Medication Genetics and EDS

What is pharmacogenomic testing and who is it for?

Debbie, a preschool teacher, seemed nervous. It was her first-time meeting with me, a clinical pharmacist with expertise in pharmacogenomics (PGx), to review and discuss her PGx test results. The testing was ordered by her primary care physician due to her many medication sensitivities.

She described a lifelong history of “bad experience” with prescription drugs such as an antidepressant (paroxetine) side effects and pain medication (tramadol) lack of efficacy. In addition, she needed higher doses of lidocaine, a numbing medication used by her dentist. Her sister recently had this testing done which revealed she does not metabolize well several medications.

Debbie was hopeful that PGx testing may shed some light on her lifelong history of drug sensitivities and lack of efficacy with lidocaine. She was recently diagnosed with hypermobile Ehlers-Danlos Syndrome (hEDS). When I explained that many patients in my clinic also have hEDS and suffer from unfavorable drug experience, Debbie visibly relaxed shifting from timid to excited. “I saw my results on my patient portal. I tried to look them up. But none of it makes sense. What exactly is PGx and how can it help me?” asked Debbie.

What is pharmacogenomics?

Pharmacogenomics — also known as pharmacogenetics or PGx — uses a person’s genetic information to predict the way they may react to a drug. It combines the sciences of pharmacology (study of drugs) and genetics (study of DNA/genes).

Deoxyribonucleic acid (DNA) is responsible for traits such as height, eye color and susceptibility to disease. These traits are passed on through genes. Humans have over 20,000 genes. We typically inherit two copies of each gene: one copy from mom and the other from dad. Genes give instructions to make proteins and enzymes, which serve many functions. For example, the CYP2D6 gene makes the CYP2D6 enzyme that breaks down some commonly used drugs such as antidepressants, blood pressure medications and pain medications.

Almost 99% of genes are identical between all of us. However, that 1% difference in the form of gene variations is what makes each one of us unique. That also means that a drug can affect each of us differently.

PGx pharmacists study these variations and their impact on drug metabolism and efficacy. With a simple cheek swab or blood draw, we can look at genes associated with drug responses to help us predict how you may react to a drug. PGx can also tell us if you are at risk for serious drug reactions.

There are currently about 200 drugs with pharmacogenomics information in their FDA drug label. This number is expected to rise as almost every new drug that enters the market goes through pharmacogenetic studies.

Have you ever had any of those issues that Debbie experienced?

Author: Adrijana Kekic, Pharm.D., BCACP