H2-receptor antagonists and antacids have an aggravating effect on Helicobacter pylori gastritis in duodenal ulcer patients.

Background: Antacids, such as aluminium-magnesium hydroxide (AIMg(OH)3), or H2-receptor antagonists, such as ranitidine, are common drugs used for treating peptic ulcer disease and acid-related symptoms.
Methods: In a prospective double-blind controlled study, 174 patients were randomized to a 4-week course of treatment with either AIMg(OH)3 (acid-binding capacity: 280 mval/day) or ranitidine 300 mg for active Helicobacter pylori-associated duodenal ulcers (as determined by histology and the urease test). Before and after treatment, two biopsy specimens each were obtained from the antrum and corpus, and the grade and activity of gastritis, as well as H. pylori density, were determined using a score ranging from 0 = none to 4 = severe.
Results: Pre- and post-treatment histology were available for 138 patients (AIMg(OH)3: 67, ranitidine; 71). Treatment with AIMg(OH)3 significantly increased the activity of corpus gastritis (Wilcoxon signed-rank: P = 0.0014), while ranitidine treatment significantly increased both the grade and activity of corpus gastritis (P = 0.0002 and P = 0.0001 respectively). In the antrum, both regimens provoked a significant increase in the frequency of intestinal metaplasia, but this may be a consequence of sampling error.
Conclusions: Ranitidine and AIMg(OH)3 have an aggravating effect on H. pylori gastritis in duodenal ulcer patients. This should be considered a side-effect of the respective drugs and is more pronounced with ranitidine.