GROWTH-INHIBITORY AND BACTERICIDAL ACTIVITIES OF LANSOPRAZOLE COMPARED WITH THOSE OF OMEPRAZOLE AND PANTOPRAZOLE AGAINST HELICOBACTER-PYLORI

Background. Helicobacter pylori plays a role in the pathogenesis of bo th duodenal and gastric ulcers. The aim of this study was to evaluate the effect of the proton pump inhibitor (PPI), lansoprazole, commonly used in eradication regimens, on growth, bactericidal activity and mor phology of H. pylori in vitro in comparison with other PPIs. Materials and Methods. Growth inhibitory activity of each of the PPIs was evalu ated by determining minimum inhibitory concentrations using an agar di lution method. Bactericidal activity was determined by analysis of the viable cells in culture at various time points after incubation with different concentrations of the PPIs. Bacterial morphology was examine d using scanning electron microscopy of fixed cells after exposure to the test substances. Urease activity in cell extracts of H. pylori tha t had been incubated with increasing concentrations of the PPIs was de termined by colorimetry. Results. The growth inhibitory activity of la nsoprazole was significantly more potent than that of omeprazole or pa ntoprazole (MIC90 6.25 vs. 25 and 100 mu g/ml, respectively). Exposure of H. pylori to lansoprazole produced loss of viability and an aberra nt bacterial morphology, which was more extensive than seen with omepr azole or pantoprazole. Lansoprazole dose dependently inhibited urease activity; its effectiveness was comparable with omeprazole but more po tent than pantoprazole. Conclusions. The mechanism of action that lead s to loss of viability of H. pylori cells appears to differ between th e three PPIs investigated; lansoprazole was the most potent of the thr ee agents in terms of growth inhibition and disruption of bacterial mo rphology.