Pharmacology · Class
Proton pump inhibitors (PPIs) !
The strongest acid reducers: they switch off the stomach's acid pump itself, so they work whatever triggers acid secretion.
Updated 2026-11-01
What they are
Prodrugs that block the H⁺/K⁺-ATPase of the parietal cell, the final step of gastric acid secretion. They are the base of treatment for reflux, peptic ulcer and H. pylori eradication.
Mechanism of action
PPIs are weak bases that collect in the very acidic secretory canaliculus of the parietal cell. There, acid converts them into a reactive sulfenamide that forms a disulfide bond with cysteines of the pump (Cys813 in all of them). The bond is irreversible, so acid secretion only returns as the cell makes new pumps; the effect outlasts the drug in the blood. Because they block the last step, they reduce acid driven by histamine, gastrin or acetylcholine alike.
Target: Gastric H⁺/K⁺-ATPase (proton pump)
Drugs in this class
- OmeprazoleSwitches off the stomach acid pump long after it leaves the blood; used for reflux, ulcers, ulcer bleeding and, with…Gastric H⁺/K⁺-ATPase (proton pump), α subunit
- PantoprazoleA proton pump inhibitor given by mouth or IV. It has fewer CYP interactions than omeprazole and does not weaken…Gastric H⁺/K⁺-ATPase (proton pump), α subunit
- EsomeprazoleThe S-isomer of omeprazole, a proton pump inhibitor given by mouth or IV. Like omeprazole, it inhibits CYP2C19 and is…Gastric H⁺/K⁺-ATPase (proton pump), α subunit
- LansoprazoleA proton pump inhibitor for ulcers, reflux and H. pylori. Its capsule granules can be sprinkled on soft food or given…Gastric H⁺/K⁺-ATPase (proton pump), α subunit
Others in the class
- esomeprazole
- lansoprazole
- dexlansoprazole
- pantoprazole
- rabeprazole
Test yourself
Think of the answer, then tap the question to see it.
Why does the acid-reducing effect of a PPI last far longer than its plasma half-life?
The drug binds the pump covalently and irreversibly; acid secretion only recovers as the parietal cell synthesises new pumps.
Why do PPIs block acid regardless of whether it is stimulated by histamine, gastrin or acetylcholine?
All three pathways converge on the H⁺/K⁺-ATPase, the final step of acid secretion, which is the PPI target.
Which three problems are associated with long-term PPI use?
Vitamin B12 deficiency, hypomagnesaemia and C. difficile infection (others: fractures, fundic gland polyps).
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Omeprazole: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2023); DailyMed - OMEPRAZOLE capsule, delayed release (DailyMed (U.S. National Library of Medicine), 2024); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.