Why is pharmacogenetics important in medicine?

The latest frontier in medicine is personalization. In this context, pharmacogenetics is emerging as a key tool to improve treatment effectiveness and reduce side effects. By studying individual genetic characteristics, it is now possible to predict how a person will respond to a medication before it is even administered. This not only enhances safety in clinical practice but also opens the door to truly personalized healthcare.

What is pharmacogenetics?

Pharmacogenetics is a branch of genetics that studies how inherited differences between individuals affect their response to medications. Each person has a unique genetic profile, which influences both the effectiveness and safety of the drugs they take. This discipline, formally established in 1959, aims to explain why the same medication, given at the same dose, can produce different results in different individuals: in some, it works effectively with no side effects; in others, it may cause serious reactions or not work at all.

This variability can be due to multiple factors, including environmental aspects such as age, sex, diet, or liver and kidney function, but also — and increasingly — to genetic factors. Medications go through a complex journey in the body: they are absorbed, distributed, metabolized, and eliminated. Along the way, they interact with proteins encoded by our genes. Therefore, variations in these genes can significantly alter how an individual responds to a treatment.

By identifying these variations, known as polymorphisms, pharmacogenetics makes it possible to anticipate whether a patient has an increased or decreased metabolic capacity for a given drug, allowing dosage adjustments or the selection of a different active substance. For those interested in understanding how these tools are transforming the healthcare sector, having a solid foundation in pharmacology and healthcare management is essential. In this regard, specialized programs such as an MBA in Healthcare & Pharma provide an integrated perspective combining biomedical innovation and strategic management.

What is pharmacogenetics used for? Benefits and areas of application

One of the main goals of pharmacogenetics is to optimize drug treatment in a personalized way. In other words, tailoring therapy to a patient’s genetic profile to maximize effectiveness and minimize side effects. In clinical practice, this means being able to predict which patients will respond well to a drug, which will not respond at all, and which may experience severe adverse effects.

This information is especially valuable in areas such as oncology, where certain chemotherapy drugs can cause severe toxicity in patients with specific genetic variants. For example, some enzymatic polymorphisms can make a treatment lethal for some patients while being perfectly safe for others. Thanks to pharmacogenetic testing, it is now common practice to analyze at least four variants before administering drugs such as fluoropyrimidines, widely used in cancer treatment.

Beyond cancer, pharmacogenetics is increasingly applied to treatments involving antidepressants, statins, anticoagulants, and commonly used drugs such as proton pump inhibitors. There have even been clear benefits in neonatal intensive care, where rapid testing can prevent irreversible damage caused by toxicity in newborns treated with gentamicin, if a specific mitochondrial variant is detected.

In the long term, it is expected that each individual could have a “pharmacogenetic passport”, a genetic profile indicating in advance how they would respond to dozens of medications. This would not only facilitate medical decision making but also reduce healthcare system costs by avoiding ineffective treatments and costly adverse events.

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What is the difference between pharmacogenetics and pharmacogenomics?

Although often used interchangeably, pharmacogenetics and pharmacogenomics are not exactly the same. Pharmacogenetics focuses on how one or several inherited genetic variants affect the response to specific drugs. It is a more targeted approach, aimed at identifying the relationship between certain genes and medications.

Pharmacogenomics, on the other hand, takes a broader perspective. It studies the entire genome to understand how its variability influences drug effectiveness, safety, and the development of new treatments. It plays a key role in research and in designing more precise therapies based on a comprehensive understanding of genetic information.

Pharmacogenomics, for example, enables the discovery of new therapeutic targets and the design of drugs tailored to specific genetic profiles, while pharmacogenetics has a more immediate clinical application, helping doctors choose the right medication for each patient.
Both disciplines, however, share a common goal: to make personalized medicine a reality, adapting treatments to each individual’s genetic profile.

Examples of pharmacogenetics in clinical practice

Advances in pharmacogenetics are already translating into real clinical applications. One of the most well documented cases is the antiretroviral drug abacavir, used in HIV treatment. In patients carrying the HLA-B*5701 allele (a specific genetic variant), this medication can trigger severe hypersensitivity reactions. For this reason, many countries require genetic testing before prescribing it.

Another example is carbamazepine, a drug used in epilepsy and bipolar disorder. In Asian populations, the presence of the HLA-B*1502 allele is associated with a significantly increased risk of developing Stevens Johnson syndrome, a potentially life threatening skin reaction. Pharmacogenetics allows healthcare professionals to identify at risk patients before such adverse effects occur.

In the treatment of type 2 diabetes, a polymorphism in the IRS1 gene (Gly972Arg) has been identified as affecting the effectiveness of certain medications by altering insulin sensitivity. This type of genetic insight helps refine treatment choices, especially in patients who do not respond well to conventional therapies.

A particularly impactful example comes from neonatal intensive care units. In suspected cases of sepsis, standard protocol often includes gentamicin. However, if a newborn carries a specific mitochondrial variant, this antibiotic can cause irreversible hearing loss. In the United Kingdom, rapid testing kits now allow this genetic test to be performed in just 25 minutes, potentially preserving both hearing and life.

Pharmacogenetics is not a future promise but a present day tool that is already transforming medicine. It enables the anticipation of adverse reactions, avoids ineffective treatments, and optimizes therapeutic outcomes. Although there are still regulatory limitations and differences in adoption across countries, scientific evidence is clear: understanding a patient’s genetic profile before prescribing medication not only saves lives but also improves healthcare quality and reduces system costs.