Pharmacogenomic & Genetic Testing

What Is Pharmacogenomic Testing?

Pharmacogenomic testing, often called pharmacogenetic testing or PGx testing, is a type of genetic test that analyzes specific genes involved in how your body processes medications. By examining variations in your DNA, this test helps your psychiatrist predict which psychiatric medications are most likely to work well for you, which may require dose adjustments, and which should be avoided due to a higher risk of side effects or ineffectiveness.

The traditional approach to prescribing psychiatric medications has long relied on a trial-and-error process. A psychiatrist prescribes a medication based on clinical guidelines and experience, waits several weeks for it to take effect, and then adjusts or switches if the response is inadequate or side effects are intolerable. This process can take months or even years before finding the right medication at the right dose. For patients already struggling with depression, anxiety, or other debilitating conditions, this prolonged trial-and-error period can be profoundly demoralizing.

Pharmacogenomic testing fundamentally changes this equation. By understanding your unique genetic profile before prescribing, your psychiatrist at RECO Integrated Psychiatry can make more informed, personalized medication decisions from the very first appointment. This precision medicine approach has been shown in clinical studies to improve treatment response rates, reduce the number of medication trials needed to find an effective treatment, decrease adverse drug reactions, and lower overall healthcare costs.

The science behind pharmacogenomics is well-established. The U.S. Food and Drug Administration has included pharmacogenomic information in the labeling of more than 300 medications, including many commonly prescribed psychiatric drugs. Major professional organizations, including the American Psychiatric Association and the Clinical Pharmacogenetics Implementation Consortium, have published guidelines supporting the clinical use of pharmacogenomic testing in psychiatric practice.

How Pharmacogenomic Testing Works

Your DNA contains the instructions your body uses to produce enzymes and proteins that metabolize medications. Variations in specific genes can cause these enzymes to work faster, slower, or differently than average, directly affecting how you respond to certain drugs.

Drug Metabolism and Genetic Variation

When you take a medication, your body uses specific enzymes, primarily in the liver, to break it down into active or inactive metabolites. The speed at which this process occurs determines the effective drug level in your bloodstream. Based on your genetic makeup, you may be classified as one of four metabolizer types for each relevant enzyme:

• Ultrarapid Metabolizer: You break down the medication too quickly, so standard doses may be ineffective because the drug is cleared from your body before it can work. Higher doses or alternative medications may be needed.
• Extensive (Normal) Metabolizer: You process the medication at a typical rate, and standard dosing guidelines are likely appropriate for you.
• Intermediate Metabolizer: You break down the medication somewhat more slowly than average. Dose reductions may be needed to avoid side effects from drug accumulation.
• Poor Metabolizer: You process the medication very slowly, leading to higher-than-expected drug levels that can increase the risk of toxicity and side effects. Significant dose reductions or alternative medications are usually recommended.

What the Test Analyzes

Pharmacogenomic tests used in psychiatric practice typically examine a panel of genes that are most relevant to the metabolism and efficacy of commonly prescribed psychiatric medications. Key genes include:

• CYP2D6: Metabolizes approximately 25% of all prescribed drugs, including many antidepressants (fluoxetine, paroxetine, venlafaxine), antipsychotics (aripiprazole, risperidone), and ADHD medications (atomoxetine).
• CYP2C19: Important for the metabolism of several SSRIs (citalopram, escitalopram, sertraline), benzodiazepines, and tricyclic antidepressants.
• CYP3A4: The most abundant liver enzyme, involved in metabolizing quetiapine, buspirone, and many other medications.
• CYP1A2: Relevant for the metabolism of clozapine, olanzapine, duloxetine, and certain other psychiatric medications.
• SLC6A4 (Serotonin Transporter): Genetic variations in this gene may influence response to SSRI and SNRI antidepressants.
• HLA-A and HLA-B: Certain variants increase the risk of severe allergic reactions to medications like carbamazepine and oxcarbazepine.
• MTHFR: Variations in this gene affect folate metabolism, which may influence depression and antidepressant response.

Benefits of Pharmacogenomic Testing

Integrating pharmacogenomic testing into your psychiatric care offers multiple significant advantages over the traditional trial-and-error approach to medication selection.

• Reduced trial-and-error: Rather than cycling through multiple medications over months or years, genetic insights help your psychiatrist narrow down the most promising options from the start, getting you to an effective treatment faster.
• Fewer side effects: By identifying medications that your body may not metabolize well, testing helps avoid drugs that are more likely to cause adverse reactions for your specific genetic profile.
• Optimized dosing: Knowing your metabolizer status allows for more precise dosing from the beginning, rather than starting at a standard dose and adjusting reactively based on your response.
• Improved adherence: Patients who experience fewer side effects and faster improvement are more likely to stay on their prescribed medication regimen, which is essential for long-term treatment success.
• Cost savings: By reducing the number of ineffective medication trials, unnecessary office visits, and emergency room visits due to adverse effects, pharmacogenomic testing can lower your overall healthcare costs.
• Lifetime value: Your genetic results never change. The information from a single test can inform medication decisions for the rest of your life, across all areas of medicine, not just psychiatry.

Who Is a Candidate for Genetic Testing?

While pharmacogenomic testing can benefit virtually any patient considering psychiatric medication, it is especially valuable in the following situations:

• You have tried one or more psychiatric medications without adequate improvement
• You have experienced significant or unusual side effects from psychiatric medications
• You are starting psychiatric medication for the first time and want to make the most informed choice possible
• You are taking multiple medications and are concerned about drug interactions
• You have a family history of poor medication response or adverse drug reactions
• You are being considered for medication management and want to take a precision medicine approach from the outset

What to Expect: The Testing Process

The pharmacogenomic testing process at RECO Integrated Psychiatry is straightforward, painless, and minimally disruptive to your schedule.

Frequently Asked Questions