Pharmacogenetics / Targeted Therapy
Pharmacogenetics, also called pharmacogenomics, precision medicine, targeted therapy, and personalized medicine, is the study of how a patient’s genetic makeup can affect their response to medications. The information gained from personalized medicine helps healthcare providers determine the best treatment for each specific patient, choosing drugs that are more likely to be effective, avoiding medications that are more likely to have side effects or toxicities, assisting in dosing of medications, and determining if closer monitoring is needed. The goal of precision medicine is to target the right treatments to the right patients at the right time.
Within the Food and Drug Administration (FDA)’s Office of Clinical Pharmacology is the Genomics and Targeted Therapy Group which works to apply personalized medicine to clinical practice through research, policy development, education, and outreach. The FDA has published a Table of Pharmacogenomic Biomarkers in Drug Labeling to guide healthcare providers in appropriate prescribing of medications. The American Medical Association (AMA) has also published an article on Pharmacogenomics.
According to the University of Illinois Medical Center, pharmacogenetics is proven to reduce 90-day readmission rates for cardiac patients by 68%. Since adverse drug reactions (ADRs) are the fourth leading cause of hospitalization and death in the United States, knowing a patient’s genetic susceptibility to ADRs through pharmacogenetic testing can greatly reduce serious and avoidable ADRs. Precision medicine will help predict which patients will benefit from an adjusted dose to prevent ADRs as well as optimize efficacy.
What to expect from Josefs
Physicians can fax in completed Authorization form at 919-212-2550 or call 919-212-2555 to authorize this test. Our pharmacogenetics test at Josefs Pharmacy is a simple cheek swab which will identify medications that may be ineffective, produce more side effects, be potentially toxic, as well as are better alternatives for each specific patient. Our test is one of the most comprehensive available that covers more than 200 prescription and over-the-counter medications as well as a Personalized Medication Review (PMR) with one of our clinical pharmacists trained in pharmacogenetics.
We always instruct the patient never to stop, start, or adjust any medication without direction from their prescribing physician.
Utility of Precision Medicine
Pharmacogenetics is proven to reduce 90-day readmission rates for cardiac patients by 68%, according to the University of Illinois Medical Center
About 1/3 of patients possess a genetic variant of CYP2C19 that causes them to not activate clopidogrel to its therapeutic molecule putting them at increased risk of thrombosis. More than 40 cardiac medications, including anticoagulants, antihypertensives, statins, and diuretics, have genetic implications.
Patients who are CYP3A4*22 intermediate metabolizers may achieve optimal lipid control with lower doses of certain statin medications, and standard higher doses may cause more adverse effects, such as myopathy and myalgias. For example, patients experiencing myopathy with simvastatin may experience fewer adverse effects by switching to pravastatin, or through a dose reduction. Patients with intermediate or low function of the transporter SLC01B1 will have a higher myopathy risk with simvastatin, thus warranting closer monitoring of CK or lower doses.
Poor metabolizers of certain enzymes such as CYP2D6, CYP2C19, CYP3A4, and CYP1A2 are at increased risk of side effects from antidepressants and ultrarapid metabolizers are less likely to show positive response to treatment. Waiting 4-6 weeks or longer to find out a medication is not working can be harmful and discouraging for the patient and frustrating for the prescriber. In the STAR*D trial, researchers found that patients who were homozygous for the HTR2A gene had an 18% reduction in the absolute risk of having no response to treatment.
Poor metabolizers may experience adverse reactions to ADHD medications because the medication accumulates in the body. Rapid metabolizers may eliminate the medications too quickly and do not receive therapeutic benefit. Common ADHD medications with pharmacogenetic testing implications include atomoxetine, dexmethylphenidate, dextroamphetamine, lisdexamfetamine, and methylphenidate.
Patients who are CYP2C9 poor metabolizers have a higher risk of gastrointestinal toxicity when taking NSAIDs such as celecoxib, diclofenac, ibuprofen, indomethacin, and meloxicam. Poor metabolizers would benefit from closer monitoring, lower dosing, or changing to ketoprofen, ketorolac, nabumetone, or naproxen.
Patients who are CYP2D6 ultrarapid metabolizers are at higher risk for overdose when taking tramadol, hydrocodone, and oxycodone. Patients who are CYP2D6 poor metabolizers will have decreased efficacy. These patients would benefit from closer monitoring, dose adjustments, or changing to buprenorphine, fentanyl, hydromorphone, meperidine, morphine, or oxymorphone.
Patients who are ultrarapid metabolizers of CYP2D6 will rapidly convert codeine to morphine potentially causing morphine toxicity, including death. Patients who are poor metabolizers of CYP2D6 will have inadequate relief.
Buprenorphine, one of the most commonly used medications for treatment of opioid dependence, is a substrate of CYP3A4. Patients who are poor metabolizers of CYP3A4 will have high buprenorphine levels in the body and those that are rapid metabolizers will have low levels in the body—both leading to adverse effects.
THIS IS NOT A MEDICAL DEVICE and does not treat, prevent or diagnose illness or disease. This test only looks at patient genotyping and that relationship to listed medications. Results are complex and must be reviewed with a pharmacist and prescribing physician before any medication changes are considered. PATIENTS SHOULD NOT MAKE ANY MEDICATION CHANGES ON THEIR OWN. Results are based on published genetics research and while some findings are strongly supported, some are merely informational and to be considered by your physician. Strength of supporting genetic evidence is variable and must be considered as such. Results are not intended to be the sole information used in making medication management decisions. The test is very specific and covers many medications but not all medications. The test will provide personalized metabolic information for the medications included on our Covered Medications List so please review the list on our website to see if a medication you are concerned about is included before taking the test. This test was developed and its performance characteristics determined by a CLIA certified vendor certified to perform high complexity lab developed tests under CLIA license. It has not been cleared or approved by the US Food and Drug Administration. Such approval is NOT required for clinical implementation of tests that have been appropriately validated.