NationMaster - Encyclopedia: Sildenafil

Sildenafil citrate, sold under the names Viagra, Revatio and generically under various other names, is a drug used to treat male erectile dysfunction (impotence) and pulmonary arterial hypertension (PAH), developed by the pharmaceutical company Pfizer. Viagra pills are blue and diamond-shaped with the words "Pfizer" on one side, and "VGR xx" (where xx stands for "25", "50" or "100", the dose of that pill in milligrams) on the other. Its primary competitors on the market are tadalafil (Cialis), and vardenafil (Levitra). In pharmacology and toxicology, a route of administration is the path by which a drug, fluid, poison or other substance is brought into contact with the body 1. ... Oral medication A medication is a licenced drug taken to cure or reduce symptoms of an illness or medical condition. ... Erectile dysfunction (ED) or impotence is a sexual dysfunction characterized by the inability to develop or maintain an erection of the penis. ... In medicine, pulmonary hypertension (PH) is an increase in blood pressure in the pulmonary artery or lung vasculature, leading to shortness of breath, dizziness, fainting, and other symptoms, all of which are exacerbated by exertion. ... A pharmaceutical company, or drug company, is a commercial business licensed to research, develop, market and/or distribute drugs, most commonly in the context of healthcare. ... Pfizer, Incorporated (NYSE: PFE) (pronounced faÉªzÉ™É¹ or faÉªzÉ™), is the worlds largest pharmaceutical company. ... Tadalafil is a drug used to treat male erectile dysfunction (impotence). ... Vardenafil (INN) is a PDE5 inhibitor used in the treatment of erectile dysfunction. ...

History

Sildenafil (compound UK-92,480) was synthesized by a group of pharmaceutical chemists working at Pfizer's Sandwich, Kent research facility. It was initially studied for use in hypertension (high blood pressure) and angina pectoris (a form of ischaemic cardiovascular disease). Phase I clinical trials under the direction of Ian Osterloh suggested that the drug had little effect on angina, but that it could induce marked penile erections.^[1]^[2] Pfizer therefore decided to market it for erectile dysfunction, rather than for angina. The drug was patented in 1996, approved for use in erectile dysfunction by the Food and Drug Administration on March 27, 1998, becoming the first pill approved to treat erectile dysfunction in the United States, and offered for sale in the United States later that year.^[3] It soon became a great success: annual sales of Viagra in the period 1999–2001 exceeded $1 billion. This article or section does not cite its references or sources. ... For other forms of hypertension, see Hypertension (disambiguation). ... In medicine, ischemia (Greek Î¹ÏƒÏ‡Î±Î¹Î¼Î¯Î±, isch- is restriction, hema or haema is blood) is a restriction in blood supply, generally due to factors in the blood vessels, with resultant damage or dysfunction of tissue. ... Cardiovascular disease refers to the class of diseases that involve the heart and/or blood vessels (arteries and veins). ... In medicine, a clinical trial (synonyms: clinical studies, research protocols, medical research) is a type of research study. ... Ian Osterloh Is a clinical researcher attributed with the creation of viagra and numerous other Cardiovascular Drugs. ... The erection of the penis, clitoris or a nipple is its enlarged and firm state. ... A patent is a set of exclusive rights granted by a state to a patentee (the inventor or assignee) for a fixed period of time in exchange for the regulated, public disclosure of certain details of a device, method, process or composition of matter (substance) (known as an invention) which... 1996 (MCMXCVI) was a leap year starting on Monday of the Gregorian calendar, and was designated the International Year for the Eradication of Poverty. ... The Food and Drug Administration (FDA) is an agency of the United States Department of Health and Human Services and is responsible for regulating food (humans and animal), dietary supplements, drugs (human and animal), cosmetics, medical devices (human and animal) and radiation emitting devices (including non-medical devices), biologics, and... March 27 is the 86th day of the year in the Gregorian Calendar (87th in leap years). ... 1998 (MCMXCVIII) was a common year starting on Thursday of the Gregorian calendar, and was designated the International Year of the Ocean. ... 1999 (MCMXCIX) was a common year starting on Friday, and was designated the International Year of Older Persons by the United Nations. ... 2001 (MMI) was a common year starting on Monday of the Gregorian calendar. ... One thousand million (1,000,000,000) is the natural number following 999,999,999 and preceding 1,000,000,001. ...

