EFFECTS OF RANITIDINE ON BLOOD-ALCOHOL LEVELS AFTER ETHANOL INGESTION - COMPARISON WITH OTHER H2-RECEPTOR ANTAGONISTS

Objective. - To determine whether the H-2-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 H-2-antagonists, cimetidine and famotidine, the latter of which does not inhibit gastric alcohol dehydrogenase. Design. - For each of the H-2-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 < .05) and 41% (P < .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.