Proton pump inhibitor

A proton pump inhibitor is a medicine that suppresses stomach acid by inhibiting the gastric hydrogen-potassium ATPase in parietal cells. Most are taken as prodrugs activated in the stomach’s acidic canaliculi.

Gastric hydrogen-potassium ATPase: A membrane enzyme in stomach parietal cells that exchanges hydrogen ions for potassium ions to secrete gastric acid. This is the pump that proton pump inhibitors bind and inhibit.
Gastroesophageal reflux disease: A chronic condition in which stomach contents reflux into the esophagus and cause troublesome symptoms or complications. Acid suppression can relieve symptoms and heal reflux-related esophageal injury.
Histamine H2 receptor antagonist: A medicine that reduces gastric acid secretion by blocking histamine H2 receptors on parietal cells. H2 blockers suppress an upstream stimulatory signal rather than directly inhibiting the acid pump.
Vitamin B12 deficiency: A condition in which inadequate vitamin B12 impairs blood-cell production and nervous-system function. Long-term acid suppression may reduce absorption of food-bound vitamin B12 in some people.
Omeprazole: A proton pump inhibitor used to treat acid-related gastrointestinal disorders. It is a widely used example of the class and illustrates CYP2C19-related variation.
Parietal cell: A stomach epithelial cell that secretes hydrochloric acid and intrinsic factor. These cells contain the acid-secreting pumps targeted by the medicines.
Peptic ulcer disease: Ulcers in the stomach or duodenum caused by mucosal injury, commonly associated with Helicobacter pylori or NSAIDs. Reducing acid supports ulcer healing, alongside treatment of the underlying cause.
Antacid: A substance that neutralizes acid already present in the stomach. Antacids act rapidly on existing acid, unlike inhibitors that reduce its production.
Hypomagnesemia: An abnormally low concentration of magnesium in the blood. Rare cases have been associated with prolonged proton pump inhibitor use.
Esomeprazole: The S-enantiomer of omeprazole, used as a proton pump inhibitor. Its relationship to omeprazole shows how stereochemistry distinguishes drugs within the class.

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