CPIC Guideline Update: CYP2D6, CYP2C19 and tricyclic antidepressants (TCAs)

The 2016 update of the guidelines by the Clinical Pharmacogenetics Implementation Consortium (CPIC) regarding the use of pharmacogenetic tests for CYP2D6 and CYP2C19 in dosing tricyclic antidepressants (TCAs) have been accepted for publication in Clinical Pharmacology and Therapeutics. The accepted article can currently be viewed on the PharmGKB and CPIC websites.
TCAs are mixed serotonin and norepinephrine reuptake inhibitors used to treat depression and several other disease states.The 2016 guideline update provides dosing recommendations:

• for TCAs based on CYP2D6 phenotype
• for TCAs based on CYP2C19 phenotype
• for amitriptyline based on both CYP2D6 and CYP2C19 phenotype.

Amitriptyline and nortriptyline are used as representative TCAs because the majority of pharmacogenomics studies have been published on these drugs. However, TCAs have comparable pharmacokinetic properties and it it may be reasonable to apply the recommendations to other TCAs.
For further details see the guidelines and supplement at PharmGKB and CPIC.