Helicobacter pylori infection potentiates the inhibition of gastric acid secretion by omeprazole

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Abstract
BACKGROUND: Omeprazole has a greater intragastric pH elevating effect in Helicobacter pylori positive than negative subjects. Ammonia production byH pylori has been suggested as a probable mechanism.AIMS: To assess the effect ofH pylori status on gastric acid secretion during omeprazole treatment, and to examine the possible role of ammonia neutralisation of intragastric acid in increased omeprazole efficacy in infected subjects.METHODS: TwentyH pylori positive and 12H pylori negative healthy volunteers were examined before and six to eight weeks after commencing omeprazole 40 mg/day. On both occasions plasma gastrin and acid output were measured basally and in response to increasing doses of gastrin 17 (G-17). Gastric juice ammonium concentrations were also measured.RESULTS: Prior to omeprazole, measurements were similar in the H pyloripositive and negative subjects. During omeprazole, median basal intragastric pH was higher in the H pyloripositive (7.95) versus negative (3.75) subjects (pH pylori positive subjects (0.0, 3.6, 6.0 mmol/h respectively) versus negative subjects (0.3, 14.2, 18.6 mmol/h) (pH pylori infection leads to a more profound suppression of acid secretion during omeprazole treatment. The effect cannot be explained by neutralisation of intragastric acid by bacterial ammonia production and its precise mechanism has to be explained.