Study to Evaluate the Performance and Safety of the MARIAL® in Association With PPI Versus PPI Alone

Inclusion Criteria: * Male or non-pregnant female, both aged ≥ 18 to ≤ 65 years. * Diagnosis of GERD Grade A esophagitis on Los Angeles Classification System grades reflux esophagitis by: * gastroscopy (done within 1-month prior baseline). * episodic heartburn and/or acid regurgitation (at least 3 times per week in the last 2 weeks); * Body mass index of ≥ 18.5 to ≤ 36 kg/m2. * Able to communicate adequately with the investigator and to comply with the requirements for the entire study. * Capable of and freely willing to provide written informed consent prior to participating in the study. Exclusion Criteria: * Intake of PPI or Marial® during the last 28 days before the start of the study. * Intake of systemic glucocorticoids or non-steroidal anti-inflammatory drugs (NSAIDs) including COX-2-inhibitors (≥ 3 consecutive days per week) during the last 28 days before the start of the study; except regular intake of enteric coated aspirin dosages up to 150 mg/d. * Previously underwent acid-lowering surgery or other surgery of the oesophagus and/or upper gastrointestinal tract (excluding appendectomy, cholecystectomy and polypectomy). * History of co-existing disease that affects the esophagus (e.g. Barrett's esophagus, Zollinger-Ellison syndrome, esophageal stricture). * History of active gastric or duodenal ulcers within 3 months of the first dose of the study drug or had acute upper gastrointestinal (GI) bleeding within last 6 months. * Documented presence of severe renal or hepatic insufficiency (i.e. GOT, GPT elevated over double the normal range). * Known hypersensitivity to omeprazole, and/or Marial® and/or Gaviscon®. * Concurrent (or within 30 days of study entry) participation in a clinical trial. * Females who are pregnant, or planning a pregnancy, or lactating. Females of child bearing potential not using reliable methods of birth control. * Clinically significant laboratory abnormality or disease which, in the opinion of the Investigator, will create a risk for the patient, or interfere with study results (i.e. GOT, GPT elevated over double the normal range). * Receiving any of the following drugs within 2 weeks before the baseline: theophylline, bismuth salts, warfarin, phenytoin, tacrolimus, diazepam, cyclosporine, disulfiram, barbiturates, antineoplastic agents, erythromycin, clarithromycin, sucralfate, clopidogrel or protease inhibitors. Benzodiazepines could be allowed only in concomitance with the endoscopy. * Taking concomitant medications that rely on the presence of gastric acid for optimal bioavailability (e.g. ketoconazole, ampicillin esters or iron salts). * Drug or alcohol abuse within 12 months of Day 0 * Malignancy (also leukemic infiltrates) within 5 years prior to Day 0 (except for treated basal cell/squamous cell carcinoma of the skin). * Psychosis, schizophrenia, mania, depressive disorders, history of suicide attempt or suicidal ideation, or any other psychiatric illness (except for intermittent anxiety). * Presence of any clinically significant medical condition judged by the investigator to preclude the patient's inclusion in the study for its safety