All are true about acetaminophen except:: (A) It is the most commonly used analgesic, (B) About 95% of acetaminophen undergoes detoxification by CYP2E1, (C) In severe doses liver failure may occur, (D) Injury to liver is produced by NAPQI
Answer is B. At therapeutic doses, about 95% of acetaminophen undergoes detoxification in the liver by phase II enzymes and is excreted in the urine as glucuronate or sulfate conjugates The injury produced by NAPQI (N-acetyl-benzoquinoneimine) involves two mechanisms: Covalent binding to hepatic proteins-Damage to cellular membranes and mitochondrial dysfunction, Depletion of glutathione, making hepatocytes more susceptible to reactive oxygen species-induced injury