IN-VITRO ACTIVITY OF LANSOPRAZOLE AGAINST HELICOBACTER-PYLORI

Lansoprazole is a gastric parietal cell proton pump inhibitor that is also active against Helicobacter pylori in vitro. We aimed to investig ate further the mechanism of its antimicrobial effect. The antimicrobi al activity of lansoprazole and of its sulfenamide, a rearrangement pr oduct occurring spontaneously in acid environments, was studied by det ermining the MICs and MBCs for II cytotoxic and eight non-cytotoxic ii . pylori strains and by measuring the rapidity of bacterial killing. T he MIC90 and MBC90 were 2.5 mg/L and 10 mg/L, respectively, both for l ansoprazole and for its sulfenamide. Cytotoxic strains were as suscept ible as noncytotoxic strains. The sulfenamide exhibited faster bacteri cidal activity. Lansoprazole did not inhibit the toxin-induced vacuoli zation of HeLa cells by a cytotoxic strain, hence its anti-H. pylori a ctivity does not depend on inhibition of a v-ATPase-mediated, toxin-in duced activity. Sulfenamide formation is likely to occur in vivo in th e gastric environment, thus enhancing the bactericidal activity of the drug. Lansoprazole is likely to be useful, in association with antibi otics, in the treatment of H. pylori infection regardless of the cytot oxicity of the infecting strain.