The Use of Lansoprazole to Treat Infants With Symptoms of Gastroesophageal Reflux

Inclusion Criteria: * At least 7 days post-surgery at the time of Screening (Study Visit 1) with no anticipated need for surgery during the study. * Experiencing symptoms of gastroesophageal reflux disease (regurgitation, vomiting or "spitting up," fussing/irritability, feeding refusal, crying during feeding, arching back, poor weight gain, or extraesophageal manifestations) or endoscopy proven reflux disease. * Must continue to have reflux symptoms during the Pretreatment Period despite reducing or eliminating exposure to tobacco smoke, using one positioning and feeding strategy the last 7 days as documented in the Daily Diary. * The infant exhibited crying, fussing, or irritability during or within 1 hour of feeding in \>25% of all feedings during the last 4 days of the Pretreatment Period as documented in the Daily Diary. Exclusion Criteria: * Body weight \<2.0 kilogram at Dosing Day 1 of the Double-Blind Treatment Period. * Unstable, congenital or acquired, clinically significant disease of any major organ system (cardiovascular, respiratory, renal, hepatic, metabolic, etc.), including suspected and/or documented culture-proven sepsis. * Coexisting esophageal disease (e.g., eosinophilic esophagitis, viral, bacterial or fungal infection) or caustic or physiochemical trauma to the esophagus. * Any congenital anomaly of the upper gastric intestinal tract that might interfere with gastrointestinal motility, pH, absorption, or active or known history of necrotizing enterocolitis that has been surgically corrected. * Use of a proton pump inhibitor within 30 days prior to Dosing Day 1. * Use of H2 Blockers (i.e. Zantac) within 7 days prior to Dosing Day 1. * Allergy to proton pump inhibitors (i.e. Prilosec, Prevacid). * Use of prokinetics (e.g., metoclopramide) unless on a stable dose for at least 3 days prior to entering the Pretreatment Period. * Unable to obtain stable drug levels after continuous treatment with required drugs including theophylline derivatives, digoxin, phenytoin, phenobarbital, or carbamazepine within the 7 days prior to Dosing Day 1. * Clinically Significant abnormalities in clinical laboratory values.