Currently, a 10-day concomitant therapy has been reported to be equally effective and safe to the 10-day sequential therapy for 1st-line anti-Helicobacter pylori(H. pylori) therapy. To our knowledge, there has been no report concerning the efficacy of this regimen used as a rescue therapy.

The aims of this study are:

1. to compare the efficacy of high dose dual therapy and concomitant therapy as rescue regimen in H. pylori eradication;
2. to compare the patient adherence and adverse effects of these treatment regimens;
3. to investigate factors that may influence H. pylori eradication by these treatment regimens.

Patients, aged 18, having H. pylori-positive chronic gastritis with/without peptic ulcers will be recruited. All undergo endoscopy with biopsy before treatment. Four to eight weeks after termination of treatment, H. pylori infection status will be examined by endoscopy with biopsy or the Carbon 13-urea breath test if the patients refuse the second endoscopy. The cytochrome P450 (CYP)2C19 genotype of each participant will be analyzed by the polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP) method. A computed generated random numbers sequence will be blocked into two subgroups, say A and B.

If the patients had received anti-H. pylori therapy previously, they will be invited to enter the study for evaluating the efficacy of rescue regimens. After giving their written informed consent, all patients will be labeled with numbers by enrolling order. Each patient will be randomly allocated to one of two treatment groups which receives medications for 10 to 14 days:

group A - high dose dual therapy (rabeprazole 20 mg qid + amoxicillin 750 mg qid for 14 days); group B - concomitant therapy (rabeprazole 20 mg + amoxicillin 1000 mg + metronidazole 500 mg + clarithromycin 500 mg, bid for 10 days).

All patients will be asked to complete a questionnaire and to record symptoms and drug consumption daily in a diary card during the treatment period. Post-treatment, the patients will be seen at the Outpatient Clinic to investigate patient adherence and adverse effects of treatment.

Inclusion Criteria:

• patients having H. pylori related chronic gastritis with/without peptic ulcers who are aged greater than 18 years and are willing to received eradication therapy.

Exclusion Criteria:

• pregnant or nursing woman
• serious concomitant illness and malignant tumor of any kind
• history of hypersensitivity to test drugs
• serious bleeding during the course of this ulcer
• previous gastric surgery
• receiving bismuth salts, proton pump inhibitors, or antibiotics in the previous month.