Pharmacogenomics
Pharmacogenetics is a type of science that analyzes how the body's genes affect the body's response to certain drugs. The word "pharmacogenetics" is a combination of the words "pharmacology" (the science of drug use and effects) and "genetics" (the science of genes and their functions) .
Each person's genetic makeup is different, and these genetic differences can affect the effectiveness of a drug or the occurrence of side effects. The main goal of pharmacogenetics is personalized, effective and safe personal health care.
Why are pharmacogenomic tests becoming more important?
Currently, the treatment of various diseases is based on the practice of standard medicine - treatment is based on general recommendations and statistics, assuming that most people will respond similarly to a particular drug or dose. For example, a doctor may prescribe a standard dose of pain medication to all patients, regardless of how well their body can metabolize the drug. Since all people are genetically different, standard therapy will only work for some people. A dose or drug adjustment will usually be made if the initial treatment does not work or causes side effects. This can take time and cause unnecessary side effects or delay effective treatment.
In the case of pharmacogenetic studies, the treatment is selected individually, taking into account the changes in the patient's genes. Genetic testing determines how a patient's body processes and responds to specific drugs, allowing doctors to tailor drugs, dosage, and even compatibility to optimize safety and effectiveness. For example, if a person has a genetic variant that causes them to metabolize codeine poorly, their doctor may prescribe an alternative pain reliever that works better for their body. Therefore, in the case of personalized therapy, treatment benefits everyone. This improves treatment outcomes and reduces the time needed to find the right treatment.
Pharmacogenetics is most often applied:
- For the treatment of cancer: e.g. targeted therapy based on tumor genetics (trastuzumab, imatinib);
- Psichinei sveikatai: pvz. personalizuotas antidepresantų ir antipsichozinių vaistų pasirinkimas;
- For cardiology: e.g. blood thinners (warfarin) or antiplatelet drugs (clopidogrel);
- For pain management: e.g. adaptation of opioid use (codeine).
Although standard medicine is usually cheaper at first, costs can add up over time due to treatment of ineffective drugs and their side effects and additional doctor visits. Therefore, in the long run, pharmacogenetic testing is more cost-effective both in terms of money and time.
Why does not the same dose of medicine work for everyone?
Medicines are metabolized (processed) by enzymes in the body. Some people have genetic changes that affect how these enzymes work, changing how quickly or slowly their body processes drugs. Based on the rate of drug processing by a specific enzyme, individuals are divided into four categories: poor metabolizers (PM), intermediate metabolizers (IM), normal metabolizers (EM), and ultrarapid metabolizers (UM).
If you are a poor metaboliser and your doctor prescribes drugs that are active in the body and metabolized into inactive forms (such as the blood thinner warfarin), you may need to reduce > dose or choose another drug to avoid harmful side effects (eg bleeding) caused by high blood levels of the drug.
- Jei esate prastas metabolizuotojas ir gydytojas jums skiria vaistus, kurie organizme yra aktyvūs ir metabolizuojami į neaktyvias formas (pvz. kraują skystinantis varfarinas), gali tekti sumažinti dozę arba pasirinkti kitą vaistą, kad išvengtumėte aukštos vaisto koncentracijos kraujyje sukeliamo kenksmingo šalutinio poveikio (pvz. nukraujavimo).
- If you are a poor metabolizer and your doctor prescribes drugs that are inactive in the body and are metabolized into active forms (such as the anti-cancer drug tamoxifen), you may need to choose a different drug to achieve the desired effect of the drug (eg reducing the risk of cancer recurrence).
Intermediate metabolizers process drugs slower than normal metabolizers, but faster than poor metabolizers. This means that although they may not experience as high a risk of side effects as poor metabolizers, they may still need to adjust their dose or choose a different drug.
- If you are an intermediate metabolizer and your doctor prescribes drugs that are active in the body and metabolized into inactive forms (eg the antidepressant amitriptyline), you may need to reduce dose or choose a different drug to avoid the harmful side effects of high blood levels.
- If you are an intermediate metabolizer and your doctor prescribes drugs that are inactive in the body and are metabolized into active forms (such as the pain reliever codeine), you may need to increase strong> dose or choose a different drug to achieve the desired effect of the drug.
Normal (extensive) metabolizers process drugs at a normal or moderate rate. This is considered the "standard" type of metabolizer. People in this category usually do not need to adjust the standard dose of the drug based on their genetic changes.
Ultrarapid metabolizers process drugs very quickly, which can cause the drug to leave the body faster than expected. Then the effectiveness of the drug is reduced, because the concentration of the drug in the body is not sufficient to achieve the desired effect.
- If you are an ultrarapid metabolizer and your doctor prescribes drugs that are active in the body and metabolized into inactive forms (eg the high blood pressure medicine metoprolol), you may need to increase dose or choose another drug to achieve the desired effect of the drug (eg blood pressure regulation).
- If you are an ultrarapid metabolizer and your doctor prescribes drugs that are inactive in the body and are metabolized into active forms (eg the antiplatelet drug clopidogrel), you may need to reduce strong> dose or choose another drug to avoid harmful side effects (eg bleeding) caused by high concentrations of the active drug in the blood.
Understanding the type of metabolizer can help ensure the most effective, safe, and personalized treatment. Based on this, your doctor can adjust medications and dosages to match everyone's unique genetic makeup.
Sources
- Ahmed S, Zhou Z, Zhou J, Chen SQ. Pharmacogenomics of Drug Metabolizing Enzymes and Transporters: Relevance to Precision Medicine. Genomics Proteomics Bioinformatics. 2016;14(5):298-313. doi:10.1016/j.gpb.2016.03.008
- Royal College of Physicians and British Pharmacological Society. Personalised prescribing: Using pharmacogenomics to improve patient outcomes. RCP and BPS, 2022. Report
