I am studying Forensic Science and I am finding the biochemistry part of my course really difficult to grasp. I am currently stuck on why ethanol is used in cases of methanol poisoning. I no its something to do with Alcohol Dehydrogenase and formaldehyde, but where does the ethanol come into it???

 

Help please?!?!

Methanol itself isn't very toxic, but it's metabolised to formaldehyde which is. The enzyme that converts methanol for formaldehyde isn't very good at it, given the choice it will spend its time oxidising ethanoil to acetaldehyde rather than methanol for formaldehyde.

So, if you have someone who has drunk methanol and you give them ethanol they don't do as good a job of converting the methanol to formaldehyde and so the stuff does less damage. The methanol is excreted via the kidneys and lungs instead of being oxidised.