From the Guidelines
Pharmacogenomic testing in psychiatry is supported by recent clinical guidelines and research evidence, and it is recommended to consider this testing primarily for patients who have experienced treatment failures, adverse effects, or unusual medication responses. The most established gene-drug pairs in psychiatry include CYP2D6 and CYP2C19 variants, which affect metabolism of many antidepressants and antipsychotics including fluoxetine, paroxetine, venlafaxine, and risperidone, as reported in a study published in the Mayo Clinic Proceedings in 2016 1.
Key Considerations
- The International Society of Psychiatric Genetics and the Clinical Pharmacogenetics Implementation Consortium recommend considering pharmacogenomic testing for patients with treatment failures or adverse effects.
- HLA-B*15:02 testing is recommended before carbamazepine use in patients of Asian ancestry to prevent severe cutaneous reactions.
- Clinicians should order comprehensive panels that include CYP2D6, CYP2C19, CYP1A2, CYP3A4, and HLA genes rather than single-gene tests.
- Results should guide medication selection and dosing, with poor metabolizers potentially needing lower doses and ultrarapid metabolizers requiring higher doses or alternative medications.
Recent Guidelines
A 2022 clinical practice guideline published in the Annals of Internal Medicine noted that while there is interest in pharmacogenomic testing, the evidence is not sufficient to make a recommendation either for or against its use 1. However, this does not negate the potential benefits of pharmacogenomic testing in personalizing psychiatric treatment, as suggested by earlier research 1.
Implementation
Pharmacogenomic testing should complement rather than replace clinical judgment and be integrated with other factors like medical history, concomitant medications, and patient preferences. By considering pharmacogenomic testing, clinicians can potentially reduce adverse effect toxicity profiles and increase response rates and overall effectiveness of psychiatric treatments.
From the Research
Guidelines for Pharmacogenomic Testing in Psychiatry
- The use of pharmacogenomic testing in psychiatry has grown significantly in recent years, despite a lack of robust evidence regarding its efficacy in clinical use 2.
- Pharmacogenomic testing can be integrated into clinical practice to help select psychotropic drugs for individuals who have failed first-line evidence-based treatments 3.
- The testing can be used to identify genetic variations that affect an individual's response to certain medications, such as selective serotonin reuptake inhibitors (SSRIs) 4.
Research Supporting Pharmacogenomic Testing
- Studies have shown that pharmacogenomic testing can help identify individuals who are at risk of adverse reactions to certain medications, such as SSRIs 5.
- However, the evidence for the clinical use of pharmacogenomic testing in psychiatry is limited, and more research is needed to fully understand its benefits and limitations 2, 5.
- A review of systematic reviews found that the most studied drug categories were anticonvulsants and SSRIs, and that the quality of the evidence was generally low 5.
Challenges and Limitations
- One of the major challenges to the implementation of pharmacogenomic testing in clinical practice is the lack of evidence regarding its efficacy and cost-effectiveness 2, 5.
- Additionally, the testing is not yet widely available, and there is a need for more education and training for healthcare professionals on how to interpret and use the results of pharmacogenomic testing 3.
- The development of guidelines and protocols for the use of pharmacogenomic testing in clinical practice is also needed to ensure that the testing is used effectively and safely 2.