Analgesic, NSAID (nonopioid), anti-inflammatory, antiplatelet, antipyretic and antirheumatic.For further information, see topic onRecommendations for safety use of NSAIDs.
Analgesic effect, relieves pain of mild to moderate intensity.
Antipyretic (lowers temperature).
Anti-platelet effect, inhibits thromboxane synthesis (inhibits platelet aggregation). Aspirin poisons the platelets for its remaining life (using an example patient with 250,000 platelet count). New platelets are generated at a rate of 10% per day (25,000/day for a patient with a 250,000 platelet count). By 2 days off aspirin, a patient will have 50,000 normal platelets (enough to counter bleeding). By 7 days off aspirin, a patient will have 70% or 175,000 normal platelets (typical level required for elective surgery). By 10 days off aspirin, a patient will have 100% normal platelets (level required by some clinicians for major surgery).
Reduction
of risk of recurrent TIAs or stroke in patients with history of TIA due to
fibrin platelet emboli or ischemic stroke.
Reduction
of risk of death or nonfatal MI in patients with history of infarction or
unstable angina pectoris or suspected acute MI.
Patients
who have undergone revascularization procedures (e.g., coronary artery bypass
graft [CABG], percutaneous transluminal coronary angioplasty [PTCA],
endarterectomy).
Unlabeled
uses: Prophylaxis against cataract formation with long-term use; prosthetic
valve thromboprophylaxis, Kawasaki disease, antithrombotic therapy in children
with Blalock-Taussing shunt and after Fontan procedure.
Use lowest appropriate dose (reduces adverse effects).
Anti-platelet action: Do not exceed 81 to 160 mg daily if on warfarin (Marevan).
Primary coronary disease prevention: 81 mg orally daily. As of 2018, aspirin is no longer recommended for primary prevention in most patients.
Tertiary prevention (post-MI): aspirin 81 mg orally daily. Similar efficacy in coronary disease prevention as the 325 mg dose. Half the risk of gastrointestinal hemorrhage as the 325 mg dose.
Cerebrovascular accident: Prevention in known vascular disease: 160-325 mg daily
Antipyretic or analgesic dose: (adult) 600 mg PO q4 hours or 650-1000 mg PO q4-6 hours.
Anti-inflammatory dose: (adult) 4 grams maximum per day.
Children with viral illness (Varicella, Influenza), risk of Reye’s syndrome(FDA black box warning).
Distribution: Crosses placenta; enters breast milk.
Excretion: Urine.
Gastrointestinal effects include gastrointestinal intolerance, gastrointestinal bleeding and peptic ulcer disease (Erosive Gastritis). Aspirin higher risk for peptic ulcer disease, for further information, see topic onPeptic ulcer, assessment and management.
Central nervous system effects (Salicylism): tinnitus, decreased hearing acuity and vertigo.
Central respiratory effects: hyperpnea with very high dose and respiratory depression or apnea with lethal doses.
Serum uric acid changes
Aspirin < 2 g/day: increases serum uric acid
Aspirin > 4 g/day: lowers serum uric acid < 2.5 mg/dL.For further information, see topic onComparison of gout therapies.
Asymptomatic hepatitis.
Exacerbation of renal insufficiency.
Hypersensitivity reaction (aspirin allergy) associated with nasal polyps and asthma.