Clinical Pharmacogenetics Implementation Consortium (CPIC) Guideline for CYP2C19 Genotype and Dosing of Selective Serotonin Reuptake Inhibitor Citalopram/Escitalopram

Selective serotonin reuptake inhibitors (SSRIs) are used for the treatment of major depressive and anxiety disorders, and may be used to treat other psychiatric conditions. Citalopram/escitalopram are metabolized by cytochrome P450 2C19 (CYP2C19) and variations in CYP2C19 may affect drug exposure. Compared to extensive metabolizers, CYP2C19 ultrarapid metabolizers may have significantly lower exposure to citalopram/escitalopram while elevated concentrations of these drugs have been observed in poor metabolizers. Therapeutic guidelines for the SSRIs citalopram/escitalopram based on CYP2C19 genotype have been published in Clinical Pharmacology and Therapeutics by the Clinical Pharmacogenetics Implementation Consortium (CPIC) and are available on the PharmGKB website (

Type Guideline
CME Available No

Date of Resource

Genomic Competencies

Experts from the disciplines listed below have tagged this resource as fulfulling genomic competencies.


  • Pharmacogenetics/Pharmacogenomics
    • P1:   To demonstrate an understanding of how genetic variation in a large number of proteins, including drug transporters, drug metabolizing enzymes, direct protein targets of drugs, and other proteins (e.g. signal transduction proteins) influence pharmacokinetics and pharmacodynamics related to pharmacologic effect and drug response
    • P2:   To understand the influence (or lack thereof) of ethnicity in genetic polymorphisms and associations of polymorphisms with drug response
    • P3:   Recognize the availability of evidence based guidelines that synthesize information relevant to genomic/pharmacogenomic tests and selection of drug therapy (e.g. Clinical Pharmacogenomics Implementation Consortium)