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From “One Size Fits All” to Personalized Medicine: The Power of Pharmacogenetics

The future of healthcare is personalized.

“Personalized medicine” is an emerging practice of medicine that uses information about an individual’s genetic makeup to guide health decisions about the prevention, diagnosis, and treatment of disease.

It moves away from the traditional “one size fits all” approach and aims to provide treatments and healthcare strategies that are most likely to work for each patient, minimizing potential side effects or ineffective treatments. Understanding a person’s genes can help select the proper medication or therapy and administer it using the proper dose or regimen.

What is our “genetic makeup”?

Our genes are made up of DNA which is passed down from your parents. The Human Genome Project worked to determine the sequence of the human genome and identify the genes that it contains. It is estimated that humans have between 20,000 and 25,000 genes.

Your DNA and your genes are a unique code that makes us who we are. It’s like our biological signature. And this signature plays a significant role in how our bodies react to different medications. This is where pharmacogenetics comes in!

Pharmacogenetics (PGx)

Pharmacogenetics is the study of how your unique genetic makeup influences your response to medications.

Did you know that 99.9% of people have gene variants impacting their medication response?

PGx can determine which medications you are more likely to have side effects to. It can also give us information about efficacy–which drugs are more likely to work for you and which ones aren’t. Finally it can tell us information about dosing and potential drug regimens. It may be suggested you use a higher or lower dose of a medication, based on your genetic makeup.

This is very empowering for you (and your healthcare team!) to make better informed treatment decisions, minimizing side effects and safety risks and selecting medications which are best for your body.

How do my genes affect the way drugs work in my body?

The human body has incredible processes to break down or activate medications. There are several important proteins in the body that play significant roles when a medication is ingested:

  • Enzymes: break down or active a drug so it can take effect

  • Protein transporters: help a drug go to where it is needed

  • Protein receptors: let the drug into the cell where it will take effect

Certain genetic variants can impact the quantity and effectiveness of these enzymes, transporters and receptors, driving wide variations in responses to medications between individuals. Genetic differences can drive large variations in dose requirements and can even cause unexpected drug-drug interactions.

A very common example is looking at how you metabolize or break down medications. People usually fall into 1 of 4 metabolizer “types”.

Intermediate Metabolizers of a drug process the drug a bit too slowly, causing a buildup of the drug at standard doses, and potential side effects.

Poor Metabolizers of a drug break down the drug very slowly, causing a build-up that can result in toxicity (side effects or safety issues), even at standard doses.

Normal Metabolizers of a drug will process the drug at “normal” (expected) rates, which means they will have an expected response at standard doses.

Ultrarapid Metabolizers of a drug will process the drug and remove it from the body much too quickly, resulting in little clinical effect at standard doses.

Let’s give an example, shall we?

I myself am a CYP 2C19 Ultrarapid Metabolizer. Commonly used antidepressants like citalopram (Celexa), escitalopram (Cipralex or Lexapro) and sertraline (Zoloft) are metabolized through this pathway. Also, all proton pump inhibitors (PPIs) used for heartburn and to treat ulcers, like lansoprazole (Prevacid), esomperazole (Nexium) and more.

What does this mean for me?

These drugs are metabolized and ‘inactivated’ so quickly through the body that they are not likely to work for me.

If I was to come down with a serious episode of depression, it is very likely that a doctor could prescribe escitalopram for me. It’s a first line drug that is very commonly used because it is typically well tolerated. Antidepressants take 6-8 weeks to start working, so without knowing my PGx information I would go 2 months taking a medication (with potential side effects) before realizing that it is not working and trying something else (to wait 2 months again.. Hopefully it is not sertraline or we would be back in the same position).

Similarly, if I had an ulcer in the future, without having my PGx test done a doctor would prescribe a PPI at the recommended dose. This is not knowing for a CYP 2C19 ultrarapid metabolizer it is recommended to use a 100 to 400% dose increase of the medication, depending on which drug you use!

What it DOESN’T Do

Pharmacogenetic testing does NOT look at disease risk. Some other DNA tests for your health look at your risk for disease (for example Alzheimer’s disease, cystic fibrosis, or certain cancers), or genetic variances that may influence lifestyle factors (like variations in muscle composition or nutrition factors).

Pharmacogenetics only looks at genes which influence your response to medications.

How Does the Test Work?

