Background: Proton pump inhibitors are reported to enhance the efficacy of antibiotics in the treatment of Helicobacter pylori infection. An elevated intragastric pH is considered to be an important factor for this increased antimicrobial efficacy. The aim of this study was to assess the effect of different doses of lansoprazole on 24-hour intragastric pH and to correlate the effect of amoxicillin on the cure rate for H. pylori infection with the intragastric pH obtained during lansoprazole treatment.
Patients and methods: Thirty-six duodenal ulcer patients who tested positively for H. pylori as assessed by a rapid urease test, culture, and histological evaluation were allocated randomly to dual treatment with amoxicillin, 3 gm/day, and lansoprazole in different doses ranging between 30 and 180 mg/day for 2 weeks. A 24-hour intragastric pH measurement was taken in all patients on the fifth day of treatment. H. pylori status was determined by culture and histological workup 6 weeks after cessation of the amoxicillin-lansoprazole medication.
Results: The H. pylori infection was treated successfully in 19 of 32 patients who completed the dual therapy (per protocol, 59.4%). The median intragastric pH in patients who were treated successfully was 4.4 (95% confidence interval [CI] = 3.7-4.7), as compared to 4.0 (95% CI = 3.5-4.5) in patients who were not treated successfully (p = .47, Wilcoxon's rank sum test). The median percentage of time that the intragastric pH exceeded 4 was not different in the two groups (p = .77). Administration of lansoprazole in doses exceeding 30 mg induced only a moderate additional increase in intragastric pH.
Conclusions: Profound inhibition of gastric acid secretion seems not to be necessary to improve the effect of amoxicillin on the cure rate for H. pylori infection in patients with duodenal ulcers.