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Chemistry

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The Chemistry of Aspirin (acetylsalicylic acid)

Chemical formula = C9H8O4 or CH3COOC6H4COOH or HC9H7O4

Aspirin is prepared by chemical synthesis from salicylic acid, through acetylation with acetic anhydride. The molecular weight of aspirin is 180.16g/mol. It is odourless, colourless to white crystals or crystalline powder.

Aspirin is an oral non-steroidal anti-inflammatory drug (NSAID) that is rapidly absorbed from the stomach and the small intestine.  It is a non-selective NSAID as it irreversibly inhibits both cyclooxygenase (COX) enzymes involved in converting arachidonic acid to prostaglandins and thromboxane3.

Prostaglandins are found throughout the body and are made to help manage injury or infection. Prostaglandins upregulate the sensitivity of pain receptors. As a control mechanism, they act locally at the site of synthesis which limits the extent of their activity. They are also broken down rapidly by the body. The enzymes that produce prostaglandins are cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2), they have diverse roles and are widely dispersed throughout body tissue.  Cox-1 has a protective role for the stomach lining and COX-2 is involved in pain and inflammation. Aspirin binds to and acetylates serine (an amino acid used by the body to make proteins) residues in the active site of cyclooxygenase enzymes, leading to reduced production of prostaglandin. This in turn mediates aspirin’s effect of reduced inflammation and pain in affected tissues. Additionally, aspirin acts on prostaglandins in the hypothalamus to reset and reduce a raised body temperature. Importantly, aspirin does not decrease normal body temperature1,2,3.

From a cardiovascular perspective aspirin also has an important role: Thromboxane A2 (TXA2) is a lipid that stimulates new platelet formation and increases platelet aggregation. Aspirin inhibits the production of thromboxane A2 (TXA2) by stopping the conversion of arachidonic acid to TXA2. This aspirin effect is mediated via COX-1 inhibition within platelets and helps stop the platelets from sticking to each other or to plaques within the artery therefore reducing the risk of blood clot (thrombus) formation within the blood stream. In this way aspirin can help lower the risk of future myocardial infarction (MI) or stroke1,3.

Aspirin, therefore, has an analgesic (reduces pain), anti-inflammatory (reduces redness and swelling), anti-platelet (reduces blood clots) and antipyretic (temperature reduction) effects1,2,3.

In cancer, aspirin is believed to impact a number of cancer signalling pathways and may induce or upregulate cancer suppressor genes3.

Because Aspirin is a non- selective COX- 1 and COX-2 inhibitor, as well as its beneficial analgesic, anti-inflammatory, anti-platelet and antipyretic effects its use can also result in peptic ulcer development and gastric bleeding. Taking aspirin and alcohol together can increase the risk of gastric bleeding 1,3.

Inside the body, aspirin is converted into its active metabolite salicylate. This happens mostly in the liver. Peak concentration of salicylate in the plasma occurs approximately 1-2 hours after ingestion. Excretion from the body is mainly through the kidney. Alkaline urine speeds up the excretion of aspirin. It takes about 48 hours to excrete an aspirin completely. The half-life of aspirin in the blood stream is 13-19 minutes and the half-life of its metabolite salicylate is around 3.5-4.5 hours. Aspirin’s inhibition of COX-1 results in reduced platelet aggregation for the 7-10-day average lifespan of platelets1.

There is a 60% structural similarity between COX-1 and COX-2 active sites: The active site of COX-2 is larger and this allows the precursor of prostaglandins, arachidonic acid, to be able to bypass aspirin molecules at lower doses. Therefore, a higher dose of aspirin is required for its analgesic and anti-inflammatory effects in comparison to its antiplatelet action1. The fact that COX-1 and COX-2 enzymes have different levels of sensitivity to aspirin and recover their cyclooxygenase activity post aspirin at different rates helps explain the different dosing regimens for aspirins varying clinical indications1.

Aspirin should not be used in children as it can produce a rare but dangerous Reye’s syndrome resulting in coma and liver damage that can prove fatal1,3.

Some drug interactions can occur when aspirin is given with other medicines. Aspirin can displace drugs from their plasma binding-sites and in this way may increases the effects of anticoagulant drugs and oral hypoglycaemics. It can also inhibit urate secretion and should be avoided in gout3.

