Definition of Methanol Poisoning

In this article, we will discuss the Definition of Methanol Poisoning. So, let’s get started.

Definition

Methanol (methyl alcohol, wood alcohol) is used as a detergent, is a component of varnishes, paint removers, wind-shield washer solutions, copy machine fluid, anti-freeze solutions and solvents. It is also a denaturant used to make ethanol unfit for consumption.

Mode of Poisoning

Methanol poisoning occurs commonly due to intentional use of cheap illicit liquor (hooch) in alcoholics as a substitute for ethanol. It may also be a contaminant in bootleg whisky. The poisoning may occur in isolation or in an epidemic proportion (hooch tragedy). People of lower socio-economic status are vulnerable to this poisoning.

Mechanism of Action

After ingestion, it is rapidly absorbed and concentrated in the liver, GI tract, eyes and kidneys. Its level peaks within 1-2 hours of ingestion. Its binding is negligible. It is mainly metabolised in the liver but up to 10% is excreted unchanged by the lungs and kidneys. In the liver, methanol is converted into formaldehyde and then into formic acid by the enzyme alcohol dehydrogenase. Both methanol and its metabolites are toxic, the latter causing more serious side effects.

The half-life of elimination at low serum levels is 14-20 hours and at high serum level is 24-30 hours. Ethanol (ethyl alcohol) competes with methanol for enzyme alcohol dehydrogenase for metabolism. Ethyl alcohol has more affinity for this enzyme hence, has found place in its treatment by increasing the elimination half-life of methanol to 30-36 hours (in the absence of enzyme, methanol is not metabolised further).

The fatal oral dose of methanol is 30-240 ml (25-150 g), but 30 ml of a 40% solution can be fatal.

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