Proton Pump Inhibitors (PPIs) and CYP2C19
Omeprazole, lansoprazole, pantoprazole and related PPIs are cleared mainly by CYP2C19. Rapid and ultrarapid metabolisers clear them faster and may get less acid suppression; poor metabolisers have higher exposure.
Why does CYP2C19 matter for Proton Pump Inhibitors (PPIs)?
Omeprazole, lansoprazole, pantoprazole and related PPIs are cleared mainly by CYP2C19. Rapid and ultrarapid metabolisers clear them faster and may get less acid suppression; poor metabolisers have higher exposure. CYP2C19 is a liver enzyme that activates or clears several widely used medicines, including clopidogrel, most proton-pump inhibitors, escitalopram and voriconazole. Two common no-function alleles (*2 and *3) and one increased-function allele (*17) make CYP2C19 activity vary widely between people, and between populations: roughly 2-5% of Europeans but 13-15% of East Asians are poor metabolisers. CPIC publishes prescribing guidance keyed to the resulting phenotype.
What does CPIC recommend for each CYP2C19 phenotype on Proton Pump Inhibitors (PPIs)?
The guidance below is the CPIC recommendation for prescribers, reproduced for reference. It is written for a clinician who knows the whole picture — never start, stop or change a medicine on the basis of this page.
| Phenotype | CPIC-based guidance |
|---|---|
| Ultrarapid Metabolizer | Increased PPI metabolism. May need higher dose or more frequent dosing for H. pylori eradication. |
| Rapid Metabolizer | May need dose increase for H. pylori eradication therapy. |
| Normal Metabolizer | Standard PPI dosing. |
| Intermediate Metabolizer | Standard PPI dosing. May have enhanced acid suppression. |
| Poor Metabolizer | Consider reduced PPI dose for chronic use. Enhanced acid suppression expected. |
Which CYP2C19 alleles decide the phenotype?
The phenotype is read from the two CYP2C19 star alleles a person carries. The full allele table, with the defining variants and their population frequencies, is on the CYP2C19 gene page.
23andMe and AncestryDNA chips genotype the defining variants of *2, *3 and *17 directly (rs4244285, rs4986893, rs12248560), so CYP2C19 is one of the better-covered pharmacogenes on consumer data. Rare alleles are not tested, and a call is only as good as the chip's read at each position.
Other drugs affected by CYP2C19
- Clopidogrel — Antiplatelet
- Escitalopram/Citalopram — SSRI Antidepressant
- Voriconazole — Antifungal
Upload your raw DNA file and see your metaboliser status → · Ask G2: “Does my CYP2C19 genotype affect Proton Pump Inhibitors (PPIs)?”
Genetic associations describe risk across populations, not a diagnosis for any one person. Most variants shift risk modestly and act alongside lifestyle, environment and other genes. Consumer DNA chips do not read every position and can be wrong at any single one. For general education only; talk to a clinician or genetic counsellor before acting on anything here, and never change a prescribed medicine without your prescriber.