Fomepizole’s role and typical dosing for methanol/ethylene glycol poisoning?

• A. Induces hepatic enzymes; loading 5 mg/kg IV, then 5 mg/kg daily.
• B. Inhibits alcohol dehydrogenase; loading 15 mg/kg IV, then 10 mg/kg every 12 hours until stable.
• C. Enhances methanol metabolism; 1 g/kg IV bolus.
• D. Chelates methanol; 20 mg/kg IV every 6 hours.

Answer: (D)

Fomepizole works by blocking alcohol dehydrogenase, so methanol and ethylene glycol aren’t converted into their toxic metabolites. This keeps the metabolites from accumulating and worsening acidosis and organ injury, and it often reduces the need for dialysis.

The standard dosing is a 15 mg/kg IV loading dose, followed by 10 mg/kg IV every 12 hours until serum methanol or ethylene glycol levels are undetectable and the patient is clinically stable. It’s not a hepatic enzyme inducer, not a chelating agent, and it doesn’t act by suddenly increasing methanol metabolism. This mechanism with this dosing best fits fomepizole’s use in methanol/ethylene glycol poisoning.