How Can Pharmacogenetics Prevent Adverse Drug Reactions? 

According to the Health Canada’s latest report published on January 3, 2025, the number of Serious Adverse Drug Reactions reports were submitted between December 2019, and September 2024 was 21761. (https://health-infobase.canada.ca/hospital-adverse-events-dashboard/#a3). 

Many of these ADRs could be avoided through personalized medicine or pharmacogenomic profiling. Having worked closely in pharmacovigilance and dealing with drug safety profiles of various marketed drugs, here is my take on use of pharmacogenetics/genomics for preventing adverse drug reactions.  

Pharmacogenetics refers to a branch of science that researches the implications of genetic makeup in the response to medications in an individual. Ultimately, pharmacogenetics will be able to identify variations in the genes that translate to differences in drug metabolism, efficacy, and safety. At this juncture, pharmacogenetics may enable the customization of medicines with the intent of lessening adverse drug reactions (ADRs). This blog explores the working of pharmacogenetics in preventing adverse drug reactions, improving patient safety, and optimizing the therapeutic efficacy of drugs.  

But first, let us understand what are adverse drug reactions (ADRs)? 

Adverse drug reactions (ADRs) are those unwanted or harmful effects resulting from the use of medicines. They can range from mild instances of nausea or dizziness to life-threatening reactions such as organ failure or death. According to the World Health Organization (WHO), about one in 10 patients might develop ADRs, with ADRs sometimes leading to hospitalization, rendering treatment of underlying medical conditions much more complicated. Given that some ADRs can be predicted through prior knowledge of the side effects of a given drug, others are not so easy to predict accurately, as they require consideration of the genetic makeup of the individual, rendering the knowledge of their occurrence that much more thus dangerous.  

ADRs must develop via a complex interplay of one or many possible events such as drug interactions, allergic reactions, inappropriate dosage, and so on. This is almost at variance with the emerging evidence indicating that genetics is a considerable determining factor in how individuals metabolize and respond to drugs. It is here that pharmacogenetics in adverse drug reactions becomes essential.  

What Is Pharmacogenetics, and How Does It Prevent ADRs? 

Pharmacogenetics is symbolic of a sub-branch within pharmacology, which attempts to find out how genetic variation works in the way people respond to drugs. Given that every individual has unique genetic characteristics, these may greatly influence the absorption, distribution, metabolism, and excretion of medications from the body. Genetic variants which might cause adverse drug reactions are tested for, so an individual can get the right treatment.  

Here’s my video on Pharmacogenomics for you: (https://youtu.be/E5IMynE6KMk?si=Kntaa4ktYaniAc7L) 

For instance, some people might possess alterations in their gene encoding cytochrome P450, a subclass of enzymes essential to the metabolism of many common drugs. Such genetic differences can mean that some people metabolize drugs very quickly during a particular application, whereas others metabolize them more slowly. If a certain drug is metabolized quickly, it may not have the desired effect in the patient, while if a medication is metabolized very slowly, it can accumulate in the body and could eventually lead to toxicity. The pharmacogenetic techniques can help a healthcare professional decide on the proper course of action, such as modification of the dose or use of alternative therapy based upon the patient's genetic information. 

Pharmacogenetics for ADR Prevention 

Adaptive Drug Dosing: The most critical function of pharmacogenetics for adverse drug reactions is the ability to tailor drug dosages to the patient's genetics. Other traditional prescribing involved in the "one-size-fits-all" method usually prescribed a standard dose according to the patient's age, weight, and medical condition. However, this method did not consider genetic variations that might affect the way a drug is processed by a patient's body. Everyone is made differently.  

Pharmacogenetics can identify genetic variants in patients that alter drug metabolism. By knowing one's genetic predispositions, doctors will get a chance to dose the patient more reliably. Some patients may need low doses of a particular drug to avoid toxicity, while others may need higher doses to achieve the required therapeutic effect. This personalized nature of treatment reduces the chances of adverse drug reactions considerably and provides better safety and efficacy. 

Identification of High-Risk Medications: There are drugs generally believed to be more likely to lead to adverse drug reactions, with known reasons by way of their genetic contexts. For example: specific cancer drugs, anticoagulants-blood thinners-and antidepressants with severe ADRs in individuals with gene-specific metabolic capabilities. Pharmacogenetics for adverse drug reactions is made available to target individuals with genetic representativeness before drug therapy commencement for future reference. 

Preventing Drug-Drug Interactions: Drug-drug interactions are other prominent causes of adverse drug reactions. A few drugs can modify the metabolism of other drugs by the body, resulting in very harmful outcomes. Pharmacogenetics aims at preventing such drug interactions by marking genetic variations affecting drug metabolism and interaction. 

Improving Drug Efficacy: Pharmacogenetics related to adverse drug reactions also serves to give drug treatment an edge. With the knowledge that a person's genetic disposition plays out in their drug response, drugs can be picked for a person that would most effectively work for them.