: Chemicals extracted from natural products are used to make pills, capsules, or syrups for oral use. Injections for direct infusion into the blood drops for eyes or ears. Preclinical research : Drugs go under laboratory or animal testing, to ensure that they can be used on Humans. Clinical testing: The drug is used on people to confirm that it

1020-499: A suitable molecular target to supporting the drug's commercial launch. Drug development is the process of bringing a new drug to the market once a lead compound has been identified through the process of drug discovery . It includes pre-clinical research (microorganisms/animals) and clinical trials (on humans) and may include the step of obtaining regulatory approval to market the drug. Drug Development Process Discovery: The Drug Development process starts with Discovery,

1088-595: A vein , or by drops put into the ear or eye . A medication that does not contain an active ingredient and is used in research studies is called a placebo . In Europe, the term is "medicinal product", and it is defined by EU law as: In the US, a "drug" is: Drug use among elderly Americans has been studied; in a group of 2,377 people with an average age of 71 surveyed between 2005 and 2006, 84% took at least one prescription drug, 44% took at least one over-the-counter (OTC) drug, and 52% took at least one dietary supplement ; in

1156-431: A vein), or through the sublingual route (dissolved under the tongue). Onset when taken orally is typically within twenty minutes and lasts for about two hours. Common side effects include headaches , heartburn , and flushed skin . Caution is advised in those with cardiovascular disease . Rare but serious side effects include vision problems, hearing loss , and prolonged erection (priapism) that can lead to damage to

1224-470: Is N-desmethylated sildenafil, which is metabolised further. 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

1292-406: Is a drug used to diagnose , cure , treat, or prevent disease. Drug therapy ( pharmacotherapy ) is an important part of the medical field and relies on the science of pharmacology for continual advancement and on pharmacy for appropriate management. Drugs are classified in many ways. One of the key divisions is by level of control , which distinguishes prescription drugs (those that

1360-493: Is a medicine or a chemical compound used to treat or cure illness. According to Encyclopædia Britannica , medication is "a substance used in treating a disease or relieving pain ". As defined by the National Cancer Institute , dosage forms of medication can include tablets , capsules , liquids, creams , and patches. Medications can be administered in different ways, such as by mouth , by infusion into

1428-571: Is available over-the-counter (OTC). The primary indication of sildenafil is treatment of erectile dysfunction (inability to sustain a satisfactory erection to complete sexual intercourse ). Its use is now one of the standard treatments for erectile dysfunction, including for males with diabetes mellitus . Tentative evidence suggests that sildenafil may help males who experience antidepressant -induced erectile dysfunction . While sildenafil improves some markers of disease in people with pulmonary arterial hypertension , it does not appear to affect

SECTION 20

#1732881501449

1496-468: Is not an indication of any disease or disorder. Unless it causes an impairment or significant distress, it is not in and of itself diagnostically relevant. The eye's lens is normally tinted yellow . This reduces the intensity of blue light reaching the retina . When the lens is removed because of cataract , it is usually replaced by an artificial intraocular lens ; these artificial lenses are clear, allowing more intense blue light than usual to fall on

1564-573: Is not clear. Sildenafil has been studied for high-altitude pulmonary edema (HAPE), but its use is currently not recommended for that indication. In clinical trials , the most common adverse effects of sildenafil use included headache , flushing , indigestion , nasal congestion , and impaired vision, including photophobia and blurred vision . Some sildenafil users have complained of seeing everything tinted blue ( cyanopsia ). This cyanopsia can be explained because sildenafil, while selective for PDE 5 , does have some affinity for PDE 6 , which

1632-401: Is not possible to determine whether these oral medicines for erectile dysfunction were the cause of the loss of eyesight or whether the problem is related to other factors such as high blood pressure or diabetes, or to a combination of these problems." A careful review of pooled data from clinical trials containing well documented information about the dose and duration of exposure to the drug for

1700-465: Is one of the world's most counterfeited medicines. According to a 2012 Pfizer study, around 80% of sites claiming to sell Viagra were selling counterfeits. An October 2023 release stated that erectile dysfunction medicines were the most seized drugs by the Interpol accounting for 22% of seizures. International networks may be active. In the US, even though sildenafil is available only by prescription from

1768-422: Is safe to use. FDA Review: drug is sent to FDA before launching the drug into the market. FDA post-Market Review: The drug is reviewed and monitored by FDA for the safety once it is available to the public. The regulation of drugs varies by jurisdiction. In some countries, such as the United States, they are regulated at the national level by a single agency. In other jurisdictions, they are regulated at

