What is the antidote for ethylene glycol poisoning?

• A. Ethanol
• B. Fomepizole
• C. N-acetylcysteine
• D. Activated charcoal

Answer: (B)

Ethylene glycol causes harm mainly after it is turned into toxic metabolites by the enzyme alcohol dehydrogenase. Those metabolites drive the dangerous metabolic acidosis and kidney injury. The best antidote works by blocking that early step, so the body stops making the harmful products. Fomepizole does this by binding strongly to alcohol dehydrogenase, preventing ethylene glycol from being metabolized. This keeps most of the substance in its non-toxic form and halts the cascade that leads to acidosis and organ damage. It also has the advantage of being easy to use without causing additional intoxication or unpredictable effects, unlike ethanol, which requires careful monitoring of alcohol levels and can complicate the clinical picture. N-acetylcysteine targets acetaminophen toxicity, not ethylene glycol, so it isn’t relevant here. Activated charcoal can absorb some substances if given very early, but it isn’t an antidote and doesn’t stop the toxic metabolic process once ethylene glycol has been absorbed. In severe cases, supportive care and dialysis may be needed to remove ethylene glycol and its metabolites, but the key initial step to prevent ongoing injury is inhibiting alcohol dehydrogenase with fomepizole.