Refractory Gastroesophageal Reflux Disease

The goal of this clinical trial is to learn if study drug Fosamprenavir-Sodium Alginate (FOS-SA) administered orally improves symptoms for Proton Pump Inhibitor (PPI)-refractory Gastro Esophageal Reflux Disease (GERD). The main questions it aims to answer are: 1. Does FOS-SA significantly improve heartburn severity over the 8-week treatment period 2. Does FOS-SA significantly improve regurgitation frequency over the 8-week treatment period 3. Does FOS-SA significantly improve symptoms of persistent GERD over the 8-week treatment period Researchers will compare FOS-SA to a placebo (a look-alike substance that contains no active drug) to see if FOS-SA works to treat PPI-refractory GERD. Participants will: 1. Take FOS-SA or placebo every day BID (twice a day) for 8 weeks 2. Visit the Adult Translational Research Unit (ATRU) seven times for consenting, screening, and checkups and tests 3. Keep a daily diary of their symptoms of persistent GERD