1836-523: Is still a lengthy, "expensive, difficult, and inefficient process" with a low rate of new therapeutic discovery. In 2010, the research and development cost of each new molecular entity (NME) was approximately US$ 1.8 billion. Drug discovery is done by pharmaceutical companies, sometimes with research assistance from universities. The "final product" of drug discovery is a patent on the potential drug. The drug requires very expensive Phase I, II, and III clinical trials, and most of them fail. Small companies have

1904-778: Is the Anatomical Therapeutic Chemical Classification System . The World Health Organization keeps a list of essential medicines . Drug discovery and drug development are complex and expensive endeavors undertaken by pharmaceutical companies , academic scientists, and governments. As a result of this complex path from discovery to commercialization, partnering has become a standard practice for advancing drug candidates through development pipelines. Governments generally regulate what drugs can be marketed, how drugs are marketed , and in some jurisdictions, drug pricing . Controversies have arisen over drug pricing and disposal of used Medicine . Medication

1972-484: Is the phosphodiesterase found in the retina. Patients thus taking the drug may experience colorvision abnormalities. Some complained of blurriness and loss of peripheral vision . In July 2005, the US Food and Drug Administration (FDA) updated labeling for tadalafil (Cialis), vardenafil (Levitra), and sildenafil (Viagra) to reflect a small number of post-marketing reports of sudden vision loss, while acknowledging that "...it

2040-460: Is the same under both brand names. Sildenafil is available as a generic drug in the United States, labeled for pulmonary arterial hypertension. In the US, Revatio and Viagra are marketed by Viatris after Upjohn was spun off from Pfizer. Pfizer's patent on sildenafil citrate expired in Brazil in 2010. In Canada, Pfizer's patent 2,324,324 for Revatio (sildenafil used to treat pulmonary hypertension)

2108-406: Is used for euthanasia and physician-assisted suicide . Euthanasia is not permitted by law in many countries, and consequently, medicines will not be licensed for this use in those countries. A single drug may contain single or multiple active ingredients . The administration is the process by which a patient takes medicine. There are three major categories of drug administration: enteral (via

Sildenafil - Misplaced Pages Continue

2176-469: Is used per day (e.g., four times a day). It may include event-related information (e.g., 1 hour before meals, in the morning, at bedtime), or complimentary to an interval, although equivalent expressions may have different implications (e.g., every 8 hours versus 3 times a day). In the fields of medicine, biotechnology , and pharmacology , drug discovery is the process by which new drugs are discovered. Historically, drugs were discovered by identifying

2244-436: Is usually some degree of restriction on the availability of certain therapeutic goods depending on their risk to consumers. Cyanopsia Cyanopsia is a medical symptom and not a sign . It is a purely subjective state and can be caused by a physical or functional abnormality of the eye, a physical or functional abnormality of the brain, or be purely psychological. Cyanopsia, if unaccompanied by any other sign or symptom,

2312-474: 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 on 11 December 2017. In December 2017, Pfizer released its own generic version of Viagra. As of 2018,

2380-604: 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. Overall, this results in

2448-506: The affinity , selectivity (to reduce the potential of side effects), efficacy/ potency , metabolic stability (to increase the half-life ), and oral bioavailability . Once a compound that fulfills all of these requirements has been identified, it will begin the process of drug development prior to clinical trials . One or more of these steps may, but not necessarily, involve computer-aided drug design . Despite advances in technology and understanding of biological systems, drug discovery