The British press portrayed Peter Dunn and Albert Wood as the inventors of the drug, a claim which Pfizer disputes.^[4] Their names are on the manufacturing patent application drug, but Pfizer claims this is only for convenience.

Even though sildenafil is only available by prescription from a doctor, it was advertised directly to consumers on US TV (famously being endorsed by Bob Dole and Football star Pelé). Numerous sites on the Internet offer Viagra for sale after an "online consultation", a mere 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 the shape and colour of Pfizer's product. Viagra is also informally known as "Vitamin V", "the Blue Pill", as well as various other nicknames. Image File history File linksMetadata Download high-resolution version (1600x1200, 965 KB) Viagra source : http://sxc. ... Image File history File linksMetadata Download high-resolution version (1600x1200, 965 KB) Viagra source : http://sxc. ... Robert Joseph Bob Dole (Born July 22, 1923) was the Republican candidate in the 1996 U.S. Presidential election. ... For the Hawaiian goddess, see Pele (mythology). ... An aphrodisiac is an agent which increases sexual desire[1] or sexual arousal. ...

In February 2007, it was announced that Boots the Chemist would trial over the counter sales of Viagra in stores in Manchester, England. Men aged between 30 and 65 would be eligible to buy four tablets after a consultation with a pharmacist.^[5] Boots is the dominant pharmacist chain in the United Kingdom, with outlets in most high streets throughout the country. ... See separate articles for over-the-counter trading and the medical condition Ornithine Transcarbamylase Deficiency. ... Manchester City Centre, seen here in 2007. ... Motto: (French for God and my right) Anthem: God Save the King/Queen Capital London (de facto) Largest city London Official language(s) English (de facto) Unification - by Athelstan AD 927 Area - Total 130,395 kmÂ² (1st in UK) 50,346 sq mi Population - 2006 est. ... The mortar and pestle is an international symbol of pharmacists and pharmacies. ...

Pfizer's worldwide patents on sildenafil citrate will expire in 2011–2013. The UK patent held by Pfizer on the use of PDE5 inhibitors (see below) as treatment of impotence was invalidated in 2000 because of obviousness; this decision was upheld on appeal in 2002. A phosphodiesterase type 5 inhibitor, often shortened to PDE5 inhibitor, is a drug used to block the degradative action of phosphodiesterase type 5 on cyclic GMP in the smooth muscle cells lining the blood vessels supplying the corpus cavernosum of the penis. ...

Mechanism of action

Part of the physiological process of erection involves the parasympathetic nervous system causing the release of nitric oxide (NO) in the corpus cavernosum of the penis. NO binds to the receptors of the enzyme guanylate cyclase which results in increased levels of cyclic guanosine monophosphate (cGMP), leading to smooth muscle relaxation (vasodilation) in the corpus cavernosum, resulting in increased inflow of blood and an erection. Autonomic nervous system innervation, showing the sympathetic and parasympathetic (craniosacral) systems, in red and blue, respectively The parasympathetic nervous system is one of three divisions of the autonomic nervous system. ... R-phrases , , , , S-phrases , , , Supplementary data page Structure and properties n, Îµr, etc. ... A corpus cavernosum is one of a pair of a sponge-like regions of erectile tissue which contain most of the blood in the male penis during erection. ... Guanylate cyclase (EC 4. ... Cyclic guanosine monophosphate (cGMP) is a second messenger derived from GTP. Cyclic guanosine monophosphate (cGMP) is a cyclic nucleotide derived from guanosine triphosphate (GTP). ... Cultured Smooth muscle of the aorta. ...

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 the corpus cavernosum, resulting in more cGMP and better erections. 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®). cGMP specific phosphodiesterase type 5 is an enzyme (EC 3. ... A corpus cavernosum is one of a pair of a sponge-like regions of erectile tissue which contain most of the blood in the male penis during erection. ... Tadalafil is a drug used to treat male erectile dysfunction (impotence). ... Vardenafil (INN) is a PDE5 inhibitor used in the treatment of erectile dysfunction. ...

