DNA promotions are everywhere to answer burning questions like who’s the daddy, who really belongs on the family tree and what health predispositions are lurking behind the scenes. DNA tests can also answer oddly strange things like one’s disposition to asparagus odor detection, cheek dimples and even ice cream flavor preference.
Beyond identifying fathers, family trees and fascinating tidbits, the DNA testing boom also extends to the field of pharmacogenetics as physicians seek insight for the best course of patient therapy. While the field of pharmacogenetics was established in the 1950s, its prevalence has increased over recent years, likely tied in part to FDA-mediated product insert relabeling to include relevant pharmacogenetic information for certain drugs.
Known by other names such as pharmacogenomics and drug gene testing, pharmacogenetics predicts the role a patient’s genes play in responding to and processing medications.
Genetics account for 20-90% of variability in drug disposition and effects, and drug gene testing looks for changes or variants in a patient’s genes to:
- determine whether a specific medication will be an effective treatment
- identify potential side effects
- guide dosage
- improve patient safety.
Genes, Medications and Scenarios
Consider a scenario in which four patients are offered the same medication at the same dosage as part of their respective treatment plans.
- Patient 1’s genetic makeup causes the medication to break down too slowly, leading to a build up of that medication in the patient’s body that results in severe side effects.
- Patient 2’s genetic makeup breaks down the medication too quickly, preventing that medication from working optimally.
- Patient 3’s genetic makeup sparks life-threatening side effects to that medication.
- Patient 4’s genetic makeup metabolizes the medication properly, resulting in an effective treatment with no side effects.
Medication: Help or Hurt?
Drug gene testing allows physicians to examine a patient’s genetic profile, identify variations in specific genes and determine whether a medication will help or hurt that patient. For the most part, these genetic variants are within a drug metabolizing enzyme that impacts the degree or rate at which a drug is converted to its metabolites. So, by understanding the relationship between a patient’s genetic variation and the efficacy or toxicity of a medication, genetic testing helps a physician optimize treatment by prescribing the right medication at the right dosage for a specific patient.
Pharmacogenetics testing is available currently for a wide range of medications, including certain drugs that treat high cholesterol, high blood pressure and heart disease, as well as cancer, pain, epilepsy and certain autoimmune and psychiatric disorders, among others. Advancements continue to be made in the field of pharmacogenetics as more genetic variations are identified.
Genetics account for 20–90% of variability in drug disposition and effects
770,000 injuries and deaths annually in the United States are tied to adverse drug reactions
≈1 in 15 patients will experience an adverse drug reaction
≈1 in 300 patients will have a fatal adverse drug reaction
Using Pharmacogenetics Wisely
Knowing when to test, who to test and how to apply the results are paramount to patient care.
There are a number of reasons healthcare providers choose gene testing, including cases in which a patient has one or more red flags.
- There are a number of reasons healthcare providers choose gene testing, including cases in which a patient has one or more red flags.
- The patient has a personal or family history of adverse drug reactions
- The patient is taking more than one prescription medication
- An additional medication is being added to the patient’s treatment plan
- An effective medication has been difficult to find
- An unusually high dosage of a medication is required
- The patient was previously prescribed an expensive or unusual drug regimen
- The patient is taking a drug metabolized by the CYP450 enzyme
- The patient is taking a drug that inhibits or stimulates the CYP 450 enzyme
- The patient is being prescribed Plavix (Clopidogrel)
Of course, genetic testing is the standard of care before starting certain medications when there is an understood drug-gene interaction. For example, a medication prescribed for inflammatory bowel disease, if metabolized slowly, can severely depress the immune system that results in life-threatening infections. For patients that have cancer or cystic fibrosis, ineffective medications can be avoided when time is precious and quality of life is on the line.
Testing, Results and Information Sharing
- Pharmacogenetics benefits both physicians and patients by substantially reducing the risk for adverse drug events and minimizing or completely avoiding trial-and-error dosing.
- A patient can be a poor, intermediate, extensive or rapid metabolizer of drugs based on their genotype for CYP 450 family of enzymes.
- A patient that is a poor or rapid metabolizer is prone to drug toxicity or lower effectiveness of drugs.
- One of the most beneficial aspects of pharmacogenetic testing is the report, which provides the patient with an extensive list of medications that are efficacious to ineffective to outright dangerous to take, so while genetic makeup does not change, treatment regimens do, and now patients have a resource to provide to all prescribers prior to starting a new medication regime.
- The rate of drug metabolism varies from person to person.
- Since a patient’s genes are at the foundation of this science, family members may have the same or a similar response to certain medications, so information sharing between family members can be beneficial.
Here to Assist You
Genetics testing can be an important – even life-saving – component of patient care, and pharmacogenetics is one of the most actionable areas of the personalized medicine paradigm.
If you are an independent physician, a distributor or laboratory sale professional that sells to independent physicians, we appreciate the opportunity to talk with you one on one about Diax Labs’ pharmacogenetic testing service. To learn more or to schedule a presentation,click the button below.