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Aspirin, also known as acetylsalicylic acid (ASA), is a salicylate medication, often used to treat pain, fever, and inflammation.〔 Aspirin also has an antiplatelet effect by stopping the binding together of platelets and preventing a patch over damaged walls of blood vessels. Aspirin is also used long-term, at low doses, to help prevent heart attacks, strokes, and blood clot formation in people at high risk of developing blood clots. Low doses of aspirin may be given immediately after a heart attack to reduce the risk of another heart attack or of the death of cardiac tissue. Aspirin may be effective at preventing certain types of cancer, particularly colorectal cancer. The main side effects of aspirin are gastrointestinal ulcers, stomach bleeding, and ringing in the ears, especially with higher doses. While daily aspirin can help prevent a clot-related stroke, it may increase risk of a bleeding stroke (hemorrhagic stroke). In children and adolescents, aspirin is not recommended for flu-like symptoms or viral illnesses, because of the risk of Reye's syndrome. Aspirin is part of a group of medications called nonsteroidal anti-inflammatory drugs (NSAIDs), but differs from most other NSAIDs in the mechanism of action. The salicylates have similar effects (antipyretic, anti-inflammatory, analgesic) to the other NSAIDs and inhibit the same enzyme cyclooxygenase (COX), but aspirin does so in an irreversible manner and, unlike others, affects the COX-1 variant more than the COX-2 variant of the enzyme. The therapeutic properties of willow tree bark have been known for at least 2,400 years, with Hippocrates prescribing it for headaches.〔http://www.bloomberg.com/news/articles/2012-03-20/hippocrates-s-3-cent-aspirin-once-a-day-may-keep-cancer-away〕 Salicylic acid, the active ingredient of aspirin, was first isolated from the bark of the willow tree in 1763 by Edward Stone of Wadham College, University of Oxford. Felix Hoffmann, a chemist at Bayer, is credited with the synthesis of aspirin in 1897, though whether this was of his own initiative or under the direction of Arthur Eichengrün is controversial. Aspirin is one of the most widely used medications in the world with an estimated 40,000 tonnes of it being consumed each year. In countries where "Aspirin" is a registered trademark owned by Bayer, the generic term is acetylsalicylic acid (ASA).〔(【引用サイトリンク】title=The use of aspirin )〕 It is on the WHO Model List of Essential Medicines, the most important medications needed in a basic health system. ==Medical use== Aspirin is used in the treatment of a number of conditions, including fever, pain, rheumatic fever, and inflammatory diseases, such as rheumatoid arthritis, pericarditis, and Kawasaki disease.〔(【引用サイトリンク】url=http://www.drugs.com/monograph/aspirin.html )〕 Lower doses of aspirin have also shown to reduce the risk of death from a heart attack, or the risk of stroke in some circumstances.〔(【引用サイトリンク】url=http://www.fda.gov/Drugs/ResourcesForYou/Consumers/BuyingUsingMedicineSafely/UnderstandingOver-the-CounterMedicines/SafeDailyUseofAspirin/ucm291433.htm )〕〔(【引用サイトリンク】url=http://www.uspreventiveservicestaskforce.org/uspstf/uspsasmi.htm )〕 There is some evidence that aspirin is effective at preventing colorectal cancer, though the mechanisms of this effect are unclear. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「aspirin」の詳細全文を読む スポンサード リンク
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