Pharmacogenomic Testing for Mental Illness Pharmacotherapy

Mental illness affects a large percentage of individuals in the United States and is generally associated with high health care and societal costs.¹

Medications are often used to treat those with mental illnesses like depression, anxiety, and schizophrenia. These medications exhibit varying degrees of efficacy depending on the diagnosis and patient-specific factors. Unfortunately, many of these medications have serious side effects associated with their use.²

Optimizing psychiatric pharmacotherapy generally takes time and patience from both the patient and the provider. Pharmacogenomics-based medication optimization may allow for more effective medication choices and reduced treatment failures.

Pharmacogenomics is the study of how the genetic makeup of an individual can impact drug disposition and action. Currently, there are many drugs that should be avoided or dose-adjusted based on the genetic disposition of the patient. These drugs can be referenced on the FDA’s list of pharmacogenomic biomarkers, and approximately 16% of the drugs listed are indicated for mental illnesses.³ That isn’t surprising because many psychiatric medications have a narrow therapeutic index and are metabolized by enzymes subject to genetic polymorphisms that can impact function.

Services provided by various personalized medicine companies claim that pharmacogenomic testing can improve medication therapy by lowering the risk of treatment failure and adverse drug events. These companies screen the patient for various polymorphisms that may impact drug therapy, which may be present in specific drug metabolizing enzymes, neurotransmitter receptors, and drug transporters. Drug and dosage recommendations are generated based on the patients’ genetic profile, as are monitoring recommendations.

These tests can also categorize the risk of treatment failure for drug regimens. The pharmacogenomics-based recommendations generated from the proprietary algorithm can assist clinicians in deciding which drug to start and at what dose.

These services are generally expensive, and not all insurance plans will cover them. Although the initial cost is high, there may be long-term cost savings.⁴

One retrospective study showed that patients classified as “high risk” for treatment failure by the tests used more health care resources and had more disability claims than “low-risk” patients. Patients who received pharmacogenomics-guided drug therapy also had improved scores on depression tests.^5,6

Unfortunately, there’s still scant evidence on the long-term benefits (or lack thereof) of pharmacogenomics-guided therapy. There’s also a paucity of information on the benefits of genetic testing for mental illnesses beyond anxiety and depression. Therefore, the true value of genetically-guided psychopharmacotherapy has yet to be fully elucidated.

Pharmacists are in a position to help educate patients on potential options available to improve their treatment. Knowledge of the benefits and costs of pharmacogenomic testing will continue to be important for pharmacists. This knowledge will likely become more crucial as personalized medicine continues to be at the forefront of many health care discussions, and more information on the value of pharmacogenomic testing becomes available.

Mental illness remains a large problem in the United States. Medications for the treatment of mental disorders carry many adverse drug reactions, as well as the risk of treatment failure. Pharmacogenomic testing may provide an option for improving pharmacotherapy in patients with mental illness.

References

1. Insel TR. Assessing the economic costs of serious mental illness. Amer J Psychiatry. 2008;165(6):663-665.

2. Mitchell PB. Therapeutic drug monitoring of psychotropic medications. Br J Clin Pharmacol. 2001;52 Suppl 1:45S-54S.

3. FDA. Table of pharmacogenomic biomarkers in drug labeling. fda.gov/Drugs/ScienceResearch/ResearchAreas/Pharmacogenetics/ucm083378.htm. Published 2015. Accessed May 11, 2016.

4. Gardner KR, Brennan FX, Scott R, Lombard J. The potential utility of pharmacogenetic testing in psychiatry. Psychiatry J. 2014;2014:730956.

5. Winner J, Allen JD, Altar CA, Spahic-Mihajlovic A. Psychiatric pharmacogenomics predicts health resource utilization of outpatients with anxiety and depression. Transl Psychiatry. 2013;3:e242.

6. Hall-Flavin DK, Winner JG, Allen JD, et al. Utility of integrated pharmacogenomic testing to support the treatment of major depressive disorder in a psychiatric outpatient setting. Pharmacogenet Genomics. 2013 Oct;23(10):535-548. doi: 10.1097/FPC.0b013e3283649b9a.