By Amanda Batterbee, PMHNP-BC, MSN, BSN, RN – January 2024
As a provider, I strongly believe in the value of personalized medicine and shared decision-making with patients. That is one of the leading principles of the practice I founded – North Springs Psychiatry & TMS Center.
You are unique. No longer can we approach treating illnesses with a “one size fits all” mindset. Stemming from The Human Genome Project funded by the National Institutes of Health, medical providers are better able to determine how your genes affect your response to certain medications.
Use of pharmacogenetic and pharmacokinetic testing is becoming more common among medical providers – particularly psychiatric prescribers. Pharmacogenetics gives us information on how a person reacts differently to medications and pharmacokinetics gives us information on how a person metabolizes medication, which can influence efficacy.
Simple and readily available pharmacogenetic testing kits are available from companies such as GeneSight, Genomind, and Tempus. A quick cheek swab in office or in the patient’s home is all it takes to generate a report that can help guide treatment planning.
Pharmacogenetic testing has been found to be significantly cost-effective. For mental health patients, it correlates with shorter hospital stays (Battig, et al., 2020), reduces adverse drug reactions (Turongkaravee et al., 2021), reduces polypharmacy, reduces side effects, and reduces healthcare utilization (Meaddough, et al. 2021).
In addition to improved quality of care, patients report a higher satisfaction with their care and improved treatment compliance with use of personalized medicine. When providers engage patients in shared decision-making and provide education on why a specific treatment plan is recommended, patients report higher confidence and improved trust in the medical provider. Ultimately, we see reduced trial and error of medications, decreased healthcare costs due to adverse effects, and improve long-term health outcomes.
Some examples of how pharmacogenetics and pharmacokinetics can influence treatment plans:
Polymorphisms of SLC6A4 serotonin transporter gene may result in a reduced response to SSRIs. This polymorphism expresses fewer than normal serotonin transporters. SSRIs increase serotonin in the post-synaptic neuron, however without serotonin transporters to cross the junction gap to the pre-synaptic neuron, serotonin transmission is still reduced.
Think of this as a crowd after a concert waiting to catch an Uber home. The number of concertgoers (serotonin in this example) leaving the concert venue (the post-synaptic neuron) will be dependent on the number of available Uber drivers (serotonin transporters). Even if we increase the number of concert goers waiting for an Uber, this won’t improve how quickly or effectively they are able to leave the venue since the number of available Uber drivers remains low. So, for patients with this polymorphism, they will be much less likely to respond to medications focused on only regulating serotonin.
Polymorphisms of the HLA-A*3101 and HLA-B*1502 can increase the risk of Stevens-Johnson Syndrome. Because of the extensive use of antiepileptic medications as mood stabilizers in psychiatry, we can minimize the risk of a potentially life-threatening adverse effect in our patients with this knowledge.
In pharmacokinetic genes, if an enzyme pathway in the Cytochrome P450 system is ultrarapid – meaning medications that are metabolized via that enzyme pathway are broken down very quickly – we know it will be difficult for the patient to maintain therapeutic drug levels. We may seek alternative medications or adjust dosing of this medication (such as twice daily dosing or higher than average dosing).
It is important to note that pharmacogenetic and pharmacokinetic testing is a tool and not the “end all be all” guide to treatment planning. In combination with presenting symptoms and chief complaint; an accurate diagnostic evaluation; risk assessment; and family history, we are much better able to tailor individualized treatment plan and offer patients a higher quality of care.
REFERENCES:
Battig, V.A., Roll, S.C., & Hahn, M. (2020). Pharmacogenetic testing in depressed patients and interdisciplinary exchange between a pharmacist and psychiatrists results in reduced hospitalization times. Pharmacopsychiatry, 53(4), 185-192.
Meaddough, E.L., Sarasua, S.M., Fasolino, T.K., & Farrell, C. (2021). The impact of pharmacogenetic testing in patients exposed to polypharmacy: A scoping review. The Pharmacogenetics Journal, 21, 409-422.
Turongkaravee, S., Jittikoon, J., & Rchanathimoke, O. (2021). Pharmacogenetic testing for adverse drug reaction prevention: Systematic review of economic evaluations and the appraisal of quality matters for clinical practice and implementation. BMC Health Services Research, 21(1042).