Psychiatry

Pharmacogenetics in Psychiatry– Benefits of Precision Prescribing

As a psychiatrist you may frequently find yourself challenged by patients with multiple health issues already taking several medications by the time they see you. And sometimes you may have one of those patients tell you she’s experienced “sensitivity” to medications in the past, but there’s frustratingly little information in her history as to what that sensitivity might be. That can make prescribing any additional medications difficult.

If the patient is seeing you for depression, you’re facing more than 20 medications approved by the FDA for the condition, with more than a few containing warnings that genetics may alter a patient’s response. If that patient is also being treated for a condition such as heart disease, you’ll be challenged by how her other medications may interact with one of these drugs, along with any herbal supplements she also takes.

Until recently, psychiatrists had little choice but to prescribe medications without knowing in advance how their patients might genetically respond. But no more: with precision prescribing by YouScript, you’ll know upfront what medications will likely prove to be most effective for your patient – and which ones will not. And you’ll know precisely how any medications will interact with the prescriptions and supplements she’s already taking.

Psychiatric Medications with Pharmacogenetic Information on the FDA Label

DrugBiomarkerDrugBiomarkerDrugBiomarker
AripiprazoleCYP2D6FluoxetineCYP2D6PerphenazineCYP2D6
AtomoxetineCYP2D6Fluoxetine and OlanzapineCYP2D6PimozideCYP2D6
Chlordiazepoxide and AmitriptylineCYP2D6FluvoxamineCYP2D6ProtriptylineCYP2D6
CitalopramCYP2C19IloperidoneCYP2D6RisperidoneCYP2D6
ClomipramineCYP2D6ImipramineCYP2D6ThioridazineCYP2D6
ClozapineCYP2D6ModafinilCYP2D6TrimipramineCYP2D6
DesipramineCYP2D6NefazodoneCYP2D6VenlafaxineCYP2D6
DiazepamCYP2C19NortriptylineCYP2D6
DoxepinCYP2C19 and CYP2D6ParoxetineCYP2D6

YouScript Helps You Achieve Optimal Prescribing

Virtually all of the medications used to treat psychiatric conditions are metabolized by CYP2D6, CYP2C19 or CYP3A4, and the table below shows how variations are extremely common.  This genetic variability is often the most important consideration in how an individual patient will respond to a medication.

DNA sensitivity includes testing of all clinically significant genetic variants in CYP2D6, CYP2C9 (including VKORC1), CYP2C19, CYP3A4 and CYP3A5 enzymes responsible for metabolizing the majority of medications.

In the case of the patient with heart disease, her DNA testing results may indicate she’s a CYP2D6 poor metabolizer, CYP2C9 intermediate metabolizer with VKORC1 intermediate sensitivity, CYP2C19 normal metabolizer, CYP3A4 normal metabolizer and CYP3A5 normal metabolizer. As the tables below demonstrate, many of your other patients may also have cytochrome variability.

The Majority of Patients Have Cytochrome P450 (CYP) Variability

GenePoor MetabolizerIntermediate MetabolizerNormal MetabolizerRapid or Ultrarapid Metabolizer
CYP2D610%35%48%7%
CYP2C92-4%>35%~60%N/A
CYP2C19*2-20%24-36%14-44%30%

*CYP2C19 variability depends on ethnicity.

Ethnicity
GeneVariant ActivityCaucasianAsianAfrican
CYP3A4Decreased5.3%0%0%
CYP3A5Decreased93%75%27-50%

 

The YouScript Precision Prescribing lab results include secure web access via YouScript.net to your patient’s cytochrome results. There, you can quickly add the five medications and two herbal supplements the patient currently takes and add Paxil, a medication often prescribed for depression. When you click the check interactions button, you’ll note in this case, Paxil is coming up in orange with a warning of a significant increase in blood levels at a standard dose.

 

YouScript Helps You with Polypharmacy Safety – Now and in the Future

Like this patient, many psychiatric patients may also be battling heart disease, pain, cancer, or other conditions that make multiple prescriptions necessary. But a body’s limited capacity to process medications is easily slowed by competition between other drugs, herbals, and over-the-counters. This is further compromised in patients with genetic variations. Whether a patient is genetically a poor metabolizer or has become a poor metabolizer because of other medications, it’s been shown by prospective trials, population analyses, and case studies they can experience an increase in adverse drug events because of reduced elimination.

For the patient with heart disease and depression, although the clinical notes in YouScript states you could start with a 75 percent of a typical Paxil dose, you may wonder if another medication might be better. By clicking the “alternative” button next to Paxil, you’ll find a list of drugs in the same class that are not as reliant on the CYP2D6 pathway. By selecting citalopram, for instance, you’ll note that there are no significant interaction warnings.

YouScript is Updated with the Latest Clinical Knowledge on Drug Metabolism

The body of knowledge on drug metabolism is constantly growing. Numerous clinical studies continue to be published on both drug metabolism and drug-gene interactions like this study of phenotype-based dosing guidelines (link to dosing guideline below) for patients on antidepressants and antipsychotics. Even the most committed physician cannot keep up with this constantly growing body of knowledge.

YouScript saves you time—Our team of pharmacists and physicians have done the research on drug metabolism and drug and gene interactions for you. YouScript is updated multiple times each month with the latest clinical information.

After navigating the YouScript analytics software for your first patient you will be impressed at how easy it is to navigate and how helpful it is in safe and effective medication selection. YouScript may help many patients in your practice.

Which Patients Benefit Most from DNA Sensitivity Testing?

DNA sensitivity testing has significant impact for many patients, including those:

  • Taking multiple medications
  • Prescribed any of the more than 100 FDA-approved drugs with pharmacogenetic information in their labels, including the following:
    • Plavix® (clopidogrel)
    • Coumadin® (warfarin)
    • Strattera® (atomoxetine)
    • Abilify® (aripiprazole)
    • Lopressor® / Toprol® (metoprolol)
    • Clozaril® (clozapine)
  • Who complain their medications are not working
  • Wary of standard dosing based on prior negative experiences
  • On complex drug treatment plans for cancer or HIV infection
DNA sensitivity testing is typically covered by most private insurers and Medicare in select cases.

Call 800-TEST-DNA to ask how it works. There is no cost to you and supplies will be sent out immediately. Pharmacists and other support staff are there to help whenever you have questions.

How to Integrate YouScript Into Your Practice

  1. Ask your YouScript consultant, call 800-TEST-DNA or sign up online.
  2. Receive your  YouScript testing supplies.
  3. Collect a swab or blood sample from your patient and ship it back in the prepaid mailer.
  4. Receive the Precision Prescribing Report with recommendations from a local YouScript network pharmacist.
  5. Counsel your patient on their YouScript results and adjust any treatment plans as needed.
  6. Learn more about YouScript