Pharmacogenomics: Getting the right drug

One of the hardest things for me in my practice is determining which medication would be the best choice for a patient. There often isn't a precise equation that can inform me which medication is the right choice.

Trying to be as conscientious as I can be, I do wonder, "Did I choose the best option for my patient?" I remember my professors from medical school telling me there is an art and a science to medicine, and that it is not black and white. However, science advances, and one of the benefits of this is pharmacogenomic testing.

How pharmacogenomic testing is performed

Pharmacogenomic testing at Mayo Clinic is performed by collecting a swab of your cheek. The test looks at your DNA for a number of different genes that code proteins that influence how medications are processed in the liver or at enzymes that influence how your body processes medications. A report is generated, and with the help of a clinical pharmacist, your health care team can consider that when choosing medications.

There can be a gap between what your health care team thinks a medication can do for you and what it does, even if you take it according to your provider's directions. Sometimes this gap can be explained by how your body processes that drug. It can build up or never really reach effective levels, depending on your genetic composition.

Where pharmacogenomic testing can help

I find pharmacogenomic testing can help determine the best medications for attention deficit hyperactivity disorder, especially in children, as well as anxiety and depression.

By ordering pharmacogenomic testing, your provider can determine if a medicine isn't right for you before prescribing it. Why take a medicine that isn't likely to be effective or will cause side effects? Why start a child on a medicine, like a stimulant, when there isn't evidence that it will be more effective than other alternatives?

There are other areas where I have found it beneficial to use pharmacogenomic testing for my patients. These include optimizing treatment of acid reflux, as some people churn through the usual medications much quicker. Therefore, we can adjust the dosing frequency. I also have seen the benefit when treating heart conditions by knowing which prescriptions will get appropriately processed.

Every time I have ordered pharmacogenomic testing, I have seen a clinically significant variant in a gene that could affect my treatment choices. In a large study population, the rate of clinically significant variants in at least one test was over 90%. If I can avoid trial and error, reduce your rate of side effects, help get a medication that is more likely to be effective or potentially get you feeling better sooner, then that is worth doing.

Troy Benson, M.D. is a Family Medicine physician in Waseca, Minnesota.