The purpose of this study is to assess the efficacy and safety of Dexlansoprazole modified release (MR) (30 mg once daily [QD] or 60 mg QD) compared to placebo in relief of daytime and nighttime heartburn over 4 weeks in subjects with symptomatic, nonerosive gastroesophageal reflux disease (GERD).

This is a Phase 3, randomized, double-blind, multicenter, placebo-controlled, 3-arm study with a 4 week treatment period. This study will compare the efficacy of Dexlansoprazole MR (30 mg QD and 60 mg QD) with that of placebo when administered orally as a single daily dose in the morning, before breakfast. The study is designed to evaluate symptom relief in subjects with symptomatic nonerosive GERD. Approximately 900 subjects will be enrolled at approximately 200 United States (US) and potentially ex-US sites. The study consists of two periods: a screening period, which will last a minimum of 7 days and a maximum of 21 days, and a treatment period, which will last 4 weeks.

Inclusion Criteria:

• Subjects identifying their main symptom as a burning feeling in the mid epigastric area and/or chest area (ie, heartburn).
• Subject has a history of episodes of heartburn for 6 months or longer prior to Screening.
• Subject must have a history of episodes of heartburn for 4 or more days during the 7 days prior to Day -1.

Exclusion Criteria:

• Endoscopic Barrett's esophagus and/or definite dysplastic changes. History of dilatation of esophageal strictures.
• Subjects with erosive esophagitis (EE) as shown by endoscopy.
• Evidence of uncontrolled systemic disease. Co-existing diseases affecting the esophagus. Current or history of Zollinger-Ellison syndrome.
• Subject has abnormal laboratory values.
• Subjects with active gastric or duodenal ulcers within 4 weeks of the first dose.
• Subject known to have acquired immunodeficiency syndrome (AIDS).
• Known hypersensitivity to any proton pump inhibitor (PPI), any component of Dexlansoprazole MR, or antacid.
• Use of prescription or non-prescription PPIs, histamine (H2) receptor antagonists, or sucralfate.
• Chronic (>12 doses per month) use of nonsteroidal anti-inflammatory drugs (NSAIDs) or cyclo-oxygenase-2 (COX-2) inhibitors.
• Use of antacids (except for study-supplied Gelusil® ).
• Use of drugs with significant anticholinergic effects.
• Subjects who cannot discontinue the use of misoprostol or prokinetics
• Need for continuous anticoagulant therapy.
• Females who are pregnant or lactating.
• History of gastrointestinal surgery except for simple oversew of ulcer.
• History of cancer within 3 years prior to screening.
• Subject has participated in a previous Dexlansoprazole study.
• Subjects who, in the opinion of the investigator, are unable to comply with the requirements of the study or are unsuitable for any reason.