Cytochrome P450 Genetics Might Guide Escitalopram Dosing or Predict Therapeutic Failure

Although genetic testing cannot yet predict the best antidepressant to prescribe to a given patient in routine practice, it might be useful to anticipate who is likely to respond poorly to specific medications. Because escitalopram is metabolized predominantly by the hepatic cytochrome P450 (CYP) enzyme 2C19, investigators analyzed retrospective data from a large Norwegian drug-monitoring registry on 2087 escitalopram recipients who were CYP2C19 genotyped and who had serum escitalopram levels drawn (10–30 hours after medication ingestion).

Patients were monitored for therapeutic failure, defined as a switch within 1 year to another antidepressant. Using genotyping, the authors divided patients into poor, intermediate, extensive, and ultrarap…