NAPQI

What it isN-acetyl-p-benzoquinone imine, the reactive acetaminophen metabolite generated by CYP2E1.

Why it mattersIn therapeutic dosing glutathione neutralizes it; in overdose glutathione runs out and NAPQI binds hepatocyte proteins — the entire mechanism of acetaminophen liver failure.

What it changesN-acetylcysteine works by restocking glutathione, and chronic alcohol use (CYP2E1 induction, glutathione depletion) shifts the danger threshold downward.