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Clopidogrel (Plavix)

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Overview

Clopidogrel is marketed under the name Plavix

What is Clopidogrel?
Clopidogrel is also called Plavix. It is a drug used by doctors to treat or prevent strokes and heart attacks. Clopidogrel works by preventing the blood from clotting so that it flows easier through the body. Clopidogrel is sometimes called a 'blood thinner'.

What is being tested?
People react differently to medicine and some of those different reactions can be related to their genes. People with certain differences in their genes might not respond to particular medications as well as others. The gene involved in how people use clopidogrel is called CYP2C19. This test will look for some of the genetic differences in the CYP2C19 gene that can make people less responsive to clopidogrel.

How will this affect my health care?
If testing shows that you might be less responsive to clopidogrel, you may be prescribed a different medication by your doctor. Your doctor may also use this information to decide on which dose to take. It is also possible that your doctor will not to do anything different.

If you have any questions about your test results or the medications you are on, please talk with your doctor.

You should follow your doctor's instructions on taking any medication. Do not change your medications on your own before speaking with your doctor.

More Questions? The National Society of Genetic Counselors has developed a directory to help locate genetic counseling services near you.

Background

Why test for genetic interactions with Clopidogrel?
By performing a test on your DNA, we may be able to anticipate how you will respond to clopidogrel and to adjust your treatment accordingly. The embedded video from the Coriell Institute looks at why the drug is prescribed and how genetic testing can predict response to Clopidogrel.

How will this affect my treatment?
If genetic testing does indicate that you may not respond optimally to treatment with clopidogrel, your doctor should change your prescription.

Can taking Clopidogrel cause any problems?
For the majority of people taking clopidogrel will not cause any problems. However, in a small proportion of people, a change in dosing or medication may be recommended to prevent bleeding and other adverse events.

Are any other complications associated with Clopidogrel?
A minority of individuals can experience severe complications after taking clopidogrel, with excessive bleeding a possibility.

Who is affected?Up to 50% of people have a genetic difference that either increases or reduces how they metabolize clopidogrel, which may warrant a change in treatment.

Do different populations respond differently to Clopidogrel?
Genetic differences in Clopidogrel response are relatively widespread across populations. However, individuals of Asian ancestry may be the most likely to have a genetic difference affecting their response to Clopidogrel.

Do reactions to Clopidogrel and other drugs run in my family?
We (typically) inherit two gene copies from each parent. If you have a genetic difference that affects how you respond to clopidogrel, it is likely to have been inherited from one or both of your parents, and it is possible you will pass this to your children. However, this is not always the case, and a large variety of inheritance scenarios are possible. If you are concerned about this, we strongly advise you to discuss with your doctor or healthcare provider.

Is there a difference between being a carrier and being predisposed to a particular drug response?
You may carry a genetic a difference that does not affect how you response to clopidogrel, but may affect how your children might respond. A full discussion of the relevant scenarios/implications are beyond the scope of this site, however, and we recommend you discuss with your doctor or healthcare provider if this is a concern.

Why do genetic differences make people respond to clopidogrel differently?
Clopidogrel must be activated by CYP450 enzymes in our body in order to work. The instructions on how the CYP450 enzymes work is determined by the CYP2C19 gene. So, differences in the CYP2C19 gene will make people use clopidogrel differently. For some people, the genetic difference makes the CYP450 enzymes work less well. If the CYP450 enzymes don’t activate the clopidogrel in the body, it will make clopidogrel less effective for the person taking it.

More Questions? The National Society of Genetic Counselors has developed a directory to help locate genetic counseling services near you.

Genetic Test

Weblink to Learn.Genetic Module, Making SNPs Make Sense

What is the test?
People react differently to medicine and some of those different reactions can be related to their genes. People with certain differences in their genes might not respond to particular medications as well as other people. The gene involved in how people use clopidogrel is called, CYP2C19. This test will look for some of the genetic differences in the CYP2C19 gene that can make people less responsive to clopidogrel.

What will the test result mean?
This test will tell us how you will likely respond to clopidogrel. Most people are 'normal metabolizers'. You might also be a 'poor metabolizer', 'intermediate metabolizer', or 'ultra-rapid metabolizer':

Normal metabolizers are people who would respond to clopidogrel as expected.

