Salicylate (Aspirin) Poisoning

Basics

Description

  • May occur with acute or chronic overdosage of the following:
    • Acetylsalicylic acid (aspirin)
    • Methyl salicylate (oil of wintergreen)
    • Bismuth subsalicylate (Pepto Bismol®)
    • Salicylic acid (a keratolytic)
    • Other salicylate-containing drugs
  • The potentially toxic acute oral dose of acetylsalicylic acid is >150 mg/kg.

Epidemiology

  • Analgesics are the most common drugs implicated in human exposures reported to U.S. poison control centers.
  • Salicylate preparations constitute ~10% of all analgesic poisoning exposures reported to poison control centers.

Pathophysiology

  • Ingested drug is absorbed in stomach and proximal intestine.
  • With therapeutic aspirin dosing, serum levels peak in 1 to 2 hours (standard preparations) or 4 to 6 hours (enteric coated).
  • After oral overdose, absorption may be prolonged and erratic.
  • Acetylsalicylate ingestion may produce gastritis and may trigger centrally mediated vomiting.
  • After overdose, the elimination half-life of salicylate becomes prolonged.
  • As blood pH falls, the proportion of nonionized salicylate rises, and more salicylate shifts into tissues, including brain.
  • Toxic salicylate exposures uncouple mitochondrial oxidative phosphorylation and increase oxygen consumption.
  • Direct stimulation of the medullary respiratory center leads to hyperventilation and respiratory alkalosis.
  • Multiple metabolic derangements produce a wide anion gap metabolic acidosis.
  • Dehydration and electrolyte shifts are common.
  • Low cerebral glucose concentrations may exist despite normal serum glucose concentrations.
  • Pulmonary and/or cerebral edema may occur.

Commonly Associated Conditions

  • Aspirin is often marketed in combination with other pharmaceuticals, which may complicate drug overdose situations.
  • Adolescents frequently overdose on >1 drug preparation.
  • Therapeutic use of acetylsalicylic acid among children with influenza has been associated with the occurrence of Reye syndrome.

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