Inclusion Criteria:

• Boy and girls and a minimum weight of 10 kg with endoscopically proven GERD including an endoscopic examination as part of their diagnostic evaluation
• Patients who have been treated with, or are currently receiving a proton pump inhibitor (PPI), H2 blockers, or antacids are eligible (as long as they can go off antacids for 24 hours, and PPIs and H2 blockers for 3 days prior to dosing, except for cimetidine, which must be discontinued for at least 7 days prior to dosing) and remain off these medications for the treatment period
• Patients who are generally healthy, other than the presence of GERD, with the exception of the following: Patients with stable asthma/reactive airway disease or cystic fibrosis-dependent GERD symptoms on stable treatment regimens or subjects on stable doses of allergy and attention deficit disorder medicines.

Exclusion Criteria:

• Patients who have a history of or current clinically significant medical illness including (but not limited to) cardiac arrhythmias or other cardiac disease, hematologic disease, coagulation disorders, lipid abnormalities, diabetes mellitus, renal or hepatic insufficiency, thyroid disease, neurologic or psychiatric disease, infection, or any other illness that the investigator considers should exclude the subject or that could interfere with the interpretation of the study results
• Primary pulmonary or ENT symptoms
• Presence of "warning signals", suggesting cause of vomiting/regurgitation other than GERD
• History of primary esophageal motility disorders or systemic condition affecting the esophagus
• History of eosinophilic esophagitis, persistent milk protein allergy, or allergic gastroenteropathy
• History of or current presence of peptic ulcers
• Current presence of Helicobacter pylori
• History of definitive acid-lowering surgery
• Significant arrhythmias.