Do you know someone who may benefit from testing to determine their genetic response to certain medications?
Sharing this information with a friend or loved
one could help them get the right drug at the right dose.
In medicine, one size doesn’t fit all. Two people who take the same
medication may have very different responses to it.
Researchers are now discovering the role that your genes play in
affecting how you’ll respond to your medications. In some cases, you may
not be getting the full benefit of a drug, but in other instances, a
drug may be harmful because of how your body processes or metabolizes
it. This science is known as pharmacogenomics, but it is often referred
to as personalized medicine because it offers your doctor a way to
tailor your treatment based on your individual genetic makeup.
Before you take a single dose of certain medications, your doctor may be
able to give you a test to see what genetic variations you have and how
those variations could affect your response. Testing could help you and
your doctor make better choices to ensure you’re taking the right drug
in the right dose.
Tests are available today that
profile the genes determining the function of three important
drug-metabolizing enzymes: CYP2D6, CYP2C9, and CYP2C19.i
Together, these enzymes are responsible for the metabolism of up to 50%
of currently available drugs. Sufficient metabolism is necessary to
convert certain drugs to an active form or to avoid potential side
effects. Genetic testing for drug metabolism can show whether you have
variations that could affect how you’ll respond to such drugs.
Important! Abruptly stopping medications can be harmful. Make sure your friend or loved one continues to take all medications as prescribed by their doctor until the doctor instructs otherwise.
What tests are available?
Enzyme Test
Medications to Check
CYP2D6 - The CYP2D6 enzyme plays a role in the metabolism of approximately 25% of currently available medications
How you metabolize the CYP2D6 enzyme can affect your response to these drugs:
- Some antiarrhythmics (heart drugs),
such as propafenone (Rythmol®) - Some antidepressants,
such as bupropion (Budeprion®, Wellbutrin®), fluoxetine (Prozac®), sertraline (Zoloft®), and amitriptyline (Elavil®) - Some antiemetic drugs (antinausea drugs),
such as ondansetron (Zofran®) - Some antiestrogen drugs (breast cancer drugs),
such as tamoxifen - Some antihistamines,
such as diphenhydramine (Benadryl®), hydroxyzine (Atarax®, Vistaril®), and promethazine (Phenergan®) - Some beta-blockers (heart drugs),
such as carvedilol (Coreg®), propanolol (Inderal®), metoprolol (Lopressor®, Toprol XL®), and nebivolol (Bystolic®) - Some narcotic analgesics (pain drugs),
such as codeine (Tylenol® with Codeine), oxycodone (OxyContin®, Percocet®, Percodan®), and methadone - Some pyschotherapeutic drugs,
such as aripiprazole (Abilify®), haloperidol (Haldol®), perphenazine (Trilafon®), and risperidone (Risperdal®) - Some smoking cessation therapy drugs,
such as bupropion (Zyban®)
CYP2C9 - The CYP2C9 enzyme plays a role in the metabolism of approximately 15% of currently available medications.
How you metabolize the CYP2C9 enzyme can affect your response to these drugs:
- Some asthma drugs,
such as zafirlukast (Accolate®) - Some anticoagulants (anticlotting drugs),
such as warfarin (Coumadin®) - Some anticonvulsant drugs,
such as phenytoin (Dilantin®) - Some antidiabetes drugs,
such as glimepiride (Amaryl®), rosiglitazone (Avandia®), glyburide (Diabeta®, Glynase®, Micronase®), glipizide (Glucotrol®, Glucotrol XL®), nateglinide (Starlix®), and tolbutamide - Some antifungals,
such as fluconazole (Diflucan®) and voriconazole (Vfend®) - Some antihypertensive drugs,
such as irbesartan (Avapro®) and losartan (Cozaar®) - Some anti-infectives,
such as sulfamethoxazole (Bactrim®, Bactrim DS®), and rifampin (Rifampin®) - Some anti-inflammatory drugs,
such as diclofenac (Cataflam®), celecoxib (Celebrex®), piroxicam (Feldene®), meloxicam (Mobic®), ibuprofen (Motrin®), Naproxen (Naprosyn®), and diclofenac (Voltaren®, Voltaren XR®)
CYP2C19 - The CYP2C19 enzyme plays a role in the metabolism of approximately 5% - 10% of currently available medications.
How you metabolize the CYP2C19 enzyme can affect your response to these drugs:
- Some antianxiety drugs,
such as diazepam (Valium®) - Some anticonvulsant drugs,
such as phenobarbital - Some antiplatelet drugs,
such as clopidogrel (Plavix®) - Some antiulcer drugs (proton pump inhibitors),
such as rabeprazole (Aciphex®), esomeprazole (Nexium®), lansoprazole (Prevacid®), omeprazole (Prilosec®), and pantoprazole (Protonix®)
Note: This table contains examples of drugs that are metabolized in part by these enzymes. This is not an all-inclusive list. Please check with your doctor or pharmacist to find out if the drugs you are taking could be affected by variations in your drug-metabolizing genes.
What you can do to help
1 Ask your family members or friends if their doctor knows about genetic tests for drugs that they are taking. Have them share this information with their doctors and pharmacists.
2 Print and share this information to inform others about genetic testing for drug-metabolizing genes.
3 If you are using one of the drugs listed above or other drugs and feel that you might not be tolerating treatment well, ask your doctor whether testing your drug-metabolizing genes could be helpful.
4 If you have had your drug-metabolizing genes tested, inform your doctor and pharmacist about your test results and ask them to note your test results in your drug profile.
5 If you want to
learn more about physician adoption of pharmacogenomics, see the
research at MedcoResearch.com. 
All rights in the product names appearing on this website, whether or not accompanied by a trademark symbol, are the property of their respective owners.
i Consumer Health Information Corporation. New genetic
tests help doctors prescribe the right medicine for you. Accessed at http://www.consumer-health.com/services/NewGeneticTestsHelpDoctorsPrescribetheRightMedicineforYou.htm
on Sept. 29, 2009.