REACTIONS

Raw Materials

Phenol C6H5-OH
Sodium Hydroxide NaOH
Carbon Dioxide CO2
Acetic Anhydride CH3COOCOCH3
Hydrogen H

 

The Reactions
The production of aspirin from raw materials can be divided into four separate reactions as shown here:

Reaction 001
Reaction 002
Reaction 003
Reaction 004

References/Biography

1. PubChem Aspirin compound summary accessed 07/05/2020 https://pubchem.ncbi.nlm.nih.gov/compound/Aspirin
2.You and Your Hormones Prostaglandins accessed 07/05/2020 @
https://www.yourhormones.info/hormones/prostaglandins
3.Trounce’s Clinical Pharmacology for Nurses. Chapter 11 Anti-inflammatory drugs: treatment of arthritis and gout. The non-steroidal anti-inflammatory drugs.

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Daniel José Piñeiro

ASSOCIATE
Name
Daniel José Piñeiro
Academic Affiliations:
Full Professor of Medicine, Universidad de Buenos Aires, Argentina Trustee, Board of Trustees, American College of Cardiology
Professional Setting:
My academic experience includes more than 40 years as a practicing medical doctor, teacher, and researcher. I have fulfilled these appointments in settings of vital social engagement and impact, most notably at the Hospital de Clínicas “José de San Martín” of the Universidad de Buenos Aires, a public hospital with high academic recognition. Additionally, I currently hold the position of Full Professor of Medicine at that same University.
Academic Activities:
  • International Meetings Participations: 180
  • Books-Editor: 1
  • Books Chapters: 39
  • Refereed Full Articles: 118 (listed in Pubmed: 29)
  • Refereed Abstracts: 221
  • Editorial Boards: 10
Profesional Associations:
  • 2005 President, Sociedad Argentina de Cardiología.
  • 2011-2013 President, Inter-American Society of Cardiology.
  • 2011-2013 Member (ex-officio), Board of Directors, World Heart Federation
  • 2017-2018 Member (at large), Board of Directors, World Heart Federation
  • 2018-2021 Trustee, Board of Trustees, American College of Cardiology
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Chia

John Chia

Name
John Chia MBBS (Spore), MRCP (UK), FAMS (Spore)
Academic Affiliations:

Adjunct Associate Professor DUKE-NUS Graduate Medical School,
Consultant Oncologist Curie Oncology Singapore,
Visiting Consultant National Cancer Centre Singapore.

Discipline:

Medical Oncology

Scientific Interests:
  • Aspirin as adjuvant therapy in established cancers
  • Adoptive T cell therapy and Dendritic cell vaccines in the treatment of solid tumors
  • Clinical Trial Design and Management
Declaration of Conflicts of Interest:

In the past 3 years, I have received consultant fees from Tessa Therapeutics, Aslan Pharmaceuticals, Novartis, and AstraZeneca.

I received grant support for investigator-initiated research from:

  • National Medical Research Council Singapore
  • Bayer AG

I hold shares in:  Roche, BMS, AstraZeneca, Incyte, Teva Pharmaceuticals, Trillium Therapeutics, Compugen, Arrowhead pharmaceuticals, Emergex, QuantumDx and Halozyme Therapeutics

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Badimon

Lina Badimon

Name
Lina Badimon BSc, PharmD, PhD, FESC, FAHA
Academic Affiliations:
Director of the Cardiovascular Science Program (ICCC) at the Hospital Santa Creu and San Pau, IIB-Sant Pau; CIBER CV. Director of the Cardiovascular Research Chair of the Autonomous University of Barcelona and Director of the UNESCO Chair in Biomedical Sciences Training and Research.
Discipline:
Pharmacology, Cardiovascular Disease
Scientific Interests:
Cardio-metabolic diseases, thrombosis, atherosclerosis and ischemic heart disease
Declaration of Conflicts of Interest:

I received consultant and speakers fees from Amgen, AstraZeneca, Bayer, Lilly and Sanofi.

    Return to Scientific Advisory Board
    Ge

    Junbo Ge

    Name

    Junbo Ge

    Ge Junbo, male, was born in Wulian, Shandong province on Nov. 8, 1962. He is the member of Chinese Academy of Sciences, professor and doctoral supervisor. He received his doctor’s degree of Medicine from German Mayence University in 1993 and now works as the director for Shanghai Institute of Cardiovascular Disease and the Center for Stem Cells and Tissue Engineering, Fudan University. He is also the designate chairman of the Cardiovascular Disease Branch of Chinese Medical Association, council member of the Cardiovascular Angiography and Interventions Association, international consultant of the American Heart Association. In Dec. 2013, he was appointed as the vice president of Tongji University.

    Prof. Ge has been engaged in clinical and scientific research work of cardiovascular disease since 1987, and his research area covers the pathogenesis of coronary heart disease, early diagnosis and treatment plan optimization.