Poor metabolizers are people where clopidogrel will not work as well to treat their condition. Therefore, someone who is a poor metabolizer may need to use a different drug or may need a larger dose of medication to get the same benefits.

Intermediate metabolizers are people who may process or use clopidogrel a bit slower than expected, but can still experience some benefit from the drug. This means that some people who are found to be an intermediate metabolizer of clopidogrel may have a slower response to clopidogrel.

Rapid metabolizers are people who may process or use clopidogrel faster than other people. This means that people who are found to be a rapid metabolizer of clopidogrel may have an improved response to this medication.

How is the test being performed?
Testing is performed on your DNA, usually extracted from a blood sample. For many patients, your hospital or treatment center may already have some of your DNA stored in a biobank. You may be asked for an additional sample or be asked to give us permission to do testing on the existing samples.

Will it hurt?
For some patients, we may need an additional blood sample. Taking blood may cause some pain, bleeding or bruising at the spot where the needle enters your body. Rarely, taking blood may cause fainting or infection.

Is it safe?
There is a risk that you may experience pain or bleeding if you need to give an additional blood sample. Risks concerning privacy are discussed under Privacy & Sharing.

How long will I have to wait for results?
Unfortunately, we cannot give an accurate estimate for the time you will have to wait for results - this will depend on the resources available at the center where you receive treatment.

Is this a standard test?
Although increasingly more common, this test is not yet standard, and is typically offered as part of a research study.

What type of test is this?
Is this test intended to confirm a diagnosis? No
Is this test intended to predict a family history of disease? No
Is this test intended to check if I am a carrier for a particular disease? No
Is this test intended to screen for genetic disorders? No
Is this test intended to screen for disorders related to pregnancy? No
Is this test intended to screen for disorders related to newborns? No

Will I need to have this test done more than once?
No, you should not need to have this test done more than once. You will need to keep track of your testing result in order to share with all of your doctors, including those you see at other medical care centers.

More Questions? The National Society of Genetic Counselors has developed a directory to help locate genetic counseling services near you.

Treatment

How will this test affect my treatment?

For most people tested, it is likely that your treatment options will stay the same and that you will begin treatment with clopidogrel as scheduled, or you will maintain you treatment with Clopidogrel. If this is not the case, your doctor will either change your recommended dose of clopidogrel or recommend a new treatment.

In the embedded video, Dr. Iftikhar Kullo (Mayo Clinic) explains that everyone does not respond in the same way to clopidogrel, and responses may be related to your genetic make-up.

How will this result be used?
The result will be put into your medical record for your doctor to use when deciding about prescribing you clopidogrel. Your doctor may:


• Do other tests to see how you might respond to clopidogrel
• Do nothing and continue with your planned course of treatment
• Switch your medications if you are on clopidogrel and found to be a poor metabolizer
• Give you another medication that is not clopidogrel to treat your condition

You should follow your doctor's instructions when taking any medication. Do not change your medications on your own before speaking with your doctor.

Will I be referred to a specialist?
It is unlikely that you will be referred to a specialist, but you may request an appointment with a genetic counselor.

Is there anything else I should know?
You should follow your doctor's instructions when taking any medication. Do not change your medications on your own before speaking with your doctor.

More Questions? The National Society of Genetic Counselors has developed a directory to help locate genetic counseling services near you.

Privacy & Sharing

Should I tell other healthcare providers about my test result?
If your doctor who prescribes medication for you doesn't already know about your test result, we do recommend that you share this information with him/her. However, as explained by Maureen Smith (Nortwestern University) in the embedded video, what you decide to do with your results is up to you.

Who will see my test results?
People who have access to your medical record will be able to see your genetic test result. This may include health professionals such as doctors, nurses, pharmacists, and genetic counselors. However, health professionals from other centers or hospitals will likely not have access to your results.

Should I tell other healthcare providers about my test result?
If your doctor who prescribes medication for you doesn't already know about your test result, you should share this information with him/her.

Should my other family members be tested to see how they might respond to clopidogrel?
You may want to share your test results with your family, since they might have the same genetic variant as you. If you are a 'poor metabolizer' of clopidogrel, they may want to consider being tested also.

Will this affect my health insurance?
No, your health insurance will not be affected by this clopidogrel test result.

Who can I contact if they have any more questions?
You can contact your local center, where you received the test. We have also included a recommend list of resources in the Videos & More tab to the right.

