Aspirin
From Pharmacopedia
More actions
Aspirin (acetylsalicylic acid; ASA)
Bayer, Ecotrin, Bufferin, St. Joseph (low-dose 81 mg), Excedrin (with acetaminophen and caffeine)
Experience
No personal reports yet
No clinical reports yet
Log in to add your own experience.
Problems
No problems yet. Be the first to suggest one.
+ Add a problemTitration strategies
No titration strategies yet. Be the first to suggest one.
Effects
No effects listed yet. Be the first to suggest one.
Relevant anecdote
No anecdotes yet. Share a relevant one.
Relevant Literature
No literature entries yet.
Log in to submit relevant literature.
Summary
Common uses
Primary cardiovascular prevention in selected patients (low-dose 81 mg, USPSTF guidance evolving)0, Secondary prevention of myocardial infarction and ischemic stroke (low-dose 81 mg daily, established benefit)0, Acute myocardial infarction (162-325 mg chewed at first medical contact)0, Transient ischemic attack / acute ischemic stroke management0, Preeclampsia prophylaxis in pregnancy (81 mg after 12 weeks in high-risk patients, USPSTF)0, Mild-to-moderate pain (FDA)0, Fever in adults (FDA; avoid in pediatric viral illness)0, Kawasaki disease (FDA, pediatric)0
Pharmacy
Starting dose
Antiplatelet: 81 mg PO once daily. Acute MI/stroke: 162-325 mg chewed. Analgesic: 325-650 mg PO every 4-6 hours as needed
Preparations
Tablets 81 (low-dose), 325, 500, 650 mg; chewable 81 mg; enteric-coated tablets; effervescent tablets; suppositories
US FDA Max
4000 mg/day (analgesic)
Pharmacology
Routes
Oral, rectal
Onset
Antiplatelet effect within 30-60 minutes; analgesic effect 30-60 minutes
Duration
Antiplatelet effect lasts the platelet's lifetime (~7-10 days) due to irreversible COX-1 acetylation; analgesic 4-6 hours
Half-life
Aspirin 15-30 minutes; salicylate metabolite 2-3 hours (concentration-dependent, saturable at high doses)[1]
Bioavailability
~50% (oral; reduced by buffering and enteric coating but onset clinically similar)[1]
Pregnancy
Low-dose (81 mg) safe and indicated for preeclampsia prophylaxis after 12 weeks in high-risk patients per USPSTF; high-dose aspirin avoid third trimester due to premature ductus arteriosus closure and bleeding risk
Legal status
OTC in US at all standard strengths
Purported mechanism
Irreversible covalent acetylation of cyclooxygenase enzymes (COX-1 and COX-2), distinguishing aspirin from all other NSAIDs, which inhibit reversibly. The platelet effect derives from COX-1 acetylation: platelets cannot synthesize new enzyme, so a single 81 mg daily dose abolishes thromboxane A2 production for the platelet's entire 7-10 day lifespan. Endothelial cells recover prostacyclin synthesis quickly because they have nuclei and can transcribe new COX. The analgesic, anti-inflammatory, and antipyretic effects come from the broader prostaglandin reduction.0 Reye syndrome: rare hepatic encephalopathy in children given aspirin during viral illness, the basis of the firm pediatric viral-illness contraindication. Aspirin-exacerbated respiratory disease (Samter triad: asthma, nasal polyps, aspirin sensitivity) is a recognized cross-reactive hypersensitivity to all COX-1 inhibitors[1].
References
- ↑ 1.0 1.1 1.2 FDA Prescribing Information, Bayer Aspirin (acetylsalicylic acid), Bayer HealthCare, current revision. https://www.accessdata.fda.gov/drugsatfda_docs/label/2009/020589s015lbl.pdf