Mechanism of action of ethanol in methyl alcohol poisoning:
(Ref: Katzung, 14th ed. pg. 404; KDT, 6th ed. pg. 387)* Ethanol acts by competitive inhibition of alcohol dehydrogenase which block further metabolism of methanol into formaldehyde and formic acid. These products also cause retinal damage leading to subsequent blindness.ADH: alcohol dehydrogenase: FDH : formaldehyde dehydrogenase F-THF-S: 10-formyl tetrahydrofolate synthetase* Catalase is a common enzyme found in nearly all living organisms exposed to oxygen. It catalyzes the decomposition of hydrogen peroxide to water and oxygen* Lactate dehydrogenase: Dummy choice and is present in heart, RBC and is used as marker for malignancy.* Acetaldehyde dehydrogenase: Converts acetaldehyde into acetic acid and is the target for disulfiram which is used to help patients quit alcohol.Remember* Ethanol is also metabolized by alcohol dehydrogenase and acts as its competitive inhibition. The enzyme's affinity for ethanol is 10-20 times higher than it is for methanol. Given via IV infusion in methanol or ethylene glycol poisoning.* Fomepizole inhibits alcohol dehydrogenase. It is a stronger competitive inhibitor of ADH and, in addition, does not cause hypoglycemia or sedation.* Fomepizole is relatively easier to administer than ethanol. It does not require monitoring of serum concentrations. Hence considered as drug of choice.
Competitively inhibits alcohol Dehydrogenase
Selectively inhibits catalase
Competitively inhibits lactate dehydrogenase
Competitive inhibition of acetaldehyde dehydrogenase
C.N.S