Phase III Study Comparing Zegerid® With Losec® for the Relief of Heartburn Associated With Gastroesophageal Reflux Disease

Inclusion Criteria: Study patients will be included in the study if they satisfy the following criteria:

1. Male or female, between 18 and 75 years old.

2. History of frequent episodes of heartburn associated with GERD for at least 2 3 daysper week during 2-4 weeks before screening and have responded to standard PPI therapyin the past 12 months.

3. Have not taken on-demand PPI therapy for > 3 consecutive days within 4 weeks beforethe screening period.

4. The patient's written informed consent must be obtained prior to inclusion.

5. Willing and able to complete the entire procedure and to comply with studyinstructions.

6. Females of childbearing potential must employ an adequate method of birth control. Inclusion criteria applicable to Screening period:

7. Recorded at least 1 evaluable episode of heartburn on 2 separate days at level 4 orhigher on the 9-point Likert severity scale (point 3 on a 0-8 point scale) prior torandomisation.

8. Competent in the use and completion of the e-diary.

Exclusion Criteria: Study patients will be excluded if they meet any of the following criteria:

1. Age < 18 or > 75 years old.

2. Intake of any medication for the purpose of the eradication of Helicobacter pylori (H.pylori) during the last 28 days before the start of the study.

3. Intake of systemic glucocorticoids or non-steroidal anti-inflammatory drugs (NSAIDs)including COX-2-inhibitors (≥ 3 consecutive days per week) during the last 28 daysbefore the start of the study; except regular intake of enteric coated aspirin dosagesup to 150 mg/d.

4. Previously underwent acid-lowering surgery or other surgery of the oesophagus and/orupper gastrointestinal tract (excluding: appendectomy, cholecystectomy andpolypectomy).

5. History of co-existing disease that affects the oesophagus (e.g. Barrett's oesophagus,Zollinger-Ellison syndrome, oesophageal stricture), and have undergone an endoscopywith results of incomplete healing of erosions following standard PPI therapy withinthe last 3 months.

6. History of active gastric or duodenal ulcers within 3 months of the first dose of thestudy drug or had acute upper gastrointestinal (GI) bleeding within last 6 months.

7. Documented presence of severe renal or hepatic insufficiency.

8. Known hypersensitivity to omeprazole.

9. Concurrent participation in a study with an investigational drug or participationwithin 30 days of study entry.

10. Females who are pregnant, or planning a pregnancy. Females of child bearing potentialnot using reliable methods of birth control.

11. Clinically significant laboratory abnormality or disease which, in the opinion of theInvestigator, will create a risk for the patient, obscure the effects of studytreatment or interfere with study results.

12. Received or require any of the following drugs within 2 weeks before the first dose ofstudy or continue to need these drugs for concurrent therapy: theophylline, bismuthsalts, warfarin, phenytoin, tacrolimus, diazepam, cyclosporine, disulfiram,benzodiazepines, barbiturates, antineoplastic agents, erythromycin, clarithromycin,sucralfate, clopidogrel or protease inhibitors.

13. Taking concomitant medications that rely on the presence of gastric acid for optimalbioavailability (e.g. ketoconazole, ampicillin esters or iron salts).

14. Onset of psychoactive medication (e.g. depressants, stimulants or hallucinogens) inthe previous 6 months and during the entire course of the study. Exclusion criteria applicable to Screening period:

15. Recorded < 1 episode of heartburn on 2 separate days at level 4 on the 9 point Likertseverity scale (point 3 on a 0-8 point scale) during the 7 day screening period priorto randomisation

16. Completing < 90% (< 9 out of 10) of the time points with evaluable data on the ediary.