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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: BACKGROUND, OBJECTIVE, METHODS, RESULTS. Meshes: Acetamides, Adult, Ambulatory Care, Circadian Rhythm, Cross-Over Studies, Cross-Sectional Studies, Drug Tolerance, Famotidine, Helicobacter Infections, Helicobacter pylori, Histamine H2 Antagonists, Humans, Hydrogen-Ion Concentration, Male, Middle Aged, Piperidines, Pyridines.
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Does helicobacter pylori infection prevent the occurrence of the tolerance phenomenon of histamine H2 receptor antagonists? Context: The attenuated anti-secretory activity of H2 receptor antagonists (H2RA) during continuous administration is referred to as the tolerance phenomenon. However, it is not clarified whether Helicobacter pylori infection affects the occurrence of tolerance to H2RA. It is also not clarified whether the tolerance phenomenon occurs to a new H2RA, lafutidine. To investigate the occurrence of the tolerance phenomenon in subjects with and without H. pylori infection during the continuous administration of lafutidine and famotidine. Subjects were 20 healthy male volunteers (seven H. pylori positive and 13 H. pylori negative cases). All subjects were examined by ambulatory intragastric pH monitoring five times without medication, on the first and 15th day of the administration of 20 mg b.d. famotidine and 10 mg b.d. lafutidine in a cross-over fashion. The tolerance phenomenon was not observed in H. pylori-positive subjects during the 15-day-long administration of both H2RAs. In contrast, the tolerance phenomenon was observed in H. pylori negative subjects, which has been previously reported.
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This study demonstrated that H. pylori infection affects the tolerance phenomenon during continuous administration of H2RAs. Final Decision: yes