Is it there a risk to my privacy?
Research that uses information from medical records and that involves genetic testing can affect your privacy. Your participation in this research will be held strictly confidential, and only coded numbers will be used to identify specimens and research records. While it is impossible to absolutely guarantee that information in our secure system will never be known by others, we are taking every possible precaution to see that this does not happen.

More Questions? The National Society of Genetic Counselors has developed a directory to help locate genetic counseling services near you.

Risks

What Should I Do If I Have Concerns About Genetic Test Results?
If you are concerned about genetic test results you have received, you should discuss your concerns with your doctor. Your doctor should be able to explain results to you, and may recommend you to a genetic counselor or another doctor that can further help you understand your results. Maureen Smith (Northwestern University) discusses these concerns in the embedded video/

Is there a reason why I may be a specific risk?
Testing is recommended for all individuals undergoing or considering undergoing treatment with clopidogrel.

Is there a reason why I may be a specific risk?
Testing is recommended for all individuals undergoing or considering undergoing treatment with clopidogrel.

Are there any implications for having children?
No.

If I am found to have a specific gene variant, am I at increased risk?
For some individuals, there gene test result may indicate that they are at an increased risk of responding poorly to clopidogrel (needing more or less of the drug), or of developing side-effects such as bleeding. Testing is done to help guide your doctor chose the best treatment for you.

Can I expect to experience emotional consequences related to my test result?
A range of reactions are possible and normal. Some patients may experience anxiety or other negative reactions related to their use/potential use of clopidogrel. If this is the case, please discuss with your doctor, who can address your concerns and refer you another health professional if required.

Can I expect to experience social consequences related to my test result?
We do not anticipate any social consequences related to use/potential use of clopidogrel. As always, however, if you do experience any negative social reactions, please discuss with your doctor who can address your concerns.

Can I expect to experience an increase in anxiety?
Many individual experience increased anxiety related to genetic testing. Again, please discuss with your doctor if this is the case.

Are there any implications in terms of discrimination arising from the test result?
Health insurance companies are prevented by law from discriminating against you based on your genetic test results. However, the same law does not apply to long-term disability insurance or to life insurance.

If I am found to be at increased risk for responding poorly to clopidogrel, are there similar health implications for my family?
If results indicate that you may respond poorly to clopidogrel, your family may be more likely to have a similar response should clopidogrel ever be considered an option for them. As such, you may want to discuss your results with your family.

Are there likely to be emotional consequences for my family?
Similar to patients, family members may experience a range of reactions, which is normal. We recommend that if you discuss any questions or problems with your healthcare provider.

More Questions? The National Society of Genetic Counselors has developed a directory to help locate genetic counseling services near you.

Videos & More

Does Everyone Respond in the Same Way to Clopidogrel?

Dr. Iftikhar Kullo, a researcher are Mayo Clinic, explains that everyone does not respond in the same way to clopidogrel, and responses may be related to your genetic make-up. Genetic testing may be used to determine appropriate doses or alternative medications.


Genetic Testing to Predict Responses to Medication

Dr. Hakon Hakonarson, a researcher at The Children's Hospital of Philadelphia explains that genetic testing can now be used to predict responses to certain medications. This will help to prevent negative reactions and improve healthcare.

RECOMMENDED WEBSITES

Find a Genetic Counselor directory developed by the National Society of Genetic Counselors.

Genetics Home Reference has basic information about genetics and links to other resources about genetics.

Medline Plus has more information about clopidogrel, other drugs, and other health conditions.

Lab Tests Online provides patient-centered reviews about lab testing and drug products.

Daily Med provides high quality information about marketed drugs.

The Pharmacogenomics Knowledge Base is a resource for medical professionals about how variation in human genetics leads to variation in response to drugs.

About

Are there geographical differences in service or treatment related to clopidogrel?
Different centers have different policies in terms of how tests are administered and results shared. However, the results discussed in this document should be relevant to most individuals tested for clopidogrel-gene interactions.

How is this paid for?
If you received this test as part of the eMERGE research study, neither you nor your insurance company will have to pay anything toward this test

When was this content last updated?
January 15, 2014.

More Questions? The National Society of Genetic Counselors has developed a directory to help locate genetic counseling services near you.
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