Toxic alcohol

  • Three-step process
  • Methanol –> formaldehyde (alcohol dehydrogenase)
  • Formaldehyde –> formic acid (aldehyde dehydrogenase)
  • Formate –> CO2 and H2O (folate-dependent pathway)
Methanol poisoning
  • CNS depression similiar to alcohol overdose
  • Metabolite formic acid causes:
    • Severe metabolic acidosis
    • Blindness
    • Coma
Treatment of methanol poisoning
  • Metabolism of methanol to formic acid can be blocked by inhibiting enzyme alcohol dehydrogenase with competing drug fomepizole (4-methylpyrazole). IV ethanol is also an effective antidote
  • Enhanced elimination via haemodialysis
  • Alkalinisation to counteract metabolic acidosis (with bicarbonate)
  • Folate and folic acid are often administered, as folate-dependent system is responsible for oxidation of formic acid to CO2
Further reading
  • Katzung BG. Basic & Clinical Pharmacology. 14th ed. United States of America: McGraw-Hill Education; 2018. 405-406, 1041, 1045 p.

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MBBS (UWA) CCPU (RCE, Biliary, DVT, E-FAST, AAA) Adult/Paediatric Emergency Medicine Advanced Trainee in Melbourne, Australia. Special interests in diagnostic and procedural ultrasound, medical education, and ECG interpretation. Editor-in-chief of the LITFL ECG Library. Twitter: @rob_buttner

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