Effect of ranitidine and cimetidine on gastric emptying of a mixed meal in man.

The effect of acute and chronic crossover administration of ranitidine and cimetidine on gastric emptying was studied in healthy volunteers and in duodenal ulcer patients, respectively. In the first series of experiments, intravenous ranitidine (50 mg) significantly (p less than 0.05) delayed emptying of both solids and liquids, whereas cimetidine (300 mg i.v.) was totally ineffective. In the second set of experiments, neither ranitidine (150 mg bd orally for two weeks) nor cimetidine (400 mg bd) significantly modified emptying rate. These results, therefore, suggest that only high blood levels of ranitidine, as elicited by intravenous administration, are able to affect gastric emptying. On the contrary, at steady state levels elicited by conventional therapeutic doses, no effect on gastric emptying is evident.