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CYP2C19 inhibitors, inducers and substrates

CYP2C19 is a liver enzyme that activates clopidogrel and clears omeprazole and other proton pump inhibitors, citalopram, escitalopram and diazepam. Its gene varies widely between people. Poor metabolizers make less of clopidogrel's active form, and strong inhibitors such as fluvoxamine can have a similar effect.

This is the desk's mapped set for CYP2C19, taken from the same catalog the desk uses to grade pairs. It is not a complete list. A drug that isn't listed here hasn't been cleared as safe; it just isn't on this list.

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What inhibition and induction mean

Inhibition. An inhibitor slows CYP2C19. Drugs that depend on CYP2C19 can build up, so their levels and effects can rise. Reversible inhibition starts as the inhibitor builds up and fades as it clears. Some inhibitors destroy the enzyme, and the effect lasts until the body makes more.

Induction. An inducer makes the body produce more CYP2C19. Levels of drugs that depend on CYP2C19 can fall, and so can their effect. Induction builds over days to weeks and takes about as long to fade after the inducer stops.

Substrates marked activation pathway are ones CYP2C19 turns into an active or reactive product. For these, inhibition can mean less of that product, and induction can mean more.

Strong, moderate and weak are the desk's grades for how much a perpetrator changes a sensitive substrate's exposure, in FDA's fold-change bins. FDA table of substrates, inhibitors and inducers.

Names with a solid underline open that drug's page of label-sourced pairs. Names with a dotted underline open the desk with that drug.

CYP2C19 inhibitors (31)

Strong inhibitors (6)

≥5-fold ↑ AUC of a sensitive index substrate

Moderate inhibitors (16)

≥2 to <5-fold ↑ AUC

Weak inhibitors (9)

≥1.25 to <2-fold ↑ AUC

CYP2C19 inducers (12)

Strong inducers (1)

≥80% ↓ AUC of a sensitive index substrate

Moderate inducers (10)

≥50 to <80% ↓ AUC

Weak inducers (1)

≥20 to <50% ↓ AUC

CYP2C19 substrates (38)

Sensitive substrates (3)

Exposure rises the most when CYP2C19 is blocked.

Major-pathway substrates (23)

CYP2C19 is one of the main routes for these.

Minor-pathway substrates (12)

CYP2C19 is a smaller route for these; other routes carry most of the load.

Pair pages that run through CYP2C19 (2)

Label-sourced pair pages where the desk's top finding is a CYP2C19 interaction, grouped by the desk's grade.

Avoid together (1)

Serious concern (1)

Educational reference only. Not FDA-cleared. The Prescribing Information governs.