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Aspirin
Aspirin is acetylsalicylic acid, an NSAID1 used to relieve pain and reduce fever and inflammation2; it also suppresses platelet function.1 A synthetic form was first produced in 1853,3 while a pure, stable form was made at Bayer in 1897, possibly by Felix Hoffmann or Arthur Eichengrün. It commonly causes stomach upset4; ulcers and bleeding are more likely with older age, alcohol, other NSAIDs, or blood thinners.
Dosage & Duration
Dosage
Doses are population estimates that vary widely between individuals.
Threshold50 mg
Heavy1.6 g
Aspirin carries significant toxicity risk at doses of 4 grams or higher. Duration of effects varies considerably with dose: low doses typically last 2–3 hours, while large doses may persist for 15–30 hours.
Duration
Onset30-90 minutes
Subjective Effects
Subjective Effects not written up yet
Pharmacology
Pharmacodynamics
Aspirin irreversibly inhibits COX-1 by acetylating a key serine residue at its catalytic centre5, suppressing prostaglandin and thromboxane synthesis5. In platelets, aspirin irreversibly inhibits COX-1, reducing thromboxane A2 formation and inhibiting platelets for their lifetime of 7–10 days5. Aspirin also modifies COX-2 activity, shifting some products toward specialized proresolving mediators6, while its salicylic acid metabolite retains anti-inflammatory, antipyretic, and analgesic activity7.
Pharmacokinetics
Aspirin is well absorbed from the gastrointestinal tract after oral administration, with some absorption in the stomach but primarily in the upper small intestine, and hydrolyzes to salicylate and acetate; absorption from extended-release tablets is delayed and prolonged8. About 50–80% of circulating salicylate is bound to serum albumin in a concentration-dependent manner, with a volume of distribution of 0.1–0.2 L/kg. Salicylate is metabolized principally in the liver through glycine conjugation, glucuronidation, and small amounts of hydroxylation8; formation of salicyluric acid and salicyl phenolic glucuronide is capacity-limited, while other salicylate metabolites appear to be formed by first-order processes8. Salicylates are excreted mainly by the kidneys, and renal clearance is strongly affected by urinary pH8.
Interactions
Interactions not written up yet
An unlisted combination is an unknown one, not a safe one. Check a dedicated combination chart before mixing.
Tolerance
Tolerance not written up yet
Harm Potential
Addiction & Dependence
Psychological
Extremely LowAspirin has no known psychological addiction potential and is not associated with compulsive use patterns or abuse.
Physical
Extremely LowAspirin does not produce physical dependence or withdrawal symptoms upon discontinuation.
Toxicity
Aspirin can be dangerous at doses of 4 g and higher. Acute overdose has an estimated mortality rate of 2%, while repeated or ongoing overdose is associated with about 25% mortality and may be particularly serious in children.
Aspirin commonly causes stomach upset and raises the chance of stomach ulcers and upper gastrointestinal bleeding, especially in older people, alcohol users, people taking other NSAIDs, and people taking anticoagulant or antiplatelet medications.
Short-term aspirin use at therapeutic doses may precipitate reversible acute kidney injury in patients with glomerulonephritis or cirrhosis; aspirin is contraindicated in some patients with chronic kidney disease.
Giving aspirin to children or adolescents for fever or viral illness can be associated with Reye syndrome, an uncommon but serious condition involving acute brain dysfunction and fatty changes in the liver.
Aspirin increases bleeding risk and is known to cause hemolytic anemia in people with glucose-6-phosphate dehydrogenase deficiency; it should not be used by people with hemophilia or other bleeding tendencies.
Aspirin causes an increased risk of cerebral microbleeds and intracerebral hemorrhage, with an estimated absolute risk increase of 12 events per 10,000 persons at average doses of 270 mg per day.
High doses may result in tinnitus (ringing in the ears).
For some individuals, aspirin can cause hives, swelling, headache, and angioedema appearing one to six hours after ingestion; aspirin may also delay healing of skin wounds.
Aspirin may worsen asthma and cause NSAID-precipitated bronchospasm in susceptible individuals.
History & Culture
Early salicylate use
Medicines made from willow and other salicylate-rich plants appear in clay tablets from ancient Sumer and the Ebers Papyrus of ancient Egypt. Hippocrates referred to salicylic tea for reducing fevers around 400 BC, and willow bark preparations remained part of Western medical practice through…
Legality
Legality not written up yet
References
Citations
Article Status
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