Sildenafil is metabolised by hepatic enzymes and excreted by both the liver and kidneys. If taken with a high-fat meal, there may be a delay in absorption of sildenafil and the peak effect might be reduced slightly as the plasma concentration will be lowered. Overview of the citric acid cycle The citric acid cycle, one of the central metabolic pathways in aerobic organisms. ... The liver is an organ in some animals, including vertebrates (and therefore humans). ... Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ... The liver is an organ in some animals, including vertebrates (and therefore humans). ... It has been suggested that Renal anomalies and Renal plasma threshold be merged into this article or section. ...

Dosage and price

As with all prescription drugs, proper dosage is at the discretion of a licensed medical doctor. The dose of sildenafil is 25 mg to 100 mg taken once per day between 30 minutes and 4 hours prior to sexual intercourse. A prescription drug (or POM Prescription Only Medicine, in UK) is a licensed medicine that is regulated by legislation to require a prescription before it can be obtained. ... It has been suggested that Duration of sexual intercourse be merged into this article or section. ...

It is usually recommended to start with a dosage of 50 mg and then lower or raise the dosage as appropriate. The drug is sold in three dosages (25, 50, and 100 mg), all three costing about US$10 per pill. Name-brand Viagra sildenafil is not scored and a fairly hard coating makes it more difficult to accurately cut the pills in half, even with a pill cutter.

Contraindications

Contraindications include: In medicine, a contraindication is a condition or factor that increases the risk involved in using a particular drug, carrying out a medical procedure or engaging in a particular activity. ...

Sodium nitroprusside (Na3Fe(CN)5NO) is a potent peripheral vasodilator which affects both arterioles and venules. ... The chemical compound amyl nitrite (here referring to isoamyl nitrite) is an alkyl nitrite. ... It has been suggested that Duration of sexual intercourse be merged into this article or section. ... The circulatory system or cardiovascular system is the organ system which circulates blood around the body of most animals. ... In medicine (nephrology) renal function is an indication of the state of the kidney and its role in physiology. ... In physiology and medicine, hypotension refers to an abnormally low blood pressure. ... A stroke, also known as cerebrovascular accident (CVA),[1] is an acute neurological injury in which the blood supply to a part of the brain is interrupted. ... Acute myocardial infarction (AMI or MI), commonly known as a heart attack, is a disease state that occurs when the blood supply to a part of the heart is interrupted. ... A phosphodiesterase (PDE) is an enzyme that catalyzes the hydrolysis of phosphodiester bonds. ...

Side effects

Amongst sildenafil's serious adverse effects are: priapism, severe hypotension, myocardial infarction, ventricular arrhythmias, sudden death, stroke and increased intraocular pressure. Bronze sculpture depicting Priapus. ... In physiology and medicine, hypotension refers to an abnormally low blood pressure. ... Acute myocardial infarction (AMI or MI), commonly known as a heart attack, is a disease state that occurs when the blood supply to a part of the heart is interrupted. ... A stroke, also known as cerebrovascular accident (CVA),[1] is an acute neurological injury in which the blood supply to a part of the brain is interrupted. ... Intraocular pressure is the fluid pressure inside the eye. ...

Common side effects include sneezing, headache, flushing, dyspepsia, prolonged erections, palpitations and photophobia. Visual changes including blurring of vision and a curious bluish tinge have also been reported. Little Sammy Sneeze by Winsor McCay A sternutation, sternutatory reflex or, more commonly known, sneeze is a semi-autonomous, convulsive expulsion of air from the nose and mouth. ... A headache is a condition of pain in the head; sometimes neck or upper back pain may also be interpreted as a headache. ... For a person to flush is to become markedly red in the face and often other areas of the skin, from various physiological conditions. ... A palpitation is an awareness of the beating of the heart, whether it is too slow, too fast, irregular, or at its normal frequency; brought on by overexertion, adrenaline, alcohol, disease (such as hyperthyroidism) or drugs, or as a symptom of panic disorder. ... Photophobia (also light sensitivity) or fear of light, is a symptom of excessive sensitivity to light and the aversion to sunlight or well-lit places. ...

