Effect of ranitidine on secretion of gastric intrinsic factor and absorption of vitamin B 12

: The effects of ranitidine, a new potent histamine H2-receptor antagonist, on gastric intrinsic factor (IF) secretion and protein-bound cobalamin absorption were evaluated in 6 patients with duodenal ulcer, before, during and after discontinuation of ranitidine therapy. Oral ranitidine (150 mg twice a day) resulted in a non significant decrease of IF concentration and IF output but was responsible for malabsorption of protein-bound cobalamin. This malabsorption was reversible upon discontinuation of ranitidine. These results indicate that occurrence of cobalamin deficiency cannot be excluded during long-term ranitidine treatment and emphasize the need for careful follow-up in these patients.