Esomeprazole is a proton pump inhibitor and S-isomer of Omeprazole. Esomeprazole suppresses gastric acid secretion by specific inhibition of the H⁺/K⁺-ATPase in the gastric parietal cells. By acting specially on the proton pump, Esomeprazole blocks the final step in acid production, thus reducing gastric acidity. Esomeprazole concentrated and converted to the active form in the acid environment of the secretory canaliculi and inhibits the enzyme H⁺/K⁺-ATPase - THE Acid Pump.

The US FDA approved Esomeprazole for maintenance of healing of erosive esophagitis and in combination with Amoxicillin and Clarithromycin, for the eradication of Helicobacter pylori infection in patients with duodenal ulcer disease and also for risk reduction of NSAID-induced stomach ulcer.