Ethanol metabolism in heavy drinkers after massive and moderate alcohol intake.

Some alcoholics have a regular daily alcohol consumption of more than 100 g. In preliminary observations we had the impression that the claimed alcohol intake in such 'heavy drinkers' was higher than could be accounted for by the ethanol elimination rate as measured routinely at 10 mmol/l (0.5 g/l). We therefore measured the ethanol elimination rate at very high blood ethanol concentrations of 40-80 mmol/l (2-4 g/l) found in eight alcoholics following heavy alcohol intake by measuring the falling blood ethanol concentrations until being less than 1 mmol/l. The elimination rate, on average 83 mumol/min per 1 blood, was about 49% higher than the elimination rate measured at 10 mmol/l in the same subject, being on average 58 mumol/min per 1/blood (paired t-test, P less than 0.05). The elimination rate following the high initial ethanol concentrations remained high until the concentration was below 5 mmol/l. Calculations of elimination rates are based on a number of assumptions concerning the physiologic and metabolic conditions. We examined specifically if the concentration-time curves could be adequately described by assuming metabolism according to a Michaelis-Menten pathway with a low Km value (simulating alcoholdehydrogenase with Km 0.2 mmol/l) or by assuming metabolism by two pathways with an alternative high-Km pathway with Km about 10 mmol/l. It was not necessary, in the statistical analysis, to include an alternative high-Km pathway. On the other hand, the data does give room for up to 50% elimination via such alternative pathways. The elimination rate at the high concentrations corresponded roughly to the claimed daily alcohol intake; furthermore the measured elimination rate at the lower concentrations were similar to values in non-alcoholics.