2516-3535: The central nervous system include psychedelics , hypnotics , anaesthetics , antipsychotics , eugeroics , antidepressants (including tricyclic antidepressants , monoamine oxidase inhibitors , lithium salts , and selective serotonin reuptake inhibitors (SSRIs)), antiemetics , anticonvulsants /antiepileptics, anxiolytics , barbiturates , movement disorder (e.g., Parkinson's disease ) drugs, nootropics , stimulants (including amphetamines ), benzodiazepines , cyclopyrrolones , dopamine antagonists , antihistamines , cholinergics , anticholinergics , emetics , cannabinoids , and 5-HT (serotonin) antagonists . The main classes of painkillers are NSAIDs , opioids , and local anesthetics . For consciousness (anesthetic drugs) Some anesthetics include benzodiazepines and barbiturates . The main categories of drugs for musculoskeletal disorders are: NSAIDs (including COX-2 selective inhibitors ), muscle relaxants , neuromuscular drugs , and anticholinesterases . Antibiotics , sympathomimetics , antihistamines , anticholinergics , NSAIDs , corticosteroids , antiseptics , local anesthetics , antifungals , and cerumenolytics. Bronchodilators , antitussives , mucolytics , decongestants , inhaled and systemic corticosteroids , beta2-adrenergic agonists , anticholinergics , mast cell stabilizers , leukotriene antagonists . Androgens , antiandrogens , estrogens , gonadotropin , corticosteroids , human growth hormone , insulin , antidiabetics ( sulfonylureas , biguanides / metformin , thiazolidinediones , insulin ), thyroid hormones , antithyroid drugs, calcitonin , diphosphonate , vasopressin analogues . Antifungal , alkalinizing agents , quinolones , antibiotics , cholinergics , anticholinergics , antispasmodics , 5-alpha reductase inhibitor , selective alpha-1 blockers , sildenafils , fertility medications . NSAIDs , anticholinergics , haemostatic drugs , antifibrinolytics , Hormone Replacement Therapy (HRT), bone regulators, beta-receptor agonists , follicle stimulating hormone , luteinising hormone , LHRH , gamolenic acid , gonadotropin release inhibitor , progestogen , dopamine agonists , oestrogen , prostaglandins , gonadorelin , clomiphene , tamoxifen , diethylstilbestrol . Emollients , anti-pruritics , antifungals , antiseptics , scabicides , pediculicides , tar products, vitamin A derivatives , vitamin D analogues , keratolytics , abrasives , systemic antibiotics , topical antibiotics , hormones , desloughing agents, exudate absorbents, fibrinolytics , proteolytics , sunscreens , antiperspirants , corticosteroids , immune modulators. Antibiotics , antifungals , antileprotics , antituberculous drugs , antimalarials , anthelmintics , amoebicides , antivirals , antiprotozoals , probiotics, prebiotics, antitoxins , and antivenoms. Vaccines , immunoglobulins , immunosuppressants , interferons , and monoclonal antibodies . Anti-allergics , antihistamines , NSAIDs , corticosteroids . Tonics, electrolytes and mineral preparations (including iron preparations and magnesium preparations ), parenteral nutrition , vitamins , anti-obesity drugs , anabolic drugs , haematopoietic drugs, food product drugs. Cytotoxic drugs , therapeutic antibodies , sex hormones , aromatase inhibitors , somatostatin inhibitors, recombinant interleukins , G-CSF , erythropoietin . Contrast media . A euthanaticum

2584-474: The corpus cavernosum . 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. Robert F. Furchgott , Ferid Murad , and Louis Ignarro won

2652-410: The human gastrointestinal tract ), injection into the body, and by other routes ( dermal , nasal , ophthalmic , otologic , and urogenital ). Oral administration , the most common form of enteral administration, can be performed using various dosage forms including tablets or capsules and liquid such as syrup or suspension. Other ways to take the medication include buccally (placed inside

2720-461: The penis . Sildenafil should not be taken by people on nitric oxide donors such as nitroglycerin (glycerin trinitrate), as this may result in a serious drop in blood pressure . Sildenafil acts by blocking phosphodiesterase 5 (PDE 5 ), an enzyme that promotes breakdown of cGMP , which regulates blood flow in the penis. It requires sexual arousal to work, and does not by itself cause or increase sexual arousal. It also results in dilation of

2788-455: The FDA announced that the labeling for all PDE 5 inhibitors, including sildenafil, required a more prominent warning of the potential risk of sudden hearing loss. Care should be exercised by people who are also taking protease inhibitors for the treatment of HIV infection . Protease inhibitors inhibit the metabolism of sildenafil, effectively multiplying the plasma levels of sildenafil, increasing

Sildenafil - Misplaced Pages Continue

2856-626: 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 1992, Pfizer filed a patent covering the substance sildenafil and its use to treat cardiovascular diseases. This would be marketed as Revatio. The patent was published in 1993 and expired in 2012. 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

2924-494: The US from a number of manufacturers, including Greenstone, Mylan, and Watson, since early 2013. Health care providers may prescribe generic sildenafil for erectile dysfunction. 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. In 1994, Pfizer filed a patent covering the use of sildenafil to treat erectile dysfunction. This would be marketed as Viagra. This patent

