Treatment for antifreeze poisoning or methanol poisoning generally includes administering ethanol. Why is this effective in combating poisoning by either of these molecules? What is it about methanol and antifreeze that makes it toxic to animals?© BrainMass Inc. brainmass.com December 24, 2021, 8:33 pm ad1c9bdddf
SOLUTION This solution is FREE courtesy of BrainMass!
When methanol or ethylene glycol (antifreeze) are ingested, they are metabolized by the enzyme alcohol dehydrogenase. Upon action of the enzyme, methanol is converted to formaldehyde, and eventually to formate. High formate level causes acidosis which is fatal. In the latter stages of intoxication, lactic acid can also accummulate when formate inhibits the electron transport chain. On the other hand, upon the action of alcohol dehydrogenase on ethylene glycol, it is converted to glycolaldehyde which is rapidly metabolised to glycolate. The latter also results in cell acidosis. Also, some glycolate will be converted to oxalate which can precipitate out calcium in the form of calcium oxalate.
As an antidote to methanol and ethylene glycol poisoning, administration of ethanol is done. Ethanol is also metabolized by alcohol dehydrogenase. It will be converted to acetaldehyde, then acetic acid, and eventually acetyl CoA. Acetyl CoA is a substrate that can enter the metabolic mainstream through the Krebs cycle where it is converted to carbon dioxide. In other words, ethanol does not cause accummulation of toxic metabolites. So when alcohol is administered during methanol/ethylene glycol poisoning, ethanol will act as competitive inhibitor. The affinity of the enzyme for ethanol is much higher. Hence, the enzyme prefers to metabolize ethanol over methanol or ethylene glycol. Presence of ethanol will therefore inhibit formation of toxic metabolites from methanol and ethylene glycol. Due to competition for the enzyme, the therapeutic ethanol concentration depends on the concentration of the other two alcohols.© BrainMass Inc. brainmass.com December 24, 2021, 8:33 pm ad1c9bdddf>