We are at the forefront of medicine. Pharmacogenomics (PGx) has evolved since it was first introduced.[i]
We are entering an era shifting from reactive testing (testing after trail and failure) to proactive testing (testing prior to prescribing). PGx is here and will continue to stay. We know that pharmacy spend is on the rise[ii] and a topic of interest for many. In one study, the estimated annual cost of drug related morbidity and mortality was $528.4 billion (equivalent to 16% of total US health care expenditures in 2016) from nonoptimized medication therapy.[iii]
Considering the benefits and side effects of a medication are important elements in managing patients. Can the patient condition afford delays in treatment or management? Let’s take lisinopril for example, a common ACE inhibitor that is given for hypertension. After initiation, monitoring serum potassium levels is very important as hyperkalemia is one of the primary adverse effects.[iv] In this case, monitoring potassium levels is a type of lab test that monitors for patient safety.
Similarly, PGx (another type of lab test) can help monitor patient safety and more. For example, it can help predict potential side effects, metabolism, and compliance if done at the right time. Thus, PGx has an additive value. It can be incorporated easily into the routine processes of clinical/therapeutic decision making and adds to the whole clinical picture. For example, PGx can assess the CYP2D6 activity. CYP2D6 metabolizes a variety of medications prescribed in primary care settings as well as other specialties. Some examples are antidepressants, analgesics, antimetabolites, and anticoagulants. Applications for CYP2D6 testing overlaps in a variety of therapeutic areas that includes mental health, cancer, and cardiovascular and immunological disorders. [v], [vi] There are 77 entries that match an FDA label annotations query for CYP2D6 alone.[vii] Nevertheless, there are many other PGx tested genes. Currently, there are over 300+ drugs that mention pharmacogenomic biomarkers in the FDA drug labeling.[viii]
The same PGx test can provide valuable information to a variety of specialties and repeatedly referenced over the years for the lifetime of the patient, unless in rare scenarios when a person can become ineligible (e.g., liver transplant) or a new variant is being tested. So, why not test? It all comes down to patient health and safety. For example, it may take up to 6 weeks for an SSRI to show results.[ix] How many weeks to months does a patient need to go through before finding the right drug or right dose? Knowledge is power and analyzing PGx information prior to prescribing may help reduce possible trial and error scenarios. Additionally, this allows for a more personalized approach versus a “fit all” approach.
If you would like information on how to start implementing PGx into your practice, we are here to help. We have a variety of resources and support. Also, if you have access to a pharmacist at your institution/clinic, they are great resources. Pharmacists can help physicians with the PGx workflow, and if CMM or MTM is integrated they can also include it in their review. They can also provide consults or review charts if needed. Interprofessional collaboration can help reduce the administrative workflow on the physician. By working together as a team, each profession can bring in their expertise to help the patient and potentially improve health outcomes.
Ghada Elnashar, PharmD, MS is a clinical and managed care pharmacist leader and is currently the Associate Director of Medical Affairs at OneOme LLC, a med tech company in Minneapolis, MN. OneOme offers additional information and PGx education which can be found at OneOme.com/education or you may reach out to email@example.com
[iii] Watanabe, Jonathan H., Terry McInnis, and Jan D. Hirsch. "Cost of prescription drug–related morbidity and mortality." Annals of Pharmacotherapy 52.9 (2018): 829-837.
[v] Kane M. CYP2D6 Overview: Allele and Phenotype Frequencies. 2021 Oct 15. In: Pratt VM, Scott SA, Pirmohamed M, et al., editors. Medical Genetics Summaries [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2012-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK574601/