What is Pharmacogenomics?

Pharmacogenomics is the study of how genes affect the way medicines work in your body, from Pharmacology (the study of drugs) and Genomics (the study of genes). When you take a medication, enzymes in your liver begin to metabolize or break down the medication allowing it to achieve the desired result. In approximately 75% of us, there are genetic variants that affect how the enzymes respond.

A certain group of enzymes, called Cytochrome P450, are responsible for metabolizing 90% of all drugs. One of these specific enzymes is the CYP2D6. The CYP2D6 is responsible for metabolizing approximately 25% of clinically prescribed drugs, yet only 48% of us have a Normal Metabolizing gene. Those of us with a genetic variant will metabolize drugs more slowly, meaning drugs stay in our system longer at risk of toxicity, or we metabolize quickly, meaning the drug will be eliminated before it has a chance to do its job. Studying these genetic variants allows physicians to make adjustments in prescribing to select the safest and most effective doses.

What is an Adverse Drug Event?

An Adverse Drug Event (ADE) is an illness resulting from the administration of a drug. An ADE could be because of an interaction with another drug, improper dosing, or because of a genetic variant in the way that an individual metabolizes a particular medication.

More than 128,000 deaths occur each year from the correct administration of medication. ADEs are responsible for over 700,000 ER visits annually, and over 3 million outpatient visits.

How is Pharmacogenomic (PGx) testing useful?

PGx testing enables your doctor to prescribe medications that will work for you in the correct dose without a costly ‘trial and error’ period. Armed with this information, physicians can more accurately predict an individual’s response to a drug. Because prescribing is more accurate and more effective, costs of unused medications and repeat office visits are saved.

The Food and Drug Administration has been working closely with drug companies who submit their products for testing, and have developed a methodology for improving the labeling and package information that accompanies a medication. Hundreds of common medications now offer recommendations on avoidance of ADEs when products are being prescribed.

Who should have PGx testing?

Ideally, PGx testing is beneficial for everyone as the results will last a lifetime and will not change. For avoidance of Adverse Drug Reactions (ADEs), those persons at greatest risk are those over 65 years of age, who must manage two or more chronic conditions and five or more medications.

The Centers for Disease Control says that almost 40% of persons who are over 65 years of age take five or more medications, increasing the risk for ADEs from drug-drug reactions.

Do I need to see my doctor to have PGx testing?

Yes. You will need to have a doctor’s order to have the test performed. Additionally, you will want to review the results with the doctor who manages your medications and conditions. You will want to share this information with all of the prescribing providers who participate in your care.

PGx testing has been made available through direct-to-consumer websites, although the FDA has issued a warning to web-based testing companies that patients may abandon their therapies or self manage dosages. The National Society of Genetic Counselors offers advice that a test ordered through a physician or genetic counselor will be the most detailed and comprehensive, and will be accompanied by the guidance you need.

Will insurance cover PGx tests?

Private Insurers are increasingly recognizing the value and cost savings of pharmacogenomic testing for improved care, avoidance of adverse drug events, and management of chronic conditions. Many payers, including Medicare, will offer coverage for testing in many cases when certain drugs are being prescribed.

When considering PGx testing, you may want to contact your insurer for specific coverage pertaining to the test that your physician has ordered. If you prefer, you may elect to self-pay for testing.