The present invention is related to novel oral compositions comprising an irreversible gastric H+/K+-ATPase proton pump inhibitor (PPI) as a gastric acid secretion inhibitor and one or more aliphatic carboxylic acid derivative molecules which activate parietal cells, wherein the derivatives possess delayed or sustained enhancement effect on the PPI activity compared to the non-derivatized acid molecules. The present invention further relates to a method of using such compositions to reduce gastric acid secretion in a mammal.
