A Study to Evaluate the Efficacy and Safety of Arbaclofen Placarbil (XP19986) as Adjunctive Therapy in Subjects With Gastroesophageal Reflux Disease (GERD)

Inclusion Criteria:

1. confirmed diagnosis of GERD by a gastroenterologist

2. minimum of 3 months of GERD symptoms prior to screening.

3. currently taking an FDA approved dose of PPI therapy for symptomatic GERD for at
least 4 weeks prior to screening

4. experienced partial relief of GERD symptoms while receiving approved dose and regimen
of PPI therapy

5. experienced GERD symptoms, defined as heartburn (with or without regurgitation or
other GERD symptoms) on ≥ 3 days during the week prior to screening

Exclusion Criteria:

1. evidence of erosive esophagitis or erosive gastritis on upper gastrointestinal
endoscopy during screening

2. has not experienced any GERD symptom improvement after an adequate course of PPI
treatment (at least 2 weeks)

3. unstable or severe medical condition