Changes in free and bound alcohol metabolites in the urine during ethanol oxidation

Free and bound ethanol, acetaldehyde, acetate, acetone and methanol in urine during alcohol oxidation were analyzed by means of a head space gas chromatography. Four healthy male volunteers drank beer for 20 min with 16 ml/kg for non-flushers (A, B) and 8 ml/kg for flushers (C, D). In the urine, the highest bound ethanol levels were between 0.5-1.1 mM for the non-flushers (NF) and 0.2-0.3 mM for the flushers (F). The urine free ethanol levels were 23-70 times as high as bound ethanol levels. The maximum free acetaldehyde in urine was 11-13 microM for the NF and 26-55 microM for the F. The urine bound acetaldehyde levels were 4-5 microM for the NF and 7-15 microM for the F. Urine acetaldehyde existed in free forms at 2.4-3.6 times as high concentrations as in bound forms during ethanol oxidation. The urine free acetate ranged between 0.3-2.0 mM. The bound acetate varied between 0.7-1.1 mM. The urine free methanol at 70-110 microM before the intake increased to 104-180 microM. The bound methanol reached to 78-126 microM from 48-97 microM before the intake. Ethanol levels in the urine were ethanol dose-dependent, whereas it was thought that free and bound acetaldehyde or acetate reflected individual metabolic abilities and not the amount of ethanol consumed.