Unlocking the Power of Personalised Medicine with Pharmacogenomics

How Your Genes Impact Medications

Many factors affect how well a medication works for you. Your ethnicity, age, weight, lifestyle, other medications, and overall health can all influence how your body responds to treatment. Even external factors like diet or smoking can play a role in the effectiveness of a prescription.

Among these influences, your genetic makeup has a significant part to play. Pharmacogenomics (PGx) is the science that explores how your genes impact the way medications are absorbed, distributed, metabolised, and excreted by your body. By understanding this, PGx testing helps to personalise treatments, ensuring you receive the right medication at the right dose for your unique genetic profile.

The Journey of a Medication Through Your Body

Every medication you take undergoes a complex journey through four key stages: absorption, distribution, metabolism, and excretion. At each stage, your genetic profile and physiological conditions play a role in determining how your body processes the drug and how effective it will be for you.

Absorption

The first step is getting the drug into your bloodstream. This process can vary depending on genetic variations in specific genes. For example, variations in the SLCO1B1 gene can affect how the antidepressant Imipramine is absorbed, which impacts how much of the drug reaches the brain to deliver its intended effect.

Distribution

Once in the bloodstream, the medication is distributed throughout your body to different tissues and organs. The effectiveness of this step can also be influenced by your genes. For instance, the antipsychotic Risperidone relies on variants in the SLC6A4 gene to regulate serotonin transport. This can determine how effectively the drug reaches serotonin receptors, directly influencing its therapeutic impact.

Metabolism

This is where most medications undergo transformation, typically in the liver, to make them easier for the body to absorb or eliminate. For example, Methylphenidate (commonly prescribed for ADHD) is metabolised by enzymes encoded by the CES1A1 gene. Variants in this gene can impact how quickly the medication is processed, affecting its efficacy and potential side effects, such as changes in focus or mood.

Excretion

Finally, the drug and its metabolites are cleared from your body, typically through urine or faeces. Variants in the UGT1A4 gene, for example, can influence how quickly the anti-anxiety medication Diazepam is eliminated, which in turn affects how long the drug remains active and how intense its effects are.

Notable Drugs in Pharmacogenomics

Certain medications have gained attention in the field of pharmacogenomics due to their complex genetic interactions. One prominent example is Clozapine, a powerful antipsychotic used to treat schizophrenia that is resistant to other treatments.

Clozapine’s metabolism is influenced by genetic variations in the CYP1A2 and CYP2D6 genes. Individuals with certain genetic profiles may experience higher drug levels, increasing the risk of severe side effects like agranulocytosis (a dangerously low white blood cell count). PGx testing can help identify these patients early, enabling clinicians to carefully tailor the dosage or explore alternative treatments.

Other notable drugs include:

Warfarin (a blood thinner): Genetic variants in the CYP2C9 and VKORC1 genes can affect how patients metabolise this medication, requiring personalised dose adjustments to prevent bleeding or clotting risks.

Codeine (a pain medication): Variations in the CYP2D6 gene can cause some individuals to convert codeine into morphine too quickly, leading to potential toxicity, while others may metabolise it too slowly for effective pain relief.

Tamoxifen (a breast cancer treatment): Variants in CYP2D6 impact the conversion of Tamoxifen into its active form, potentially reducing its effectiveness in patients with certain genetic profiles.

These examples underscore the importance of PGx testing in optimising treatment outcomes and minimising adverse risks for patients.

Why Pharmacogenomics Matters

PGx-guided treatments can significantly improve the odds of successful therapy. Studies have shown that matching medications to genetic profiles can improve response rates by up to 70%. This means fewer side effects, faster recovery, and more effective management of conditions ranging from depression and anxiety to cancer and chronic pain. It has been predicted that the NHS could save as much as £2B per year by adopting a widespread approach to PGx, minimising trial and error, while maximising the effectiveness of treatment.

How to Bring PGx Insights to Your Doctor

If you’ve undergone pharmacogenomic testing, you now hold valuable insights into how your body processes medications. But how do you make the most of this information?

The next time you’re prescribed a medication, consider discussing your genetic test results with your doctor. For example, if your results indicate you’re a slow metaboliser for a specific drug, your doctor might adjust the dose or choose a different medication to reduce the risk of side effects. Our blog aims to empower you with the knowledge to broach this conversation confidently and advocate for a treatment plan tailored to your unique genetic profile.

The Future of Personalised Medicine is Here

Pharmacogenomic testing is not just about optimising your current prescriptions—it’s about paving the way for more effective, personalised treatments in the future. With these insights, you’re better equipped to navigate your healthcare journey, ensuring the medications you take are the best fit for your body.

To learn more about how your genes influence medication response, explore pharmacogenomics for Mental Health, Cardiovascular, or Contraceptive and Hormone Replacement Therapy.

Are you a healthcare professional? Book a PGx demo and we’ll walk you through the PGx report and testing process.

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