Care should be exercised by patients who are also taking Protease inhibitors for the treatment of HIV. Protease inhibitors inhibit the metabolism of sildenafil, effectively multiplying the plasma levels of sildenafil, increasing the incidence and severity of side-effects. It is recommended that patients using protease inhibitors limit their use of sildenafil to no more than one 25-mg dose every 48 hours. Protease inhibitors are a class of medication used to treat or prevent viral infections. ... Human immunodeficiency virus or HIV is a retrovirus that causes Acquired Immunodeficiency Syndrome (AIDS), a condition in which the immune system begins to fail, leading to life-threatening opportunistic infections. ...

Some sildenafil users have complained of blurriness and loss of peripheral vision. In May of 2005, the U.S. Food and Drug Administration found that sildenafil could lead to vision impairment^[7] and a number of studies have linked sildenafil use with nonarteritic anterior ischemic optic neuropathy.^[8]^[9]^[10]^[11]^[12]^[13] Peripheral vision is a part of vision that occurs outside the very center of gaze. ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... For other uses, see United States (disambiguation) and US (disambiguation). ... The Food and Drug Administration (FDA) is an agency of the United States Department of Health and Human Services and is responsible for regulating food (humans and animal), dietary supplements, drugs (human and animal), cosmetics, medical devices (human and animal) and radiation emitting devices (including non-medical devices), biologics, and... Anterior ischemic optic neuropathy (AION) is a medical condition involving loss of vision due to damage to the optic nerve from insufficient blood supply. ...

When used with an alpha blocker, take them at least four hours apart to avoid hypotension.^[14] Alpha blockers (also called alpha-adrenergic blocking agents) constitute a variety of drugs which block alpha-adrenergic receptors in arteries and smooth muscles. ... In physiology and medicine, hypotension refers to an abnormally low blood pressure. ...

Other uses

Pulmonary hypertension

As well as erectile dysfunction, sildenafil citrate is also effective in the rare disease pulmonary arterial hypertension (PAH). It relaxes the arterial wall, leading to decreased pulmonary arterial resistance and pressure. This in turn reduces the workload of the right ventricle of the heart and improves symptoms of right-sided heart failure. Because PDE-5 is primarily distributed within the arterial wall smooth muscle of the lungs and penis, sildenafil acts selectively in both these areas without inducing vasodilation in other areas of the body. Pfizer submitted an additional registration for sildenafil to the FDA, and sildenafil was approved for this indication in June 2005. The preparation is named Revatio, to avoid confusion with Viagra, and the 20 milligram tablets are white and round. Sildenafil joins bosentan and prostacyclin-based therapies for this condition.^[15] A rare disease (sometimes known as an orphan disease) has such a low prevalence in a population that a doctor in a busy general practice would not expect to see more than one case a year. ... In medicine, pulmonary hypertension (PH) is an increase in blood pressure in the pulmonary artery or lung vasculature, leading to shortness of breath, dizziness, fainting, and other symptoms, all of which are exacerbated by exertion. ... In the heart, a ventricle is a heart chamber which collects blood from an atrium (another heart chamber that is smaller than ventricle) and pumps it out of the heart. ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... Bosentan is an endothelin receptor antagonist important in the treatment of pulmonary artery hypertension. ... Prostacyclin is a member of the family of lipid molecules known as eicosanoids. ...

Raynaud's phenomenon

In 2005, Dr. Roland Fries and colleagues reported that sildenafil cut the frequency of Raynaud's phenomenon attacks, reduced their duration by roughly one half, and more than quadrupled the mean capillary blood velocity. This was a double-blind, placebo-controlled crossover trial and the patients had both the primary and secondary forms and had all discontinued the more conventional treatments for this.^[16] In medicine, Raynauds phenomenon is discoloration of the fingers or toes due to emotion or cold in a characteristic pattern in time: white, blue and red. ...

Non-medical use

Aphrodisiac

Sildenafil is commonly and increasingly used as an aphrodisiac. While there is no clinical evidence that it has aphrodisiac activity, many seem to believe it will improve sexual performance as well as erectile function and enhance the sexual experience that will occur.^{[citation needed]} An aphrodisiac is an agent which increases sexual desire[1] or sexual arousal. ...

