Helicobacter pylori infection prevents the occurrence of the tolerance phenomenon of histamine H2 receptor antagonists.

Background: 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 pylon infection affects the occurrence of tolerance to H2RA. It is also not clarified whether the tolerance phenomenon occurs to a new H2RA, lafutidine. Aim: To investigate the occurrence of the tolerance phenomenon in subjects with and without H. pylon infection during the continuous administration of lafutidine and famotidine. Subjects and Methods: Subjects were 20 healthy male volunteers (seven H. pylon positive and 13 H. pylon 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. Results: The tolerance phenomenon was not observed in H. pylon-positive subjects during the 15-day-long administration of both H2RAs. In contrast, the tolerance phenomenon was observed in H. pylon negative subjects, which has been previously reported. Conclusions: This study demonstrated that H. pylon infection affects the tolerance phenomenon during continuous administration of H2RAs. [ABSTRACT FROM AUTHOR]