Low- versus high-dose azithromycin triple therapy for Helicobacter pylori infection.

BACKGROUND: We report a clinical trial which evaluated the effectiveness of triple therapy containing low- and high-dose azithromycin to treat Helicobacter pylori infection. METHODS: From March 1997 to March 1998, patients infected with H. pylori were assigned to receive either: Treatment 1: ranitidine bismuth citrate (RBC) (400 mg b.d.) and amoxycillin (1 g b.d.) for 10 days with azithromycin 500 mg o.m. for 3 days: or Treatment 2: RBC and amoxycillin for 10 days with azithromycin 1 g o.m. for 3 days. H. pylori eradication was established by a urea breath test at least 4 weeks after therapy. Side-effects and compliance were assessed using a diary. RESULTS: Sixty-eight patients were enrolled. Fifty-seven per cent of patients were treated for active peptic ulcer disease or a history of peptic ulcer disease. Treatment 1 cured H. pylori in 44% and 44% by per protocol and intention-to-treat analysis, respectively. The corresponding eradication rates for Treatment 2 were 79% and 75%. Two patients taking Treatment 2 dropped out of the study because of side-effects. CONCLUSIONS: With RBC and amoxycillin for 10 days, azithromycin at a dose of 1 g/day for 3 days was significantly better at curing H. pylori infection than azithromycin 500 mg/day for 3 days.

Lansoprazole and ranitidine affect the accuracy of the 14C-urea breath test by a pH-dependent mechanism.

OBJECTIVES: To determine the effect of lansoprazole and high dose ranitidine on the accuracy of the 14C-urea breath test (UBT). Using intragastric pH recordings, we correlated the effect of these agents on the UBT with their potency of gastric acid suppression. METHODS: Patients with active Helicobacter pylori infection underwent a baseline UBT before receiving 14 days of lansoprazole (30 mg/day) or ranitidine (300 mg b.i.d.). During therapy, patients were asked to undergo 24-h intragastric pH monitoring. Repeat breath testing was performed 1 day after completion of the study drugs. If the UBT was equivocal or negative (14CO2 excretion was < 200 dpm), further UBTs were completed until the 14CO2 excretion was > 200 dpm. RESULTS: Thirteen patients received lansoprazole. Eight of thirteen patients developed a negative or equivocal UBT. All patients had 14CO2 excretion > 200 dpm 5 days after the cessation of lansoprazole. Eleven patients received ranitidine. Ranitidine led to equivocal or false negative UBTs in 2 of 11 cases. This effect resolved within 5 days of stopping ranitidine. Intragastric pH recordings revealed that the patients who experienced the most profound gastric acid suppression were those that developed equivocal or false negative UBTs. CONCLUSIONS: Lansoprazole significantly affected the accuracy of the UBT, causing equivocal or false negative results in 61%. High dose ranitidine affected the breath test in only 18%. The ability of these drugs to suppress gastric acid secretion predicted those patients who developed equivocal or false-negative UBTs. The effect on the accuracy of the UBT resolved within 5 days of drug cessation.