You've probably heard that the same medicine for the same disease works for some people, doesn't work for others, and has side effects for others. Why is that? Is it because our bodies are different? Yes, that's one reason. That's a related, somewhat complicated, but very important topic that we're going to talk about today. This is called pharmacogenomics.
What is Pharmacogenomics?
Simply put, pharmacogenomics is the study of how we respond to drugs based on our genes. Remember, pharmacology is the study of the use and effects of drugs. Genomics is the study of genes and their function. The combination of the two is called pharmacogenomics. It is sometimes called pharmacogenetics.
This really falls under the larger field of 'Precision Medicine' . That is, providing you with a personalized treatment plan based on things like your genes, the environment you live in, and your lifestyle. Pharmacogenomics can help your doctor choose a drug that has fewer side effects or that works best for you .
But it should be noted that this method is not yet used for every disease or every drug. Currently, it is mostly used for a limited number of conditions and drugs, such as HIV, some types of cancer, depression, and heart disease. But this field is developing very quickly. Researchers hope that this method will soon help to choose better drugs for even the most common diseases.
How do genes affect the way drugs work?
Think of it this way: our genes are like a set of instructions for the cells in our body. These genes help us make protein molecules called enzymes . Enzymes have a million jobs in our bodies. One of them is to break down drugs in the body, or metabolize them . If some people don’t respond to drugs as expected, it could be because they have certain changes in their genes. These changes could cause the enzymes to be less effective or the enzymes to not work properly.
Now imagine, what would happen if your body broke down a drug too quickly, or too slowly, or not at all? Then the drug, given at the usual dose, would not work as expected. Either the drug could cause serious side effects , or it could have no effect on the current illness.
For example, some people don't fall asleep quickly after drinking coffee, while others don't. One reason for this is that our genes affect how quickly our bodies break down caffeine. The same can happen with medications.
What is this pharmacogenomic test?
A pharmacogenomic test is a genetic test. It can look at one or more genes, specifically to look for specific genetic variants that affect the breakdown of a drug. It's like checking for a typo in our body's 'instruction manual'.
Doctors usually use a blood sample or a buccal swab to do this. This sample is taken from you and sent to a lab. There, a technician checks your DNA for specific changes. The gene or genes they look for will depend on the test your doctor has ordered, the condition they are trying to treat, and the medications they are planning to give you.
When do I need a pharmacogenomic test?
If you are taking medication for certain medical conditions, you may also be eligible for pharmacogenomic testing. Here are some examples (and there may be more):
High cholesterol
Due to certain variants of the ``SLCO1B1 gene`` in our body, if you take certain medications called statins for high cholesterol, you may experience muscle pain and weakness. Examples of these statins are:
- Atorvastatin (e.g. Lipitor®)
- Fluvastatin (e.g. Lescol®)
- Lovastatin (e.g. Altoprev®)
- Pitavastatin (e.g. Livalo®)
- Pravastatin (e.g. Pravachol®)
- Rosuvastatin (e.g. Crestor®)
- Simvastatin (e.g. Zocor®)
So before you start taking a medication like this, or if you have any problems while using it, your doctor can talk to you about a test like this.
Depression
Variations in the genes CYP2D6 and CYP2C19 can affect how quickly your body breaks down some antidepressants. Examples of these medications include:
- Amitriptyline (e.g. Elavil®) - This is a type of tricyclic antidepressant .
- `SSRI` class of drugs : `Citalopram` (e.g. `Celexa®`), `Escitalopram` (e.g. `Lexapro®`), `Sertraline` (e.g. `Zoloft®`), `Paroxetine` (e.g. `Paxil®`) and `Fluvoxamine` (e.g. `Luvox®`).
- Venlafaxine (e.g. Effexor®) - This is a type of SNRI.
This test can be useful when starting medications like this, or when one medication is not working and you are trying to switch to another.
Cancers
If you are taking medication for a specific type of cancer, you may benefit from pharmacogenomic testing. Here are some examples:
- Breast cancer: The drug trastuzumab (e.g. Herceptin®) only works in people with HER2-positive breast cancer . This means that the cancer cells have a genetic mutation that causes them to produce too much of the HER2 protein.
- Acute Lymphoblastic Leukemia (ALL): People with low levels of the enzyme Thiopurine Methyltransferase (TPMT) may experience severe side effects and an increased risk of infection if given the usual dose of Mercaptopurine (e.g. Purinethol®).
