Compound Sodium Alginate Oral Suspension Sachet 4-hour Esophageal pH Study in GERD Patients

Inclusion Criteria: * Primary diagnosis: Current evidence of symptomatic GERD in accord with the Montreal definition. Patients should have a GERD history of frequent episodes of GERD-related symptoms during at least the last 2 months prior to study screening. The patient must also meet the following criteria: * The main symptom is heartburn and/or acid reflux. Symptoms persist or have occurred repeatedly for at least the last 2 months; * The frequency of occurrence of heartburn is ≥ 3 days/week and the score of severity of heartburn in general is moderate or severe within 3 weeks before screening * Patients who are willing to consume the entire standard refluxogenic test meal. * Patients who have a screening 24 h pH monitoring test assessing the percentage of time when the pH falls below pH 4 which confirms significant acid reflux of \>4.2% over the 24 h period. Exclusion Criteria: * Patients who have a history of drug, solvent or alcohol abuse (weekly alcohol intake ≥ 140g). * 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 (e.g. gastric or duodenal erosions and polyps larger than 0.5 cm), erosive GERD Los Angeles \[LA\] classification grades C-D, Barrett's esophagus, acute peptic ulcer and/or ulcer complications, Zollinger-Ellison syndrome, gastric carcinoma, pyloric stenosis, oesophageal or gastric surgery, intestinal obstruction, current pernicious anaemia, hiatal hernias greater than 3 cm, requirement for low sodium diet, known gastrointestinal bleeding (hematochezia or hematemesis) within the last 3 months, and severe diseases of other major body systems. * Patients who have taken anti-cholinesterase drugs, traditional Chinese medicines for treating gastrointestinal disease, sucralfate or misoprostol preparations within 7 days prior to screening or throughout the study. * Patients who have taken Proton Pump Inhibitors (PPIs) during the 28 days prior to screening, prokinetics or H2 antagonists during the 5 days prior to screening, or systemic glucocorticosteroids, non-steroidal anti-inflammatory drugs (NSAIDs except low dose aspirin given for cardioprotection) on more than 3 consecutive days during the last 28 days prior to screening. * Patients who have taken any antacids within 24 hours before screening (Visit 1) and throughout the remainder of the study. * Patients taking mucous membrane protection drugs or motility stimulants for 5 days prior to screening and throughout the study. * Patients who are vegetarian. * Patients with difficulty in swallowing. * Patients with known hypophosphataemia, phenylketonuria or hypercalcaemia. * Patients who have previously undergone esophageal, gastric or duodenal surgery at any time or who have undergone any other major surgery with general anaesthesia within the last three months. * Patients with severe constipation, or history of intestinal obstruction. * In the opinion of the Investigator, patients with insufficient heart or kidney function and patients who require a low sodium diet. * Patients either with any co-existing condition which, in the opinion of the Investigator, would be likely to compromise patient safety or interfere with assessment of efficacy; or with any clinically significant abnormal laboratory values. * Patients with impaired renal function or severe renal insufficiency. * Any previous history of allergy or known intolerance to any of the formulation constituents * Clinically significant abnormalities in the physical examination, electrocardiogram (ECG) and safety analysis. * Patients taking or requiring to take macrolide antibiotics, such as erythromycin, azithromycin, from the day before screening. * Previously randomised into the study. * Employee at study site. * Partner or first-degree relative of the Investigator. * Participation in a clinical study in the previous 6 months. * Unable in the opinion of the Investigator to comply fully with the study requirements.