Aspirin

Aspirin is one of the most widely used medicinal compounds in the world. It is an ingredient in hundreds medications and is approved for use as an analgesic, antiinflammatory, anticoagulant and antipyretic. 

Indications for which aspirin may be prescribed:

1. Relief of pain, fever and inflammation from: flu, the common cold, neck and back pain, dysmenorrhea, headache, tooth pain, sprains, fractures, myositis, neuralgia, synovitis, arthritis, bursitis, burns, and various injuries. It is also used for symptomatic pain relief after surgical and dental procedures (Aspirin|DRUGBANK n.d.)
2. Inhibit platelet aggregation
   1. Strokes: Aspirin use recommended in both men and women to treat mini-strokes (transient ischemic attack --TIA) or ischemic stroke to prevent subsequent cardiovascular events or death.
   2. Heart Attacks:
      Aspirin:
      • reduces the risk of death in patients with suspected acute heart attacks (myocardial infarctions)
      • prevents recurrent heart attacks and
      • reduces the risk of heart attacks or sudden death in patients with unstable and chronic stable angina pectoris (chest pain).
   3. Other coronary conditions: Aspirin can be used to treat patients who have had certain revascularization procedures such as angioplasty, and coronary bypass operations -- if they have a vascular condition for which aspirin is already indicated.
3. Rheumatologic diseases: Aspirin is indicated for relief of the signs and symptoms of rheumatoid arthritis, juvenile rheumatoid arthritis, osteoarthritis, spondylarthropathies, and arthritis and pleurisy associated with systemic lupus erythematosus (U.S. FDA, 2015).

Contraindications to Aspirin Therapy (Miser, 2011).

Absolute contraindications

• Active peptic ulcer
• Aspirin allergy or intolerance
• Bleeding disorder (hemophilia, von Willebrand disease, etc)
• History of GI bleeding
• History of recent intracranial bleeding
• Renal failure
• Severe liver disease
• Thrombocytopenia

Relative contraindications

• Age younger than 21 years (increased risk of Reye syndrome)
• Concurrent anticoagulation therapy
• Concurrent use of NSAID therapy
• Poorly controlled hypertension (risk of intracranial bleeding)

Mechanism of action (Click here to visit Speedy Pharmacology-NSAID & Prostaglandin Analogs, Youtube video)

https://www.youtube.com/watch?v=IDlD3jdUd38

Aspirin reduces pain by inhibiting the oxidation of arachadonic acid by cyclooxygenase 1 and 2. Arachadonic acid is a ubiquitous membrane fatty acid released in response to injury or stress. Without aspirin, arachadonic acid is initially oxidized by cyclooxygenase to prostaglandin G₂, subsequent steps produce: Thromboxane_a, prostacyclin I₂, prostaglandin E₂, prostaglandin D₂ and prostaglandin F_2a.

• Thromboxane _a mediates platelet aggregation and vasoconstriction (Rucker D. 2022)
  
• Prostacyclin I₂ decreases platelet aggregation, increases renal blood flow, increases vasodilation (Physiology, prostaglandin I2 - STATPEARLS - NCBI BOOKSHELF. (n.d.-a))
  
• Prostaglandin E₂ increases renal blood flow, vasodilation, natriuresis, inhibits gastric acid production (Wang et al., 2022)
• Prostaglandin D₂- Involved in allergic inflammation and vasodilation (Tkacs & Herrmann, 2020). Enhances mucus secretion by goblet cells and induces antibacterial immunity(Tearle et al., 2023)
  
• Prostaglandin F_2a decreases progestrone, increases smooth muscle (uterine) contraction, potent vasoconstrictor increases with age and bronchconstriction (Zeng et al., 2023).

 

Like other non-steroidal anti-inflammatory drugs (NSAIDS), aspirin has a maximum dose ceiling and significant side effects including increased bleeding time and gastric ulceration.

Aspirin can cause gastric irritation and affects platelet function, thus increasing the risk of bleeding. Aspirin has also been linked to the development of Reye’s syndrome in children and teens. Reye's syndrome is a life threatening condition that causes acute encephalopathy and fatty infiltration of the liver and other organs in children recovering from viral infection.

Because of this association, aspirin should not be given to persons under the age of 20 unless ordered by a physician. Since 2003, the U.S. Food and Drug Administration (FDA) has required that all aspirin products contain a warning label describing the potential for the development of Reye’s syndrome.

FDA Drug Safety Communication: FDA warns about serious bleeding risk with over-the-counter antacid products containing aspirin

Aspirin is a commonly used pain reducer and fever reducer. It is a nonsteroidal anti-inflammatory drug (NSAID) that can increase the risk of bleeding, including in the stomach and gastrointestinal (GI) tract.

If you have one or more of the following risk factors, you may have a higher chance of serious bleeding when taking aspirin-containing antacid products:

• Are 60 years or older
• Have a history of stomach ulcers or bleeding problems
• Take a blood-thinning or steroid medicine
• Take other medicines containing NSAIDs such as ibuprofen or naproxen
• Drink three or more alcoholic drinks every day

Taking more of these medicines than the amount recommended or for a longer period than recommended will increase the risk of serious bleeding.

References:

Aspirin. Uses, Interactions, Mechanism of Action | DrugBank Online. (n.d.). https://go.drugbank.com/drugs/DB00945

Lau KE, Lui F. Physiology, Prostaglandin I2. [Updated 2023 Aug 28]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK562273/

Miser, W. F. (2011, June 15). Appropriate aspirin use for primary prevention of cardiovascular disease. American Family Physician. https://www.aafp.org/pubs/afp/issues/2011/0615/p1380.html

Physiology, prostaglandin I2 - STATPEARLS - NCBI BOOKSHELF. (n.d.-a). https://www.ncbi.nlm.nih.gov/books/NBK562273/

Rucker D, Dhamoon AS. Physiology, Thromboxane A2. [Updated 2022]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK539817/

Tkacs, N. C., & Herrmann, L. L. (2020). Advanced Physiology and Pathophysiology: Essentials for Clinical Practice. Springer Publishing Company, LLC.

Tearle, J. L. E., Tang, A., Vasanthakumar, A., & James, K. R. (2023). Role reversals: Non-canonical roles for immune and non-immune cells in the gut. Mucosal Immunology. https://doi.org/10.1016/j.mucimm.2023.11.004

Wang, L., Wu, Y., Jia, Z., Yu, J., & Huang, S. (2022). Roles of EP Receptors in the Regulation of Fluid Balance and Blood Pressure. Frontiers in endocrinology, 13, 875425. https://doi.org/10.3389/fendo.2022.875425

Zeng, C., Liu, J., Zheng, X. et al. (2023) Prostaglandin and prostaglandin receptors: present and future promising therapeutic targets for pulmonary arterial hypertension. Respir Res 24, 263. https://doi.org/10.1186/s12931-023-02559-3

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