RELATIONSHIP BETWEEN THE EFFICACY OF AMOXICILLIN AND INTRAGASTRIC PH FOR THE TREATMENT OF HELICOBACTER-PYLORI INFECTION

Background. Proton pump inhibitors are reported to enhance the efficac y 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 as sess the effect of different doses of lansoprazole on 24-hour intragas tric pH and to correlate the effect of amoxicillin on the cure rate fo r H. pylori infection with the intragastric pH obtained during lansopr azole treatment. Patients and Methods. Thirty-six duodenal ulcer patie nts 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 differe nt doses ranging between 30 and 180 mg/day for 2 weeks. A 24-hour intr agastric 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 medica tion. Results. The H. pylori infection was treated successfully in 19 of 32 patients who completed the dual therapy (per protocol, 59.4%). T he median intragastric pH in patients who were treated successfully wa s 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 int ragastric pH exceeded 4 tvas 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. Profou nd inhibition of gastric acid secretion seems not to be necessary to i mprove the effect of amoxicillin on the cure rate for H. pylori infect ion in patients with duodenal ulcers.