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CYP2D6 inhibitors and substrates

CYP2D6 is a liver enzyme that clears many antidepressants, antipsychotics, beta-blockers such as metoprolol, and opioids. It turns codeine and tramadol into stronger opioids and turns tamoxifen into its main active form. Its gene varies widely: people range from poor to ultrarapid metabolizers. Strong inhibitors such as paroxetine, fluoxetine, bupropion and quinidine can make a normal metabolizer act like a poor one. Medicines rarely induce CYP2D6.

This is the desk's mapped set for CYP2D6, 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 CYP2D6. Drugs that depend on CYP2D6 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 CYP2D6. Levels of drugs that depend on CYP2D6 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 CYP2D6 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.

CYP2D6 inhibitors (48)

Strong inhibitors (6)

≥5-fold ↑ AUC of a sensitive index substrate

Moderate inhibitors (17)

≥2 to <5-fold ↑ AUC

Weak inhibitors (25)

≥1.25 to <2-fold ↑ AUC

CYP2D6 inducers (0)

No inducers are mapped for CYP2D6 on the desk.

CYP2D6 substrates (83)

Sensitive substrates (10)

Exposure rises the most when CYP2D6 is blocked.

Major-pathway substrates (52)

CYP2D6 is one of the main routes for these.

Minor-pathway substrates (21)

CYP2D6 is a smaller route for these; other routes carry most of the load.

Pair pages that run through CYP2D6 (9)

Label-sourced pair pages where the desk's top finding is a CYP2D6 interaction, grouped by the desk's grade.

Avoid together (9)

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