What is the antidote for methanol poisoning?

What is the antidote for methanol poisoning?

• A. Ethanol
• B. Fomepizole
• C. N-acetylcysteine
• D. Vitamin K

Answer: (B)

Blocking formation of toxic metabolites by inhibiting alcohol dehydrogenase is the key idea. Methanol itself isn’t the main danger; its metabolites—formaldehyde and formic acid—cause severe acidosis and optic injury. An antidote that effectively stops methanol from being turned into these toxic products is fomepizole, which binds to alcohol dehydrogenase with high affinity and prevents methanol metabolism. By keeping methanol in its unmetabolized form, the body can eliminate it more safely and the toxic effects are reduced. Ethanol can also inhibit the enzyme and has been used when fomepizole isn’t available, but fomepizole is preferred due to more predictable effects and fewer complications. The other options don’t address the metabolic activation of methanol: N-acetylcysteine treats acetaminophen toxicity, and vitamin K is used for anticoagulant-related issues. In severe cases, additional measures like bicarbonate for acidosis or hemodialysis may be needed to rapidly remove methanol and metabolites.

Blocking formation of toxic metabolites by inhibiting alcohol dehydrogenase is the key idea. Methanol itself isn’t the main danger; its metabolites—formaldehyde and formic acid—cause severe acidosis and optic injury. An antidote that effectively stops methanol from being turned into these toxic products is fomepizole, which binds to alcohol dehydrogenase with high affinity and prevents methanol metabolism. By keeping methanol in its unmetabolized form, the body can eliminate it more safely and the toxic effects are reduced. Ethanol can also inhibit the enzyme and has been used when fomepizole isn’t available, but fomepizole is preferred due to more predictable effects and fewer complications. The other options don’t address the metabolic activation of methanol: N-acetylcysteine treats acetaminophen toxicity, and vitamin K is used for anticoagulant-related issues. In severe cases, additional measures like bicarbonate for acidosis or hemodialysis may be needed to rapidly remove methanol and metabolites.