The
alcohols,
methanol,
ethylene glycol and
diethylene glycol, have many features in common, the most important of which is the fact that the compounds themselves are relatively non-toxic but are metabolized, initially by
alcohol dehydrogenase, to various toxic intermediates. These compounds are readily available worldwide in commercial products as well as in homemade alcoholic beverages, both of which lead to most of the
poisoning cases, from either unintentional or intentional ingestion. Although relatively infrequent in overall occurrence,
poisonings by metabolically-toxic
alcohols do unfortunately occur in outbreaks and can result in severe morbidity and mortality. These
poisonings have traditionally been treated with
ethanol since it competes for the active site of
alcohol dehydrogenase and decreases the formation of toxic metabolites. Although
ethanol can be effective in these
poisonings, there are substantial practical problems with its use and so
fomepizole, a potent competitive inhibitor of
alcohol dehydrogenase, was developed for a hopefully better treatment for metabolically-toxic alcohol
poisonings.
Fomepizole has few side effects and is easy to use in practice and it may obviate the need for haemodialysis in some, but not all, patients. Hence,
fomepizole has largely replaced
ethanol as the toxic alcohol
antidote in many countries. Nevertheless,
ethanol remains an important alternative because access to
fomepizole can be limited, the cost may appear excessive, or the physician may prefer
ethanol due to experience.