Backgrounds and aims: Eradication rates of Helicobacter pylori by a proton pump inhibitor-based triple therapy depend on CYP2C19 genotype status. We investigated whether gastric acid inhibition during an eradication therapy would influence the eradication rates attained by the triple therapy.
Methods: Thirty-two patients with H. pylori infection underwent the first-line triple therapy with lansoprazole 30 mg, amoxicillin 750 mg, and clarithromycin 400 mg b.i.d. for 1 week. In all 32 patients, the 24-hour intragastric pH monitoring was performed on day 6 during the treatment period.
Results: The intention-to-treat-based eradication rate by the first-line therapy was 75.0% (24/32, 95%CI: 56.60–88.54%). In patients with successful eradication, the median 24-hour pH was 6.4 (range; 5.0–7.6), which was significantly higher than that in patients without eradication [5.2 (2.2–6.2), p = .0131]. The median percentage time of pH < 4.0 during 24-hour postdose in patients with eradication [0.5% (0.0–31.6%)] was significantly shorter than that in patients without eradication [26.7% (6.0–72.2%), p = .0017]. These parameters for acid inhibition significantly differed among the different CYP2C19 genotype groups. When the percentage time of pH < 4.0 and 24-hour pH were attained < 10% and > 6.0, respectively, during the eradication treatment, the majority of patients could eradicate H. pylori infection, irrespective of the bacterial susceptibility to clarithromycin.
Conclusions: The sustained intragastric pH > 4.0 for a longer postdose time appears to be required for a successful eradication of H. pylori with lansoprazole and acid-labile antibiotics.