Paper I — 2019 July (Supplementary) (2010 Scheme) — Q9
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Paper I
2019 July (Supplementary) (2010 Scheme) · 40 marks · 120 min
Question
Fomepizole in methanol poisoning
Q91 marksShort Answers
Answer
Methanol is metabolized by alcohol dehydrogenase to formaldehyde and then formic acid, the toxic metabolite responsible for metabolic acidosis and ocular toxicity. Fomepizole is a direct, potent competitive inhibitor of alcohol dehydrogenase, blocking the conversion of methanol to its toxic metabolites, allowing unmetabolized methanol to be safely excreted renally or removed by haemodialysis. It is preferred over ethanol as an antidote because it does not cause the CNS depression/intoxication associated with ethanol therapy and has more predictable pharmacokinetics.