D. Jacobsen et al., KINETIC INTERACTIONS BETWEEN 4-METHYLPYRAZOLE AND ETHANOL IN HEALTHY HUMANS, Alcoholism, clinical and experimental research, 20(5), 1996, pp. 804-809
4-Methylpyrazole (4-MP), a potent inhibitor of alcohol dehydrogenase a
ctivity, is a candidate to replace ethanol as the antidote for methano
l and ethylene glycol intoxications, because it has a longer duration
of action and apparently fewer adverse effects. To study a probable mu
tual inhibitory effect between ethanol and 4-MP on their elimination,
two studies were performed in healthy human volunteers using double-bl
ind crossover designs. In study A, 4-MP in the presumed therapeutic do
se range of ID to 20 mg/kg caused a 40% reduction in the rate of elimi
nation of ethanol in 12 subjects given 0.5 to 0.7 g/kg of ethanol. The
se data suggest that such doses of 4-MP inhibit alcohol dehydrogenase
activity in humans in vivo and would be effective at blocking methanol
or ethylene glycol metabolism. In study B, ethanol (0.6 g/kg followed
by 0.2 g/kg twice) significantly decreased the rate of elimination of
4-MP (5 mg/kg, given intravenously to four subjects). These moderate
doses of ethanol also inhibited the rate of urinary excretion of 4-car
boxypyrazole, the primary metabolite of 4-MP in humans. Data suggest t
hat ethanol inhibits 4-MP metabolism, thereby increasing the duration
of therapeutic blood levels of 4-MP in the body. This mutual interacti
on may have clinical implications, because most self-poisoned patients
have also ingested ethanol. Theoretically, methanol and ethylene glyc
ol might also show such interactions with 4-MP.