Drug therapy can be a mix of decision making based on known drug pharmacology plus some trial and error on a patient by patient basis. Not that we don’t understand the mechanism of drug action – most of the time we do, right down to the receptors that a drug might act on within the body as well as the enzymes that are responsible for the drug’s elimination. This is well founded and part of any drug’s mechanism of action.
So why do so many people not respond in the same way to a given medication and why do some people experience more adverse effects than others as a result of the same drug/dose used? That’s where genetic variability comes in. We’ve known for some time that some people just don’t metabolize certain drugs as well as others or that some people actually metabolize a drug faster than the general population. In both cases, this will result in different drug responses – good and bad – which may include the adverse effects, the side effects if you will, that are possible with any drug. There are more cellular processes that affected by this genetic variability – metabolism is just one of them.
This is not about good drugs or bad drugs, as this variability in response can occur with some of the best drugs on the market. Drugs that have been dosed to millions of patients for many, many years. The variable is the genetic variation from person to person.
How can this genetic variability affect response to a drug?
The body contains proteins called enzymes, once a medication is taken these either break down or activate the drug so that it can take effect. Other proteins transport the drug where it needs to go (transporters) or let the drug into the cells (receptors) where it will take effect. Depending on what genetic variations a person has inherited, protein and enzyme activity will differ. For example, some people may inherit enzymes that are slower to break down drugs. This could mean a standard dose of the drug remains in their body for a longer time, potentially leading to adverse effects. This is why knowing what genetic variations you have can be important: it can help healthcare professionals more accurately identify which drug (and what at what dose) will work best for each individual BEFORE they are treated, so they can feel better sooner with less medication “trial and error”.
Most of us carry “gene variants” that can impact effectiveness of some medications (or put us at a higher risk of side effects)
Drug-related “adverse events” (side effects and/or drug interactions) are the fourth leading cause of death in Canada and cause one-third of all hospitalizations. Pharmacogenetic testing may help prevent some of these hospitalizations by identifying patients who are at increased risk of severe side effects or drug-drug interactions because of gene variants they carry. Instead of relying on a “trial and error” approach, pharmacogenetics can help healthcare professionals and their patients find the safest and most effective drugs and doses for them, faster.
A recent study of over 3,000 patients with mood and anxiety disorders showed that individuals who underwent pharmacogenetic testing had 40% fewer emergency room visits and 58% fewer hospitalizations overall than those who did not.
Your genes carry the “code” for how you will likely respond to different medications.
Genes are specific segments of our DNA (like individual “words in the recipe book” for what makes you unique) that each have a distinct purpose. Each gene “codes” for the production of a protein or enzyme that has specific functions in the body, and some have important roles in how your body processes medications. Your cells make proteins and enzymes by “reading” the sequence of individual building blocks of the DNA called nucleotides. Nucleotides are like the “letters” comprising the words in your recipe book, and there are four different types: adenine (A), guanine (G), cytosine (C), and thymine (T). Gene “variants” (also known as “single nucleotide polymorphisms” or “SNPs”) are variations in the order of the four nucleotides A, C, G, and T in specific genes (For example, a gene might typically begin with the sequence ATTGCT, but another variation might begin ACTGCT instead). Although any two unrelated people have about 99.9% of the same sequences of these “letters” (nucleotides), the remaining 0.1% is important, because it these genetic “variants” that influence how people differ (for example in their risk of disease or their response to drugs).
Any two unrelated people have about 99.9% of the same nucleotides but it’s the remaining 0.1% that’s important.
It is these genetic “variants” that influence how people differ (for example in their hair color or in their response to drugs). Any change in the order of these nucleotides can affect how a gene codes for an enzyme involved in processing medications (eg. your body may make too much or too little of an enzyme, or it may affect how well the enzyme works). This, in turn, can affect how your body responds to the medication. Sometimes the impact of a gene variant can be very slight, and sometimes it may be very significant. There are millions of possible gene variants (SNPs) in the human genome. For researchers in the field of pharmacogenetics, the goal is to find connections between gene variants and individual responses to medication. Gene variants can, therefore, be used as predictive markers for whether a person may react well or poorly to a given medication BEFORE the medication is even taken. This could potentially save time and money, by reducing the “trial and error” involved in finding a safe, tolerable, and effective treatment.
The benefits of pharmacogenetic testing last a lifetime.
The genes you were born with stay with you for life, and so do your Personalized Insights™ test results. You never have to repeat the test, and your results are updated regularly to reflect new data or new medications. Let pharmacogenetics be your GPS to help you arrive at the best treatment plan for YOU faster. Follow the clues provided by your genes with Inagene Personalized Insights™, and feel better, sooner.
- Pharmacogenetic Testing Available at Stafford Pharmacy & Home Healthcare
- Inagene: The Cheek Swab Test Kit
- Global News: Is pharmacogenetic testing the future of drug prescribing?
- Alberta Health: What is pharmacogenetics? (pdf file)
- Pharmacogenetics: The future of medication (Sun Life)