2992-643: The active ingredient from traditional remedies or by serendipitous discovery. Later chemical libraries of synthetic small molecules , natural products , or extracts were screened in intact cells or whole organisms to identify substances that have a desirable therapeutic effect in a process known as classical pharmacology . Since sequencing of the human genome which allowed rapid cloning and synthesis of large quantities of purified proteins, it has become common practice to use high throughput screening of large compound libraries against isolated biological targets which are hypothesized to be disease-modifying in

3060-476: The art or science to which it pertains" to produce it. It added further: "As a matter of policy and sound statutory interpretation, patentees cannot be allowed to 'game' the system in this way. This, in my view, is the key issue in this appeal." Teva Canada launched Novo-Sildenafil, a generic version of Viagra, on the day the Supreme Court of Canada released its decision. To remain competitive, Pfizer then reduced

3128-399: The basis of pharmacological properties like mode of action and their pharmacological action or activity, such as by chemical properties , mode or route of administration , biological system affected, or therapeutic effects . An elaborate and widely used classification system is the Anatomical Therapeutic Chemical Classification System (ATC system). The World Health Organization keeps

3196-533: The blood vessels in the lungs. Pfizer originally discovered the medication in 1989 while looking for a treatment for angina . It was approved for medical use in the United States and in the European Union in 1998. In 2022, it was the 157th most commonly prescribed medication in the United States, with more than 3   million prescriptions. It is available as a generic medication . In the United Kingdom, it

3264-400: The cheek), sublingually (placed underneath the tongue), eye and ear drops (dropped into the eye or ear), and transdermally (applied to the skin). They can be administered in one dose, as a bolus . Administration frequencies are often abbreviated from Latin, such as every 8 hours reading Q8H from Quaque VIII Hora . The drug frequencies are often expressed as the number of times a drug

3332-559: The common side effect of erectile dysfunction, a combination known as " sextasy ", "rockin' and rollin,'" "hammerheading," or "trail mix". Mixing it with amyl nitrite , another vasodilator , is particularly dangerous and potentially fatal. The 2007 Ig Nobel Prize in aviation went to Patricia V. Agostino, Santiago A. Plano, and Diego A. Golombek of Universidad Nacional de Quilmes , Argentina, for their discovery that sildenafil helps treat jet lag recovery in hamsters . Professional athletes have been documented using sildenafil, believing

3400-610: The corpus cavernosum, resulting in more cGMP and increased penile response to sexual stimulation. 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

3468-414: The drug's association with treating erectile dysfunction has led to its recreational use. The reasons behind such use include the belief that the drug increases libido, improves sexual performance, or permanently increases penis size. Studies on the effects of sildenafil when used recreationally are limited, but suggest it has little effect when used by those who do not have erectile dysfunction. In one study,

SECTION 50

#1732881501449

3536-568: 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 . In 2017, the Medicines and Healthcare products Regulatory Agency (MHRA) enacted legislation that expanded this nationwide, allowing

3604-504: The incidence and severity of side effects. Those using protease inhibitors are recommended to limit their use of sildenafil to no more than one 25 mg dose every 48 hours. Other drugs that interfere with the metabolism of sildenafil include erythromycin and cimetidine , both of which can also lead to prolonged plasma half-life levels. The use of sildenafil and an α 1 blocker (typically prescribed for hypertension or for urologic conditions, such as benign prostatic hypertrophy ) at

3672-425: The laws are drafted to ban analogs of illegal drugs of abuse, rather than analogs of prescription medicines. However, at least one court case has resulted in a product being taken off the market. The US Food and Drug Administration (FDA) has banned numerous products claiming to be Eurycoma longifolia that, in fact, contain only analogs of sildenafil. Sellers of such fake herbals typically respond by just changing

3740-491: 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. Sildenafil protects cyclic guanosine monophosphate (cGMP) from degradation by cGMP-specific phosphodiesterase type 5 (PDE5) in

3808-623: The opening of their blood vessels will enrich their muscles. In turn, they believe it will enhance their performances. Acetildenafil and other synthetic structural analogs of sildenafil which are PDE5 inhibitors have been found as adulterants in a number of "herbal" aphrodisiac products sold over-the-counter. These analogs have not undergone any of the rigorous testing that drugs like sildenafil have passed, and thus have unknown side-effect profiles. Some attempts have been made to ban these drugs, but progress has been slow so far, as, even in those jurisdictions that have laws targeting designer drugs,