Recreational use

Viagra's popularity with young adults has increased over the years.^[17] It is sometimes used recreationally. Some users mix Viagra with methylenedioxymethamphetamine (MDMA, ecstasy) in an attempt to compensate for the side effect common to many amphetamines of erectile dysfunction, a combination known as "sextasy", "rockin' and rollin', or 'trail mix'." MDMA (3,4-methylenedioxy-N-methylamphetamine), known by the street names ecstasy/extasy, E, XTC, or Thizz is a semisynthetic entactogen of the phenethylamine family, whose primary effect is believed to be the stimulation of secretionâ€”as well as inhibition of re-uptakeâ€”of large amounts of serotonin, as well... Sextasy is a drug mixture of methylenedioxymethamphetamine (MDMA), commonly known as Ecstasy, and a prescription drug such as sildenafil citrate (Viagra), which is a PDE5 inhibitor used for erectile dysfunction. ...

Prevention of plant wilting

A low-concentration solution of sildenafil in water significantly prolongs the time before cut flowers wilt; one experiment showed a doubling in time from one week to two weeks. The mechanism of action is similar to that in humans: nitric oxide leads to the production of cGMP whose degradation by PDE5 is inhibited by sildenafil.^[18]

Chemical Synthesis

The preparation steps for synthesis of Viagra (sildenafil citrate) are as follows:

Methylation is a term used in the chemical sciences to denote the attachment or substitution of a methyl group on various substrates. ... Hydrolysis is a chemical reaction or process in which a molecule is split into two parts by reacting with a molecule of water, which has the chemical formula H2O. One of the parts gets an OH- from the water molecule and the other part gets an H+ from the water. ... Nitration is a general chemical process for the introduction of a nitro group in a chemical compound by means of a chemical reaction. ... Semi-accurate illustration of a redox reaction Redox reactions include all chemical processes in which atoms have their oxidation number (oxidation state) changed. ... In chemistry, acylation is the process of adding an acyl group to a compound. ... Chemical structure of sulfonic acid. ... Water vapor condensing over a cup of hot tea Condensation is the change in matter of a substance to a denser phase, such as a gas (or vapor) to a liquid. ...

See also

Tadalafil is a drug used to treat male erectile dysfunction (impotence). ... Vardenafil (INN) is a PDE5 inhibitor used in the treatment of erectile dysfunction. ...

Notes

^ Boolell M, Allen MJ, Ballard SA, Gepi-Attee S, Muirhead GJ, Naylor AM, Osterloh IH, Gingell C (1996). "Sildenafil: an orally active type 5 cyclic GMP-specific phosphodiesterase inhibitor for the treatment of penile erectile dysfunction". Int J Impot Res 8 (2): 47–52. PMID 8858389.
^ Terrett NK et al (1996). "Sildenafil (Viagra), a potent and selective inhibitor of Type 5 cGMP phosphodiesterase with utility for the treatment of male erectile dysfunction". Bioorg Med Chem Lett 6: 1819–1824.
^ Kling J (1998). "From hypertension to angina to Viagra". Mod Drug Discov 1: 31–38.
^ Bellis M. Viagra, the patenting of an aphrodisiac. About.com.
^ Over-the-counter Viagra piloted. British Broadcasting Corporation (2007-02-11).
^ Cheitlin MD, Hutter AM Jr, Brindis RG, Ganz P, Kaul S, Russell RO Jr, Zusman RM (1999). "ACC/AHA expert consensus document. Use of sildenafil (Viagra) in patients with cardiovascular disease. American College of Cardiology/American Heart Association". Journal of the American College of Cardiology 33 (1): 273-82. PMID 9935041.
^ Alert for Healthcare Professionals: Sildenafil citrate (marketed as Viagra). United States Food and Drug Administration (July 2005).
^ Pomeranz HD and Bhavsar AR (2005). "Nonarteritic ischemic optic neuropathy developing soon after use of sildenafil (viagra): a report of seven new cases". J Neuroophthalmol 25 (1): 9-13.
^ Egan R and Pomeranz H (2000). "Sildenafil (Viagra) associated anterior ischemic optic neuropathy". Arch Ophthalmol 118 (2): 291-2.
^ Pomeranz HD, Smith KH, Hart WM, Egan RA (2002). "Sildenafil-associated nonarteritic anterior ischemic optic neuropathy". Ophthalmology 109 (3): 584-7.
^ Cunningham AV and Smith KH (2001). "Anterior ischemic optic neuropathy associated with viagra". J Neuroophthalmol 21 (1): 22-5.
^ Boshier A, Pambakian N, Shakir SA (2002). "A case of nonarteritic ischemic optic neuropathy (NAION) in a male patient taking sildenafil". Int J Clin Pharmacol Ther 40 (9): 422-3.
^ Akash R, Hrishikesh D, Amith P, Sabah S (2005). "Case report: association of combined nonarteritic anterior ischemic optic neuropathy (NAION) and obstruction of cilioretinal artery with overdose of Viagra". J Ocul Pharmacol Ther 24 (4): 315-7.
^ Kloner RA (2005). "Pharmacology and drug interaction effects of the phosphodiesterase 5 inhibitors: focus on alpha-blocker interactions". Am J Cardiol 96 (12B): 42M-46M.
^ Pfizer, Inc. (June 6, 2005). FDA Approves Pfizer's Revatio as Treatment for Pulmonary Arterial Hypertension. 2005 News Releases. Pfizer. Retrieved on December 27, 2005.
^ Fries, Roland; Kaveh Shariat, Hubertus von Wilmowsky, and Michael Böhm (November 8, 2005). "Sildenafil in the treatment of Raynaud's phenomenon resistant to vasodilatory therapy". Circulation 112 (19): 2980-5. PMID 16275885.
^ Peterson K. "Young men add Viagra to their drug arsenal", USAToday, 2001-03-21.
^ Siegel-Itzkovich J (1999). "Viagra makes flowers stand up straight". Student BMJ (9).
^ Dunn PJ. "Synthesis of Commercial Phosphodiesterase(V) Inhibitors". Org Process Res Dev 2005 (1): 88-97. DOI:S1083-6160(04)00019-2 10.1021/op040019c S1083-6160(04)00019-2.