- Colon cancer: People with low levels of the enzyme UGT1A1 may be at increased risk of severe diarrhea and infection if given the drug Irinotecan (e.g. Camptosar®).
Also, the anticancer drug fluorouracil, `5-FU` (e.g. Adrucil® - `Adrucil®`), can cause serious side effects if given at normal doses to people with low levels of the enzyme dihydropyrimidine dehydrogenase (`Dihydropyrimidine Dehydrogenase - DPD`). Doctors may prescribe this drug for colorectal cancer, breast, stomach and pancreatic cancers.
Blood clot prevention
People with certain genetic variants need to take a lower dose of the anticoagulant drug warfarin (e.g. Coumadin®). Too much can cause bleeding.
Also, a change in the CYP2C19 enzyme in your liver may prevent the antiplatelet medication clopidogrel (e.g. Plavix®) from working properly . This is a medicine used to prevent things like heart attacks and strokes.
HIV infection
A certain variant of the HLA-B gene can cause a severe skin reaction to the drug Abacavir (e.g. Ziagen®).
Also, a variant in the CYP2B6 gene may increase the risk of side effects such as neurological changes from the drug efavirenz (e.g. Sustiva®).
Immune system issues
If you are taking an immunosuppressant, you may benefit from pharmacogenomic testing:
- Due to variations in the proteins `TPMT` and `NUDT15`, bone marrow function may be suppressed if you take the drug `Azathioprine` (e.g. `Imuran®`) after a kidney transplant or for immune system conditions such as multiple sclerosis.
- Due to variations in the CYP3A5 enzyme, if you take tacrolimus (e.g. Prograf®) after an organ transplant, the risk of organ transplant rejection may increase.
What are the advantages of pharmacogenomics?
As researchers and doctors continue to study and use pharmacogenomics, it could yield many benefits. Take a look:
- Improved safety: Doctors will be able to avoid prescribing medications that cause harmful side effects in some people, or that can cause problems when taken in excess. This means you won't have to suffer unnecessarily.
- Efficiency and reduced healthcare costs: If doctors can know in advance which drugs work and which don't, they can prescribe the most effective drugs first , saving money and time .
- Targeted drug development: Some diseases are caused by a specific change (variant) in a gene. Pharmacogenomics allows researchers to find new drugs by directly targeting that genetic variation. Just like creating a drug that fits the disease.
What are the limitations/disadvantages of pharmacogenomics?
While your genetic makeup is important in determining the best treatment for many conditions, it doesn't fully explain how your body processes medications. Doctors still have to consider other factors when choosing the right medication. For example:
- Other medications: The medications you are currently taking may interfere with the effectiveness of new medications.
- Other health conditions: Some illnesses can change the way your body processes medications. For example, if your kidneys aren't working properly, some medications will be excreted from your body.
- Lifestyle: Things like what you eat, how much exercise you get, and your tobacco and alcohol use can affect how well your medication breaks down.
Other challenges in the development and application of pharmacogenomics include:
- Cost: Although the cost of pharmacogenomic testing is gradually decreasing, the cost per person, or out-of-pocket costs, often vary depending on insurance coverage. This test may not be available to everyone.
- Accessibility: Access to some genetic tests may be limited, depending on where you live and the type of doctor who treats you.
Currently, doctors can only use pharmacogenomics for a limited number of conditions and medications. However, this exciting field of 'precision medicine' is growing rapidly. Talk to your doctor about how pharmacogenomics can help your health and what benefits it could bring. You can also ask about clinical trials in this field.
Finally, finally, remember this.
Okay, so, although the term pharmacogenomics we talked about today is a bit complicated, what it means is that it helps us choose the medicine that best suits us and has the fewest side effects, based on our genes.
Our genes are a big reason why the same medicine doesn't work the same way for everyone. Pharmacogenomics is an attempt to understand that secret and give us more personalized, more effective treatments.
Although this is still a developing field, it has the potential to change the way many diseases are treated in the future. If you have any questions about a particular medication, especially whether it will work for you or whether it will cause side effects, don't be afraid to talk to your doctor about these pharmacogenomic tests. They may be very helpful to you.
Remember, your genes are only one important part of your health story. A good diet, exercise, and following your doctor's advice are just as important!
` Pharmacogenomics, genes, drugs, medications, precision medicine, genetic testing, side effects
💬 අදහස් (0)
තවමත් කිසිදු අදහසක් පළ කර නොමැත. ඔබේ අදහස පළමු වරට මෙහි එක් කරන්න.
ඔබේ අදහස එක් කරන්න