Aspirin

Aspirin (ASA)

Class:
  • Nonsteroidal Anti-Inflammatory Drug (NSAID)–acetylsalicylic acid (ASA)
Actions:
  • reduction of inflammation (also antipyretic effect)
  • analgesic (prostaglandin inhibitor)
  • anti-platelet (blocks formation of thromboxane A2 reducing platelet aggregation and vasoconstriction of coronary arteries)
Indications:
  • Suppression of inflammation associated with arthritis
  • Mild to moderate musculoskeletal pain or headache
  • Antipyretic for fever in adults (contraindicated in children due to risk of Reyes' syndrome)
  • Dysmenorrhea (prostaglandin inhibitor)
  • Acute Coronary Syndrome (ACS)–suppresses platelet aggregation
Pharmacokinetics:
  • Absorption:  Rapid from upper GI tract orally; slower from lower GI tract per rectum
  • Onset: 15 minutes
  • Peak: 15 minutes – 2 hours
  • Distribution:  Bound to serum albumin
  • Half-Life: 15-20 minutes
  • Metabolism:  Hydrolized to salicylate which is metabolized in liver
Adverse Effects:
  • Gastrointestinal:  GI bleeding, gastric irritation, burning, nausea, heartburn
  • Respiratory: Bronchospasms
  • Hematological:  Thrombocytopenia, hemolytic anemia, prolonged bleeding time
  • Potential for acute renal failure (NSAID)

 

Signs of Toxicity:
  • (plasma levels exceed 200 mcg/ml)
  • Salicylism: tinnitus, sweating, headache, and dizziness
  • Kussmaul respirations (metabolic acidosis)
  • Acute poisoning: Kussmaul respirations progressing to respiratory depression, hyperthermia, metabolic acidosis, sweating, dehydration
  • Reye's Syndrome: encephalopathy & fatty liver (20-30% occurrence among children and adolescents taking aspirin for influenza or chicken pox)
Contraindications:
  • Asthma
  • Hypersensitivity to salicylates or NSAIDs
  • Children & adolescents
  • Active ulcer disease
Dosages & Routes:
  • PO:  (analgesic/antipyretic) 325 -650 mg q 4 hours (maximum dose 3.6-5.4 gm/day for adult)
  • PO:  (acute chest pain) 160-325 mg nonenteric coated preferably chewed
  • PO:  (anti-platelet prophylaxis) 81 mg chewable aspirin daily  (Older regimen was 325 mg enteric coated 3 times weekly, e.g. MWF)
  • Per Rectum: (analgesic/antipyretic) 325 -650 mg q 4 hours (maximum dose 3.6-5.4 gm/day for adult)
Nursing Implications:
  • If ACS patient is hypersensitive or contraindicated for ASA, patient may be considered for clopidogrel (Plavix®) orally.
  • Drug Interaction with warfarin and heparin:  Additive anticoagulation effect which increases risk for bleeding
  • Drug Interactions: increased risk for GI bleeding with glucocorticoids, alcohol, or NSAIDs
  • Drug Interaction with ibuprofen: decreased antiplatelet effect
  • Assess patient for signs of bleeding (petechiae, ecchymosis, bloody or black stools, bleeding gums).
  • Drink adequate fluids while taking aspirin.
  • Advise patient to avoid alcohol when prescribed high doses of aspirin.
  • Baby aspirin is preferred for acute or prophylactic  management of heart disease.
  • Discontinue aspirin use if ringing or buzzing in ears or unrelieved GI discomfort.
  • Not recommended for children with influenza or chicken pox.
  • Treatment for poisoning consists of 1) gastric lavage, 2) activated charcoal, 3) respiratory support, 4) fluid hydration, and 5) urine alkalization with sodium bicarbonate–6) hemodialysis in unresponsive cases

 

References:

American Heart Association. (2006). Handbook of Emergency Cardiac Care (p. 46). Salem, MA: AHA.

Lehne, R.A. (2010). Pharmacology for nursing care (7th ed., pp. 829-834, 620).  St. Louis: Saunders Elsevier.

Wilson, B.A., Shannon, M.T., Shields, K.M., & Stang, C.L. (2007).  Prentice Hall Nurse's Drug Guide 2007 (pp. 123-127).  Upper Saddle River, NJ: Pearson Prentice Hall.

 

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