Pharmacogenetic testing involves a simple saliva test done in the privacy and comfort of your own home. A sample test kit is shipped directly to your home with everything you need to collect the sample and send it back to the lab. Once the sample is received by the lab it takes about 1-2 weeks to process the results and have it interpreted by the pharmacist.

As the benefits of pharmacogenetic testing are being realized, more and more private insurers are starting to cover the test. If you have private insurance, definitely check with them. Some may require you work with a specific test. At Your Simple Health, we work with all pharmacogenetic tests on the market. If you have coverage for a specific test, it’s important we know about it before so we can maximize your insurance coverage for the service.

Be Proactive

One of the reasons pharmacogenetic testing is so useful is because your genes don’t change! The genes that you were born with you stay with you for life. This means that getting your test done, before you need the medications, can be really helpful. If your health status changes in the future, for example if you break a leg and need pain medication, you would be prepared as to which drugs are likely to work best for you. Test results are even updated regularly to reflect new data or new medications.

Knowing which genetic variants you have can help healthcare professionals more accurately identify the most effective and safest treatment options for your BEFORE a prescription is written, so you can feel better sooner.

Who Should Get a Pharmacogenetic Test?

In my perspective, we have three categories of people who should get their PGx test done today.

Anyone considering taking medication for a mental health condition like depression or anxiety

  • Efficacy rates for antidepressants are very low (up to 2 out of 3 people do not respond properly to the 1st treatment they are prescribed) and there are a lot of options available. Avoid the trial and error that comes along with prescribing for mental health.

  • These meds take a long time to start working. Get on the right treatment, sooner.

  • In fact, a study of >3000 patients with mood and anxiety disorders showed that individuals who underwent PGx testing had 40% fewer emergency room visits and 58% fewer hospitalizations overall than those that did not.

  • This can be useful if you are not taking medication, but considering starting one, or if you’re taking one but have not found the “right” one (it is not working for you, or you are coming up against side effects).

Anyone who feels “sensitive” to medication side effects, or that medication(s) haven’t worked for them.

  • Depending on the medication and what you are using it for, PGx could be the key to show you why these experiences are showing up for you, and which medications would be better suited to your body.

Anyone who wants to be proactive about their health.

  • Your genes don’t change, so if your health status changes in the future, you will be armed with the information you need to make better informed health decisions.

  • Avoid medications which are more likely to cause you side effects, and choose medications which are most likely to be effective for you based on your genes.

The Key to Unlocking Pharmacogenetic Information: Application to YOU

One of the reasons, I believe pharmacogenetic testing isn’t being used more widely today, is barriers in application and interpretation of test results.

Test results can be upwards of 50+ pages including lists of medications classified as “Red” (do not use), “Yellow” (use with caution), or “Green” (use as directed).

However, what does that mean for YOU? Based on your own medical history, current health status, and family history, what is relevant for you now or in the future?

To be honest, doctors and healthcare professionals in today’s world don’t have the time or expertise to sift through these dozens of pages of results, interpreting the associated evidence with each gene-drug interaction and applying it to what is relevant to you.

Working with a Pharmacist who is educated and experienced in applying these results can help you better understand this information as well as inform your doctor(s) and care team about any important medication changes you need today.

That’s exactly what we do at Your Simple Health!

Our Service: Pharmacogenetic Testing with Your Simple Health

At Your Simple Health, we’ve been using PGx testing for years. We digest your PGx test and apply it to your own unique health situation, and interpret in a way that is easy for you (and your health team) to understand.

Our services are offered virtually, across Canada, so they are accessible for your wherever you may be.

We offer PGx testing in two ways.

→ If you are currently experiencing a health challenge (for example have tried multiple medications which don’t work for you or have been causing you side effects) and need help finding the right medication for you, we offer PGx as part of a Targeted Medication Review. In this service, we will get to the bottom of what is going on for you taking into account all of the factors (including your PGx!) that influence your personalized treatment decision. We also work directly with your care team to implement and follow through on recommendations.

→ If you want to be proactive about your health and get your PGx test, but don’t have an active health issue, we offer our Personalized Medicine Test & Consultation service. This includes the PGx test as well as interpretation and application of your results to YOU. In addition to your test results, you will get a personalized interpretation report and 1:1 virtual consultation to go over your results with the pharmacist.

Questions about what is right for you?

Feel free to book a complimentary discovery call to explore how we can help you get to your best health yet.


  1. National Human Genome Research Institute. Personalized Medicine. Updated: September 14, 2023.

  2. Medline Plus. What is a gene?

  3. Inagene. What is Pharmacogenetics?


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