Esomeprazole-d 6 sodium is the deuterium labeled Esomeprazole. Esomeprazole ((S)-Omeprazole) is a potent and orally active proton pump inhibitor and reduces acid secretion through inhibition of the H + , K + -ATPase in gastric parietal cells. Esomeprazole has the potential for symptomatic gastroesophageal reflux disease research.