Medically reviewed by, Russell Braun RPH
Modern medicine has began to turn away form a one size fits all approach in treating patients. One of the new words to continuously crop up is precision medicine. The idea is to be more precise in the way people are treated, instead of a one size fits all approach. Pharmacogenomics (PGx) is the path forward to precision medicine.
1. What is Pharmacogenomics (PGx)?
Simply put, pharmacogenomics is the idea of taking into account gene variability when prescribing medication to treat a disease. Your genes can play a role in how you react to drugs based on how they are metabolized. Pharmacogenomics combines:
- Pharmacology – The study of how drugs work in the body.
- Genomics – The study of the human genome.
Your DNA, which is the building blocks of everything that make you, you is unique and different than anyone else. However there are components of your genetic makeup that are similar across groups of the population.
When doctors take your pharmacogenomic information and pair it with lifestyle, environment and social factors about you, personalized medicine is born. Now decisions on how to treat something like acid reflux would take all of these things into account. Instead of just a random medicine for that disease.
Is pharmacogenomics new?
Pharmacogenomics actually dates back to the 1950’s, although researchers at the time were mostly flying blind. Then the Human Genome Project (HGP) that ran from 1990 to 2003 has unlocked many new ways for pharmacogenetics to be applied. This full sequencing of human DNA propelled pharmacogenomics forward where many more genetic variants can be identified and studied.
2. What are the benefits of Pharmacogenomics (PGx)?
Now pharmacogenomics is helping to identify the medications or classes of medication that will be the best for a patient in the following areas:
- Fewer adverse effects
- Most cost effective
In addition to benefits for patients, healthcare overall is better served by PGx also. The idea is to use certain variations in the genes of people who are tested to help develop better drugs in the future. The Journal of Clinical Medicine Research describes this as the right drug to the right person, which leads to better patient care overall.
3. Why is PGX important?
Ever wondered why some medications may not seem to help you as much as others?
Have you ever changed the dose or stopped taking a medication because you didn’t think it worked for you or didn’t like the way it made you feel?
Want to know how a medication may affect you before you take it?
Data can empower you, one size fits all doesn’t! Knowing your genomic information can help drive a patient and doctor relationship, where data is shared and joint decision making is encouraged. Having this insight and view of your health empowers patients.
PGx can guide your health care provider into talioring your medications for some of the following disease states. This list is just the tip of the iceberg as more are being added all the time.
|Cancer||High blood pressure|
|Thyroid disorders||Organ transplant|
|Asthma and COPD||Migraines|
4. What is CGx and how is it different than PGx?
CGx is a abbreviation to describe the evolving field of cancer genomics. There are genes that drive the growth of many different types of cancer. Having these genes makes people more at risk for certain cancers. This type of genetic testing is being used to test people with a family history of cancer to determine their risk of developing the same type.
Doctors and patients can come up with preventative measures to help decrease the chance of certain cancers based on the CGx reports. If you have had multiple family members who have had cancer then discussing one of these tests with your doctor may be a good idea.
5. What is the PGx Test?
Typically a PGx test will be ordered by your doctor, when there is a question about how a particular drug will interact with your genetic makeup. Some large health systems are now doing pharmacogenetics testing when high risk and high cost drugs are being ordered. The goal is to minimize risk of adverse effects and decrease cost by eliminating trial and error.
Does a doctor have to order the test?
Unlike many of the genetic tests that look at ancestry, most pharmacogenomic tests will need to be ordered by a licensed doctor.
Can I eat before the test is done?
Often patients are not able to eat or drink before various medical tests or procedures are preformed. However, in the case of a PGX test the only restriction would be not eating 30 minutes prior to a saliva test being taken.
How is the test done?
Fortunately, PGx tests can be done using saliva or blood. Therefore, a mouth swab of the cheek can be done. When blood is required it would just be a normal blood draw similar to what is done for any other lab test.
What are the risks?
There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly. There is no risk to having a saliva test.
What do PGx tests look for?
There are two main principles of pharmacology that need to be taken into consideration. These deal with the way your body breaks down and then eliminates a drug. Gene sequences that affect these pharmacologic effects are what PGx tests look for.
- Pharmacokinetic effects – looking at how fast your liver breaks down the medication so it can be excreted in the urine or feces. This is referred to as metabolism and people may be slow, average or fast metabolizers. Knowing this helps predict if a drug and dose will work for a particular patient.
