Acetylcysteine for acetaminophen poisoning

A 25- year- old man presents to the emergency department with a toothache. During the evaluation, the physician determines that the patient has been taking large doses of over- the- counter acetaminophen along with an acetaminophen - hydrocodone product for the past 5 days. His daily dose of acetaminophen has been 12 g per day ( maximum recommended dose, 4 g per day). He has no other medical problems and typically consumes two beers a day. The patient has no symptoms beyond his toothache, is not icteric, and has no hepatomegaly or right- upper- quadrant tenderness. His serum acetaminophen concentration 8 hours after the most recent dose is undetectable. His serum alanine aminotransferase concentration is 75 IU per liter, his serum bilirubin concentration is 1.2 mg per deciliter ( 20.5 mu mol per liter), and his international normalized ratio ( INR) is 1.1. The emergency department physician contacts the regional poison- control center, which recommends treatment with acetylcysteine.