In salicylate overdosage resulting from acute ingestion of aspirin, little or no toxicity generally occurs in individuals ingesting less than 150 mg/kg, mild to moderate toxicity in those ingesting 150 to 300 mg/kg, severe toxicity in those ingesting 300 to 500 mg, and potentially lethal toxicity in those ingesting greater than 500 mg/kg. A single lethal dose of aspirin in adults is not known with certainty but death may be expected at 30 g.
The principal toxic effects of salicylate overdosage are extension of pharmacologic actions and include local gastrointestinal irritation, direct central nervous system stimulation of respiration, severe acid-base and electrolyte disturbances and are complicated by hyperthermia and dehydration. Respiratory alkalosis occurs early while hyperventilation is present, but is quickly followed by metabolic acidosis.
Treatment consists primarily of supporting vital functions, increasing salicylate elimination, and correcting the acid-base disturbance. Gastric emptying and/or lavage is recommended as soon as possible after ingestion, even if the patient has vomited spontaneously. After lavage and/or emesis, administration of activated charcoal (as a slurry), is beneficial, if less than 3 hours have passed since ingestion. Charcoal adsorption should not be employed prior to emesis and lavage.
Severity of aspirin intoxication is determined by measuring the blood salicylate level. Acid-base status should be closely followed with serial blood gas and serum pH measurements. Fluid and electrolyte balance should be maintained.
Hemodialysis and peritoneal dialysis may be performed to reduce the body drug content. Dialysis is usually required in patients with renal insufficiency or in cases of life-threatening intoxication.