Aims To investigate the absorption, distribution and elimination of ethanol in women with abnormal gut as a result of gastric bypass surgery. Patients who undergo gastric bypass for morbid obesity complain of increased sensitivity to the effects of alcohol after the operation.

Methods Twelve healthy women operated for morbid obesity at least 3 years earlier were recruited. Twelve other women closely matched in terms of age and body mass index (BMI) served as the control group. After an overnight fast each subject drank 95% v/v ethanol (0.30 g kg⁻¹ body weight) as a bolus dose. The ethanol was diluted with orange juice to 20% v/v and finished in 5 min. Specimens of venous blood were taken from an indwelling catheter before drinking started and every 10 min for up to 3.5 h post‐dosing. The blood alcohol concentration (BAC) was determined by headspace gas chromatography.

Results     The    maximum    blood‐ethanol    concentration    (C_max)    was   0.741 ± 0.211 g l⁻¹ (± s.d.) in the operated group compared with 0.577 ± 0.112 g l⁻¹ in the controls (mean difference 0.164 g l⁻¹, 95% confidence interval (CI) 0.021, 0.307). The median  time  to  peak  (t_max) was 10 min in the bypass patients compared with 30 min in controls (median difference −15 min (95% CI −10, −20 min). At 10 and 20 min post‐dosing the BAC was higher in the bypass patients (P < 0.05) but not at 30 min and all later times (P > 0.05). Other pharmacokinetic parameters of ethanol were not significantly different between the two groups of women (P > 0.05).

Conclusions  The higher sensitivity to ethanol after gastric bypass surgery probably reflects the more rapid absorption of ethanol leading to higher C_max and earlier t_max. The marked reduction in body weight after the operation might also be a factor to consider if the same absolute quantity of ethanol is consumed.