Omeprazole is the first drug to be marketed in a group of  agents which reduce gastric  acid secretion by inhibition H⁺/K⁺ATPase (the 'proton pump') of the parietal cell. These agents are the most potent inhibitors of gastric acid secretlon.

Omaprazole is indicated  where suppression of acid secretion is of therapeutic benefit. It may be used for short and long term therapy in -
i) Duodenal ulcer ii) Gastric ulcer iii) Reflux esophagitis and esophageal ulceration iv) Maintenance of healing of erosive esophagitis v) Pathological hypersecretory conditions (e.g. Zollinger-Ellison Syndrome, multiple endocrine adenomas and systemic mastocytosis) vi) Resistant peptic ulcer vii)  Eradication of  Helicobacter pylori in combination with suitable antibiotics.