Methyl Alcohol Poisoning
METHANOL (METHYL ALCOHOL) POISONING:
- Highly toxic alcohol.
- Metabolized to formaldehyde (by alcohol dehydrogenase) and formic acid (by acetaldehyde dehydrogenase).
- Can be present in contaminated country liquor used to denature ethanol.
Accumulation of formic acid
- causes toxic effects in methanol poisoning.
- Results in lactic acidosis/high anion gap metabolic acidosis with low plasma
- Bicarbonates, blindness due to retinal damage, papilledema and optic atrophy
Symptoms of poisoning
- Nausea, vomiting,
- Dizziness, confusion,
- Headache, abdominal pain, respiratory
- Depression, cyanosis, acute tubular necrosis,
- Hypothermia, fixed dilated pupils, visual disturbance (blurring of vision photophobia)
- Odor of spirit in breath.
Fatal dose : in adults is 60-240 ml in adults, but as little as l5 ml can cause blindness
- gastric lavage and sodium bicarbonate (to treat acidosis)
- ethanol is useful because it competitively inhibits the conversion of methanol to formic acid.
- Fomepizole can also be used as it is a specific inhibitor of alcohol dehydrogenase.
- Folic acid or folinic acid enhance the metabolism of formic acid to CO2 .
- Hemodialysis may also be used in severe poisoning.