ASPRIN (NSAID)

Aspirin is a nonsteroidal anti-inflammatory drug (NSAID), mostly used as a pain reliever, fever-killer, and reduces inflammation a great deal.

The Composition of Aspirin

The composition of aspirin is 2-acetyloxybenzoic acid, also known as acetylsalicylic acid or ASA. Having a chemical formula [C9H8O4] and the molecular weight of 180.16 g/mol. It is a white crystalline powder that is slightly soluble in water. Aspirin is derivative salicylate, a compound naturally existing in plants such as willow bark, meadowsweet and wintergreen. Over several decades, Salicylate has proven to be medically advantageous, i.e. since 1853. Famous chemists; Charles Frédéric Gerhardt and Felix Hoffman [Bayer] have a renowned history with the evolution and procedural improvement of salicylate.

Charles Gerhardt synthesized aspirin by combining acetylating salicylic acid with acetyl chloride. However, the final product was not in a stable form and caused severe irritation. In 1897, Felix Hoffmann, working with Bayer, rediscovered and patented aspirin as a stable and less irritating form of salicylate.

Functions of Aspirin

Mostly known for its ability to inhibit the enzyme cyclooxygenase (COX), that is essential in the synthesis of prostaglandins and thromboxanes. Prostaglandins and thromboxanes are lipid mediators; which are responsible for the regulation of various physiological processes such as inflammation, pain, fever, blood clotting, and gastric mucosal protection.

When COX is inhibited from functioning, the lipid mediators, prostaglandins and thromboxanes are not synthesized hence the modulation of their effects on an individual.

The dosage, route of administration are either orally, rectally, or intravenously, and indication affect the effectiveness of aspirin to an individual.

The oral bioavailability of aspirin is about 80-100%, but it can be affected by factors such as food intake, gastric pH, and drug interactions. The plasma half-life of aspirin is dose-dependent; ranging from 2-3 hours for low doses, i.e. below 100mg to 15-30 hours for high doses, i.e. above 4g.

Aspirin is metabolized in the liver by CYP2C19 and CYP3A enzymes and hydrolyzed in the gut wall to salicylic acid, which is then conjugated with glycine or glucuronic acid and excreted in the urine.

Some of the common uses of aspirin are:

• Pain relief

Aspirin can relieve mild to moderate pain caused by headaches, toothaches, menstrual cramps, arthritis, sprains, strains, and other injuries.

Dosage: 325-650 mg every 4-6 hours.

• Fever reduction

Aspirin can lower body temperature by inhibiting prostaglandins that mediate fever in the hypothalamus.

Dosage: 325-650 mg every 4-6 hours.

• Inflammation reduction

Aspirin can reduce inflammation by inhibiting prostaglandins that mediate vasodilation, edema, leukocyte migration, and cytokine release.

Dosage: 650-1000 mg every 4-6 hours.

• Cardiovascular prevention

Aspirin can prevent cardiovascular events attacks such as heart attacks, strokes, and angina by inhibiting thromboxane A2, which promotes platelet aggregation and vasoconstriction.

Dosage: 75-325 mg once daily.

• Cancer prevention

Aspirin may reduce the risk of colorectal cancer and other cancers by inhibiting COX-2, which promotes tumor growth and angiogenesis.

Dosage: 75-325 mg once daily.

Some of the common side effects of aspirin are:

• Gastrointestinal

Aspirin can cause stomach irritation, ulcers, bleeding, or perforation by inhibiting prostaglandins that protect the gastric mucosa. It can also cause nausea, vomiting, diarrhea, or constipation.

• Allergies

Aspirin can cause allergic reactions such as rash, hives, itching, swelling, or anaphylaxis in some people who are hypersensitive to it or other NSAIDs. It can also cause asthma exacerbation or nasal polyps in some people who have aspirin-exacerbated respiratory disease (AERD).

• Hematologic

Aspirin can cause bleeding or bruising by inhibiting platelet function and prolonging bleeding time. It can also cause anemia, thrombocytopenia, or hemolytic anemia in some people who have genetic or acquired disorders of blood cells.

• Renal

Aspirin can cause kidney damage or failure by inhibiting prostaglandins that regulate renal blood flow and glomerular filtration. It can also cause fluid retention, edema, or hypertension in some people who have renal impairment or heart failure.

• Hepatic

Aspirin can cause liver damage or failure by inducing hepatotoxicity or Reye's syndrome. Reye's syndrome is a rare but serious condition that affects children and adolescents who take aspirin for viral infections such as influenza or chickenpox. It causes liver dysfunction and encephalopathy.

• Neurologic

Aspirin can cause tinnitus, hearing loss, vertigo, or headache by stimulating the cochlear nerve and increasing intracranial pressure. It can also cause cerebral hemorrhage or ischemia by altering the cerebral blood flow and increasing the risk of bleeding.

Aspirin can also interact with other drugs or substances and affect their efficacy or safety.

Some of the common interactions of aspirin are:

• Anticoagulants

Aspirin can increase the risk of bleeding when taken with anticoagulants such as warfarin, heparin, dabigatran, rivaroxaban, apixaban, or edoxaban. The dose of anticoagulants may need to be adjusted when used with aspirin. It also has antiplatelet and antithrombotic effects, which means it can prevent blood clots from forming or growing.

• Antiplatelets

Aspirin can increase the risk of bleeding when taken with antiplatelets such as clopidogrel, ticagrelor, prasugrel, dipyridamole, or cilostazol. The combination of aspirin and antiplatelets may be beneficial for some people with high cardiovascular risk but should be used with caution and under medical supervision.

• NSAIDs

Aspirin can increase the risk of gastrointestinal bleeding when taken with other NSAIDs such as ibuprofen, naproxen, diclofenac, indomethacin, ketorolac, or celecoxib. The combination of aspirin and NSAIDs may also reduce the cardiovascular benefit of aspirin by interfering with its antiplatelet effect.

• Corticosteroids

Aspirin can increase the risk of gastrointestinal bleeding when taken with corticosteroids such as prednisone, hydrocortisone, dexamethasone, or methylprednisolone. The dose of corticosteroids may need to be adjusted when used with aspirin.

• Alcohol

Aspirin can increase the risk of gastrointestinal bleeding when taken with alcohol. Alcohol can also interfere with the metabolism and elimination of aspirin and increase its toxicity.

• ACE inhibitors

Aspirin can reduce the effectiveness of ACE inhibitors such as lisinopril, enalapril, captopril, or ramipril by inhibiting prostaglandins that mediate their antihypertensive effect. The dose of ACE inhibitors may need to be adjusted when used with aspirin.

References

https://www.drugs.com/aspirin.html

https://en.wikipedia.org/wiki/Aspirin

https://www.medicalnewstoday.com/articles/161255