It’s not unusual for patients to come to Bob Denitzio, MD, after having tried five to 10 different antidepressant medications with little to no success, or having experienced distressing side effects, including extreme fatigue, vomiting, even thoughts of suicide. Dr. Denitzio, an integrative and functional medicine doctor at the Main Line Health Center in Concordville, explains that patients commonly have a partial response from one medication or bad side effects from another, or from multiple medications combined. The reason for so much trial and error is simple: Every person is genetically different so each body responds differently to different medications.
Thanks to a genetic test called GeneSight®, a quick swab of the inside of a patient’s cheek can help determine which class of antidepressant medication might work best and eliminate or lessen its side effects. Recently published results of a large study showed that patients were:
- 50 percent more likely to achieve remission of symptoms of major depressive disorder
- 30 percent more likely to respond to treatment when the GeneSight® test was used to guide the medication treatment
GeneSight is one testing method in an emerging field called pharmacogenomics or drug-gene testing, an aspect of personalized medicine that is having a widespread impact on how people are being treated with medications.
How does genetic testing for medications work?
Genetic testing for medications is based on the human genome (all of the genes in the human body) which is estimated to consist of 20,000 to 25,000 genes. Of these, certain genes have been identified to influence functional aspects of the body. For example, some genes influence the way enzymes (which aid in the metabolic process) break down medications in the body. This is important in the field of pharmacogenomics, as understanding of the enzyme behavior in an individual tells us a lot about how the person may respond to a particular medication. If an enzyme works too quickly, the person may metabolize the medication quickly and it won’t work for them. If the enzyme works too slowly, the medication can build up and produce toxic side effects.
“Genetic testing for medications gives physicians insight into what things we should and should not think about prescribing in order to do the least harm,” adds Dr. Denitzio.
Getting a genetic test for antidepressants
The GeneSight test looks at 12 different genes that influence how a person metabolizes nearly 60 different antidepressant drugs that are commonly prescribed for conditions such as anxiety, obsessive compulsive disorder, post-traumatic stress disorder, depression, bipolar disorder, and schizophrenia. In his practice, Dr. Denitzio has used GeneSight testing on three primary groups. This includes people who:
- Have attention deficit disorder (ADD)
- Are taking chronic pain medications
- Have depression and anxiety
Many patients in these groups take medications that need to be used on a trial and error basis. Within a few days of administering the swab test, he receives the results in a three-column format, color-coded as follows:
- Green - indicating “use as directed”
- Yellow - demonstrating a “moderate gene-drug interaction”
- Red - for “significant gene-drug interaction”
The report further indicates where a lower dose of a particular drug may work better. The physician then makes an assessment based on review of the patient’s medical history as well as current health and a variety of factors in order to recommend an antidepressant that should produce the optimal result with the fewest side effects.
“I’ve had patients say they’ve never been able to take any medication,” says Dr. Denitzio. “While some of that might just be anxiety, a large segment of those folks have a problem with detoxification enzymes in the liver and indeed don’t tolerate medication very well.” He recalls one patient who refused to have cancer surgery because the person had such a problem with pain medication and also had a concern about the effects of anesthesia. “Being able to get their genetic profile on the enzymes needed to break down these medications was very reassuring for the patient.”
How much does GeneSight testing cost?
As with any type of testing, check with your insurance provider to see what is covered. When paying out of pocket, 95 percent of patients pay $330 or less for GeneSight® testing. GeneSight also provides a financial assistance program for qualifying patients.
Dr. Denitzio advises patients to consider not only the value of eliminating trial and error when it comes to antidepressants and other medications, but to appreciate the lifelong value of the genetic test. “Once you know your profile, it can be applied to any medicine you take for the rest of your life.”
Main Line Health serves patients at hospitals and health centers throughout the western suburbs of Philadelphia. To schedule an appointment with Dr. Denitzio, call 484.227.7858.