3876-518: The price of Viagra in Canada. However, on 9 November 2012, Pfizer filed a motion for a re-hearing of the appeal in the Supreme Court of Canada, on the grounds that the court accidentally exceeded its jurisdiction by voiding the patent. Finally, on 22 April 2013, the Supreme Court of Canada invalidated Pfizer's patent altogether. Medication A medication (also called medicament , medicine , pharmaceutical drug , medicinal drug or simply drug )

3944-402: The retina, leading to the phenomenon. Hayashi and Hayashi (2006) compared visual function in people given yellow-tinted intraocular lenses with that in people given non-tinted intraocular lenses. Those with the yellow-tinted lenses were less likely to report cyanopsia than those with the clear lenses. Hayashi and Hayashi found no differences in visual acuity or in contrast sensitivity between

4012-580: The risk of death or serious side effects. Sildenafil and other PDE 5 inhibitors are used off-label to alleviate vasospasm and treat severe ischemia and ulcers in fingers and toes for people with secondary Raynaud's phenomenon ; these drugs have moderate efficacy for reducing the frequency and duration of vasospastic episodes. As of 2016, their role more generally in Raynaud's was not clear. Sildenafil has shown some potential for improving exercise performance at high altitudes . However, its overall efficacy

4080-414: The same time may lead to low blood pressure, but this effect does not occur if they are taken at least 4 hours apart. Contraindications include: Sildenafil should not be used if sexual activity is inadvisable due to underlying cardiovascular risk factors. Sildenafil's popularity with young adults has increased over the years. Sildenafil's brand name, Viagra, is widely recognized in popular culture, and

4148-418: The shape and colour of Pfizer's product. Viagra is also informally known as "vitamin V", "the blue pill", or "blue diamond", as well as various other nicknames. Viagra and other products for sexual dysfunction, termed sexuopharmaceuticals, proliferated new types of specialised marketing for such products. Viagra and similar prescription pharmaceuticals were promoted by images in media to the extent of becoming

SECTION 60

#1732881501449

4216-516: The state level, or at both state and national levels by various bodies, as is the case in Australia. The role of therapeutic goods regulation is designed mainly to protect the health and safety of the population. Regulation is aimed at ensuring the safety, quality, and efficacy of the therapeutic goods which are covered under the scope of the regulation. In most jurisdictions, therapeutic goods must be registered before they are allowed to be marketed. There

4284-545: The two groups. They also found that no one reported cyanopsia three months after the cataract operation, suggesting that some form of neural adaptation or colour constancy had taken place. The author of Viagra and vision attributes cyanopsia after taking sildenafil to diminished enzyme activity, thereby sensitizing the retinal rod cells . Rod cells are most sensitive to light of wavelengths near 498 nm; such light appears blue-green. When light levels are low enough for both rods and cone cells to be active ( mesopic vision )

4352-483: The use of such advertisements. In 2000, Viagra sales accounted for 92% of the global market for prescribed erectile dysfunction pills. By 2007, Viagra's global share had plunged to about 50% 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. In 2008, the FDA forced Pfizer to remove Viva Cruiser , an advergame for Viagra, from appearing on Forbes , after

4420-568: 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. It soon became a great success: annual sales of Viagra peaked in 2008 at US$ 1.934 billion. Counterfeit Viagra, despite generally being cheaper, can contain harmful substances or substances that affect how Viagra works, such as blue printer ink, amphetamines , metronidazole , boric acid , and rat poison . Viagra

4488-598: Was found invalid by the Federal Court in June 2010, on an application by Ratiopharm Inc. On 8 November 2012, the Supreme Court of Canada ruled that Pfizer's patent 2,163,446 on Viagra was invalid from the beginning because the company did not provide full disclosure in its application. The decision, Teva Canada Ltd. v. Pfizer Canada Inc. , pointed to section 27(3)(b) of The Patent Act which requires that disclosure must include sufficient information "to enable any person skilled in

4556-646: Was initially studied for use in hypertension (high blood pressure) and angina pectoris (a symptom of ischaemic heart disease ). The first clinical trials were conducted in Morriston Hospital in Swansea . 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 . Pfizer therefore decided to market it for erectile dysfunction, rather than for angina; this decision became an often-cited example of drug repositioning . The drug

4624-547: Was published in 2002 and expired in 2019. Teva sued to have the latter patent invalidated, but Pfizer prevailed in an August 2011 federal district court case. An agreement with Pfizer allowed Teva to begin to provide the generic drug in December 2017. 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). The substance

#448551