2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the Anno Domini (common) era. ... February 11 is the 42nd day of the year in the Gregorian Calendar. ... Ongoing events â€¢ 2005 Atlantic and Pacific hurricanes â€¢ 2005 Maharashtra floods â€¢ 2005 Gujarat Flood â€¢ Expo 2005 in Aichi, Japan â€¢ Fuel prices â€¢ Gomery Comm. ... December 27 is the 361st day of the year in the Gregorian Calendar (362nd in leap years). ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... November 8 is the 312th day of the year (313th in leap years) in the Gregorian Calendar, with 53 days remaining. ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... 2001 (MMI) was a common year starting on Monday of the Gregorian calendar. ... March 21 is the 80th day of the year in the Gregorian Calendar (81st in leap years). ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ...

External links

HowStuffWorks is a website created by Marshall Brain but now owned by the Convex Group. ... Image File history File links Commons-logo. ...

A phosphodiesterase inhibitor is a drug that blocks one or more of the five subtypes of the enzyme phosphodiesterase (PDE), preventing the inactivation of the intracellular second messengers, cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). ... A section of the Anatomical Therapeutic Chemical Classification System. ... A section of the Anatomical Therapeutic Chemical Classification System. ... Vinpocetine (brand names: Cavinton, Intelectol; chemical name: ethyl apovincaminate) is a semisynthetic derivative of vincamine, which is extracted from the periwinkle plant. ... EHNA (erythro-9-(2-hydroxy-3-nonyl)adenine) is a phosphodiesterase inhibitor that selectively inhibits phosphodiesterase type-2 (PDE2). ... Amrinone (INN) or inamrinone, trade name InocorÂ®, is a pyridine phosphodiesterase inhibitor. ... Bucladesine is a phosphodiesterase inhibitor. ... Enoximone (INN, trade name PerfanÂ®) is an imidazole phosphodiesterase inhibitor. ... Milrinone is a phosphodiesterase III inhibitor. ... Mesembrine, is an alkaloid present in Sceletium tortuosum [1]. It has been shown to be an extremely potent serotonin reuptake inhibitor, active at dosages as low as 100Î¼g (micrograms) [2]. It has also been shown to be a PDE4-inhibitor [3]. Mesembrine may contribute to the antidepressant effects of... Rolipram is a phosphodiesterase inhibitor. ... Tadalafil is a drug used to treat male erectile dysfunction (impotence). ... Vardenafil (INN) is a PDE5 inhibitor used in the treatment of erectile dysfunction. ...

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