MEDizzy - A 50-year-old man has been consuming large amounts of

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The central nervous system 2

A 50-year-old man has been consuming large amounts of ethanol on an almost daily basis for many years. One day, unable to find any ethanol, he ingests a large amount of methanol (wood alcohol) that he had bought for his camp lantern. Which of the following drugs should we administer to treat best the poisoning and the signs and symptoms that occurred?

ExplanationMethanol is metabolized by the same enzymes that metabolize ethanol, but the products are different: formaldehyde and formic acid in the case of methanol. Headache, vertigo, vomiting, abdominal pain, dyspnea, and blurred vision can occur from the accumulation of these metabolic intermediates. However, the most dangerous (or at least permanently dis- abling) consequence in severe cases is hyperemia of the optic disc, which can lead to blindness. The rationale for administering ethanol to treat methanol poisoning is fairly simple. Ethanol has a high affinity for alcohol and aldehyde dehydrogenases and competes with methanol as a substrate for those enzymes, reducing the metabolism of methanol to its more toxic products. Important adjunctive treatments include hemodialysis to enhance the removal of methanol and its products; and administration of systemic alkalinizing salts (e.g., sodium bicarbonate) to counteract metabolic acidosis. None of the other drugs listed would be appropriate. They may alleviate some of the signs and symptoms resulting from methanol poisoning, but they would have no beneficial effects on the crux of the problem—the metabolism of the methanol.