Effects of ranitidine on blood alcohol levels after ethanol ingestion. Comparison with other H2-receptor antagonists.

OBJECTIVE

To determine whether the H2-receptor antagonist, ranitidine, which is a potent inhibitor of gastric alcohol dehydrogenase activity in vitro, increases the bioavailability of orally administered ethanol (0.3 g/kg of body weight) and to compare the resulting blood alcohol concentrations with those of two other H2-antagonists, cimetidine and famotidine, the latter of which does not inhibit gastric alcohol dehydrogenase.

DESIGN

For each of the H2-receptor antagonists, a different group of subjects was used. In each group, a paired design was adopted with each subject serving as his own control.

SETTING

Hospital laboratory.

SUBJECTS

Normal, healthy men aged 24 to 46 years.

INTERVENTION

Eight men were treated for 1 week with ranitidine (300 mg/d), six with cimetidine (1000 mg/d), and six with famotidine (40 mg/d).

MEASURES

Peak blood alcohol concentrations, areas under the blood alcohol curve, first-pass metabolism, and bioavailability of orally consumed ethanol.

RESULTS

Relative to baseline, ranitidine increased the mean peak concentration and the area under the curve of blood alcohol concentrations by 34% (P less than .05) and 41% (P less than .01), respectively. First-pass metabolism of ethanol was decreased from 70 +/- 10 to 31 +/- 9 mg/kg of body weight, with a corresponding increase in ethanol bioavailability of 79.6% to 92.6%. By comparison, cimetidine had even a greater effect on blood alcohol levels, while famotidine had no significant effects.

CONCLUSION

Patients treated with ranitidine or cimetidine should be warned of possible functional impairments after consumption of amounts of ethanol considered safe in the absence of such therapy.