Methanol poisoning

Methanol poisoning occurs when industrial sprit is consumed or when the supply of liquor is adulterated with methyl alcohol .Methanol is a mild CNS depressant. Methanol as such is not a toxic agent. However its metabolites formaldehyde and formic acid are responsible for its toxicity. The enzyme responsible for conversion of methanol to formaldehyde is alcohol dehydrogenase while aldehyde dehydrogenase, formaldehyde dehydrogenase and other enzymes convert formaldehyde to formic acid. Oxidation of methanol is much slower than that of ethanol. In presence of both ethanol and methanol, the former is preferentially metabolized by alcohol dehydrogenase resulting in a reduced toxicity of methanol. Most preferred clinical features are early manifestations are caused by methanol and late manifestations are due to the methanol metabolic formic acid, methanol produces nausea , vomiting ,abdominal pain , headache, vertigo, confusion, obtundation, convulsions and coma, but other manifestations are rapid breathing due to metabolic acidosis, myocardial depression ,bradcardia , shock and anuria. Diagnosis is confirmed by measurement of serum methanol level which is usually more than 20mg/dL. Methanol derived formic acidosis can be confirmed by a large anion gap, low serum bicarbonate, and elevated serum formate levels. The osmolol gap is elevated due to methanol.