title: Growth inhibitory and bactericidal activities of lansoprazole compared with those of omeprazole and pantoprazole against Helicobacter pylori.
abstract: BACKGROUND
  Helicobacter pylori plays a role in the pathogenesis of both 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 morphology of H. pylori in vitro in comparison with other PPIs.
  
  
  METHODS
  Growth inhibitory activity of each of the PPIs was evaluated by determining minimum inhibitory concentrations using an agar dilution 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 examined using scanning electron microscopy of fixed cells after exposure to the test substances. Urease activity in cell extracts of H. pylori that had been incubated with increasing concentrations of the PPIs was determined by colorimetry.
  
  
  RESULTS
  The growth inhibitory activity of lansoprazole was significantly more potent than that of omeprazole or pantoprazole (MIC90 6.25 vs. 25 and 100 micrograms/ml, respectively). Exposure of H. pylori to lansoprazole produced loss of viability and an aberrant bacterial morphology, which was more extensive than seen with omeprazole or pantoprazole. Lansoprazole dose dependently inhibited urease activity; its effectiveness was comparable with omeprazole but more potent than pantoprazole.
  
  
  CONCLUSIONS
  The mechanism of action that leads to loss of viability of H. pylori cells appears to differ between the three PPIs investigated; lansoprazole was the most potent of the three agents in terms of growth inhibition and disruption of bacterial morphology.
authors.affiliation: Pharmaceutical Research Laboratories III, Takeda Chemical Industries Ltd., Osaka, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Nakao
authors.forename: P
authors.initials: P
authors.lastname: Malfertheiner
mesh_terms: D053799:2-Pyridinylmethylsulfinylbenzimidazoles; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000897:Anti-Ulcer Agents / Q000494:pharmacology*; D001562:Benzimidazoles / Q000494:pharmacology; D006131:Growth Inhibitors / Q000494:pharmacology*; D016480:Helicobacter pylori / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D064747:Lansoprazole; D008855:Microscopy, Electron, Scanning; D009853:Omeprazole / Q000031:analogs & derivatives / Q000494:pharmacology; D000077402:Pantoprazole; D013454:Sulfoxides / Q000494:pharmacology; D014510:Urease / Q000378:metabolism
chemical_list: D053799:2-Pyridinylmethylsulfinylbenzimidazoles; D000900:Anti-Bacterial Agents; D000897:Anti-Ulcer Agents; D001562:Benzimidazoles; D006131:Growth Inhibitors; D013454:Sulfoxides; D064747:Lansoprazole; D000077402:Pantoprazole; D014510:Urease; D009853:Omeprazole