N-acetylcysteine vs Fomepizole
How to tell N-acetylcysteine and Fomepizole apart when a board question makes them look alike.
NAC restores glutathione for acetaminophen; fomepizole blocks alcohol dehydrogenase for toxic alcohols.
Side by side
Acetaminophen overdose antidote that restores glutathione and detoxifies NAPQI.
Methanol or ethylene glycol antidote that inhibits alcohol dehydrogenase to prevent toxic acid metabolites.
N-acetylcysteine replenishes hepatic glutathione and improves detoxification of acetaminophen metabolites.
Fomepizole competitively inhibits alcohol dehydrogenase, blocking conversion to formic acid or glycolic/oxalic acid metabolites.
Acetaminophen level nomogram, rising AST/ALT, or NAPQI wording points N-acetylcysteine.
Osmolar gap plus anion-gap acidosis, visual symptoms, or calcium oxalate crystals points fomepizole.
The trap
Both are antidotes for metabolic poisonings, but only toxic alcohols need alcohol dehydrogenase blockade.
The repair move
For antidotes, match the toxic metabolite pathway, not just the presence of acidosis.
Try a free question
CoreA patient presents after acetaminophen overdose. The antidote is started to restore hepatic glutathione and detoxify the reactive metabolite NAPQI. Which medication is this?
Show answer and explanation
Answer: A. N-acetylcysteine. N-acetylcysteine replenishes glutathione and is the antidote for potentially hepatotoxic acetaminophen ingestion.
Why the other choices are tempting
- B. Fomepizole blocks alcohol dehydrogenase for methanol or ethylene glycol poisoning.
- C. Naloxone reverses opioid toxicity.
- D. Flumazenil reverses benzodiazepine-site effects in selected cases.
- E. Leucovorin rescues methotrexate toxicity.
Flashcards
Tap a card to flip it.
What is the fastest separator for N-acetylcysteine vs Fomepizole?
NAC restores glutathione for acetaminophen; fomepizole blocks alcohol dehydrogenase for toxic alcohols.
What clue should make you choose N-acetylcysteine?
Acetaminophen overdose antidote that restores glutathione and detoxifies NAPQI.
Quick answers
What is the fastest way to tell N-acetylcysteine from Fomepizole?
NAC restores glutathione for acetaminophen; fomepizole blocks alcohol dehydrogenase for toxic alcohols.
What is the key clue for N-acetylcysteine?
Acetaminophen overdose antidote that restores glutathione and detoxifies NAPQI.
What is the key clue for Fomepizole?
Methanol or ethylene glycol antidote that inhibits alcohol dehydrogenase to prevent toxic acid metabolites.
What is the common trap with N-acetylcysteine vs Fomepizole?
Both are antidotes for metabolic poisonings, but only toxic alcohols need alcohol dehydrogenase blockade.