Pharm 101: Methanol
Class
Toxic alcohol
Metabolism
- 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
- Buttner R. Pharm 101: Ethanol
References
- Katzung BG. Basic & Clinical Pharmacology. 14th ed. United States of America: McGraw-Hill Education; 2018. 405-406, 1041, 1045 p.
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Adult/Paediatric Emergency Medicine Advanced Trainee in Melbourne, Australia. Special interests in diagnostic and procedural ultrasound, medical education, and ECG interpretation. Co-creator of the LITFL ECG Library. Twitter: @rob_buttner