- Pharmacodynamic effects – which is the response of the body to the drug. Gene mutations and abnormalities play a critical role in this aspect.
Most PGx tests will show results for enzymes commonly referred to as cytochrome P-450 enzymes. These are responsible for the pharmacokinetic effects seen from a drug. They do the metabolizing and breaking down of almost all prescription, over the counter and herbal supplements used. Additionally they will also show certain gene mutations or abnormalities that can affect pharmacodynamics.
How do I understand what the test results mean?
Luckily pharmacogenomic test results will be sent to your doctor or pharmacist first in most cases. They will review the results and schedule time to discuss with you. Several companies that offer the test will provide a consultation with a pharmacist that works for them as well. You may find that your doctor is not that well versed in pharmacogenomics and needs a refresher themselves.
Companies that provide pharmacogenomic testing today
|Quest Diagnostics||Dynamic DNA||Myriad Genetics|
**This is not an all inclusive list.
6. When should you ask for a PGx test to be done?
Differences in the responses seen to medications can be due to many factors not related to genetics including:
- Drug interactions
- Liver function
- Kidney function
Your doctor should take these factors into account to ensure the drug and dose are optimized before genetic testing would be warranted.
The only way to know for sure how a medication is affecting you is to document its effects. Simply relying on a recollection of feelings before and after the medication was started can be misleading. Bullet journaling medication effects describes how to document medication effects. Once you capture this information then ask these questions.
1. Do you struggle with an ongoing health concern that is related to one of the disease states listed above?
2. Has your doctor prescribed one or more drugs that never really took care of the problem?
If you answered yes to these questions then a conversation with your doctor about PGx testing would be a good idea. This may reduce the trial an error that goes on with medications that costs money and could lead to side effects.
7. Pharmacogenomic (PGx) vs. genetic testing
Pharmacogenomic testing looks for specific gene(s) that will affect prescribing of medications. Many genetic tests that can be bought directly by patients analyze ancestry or likelihood of developing a certain disease. These are different types of tests and should not be thought of in the same way!
Some of the tests sold directly to consumers started adding information about medication effects to their results. However, in 2018 the Food and Drug Administration (FDA) sent letters to these companies warning them about making false claims of how a gene may impact a medications effects.
The FDA was trying to ensure that there was good clinical evidence that a gene can actually impact the way a drug works in the body. Since then the FDA has updated the prescribing information for doctors of over 250 drugs about pharmacogenomic information.
8. Current evidence for PGx
Having research that proves certain genes actually impact the way drugs work is crucial for pharmacogenomics to be more widely used. The Clinical Pharmacogenetics Implementation Consortium (CPIC) is the trusted source of information about pharmacogenomic tests.
PharmGKB is a datasource funded by the National Insitutes of Health that collects genetic testing information and how genes impact drug responses. This database pulls together information from the CPIC as well as the FDA. It serves as a place for doctors to go to find the latest information on PGx testing.
Any changes you and your doctor plan to make based on PGx tests should be based on evidence from CPIC that can be easily searched on PharmGKB.
9. How much does PGx testing cost?
Today, these tests are expensive!
Costs can vary based on what is actually ordered and the company providing the testing. However, it is not uncommon for them to cost $2500. The hope is over time as technology improves the costs will come down.
Does insurance cover the test?
Today many insurers including Medicare will cover genetic tests, but not in all cases. Coverage is more likely if the tests are focused on drugs used for mental health. Coverage may vary based on:
- Reason for test
- Previous failure of other medications
- Severity of disease being treated
If, your insurance does cover the test, it can lower the patient cost down to the $300-$400 range.
The future for PGx
More and more healthcare professionals are learning about the advantages of pharmacogenetic testing. This will continue to increase as further information is gathered, stored and refined by trusted data sources such as CPIC and PharmGKB. This will make PGx easier to implement in technology solutions that will help drive overall spending on medication down.
For patients this means less time waiting to find the right drug and less exposure to drugs that could cause side effects. While today PGx testing can’t tell you the exact drug one should use, that is probably going to be possible with more research. Eventually, PGx tests will be like getting bloodwork done to help doctors make the best prescribing choices.
Personalized medicine using PGx along with patient environment, lifestyle and other social factors will prove important in getting the best outcomes. Analyzing this data is important for patients and doctors to get the full picture to maximize health.
Click here to get Dr. Jason Reed’s exclusive list of medication questions you MUST ask your doctor, for FREE!
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