Esomeprazole is the S-isomer of omeprazole, with gastric proton pump inhibitor activity. In the acidic compartment of parietal cells, esomeprazole is protonated and converted into the active achiral sulfenamide; the active sulfenamide forms one or more covalent disulfide bonds with the proton pump hydrogen-potassium adenosine triphosphatase (H+/K+ ATPase), thereby inhibiting its activity and the parietal cell secretion of H+ ions into the gastric lumen, the final step in gastric acid production. H+/K+ ATPase is an integral membrane protein of the gastric parietal cell.

Domperidone is a peripheral-specific antagonist of the dopamine receptor D2 (D2R), with antiemetic, gastrokinetic and galactagogue activities. Following administration, domperidone binds to D2R expressed by peripheral neurons; this inhibits dopamine binding and D2R-mediated signaling. Inhibition of peripheral D2R signaling prevents or relieves various gastrointestinal (GI) symptoms, such as nausea and vomiting, and may help relief reflux and symptoms of a variety of other upper GI disorders.