Compound Sodium Alginate Double Action Chewable Tablets 4-hour Esophageal pH Study in GERD Patients

Inclusion Criteria: * meets the diagnostic criteria for GERD with a GERD history of frequent episodes of GERD-related symptoms during the last 2 months prior to study screening. The patient must also meet the following criteria: 1. The only or main symptom is heartburn (burning feeling back of breast bone) and/or acid reflux. Symptoms persist or have occurred repeatedly for more than 2 months; 2. As assessed by the Investigator at screening by questioning of the patient, the frequency of occurrence of heartburn is ≥ 3 days/week and the score of severity of heartburn in general is ≥ moderate within 3 weeks before screening Exclusion Criteria: * Patients who have a history of drug, solvent or alcohol abuse (weekly alcohol intake ≥ 140 g). * Patients who have suffered cardiac chest pain within the last year. * Patients who have suffered a recent, significant unexplained weight loss of more than 6 kg in the last 6 months. * Female patients of childbearing potential who, for the duration of the study, are either unwilling or unable to take adequate contraceptive precautions or are unwilling to be sexually abstinent. * Pregnancy or lactating mother. * Patients with a history and/or symptom profile suggestive of the following: any other gastrointestinal (GI) disease, erosive GERD (Los Angeles \[LA\] classification grades C-D), Barrett's oesophagus, acute peptic ulcer and/or ulcer complications, Zollinger-Ellison syndrome, gastric carcinoma, pyloric stenosis, oesophageal or gastric surgery, intestinal obstruction, current pernicious anaemia, indication for H. pylori eradication therapy, known gastrointestinal bleeding (hematochezia or hematemesis) within the last 3 months, and severe diseases of other major body systems. * Patients who are observed at screening to have a hiatus hernia with a diameter which exceeds 3 cm. * Patients who have taken anti-cholinesterase drugs, traditional Chinese medicines for treating gastrointestinal disease, ulcerlmin or misoprostol preparations within 7 days prior to screening or throughout the study. * Patients who have taken PPIs during the 10 days prior to screening, prokinetics or H2 antagonists during the 5 days prior to screening or systemic glucocorticosteroids, non-steroidal anti-inflammatory drugs (except for low dose aspirin which can be given for cardioprotection) on more than 3 consecutive days or PPI-based triple or quadruple therapy for eradication of H. pylori during the last 28 days. * Patients taking or requiring to take macrolide antibiotics, such as erythromycin, azithromycin, from the day before screening. * Patients with difficulty in swallowing. * Patients with known hypophosphataemia, phenylketonuria or hypercalcaemia. * Patients with severe constipation, or history of intestinal obstruction. * In the opinion of the Investigator, patients with damaged heart or kidney function and patients who require a low sodium diet.