Cytochrome P450 2D6 (CYP2D6)

PG4KDS - Priority Genes

CYP2D6 is an enzyme that is responsible for breaking down (metabolizing) many of the drugs that are commonly used today. Some medications, such as codeine, require activation by CYP2D6 in order for the medication to be effective. Other drugs, such as tricyclic antidepressants (e.g., amitriptyline and imipramine), are metabolized to forms that are not active and are more easily eliminated from the body. There are many other medications that may be affected by CYP2D6 (see this link

For some of these medications, it is not absolutely clear what changes in dosing should be driven by CYP2D6 genotype; in this study, we will build up the “rules” to decide which medications to link to the priority genotypes. Over 100 known differences exist in the gene for CYP2D6. These differences in the CYP2D6 gene lead to the production of an enzyme that ranges from completely inactive to overactive. A system designed to classify patients into 4 genotype metabolizer categories based on the ability of their CYP2D6 to break down drugs is used by clinicians to help guide drug therapy decisions.

Priority genotypes

Routine genotypes. We do not routinely adjust medicine doses based on the following genotypes, except in rare instances:

More information for patients...

"Do you know..." info sheet: Cytochrome P450 2D6 (CYP2D6) and medicines

More information for healthcare professionals, visit

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