Acetylsalicylic acid

Acetylsalicylic acid (ASA) or more commonly known as aspirin is a nonsteroidal anti-inflammatory drug (NSAID, NSA) used as an analgetic, antipyretic, antiphlogistic (anti-inflammatory) and antithrombotic drug. It is therefore used to treat pain, fever, inflammation, but also has the potential to reduce major adverse cardiovascular events by inhibiting platelet aggregation - preventing blood clot formation which could lead to stroke or myocardial infarction (MI).

Trade names of acetylsalicylic acid: Acylpyrin®; Aspirin®

Mechanism of action
Chemically, acetylsalicylic acid is a derivative of salicylic acid, which belongs to aromatic hydroxy acids. It irreversibly inhibits (by means of acetylation) the enzyme cyclooxygenase (COX) both type 1 and 2 but has a greater affinity to COX-1. COX-1 is a constitutive enzyme, while COX-2 is inducible. By inhibiting the COX enzymes, acetylsalicylic acid blocks the synthesis of eicosanoids (prostaglandins, prostacylin, thromboxanes, ...) from arachidonic acid.

Dosing

 * Low dose (75-100 mg daily) – inhibition of platelet aggregation
 * Low dose of aspirin is recommended as a long-term aspirin therapy in prevention of cardiovascular disease events (stroke, MI).
 * Intermediate dose (< 3000g /day) – antipyretic and analgesic effect of aspirin
 * High dose (> 3000g /day) – anti-inflammatory effect of aspirin
 * Aspirin is an effective anti-inflammatory agent in rheumatic disorders, but high doses of aspirin result in toxicity, including tinnitus, hearing loss and gastric intolerance.  Giving aspirin to children under 12 years of age is not recommended due to the risk of Reye's syndrome, which is a rare but severe case of acute encephalopathy and hepatic steatosis in children and adolescents.

Related articles

 * Non-steroidal anti-inflammatory drugs (NSAIDs)
 * Non-opioid analgesics
 * Reye's Syndrome