SSRIs

SSRI antidepressants and pharmacogenetics

Also known as: Selective Serotonin Reuptake Inhibitors

6 medications 6 brand products CYP2C19CYP2D6

Why pharmacogenetics matter for ssri antidepressants

SSRIs (selective serotonin reuptake inhibitors) are the most-prescribed antidepressant class, used for major depression, anxiety disorders, PTSD, OCD, and premenstrual dysphoric disorder. Most SSRIs are cleared by CYP2C19, CYP2D6, or a mix of both. Because these enzymes vary widely across the population, how fast someone clears an SSRI can swing plasma levels twofold or more, which is a big part of why two people on the same drug at the same dose can have very different experiences.^[1]

CYP2C19 pharmacogenetics are especially relevant for citalopram, escitalopram, and sertraline. CPIC publishes dose recommendations for all three based on CYP2C19 phenotype,^[2] and the FDA has specific dose caps for citalopram in CYP2C19 poor metabolizers.^[3]

Key genes in this class

CYP2C19

Cytochrome P450 2C19

CYP2C19 handles several SSRIs (citalopram, escitalopram, sertraline), proton pump inhibitors (omeprazole, esomeprazole), and the blood thinner clopidogrel. About 2 to 5 percent of people of European descent and 15 to …

CYP2D6

Cytochrome P450 2D6

CYP2D6 is the most clinically important pharmacogene. It metabolizes around a quarter of all prescription drugs, including many antidepressants, opioids, and stimulants. The gene is unusually variable: roughly 7 percent …

Medications in this class with pharmacogenetic guidelines

Each link goes to the drug's full pharmacogenetics page with CPIC and FDA phenotype recommendations.

Citalopram CYP2C19 Escitalopram CYP2C19 Fluvoxamine CYP2D6 Paroxetine CYP2D6 Sertraline CYP2B6 / CYP2C19 Vortioxetine CYP2D6

Brand products in the SSRIs class

Combined products and brand names for the medications above. Each links to a pharmacogenetic breakdown.

References

PharmGKB / Stanford University. PharmGKB: The Pharmacogenomics Knowledge Base. pharmgkb.org
CPIC. CPIC Guideline for SSRI and SNRI Antidepressants and CYP2D6, CYP2C19, CYP2B6, SLC6A4, and HTR2A (2023). cpicpgx.org
U.S. Food and Drug Administration. Table of Pharmacogenomic Biomarkers in Drug Labeling (2024). fda.gov

Which ssris is right for your genetics?

This page covers the pharmacogenetics of ssri antidepressants in general. A Gene2Rx report tells you how your personal genotype interacts with every drug on this page.

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Informational only, not medical advice. Pharmacogenetic guidelines describe population-level patterns that inform prescribing decisions. Never start, stop, or change a medication without talking to your prescribing clinician.