Acetaminophen hepatotoxicity and overdose.

Acetaminophen is a widely available and frequently recommended over-the-counter analgesic and antipyretic. Chronic doses in excess of 5 Gm. per day and acute doses of as little as 7 Gm. have caused hepatic damage in adults. Larger doses may be fatal. The hepatotoxicity, which is due to metabolic transformation of the acetaminophen to an alkylating agent, can be palliated or avoided by prompt treatment. Blood levels over 200 micrrograms per mL. four hours after ingestion correlate with severe hepatotoxicity. Clinical trials have shown N-acetylcysteine (NAC) to be a specific antidote when administered within eight hours of an acute ingestion.