Esomeprazole

Esomeprazole is the S-enantiomer of omeprazole and a proton-pump inhibitor. It suppresses gastric acid secretion by inhibiting the stomach’s parietal-cell proton pump.

H+/K+-ATPase: A membrane enzyme in gastric parietal cells that exchanges intracellular hydrogen ions for potassium ions, secreting stomach acid. Esomeprazole’s active form binds this pump and blocks the final step of acid secretion.
Gastroesophageal reflux disease: A chronic condition in which stomach contents reflux into the esophagus, causing troublesome symptoms or complications. Esomeprazole reduces acid exposure that drives symptoms and esophageal injury.
Omeprazole: A proton-pump inhibitor that contains both R- and S-enantiomers and suppresses gastric acid secretion. Esomeprazole is omeprazole’s S-enantiomer, rather than the racemic mixture.
Hypomagnesemia: An abnormally low concentration of magnesium in the blood. Long-term proton-pump inhibitor use has been associated with rare cases of low magnesium.
Enantiomer: One of two stereoisomers that are nonsuperimposable mirror images of each other. Esomeprazole is specifically the S-enantiomer of omeprazole.
Prodrug: A pharmacologically inactive or less active compound converted in the body into an active drug. Esomeprazole becomes active after acid-triggered conversion near parietal-cell proton pumps.
Peptic ulcer disease: A disorder involving open sores in the stomach or duodenal lining, commonly associated with Helicobacter pylori or NSAIDs. Acid suppression supports ulcer healing, usually alongside treatment of the underlying cause.
Lansoprazole: A proton-pump inhibitor used to reduce gastric acid secretion and treat reflux and ulcer disorders. It is a related acid-suppressing alternative with different pharmacokinetic properties.
Vitamin B12 deficiency: A shortage of vitamin B12 that can impair blood-cell formation and nervous-system function. Sustained acid suppression may reduce absorption of food-bound vitamin B12 in some people.
Chirality: The property of an object or molecule that makes it distinct from its mirror image. Chirality distinguishes esomeprazole from omeprazole’s other molecular form.

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Proton pump inhibitorBroader topic: Its relationship to omeprazole shows how stereochemistry distinguishes drugs within the class.