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01-26-16 Do you DEWshine?

Question of the Week

January 26, 2016

Do you DEWshine?

This past week, the poison center was involved in the care of 4 teenagers from Robertson County who drank Mountain Dew mixed with racing fuel (so called Dewshine). Racing fuel (used for drag racing) is almost 100% methanol.  There were two deaths.

It is difficult to determine the incidence of this practice in Tennessee.  Clearly, it is a practice of which we need to be aware.

According to the internet (a very reputable source we all know) Mountain Dew and Sun Drop are favorites to mix with corn liquor (better known to most as Moonshine) in the Appalachians.

The life threat is the methanol.  Methanol has relatively low toxicity but it is metabolized to formaldehyde which is subsequently oxidized to formic acid.  The conversion from formaldehyde to formic acid is very rapid and occurs within minutes.  Formic acid is converted by 10-formyl tetrahydrofolate synthetase to carbon dioxide and water.  Formic acid accumulates.  Not surprisingly, there is a direct correlation between formic acid concentration and morbidity and mortality.  Formic acid inhibits cytochrome oxidase, the inhibition increases as the pH decreases, and cellular injury occurs. Lactate is produced as formic acid interferes with intracellular respiration and promotes anaerobic metabolism.  The combination of the formic acid and lactic acid can cause a life-threatening acidosis. 

Ocular toxicity is caused by formic acid directly. MRI reveals edema and necrotic damage in the basal ganglia and putamen and hemorrhage in the white matter.  Cause is thought to be due to failure of Na-K ATPase pump as the formic acid inhibits cytochrome oxidase. 

Signs and symptoms include nausea/vomiting and CNS depression (depending on methanol dose).  A latent period lasting 12-124 hours and blurred vision may occur. 

Blood analysis reveals an osmolar gap (depending on the amount of methanol that has not been metabolized); an acidosis (depending on the amount of methanol that has been metabolized); and an anion gap.

Treatment is correction of the acidosis with sodium bicarbonate and administration of fomepizole which is a potent inhibitor of alcohol dehydrogenase.  Prior to fometpizole, ethanol was administered but there were multiple problems with that administration. (Drunk people in the PICU/ICU can be difficult to manage).  Depending on the methanol concentration and the clinical picture, hemodialysis may be necessary.

This question prepared by:  Donna Seger, MD  Medical Toxicologist