Toxicity of acetaminophen overdose

Symptoms of toxicity following overdose of acetaminophen (APAP), now a common household medication, occur 24 to 48 hours following ingestion. Toxicity is mainly to the liver but, while data has implicated a minor metabolite, the precise mechanism is not known. Toxicity is likely to occur after a minimum ingestion of 140 mg/kg, but the toxic dose may vary as a function of individual glutathione levels. Since the early clinical picture is not diagnostic, APAP plasma levels must be measured. Supportive care alone has resulted in a 5% to 10% mortality with a high incidence of hepatic toxicity. Treatment within 10 to 12 hours following ingestion with any therapeutic agent reduced mortality to zero and diminished liver toxicity. N-acetylcysteine is an investigational new drug for treating APAP toxicity and can ethically be used if the patient is first enrolled in the current nationwide evaluation. Recommended treatment steps in a suspected APAP poisoning are 1) emesis or lavage; 2) plasma APAP determination; 3) obtain treatment protocol from the Rocky Mountain Poison Center; 4) history of use of other pharmacologic agents, and 5) diuresis, alkalinization or hemodialysis, as in aspirin poisoning, are contraindicated.