[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › Potassium-competitive acid blockers (P-CABs)

# Potassium-competitive acid blockers (P-CABs)

Acid blockers that bind the proton pump at its potassium site, reversibly and without needing acid activation, unlike PPIs.

Updated Nov 1, 2026

## What they are

A newer class of gastric acid suppressants for erosive oesophagitis, reflux and Helicobacter pylori eradication. They block the same H+/K+-ATPase as proton pump inhibitors but in a different way, giving fast and long acid control.

## Mechanism of action

P-CABs are weak bases that concentrate in the acid space of the parietal cell and bind competitively and reversibly to the potassium-binding site of the H+/K+-ATPase. Unlike PPIs they are not prodrugs, do not need acid to be activated and do not bind covalently, so the effect starts quickly. They depend less on CYP2C19 than PPIs.

Target: Gastric H+/K+-ATPase (proton pump), at its potassium-binding site

## Key points

- Same pump as PPIs, different binding: reversible, potassium-competitive, no acid activation needed.
- Vonoprazan is used with amoxicillin, with or without clarithromycin, for H. pylori.
- Long-term acid suppression risks resemble those of PPIs: C. difficile diarrhoea, low magnesium, low vitamin B12, fractures, gastric polyps.
- Less dependence on CYP2C19 genotype than PPIs.

## Drugs in this class

- [**Vonoprazan** A potassium-competitive acid blocker that switches off the stomach's proton pump quickly. Used for erosive… Gastric H+/K+-ATPase (proton pump), potassium-binding site](https://durgical.com/en/pharmacology/vonoprazan/)

## Others in the class

- Tegoprazan
- Revaprazan
- Fexuprazan

## Test yourself

Think of the answer, then tap the question to see it.

## How does a P-CAB bind the proton pump differently from a PPI?

Reversibly and competitively at the potassium site, without acid activation; PPIs are acid-activated prodrugs that bind covalently.

## Which indications does it share with PPIs?

Erosive oesophagitis, reflux, or H. pylori eradication with antibiotics.

## Which CYP enzyme matters less for P-CABs than for PPIs?

CYP2C19.

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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [Vonoprazan: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a624006.html) (MedlinePlus (U.S. National Library of Medicine), 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=A02BC) (WHO Collaborating Centre for Drug Statistics Methodology, 2026); [RCSB PDB - 5YLU: Crystal structure of the gastric proton pump complexed with vonoprazan](https://www.rcsb.org/structure/5YLU) (RCSB Protein Data Bank, 2026).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/classes/potassium-competitive-acid-blockers/