by ANTHONY MELVIN CRASTO

ALL ABOUT DRUGS

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Basic drugs

1 Aspirin

2-acetoxybenzoic acid Aspirin , also known as acetylsalicylic acid is a salicylate drug, often used as an analgesic to relieve minor aches and pains, as an antipyretic to reduce fever, and as an anti-inflammatorymedication. Aspirin was first isolated by Felix Hoffmann, a chemist with the German company Bayer in 1897.[1][2] Salicylic acid, the main metabolite of aspirin, is an integral part of human and animal metabolism. While in humans much of it is attributable to diet, a substantial part is synthesized endogenously.[3] Aspirin also has an antiplatelet effect by inhibiting the production of thromboxane, which under normal circumstances binds platelet molecules together to create a patch over damaged walls of blood vessels. Because the platelet patch can become too large and also block blood flow, locally and downstream, 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.[4] It has also been established that 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.[5][6] Aspirin may be effective at preventing certain types of cancer, particularly colorectal cancer.[7][7][8][9] The main undesirable side effects of aspirin taken by mouth are gastrointestinal ulcers, stomach bleeding, and tinnitus, especially in higher doses. In children and adolescents, aspirin is no longer indicated to control flu-like symptoms or the symptoms of chickenpoxor other viral illnesses, because of the risk of Reye's syndrome.[10]
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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. Though it, and others in its group called the salicylates, have similar effects (antipyretic, anti-inflammatory, analgesic) to the other NSAIDs and inhibit the same enzymecyclooxygenase, aspirin (but not the other salicylates) does so in an irreversible manner and, unlike others, affects more the COX-1 variant than the COX-2 variant of the enzyme.[11] Today, aspirin is one of the most widely used medications in the world, with an estimated 40,000 tonnes of it being consumed each year.[12] In countries where Aspirin is a registered trademark owned by Bayer, the generic term is acetylsalicylic acid (ASA).[13]
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Synthesis

The synthesis of aspirin is classified as an esterification reaction. Salicylic acid is treated with acetic anhydride, an acid derivative, causing a chemical reaction that turns salicylic acid's hydroxyl group into an ester group (R-OH → R-OCOCH3). This process yields aspirin and acetic acid, which is considered a byproduct of this reaction. Small amounts of sulfuric acid (and occasionally phosphoric acid) are almost always used as a catalyst. This method is commonly employed in undergraduate teaching labs.[104]
Aspirin synthesis.png
Reaction Mechanism
Acetylation of salicylic acid, mechanism
  1. Sneader, W. (2000). "The discovery of aspirin: A reappraisal". BMJ (Clinical research ed.) 321 (7276): 1591–1594. doi:10.1136/bmj.321.7276.1591. PMC 1119266.PMID 11124191. edit
  2. Karsten Schrör (2009). Acetylsalicylic acid. ISBN 978-3-527-32109-4.
  3. Paterson, John R.; Baxter, Gwendoline; Dreyer, Jacob S.; Halket, John M.; Flynn, Robert; Lawrence, James R. (2008)."Salicylic Acid sans Aspirin in Animals and Man: Persistence in Fasting and Biosynthesis from Benzoic Acid". Journal of Agricultural and Food Chemistry 56 (24): 11648–11652.doi:10.1021/jf800974z. PMC 2800778.PMID 19053387. edit
  4. Lewis, H D; J W Davis, D G Archibald, W E Steinke, T C Smitherman, J E Doherty, H W Schnaper, M M LeWinter, E Linares, J M Pouget, S C Sabharwal, E Chesler, H DeMots (18 August 1983). "Protective effects of aspirin against acute myocardial infarction and death in men with unstable angina. Results of a Veterans Administration Cooperative Study". The New England Journal of Medicine 309 (7): 396–403.doi:10.1056/NEJM198308183090703. ISSN 00284793.PMID 6135989.
  5. Julian, D G; D A Chamberlain, S J Pocock (24 September 1996). "A comparison of aspirin and anticoagulation following thrombolysis for myocardial infarction (the AFTER study): a multicentre unblinded randomised clinical trial". BMJ (British Medical Journal) 313 (7070): 1429–1431.doi:10.1136/bmj.313.7070.1429. PMC 2353012.PMID 8973228.
  6. Krumholz, Harlan M.; Martha J. Radford, Edward F. Ellerbeck, John Hennen, Thomas P. Meehan, Marcia Petrillo, Yun Wang, Timothy F. Kresowik, Stephen F. Jencks (1995). "Aspirin in the Treatment of Acute Myocardial Infarction in Elderly Medicare Beneficiaries : Patterns of Use and Outcomes". Circulation 92(10): 2841–2847. PMID 7586250.
  7. Algra, Annemijn M; Rothwell, Peter M (2012). "Effects of regular aspirin on long-term cancer incidence and metastasis: A systematic comparison of evidence from observational studies versus randomised trials". The Lancet Oncology.doi:10.1016/S1470-2045(12)70112-2.
  8. Rothwell, Peter M; Price, Jacqueline F; Fowkes, F Gerald R; Zanchetti, Alberto; Roncaglioni, Maria Carla; Tognoni, Gianni; Lee, Robert; Belch, Jill FF et al. (2012). "Short-term effects of daily aspirin on cancer incidence, mortality, and non-vascular death: Analysis of the time course of risks and benefits in 51 randomised controlled trials". The Lancet. doi:10.1016/S0140-6736(11)61720-0. Rothwell, Peter M; Wilson, Michelle; Price, Jacqueline F; Belch, Jill FF; Meade, Tom W; Mehta, Ziyah (2012). "Effect of daily aspirin on risk of cancer metastasis: A study of incident cancers during randomised controlled trials". The Lancet.doi:10.1016/S0140-6736(12)60209-8.
  9. Macdonald S (2002). "Aspirin use to be banned in under 16 year olds". BMJ 325 (7371): 988.doi:10.1136/bmj.325.7371.988/c. PMC 1169585.PMID 12411346.
  10. Burke, Anne; Smyth, Emer; FitzGerald, Garret A. (2006). "26: Analgesic Antipyretic and Antiinflammatory Agents".Goodman and Gilman's the pharmacological basis of therapeutics (11 ed.). New York: McGraw-Hill. pp. 671–716.ISBN 978-0-07-142280-2.
  11. Warner, T. D.; Warner TD, Mitchell JA (2002)."Cyclooxygenase-3 (COX-3): filling in the gaps toward a COX continuum?". Proc Natl Acad Sci USA 99 (21): 13371–3.doi:10.1073/pnas.222543099. PMC 129677.PMID 12374850.
  12. "The use of aspirin". Wordconstructions.com. Retrieved 11 May 2011.

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