Ethyl glucuronide (EtG) and ethyl sulphate (EtS) are minor metabolites of ethanol, and their presence in urine provides a strong indication of recent alcohol administration. In this study, we performed a drinking experiment to investigate the kinetics of EtG and EtS formation and elimination after the administration of two doses of alcohol.
Nineteen volunteers provided urine and serum (only 18) after administration of 4 and 8 units of alcohol (1 unit corresponds to 10 ml or ∼8 g of pure ethanol). The analysis was performed using a validated ultra-performance liquid chromatography-mass spectrometry (UPLC®-MS/MS) method.
After 4 units, the median EtG maximum concentration (Cmax) was 0.4 µg/ml and the interquartile range (0.3 µg/ml) in serum and 3.5 mg/h (1.2 mg/h) in urine and were reached (Tmax) after 2.0 h (0.8 h) and 3.0 h (1.0 h), respectively. EtS Cmax was 0.2 µg/ml (0.1 µg/ml) in serum and 1.3 mg/h (0.6 mg/h) in urine, and the corresponding Tmax were 1.0 h (1.0 h) and 2.0 h (0.5 h). After 8 units, EtG Cmax was 1.3 µg/ml (0.4 µg/ml) in serum and 10 mg/h (3.4 mg/h) in urine and was reached after 4.0 h (1.8 h) and 4.0 h (2.0 h), respectively. EtS Cmax was 0.6 µg/ml (0.1 µg/ml) in serum and 3.5 mg/h (1.1 mg/h) in urine, the corresponding Tmax were 3.0 h (1.0 h) and 3.0 h (1.0 h). The EtG/EtS ratio increased as a function of the time after alcohol administration in both serum and urine samples but to a lesser extent after 8 units than 4.
These results correlate with values obtained in previous studies. Tmax of EtG and EtS increased between 4 and 8 units. The EtG:EtS ratio increased in the serum and urine samples of all volunteers as a function of time at least up to 4 h after alcohol administration.
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