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    Langley

    Ruth Langley

    Name
    Ruth Langley PhD, FRCP
    Academic Affiliations:
    Professor of Oncology and Clinical Trials, MRC Programme Leader and Chair of the Cancer Group, MRC Clinical Trials Unit at UCL, honorary consultant in medical oncology at the Brighton and Sussex University Hospital.
    Discipline:
    Medical oncologist; trialist
    Scientific Interests:
    • Aspirin
    • Gastro-oesophageal malignancy
    • Transdermal oestrogen in the treatment of prostate cancer
    • Trials methodology
    Declaration of Conflicts of Interest:
    Has received honorarium from Bayer
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    Chan

    Andrew T Chan

    Name
    Andrew T. Chan MD, MPH
    Academic Affiliations:
    Chief, Clinical and Translational Epidemiology Unit, Vice Chair, Division of Gastroenterology, Massachusetts General Hospital, Boston, Co-leader, Cancer Epidemiology Program, Dana-Farber/Harvard Cancer Center, Boston.
    Discipline:
    Gastroenterology
    Scientific Interests:
    • The role of aspirin in the prevention of colorectal cancer and other cancers
    • The role of the gut microbiome in colorectal cancer and other chronic gastrointestinal diseases, including inflammatory bowel disease and diverticulitis
    • The role of diet and lifestyle in colorectal cancer and other chronic gastrointestinal cancers
    Declaration of Conflicts of Interest:

    AACR Honors Dr. Andrew T. Chan With 2019 AACR-Waun Ki Hong Award

    Click here to find the press release.

    I received consultant Bayer and Pfizer, Inc.

    I received grant support for investigator-initiated research from:

    • National Institutes of Health
    • National Cancer Institute
    • Crohn’s and Colitis Foundation
    • Bayer AG
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    Gaziano

    Mike Gaziano

    Name
    J Michael Gaziano MD, MPH
    Academic Affiliations:

    Professor of Medicine, Harvard Medical School; Chief Division of Aging, Brigham and Women’s Hospital; Director of Preventive Cardiology and Director of Massachusetts Veterans Epidemiology Research and Information Center (MAVERIC), VA Boston Healthcare System.
    Discipline: Cardiology and Epidemiology

    Scientific Interests:
    I am a chronic disease epidemiologist with a particular interest in the roles that individual lifestyle choices (diet, exercise, smoking), metabolic factors (obesity, high cholesterol, and hypertension), and biochemical and genetic markers play on the risk of cardiovascular disease and other chronic illnesses. Also, of interest is the impact that vascular disease has on other organ systems, including cognitive dysfunction and renal disease. I have an interest in the design of large-scale trials and observational studies nested in large health care systems using big data analytic techniques.
    Declaration of Conflicts of Interest:

    I received consultant and speaker fees Bayer.

    I received grant support as a principal investigator or co-investigator for research from the VA, DOD, NIH, Merck and Kowa.

    Return to Scientific Advisory Board
    Pierre A Web Photo

    Pierre Amarenco

    Name

    Pierre Amarenco, MD, FAHA, FAAN

    Academic Affiliations:
    • Professor of Neurology at Paris-Diderot Sorbonne University 
    • Chairman of the Department of Neurology and Stroke Center; Bichat University Hospital
    • Co-Director INSERM Unit-698 “Clinical Research in Atherothrombosis”
    Discipline:

    Neurology and Vascular Neurology

    Scientific Interests:
    • Understanding and preventing stroke and vascular diseases
    • Clinical trials in prevention of vascular diseases
    • Carotid intima-media thickness studies
    • Lipid trials: prevention and therapeutic –protective- evaluation
    Declaration of Conflicts of Interest:

    N/A

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    CarloPatrono

    Carlo Patrono

    CHAIR
    Name
    Carlo Patrono MD, FESC, FRCP
    Academic Affiliations:
    Adjunct Professor of Pharmacology at the Catholic University School of Medicine in Rome (Italy) and at the Perelman School of Medicine of the University of Pennsylvania in Philadelphia (USA).
    Discipline:
    Clinical Pharmacology
    Scientific Interests:
    • Studying platelet activation and inhibition in diabetes mellitus
    • Studying platelet activation and inhibition in myeloproliferative neoplasms
    • Investigating the mechanism of action of low-dose aspirin in preventing colorectal cancer
    Declaration of Conflicts of Interest:

    I received consultant and speakers fees from Acticor Biotech,  Amgen,  Bayer, GlaxoSmithKline,  Tremeau,  Zambon.

    I received grant support for investigator-initiated research from:

    • AIFA (Italian Drug Agency)
    • Bayer AG
    • Cancer Research UK
    • European Commission, FP6 and FP7 Programmes

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