One factor that your physician might overlook when prescribing medication is your genetic makeup.
A report released on Wednesday in Science Translational Medicine revealed that nearly 25% of study participants had been given prescriptions that could have warranted a different medication or dosage based on their genetic information.
The investigation, conducted by scientists at the University of Pittsburgh, analyzed 16 genes that influence how the body reacts to medications.
DNA samples from 98,590 individuals participating in the National Institutes of Health’s All of Us Research Program were evaluated and correlated with available medical records.
Each participant possessed at least one genetic variation that could impact their response to specific medications, with the average individual carrying nine variations. Among those with both genetic and clinical data, 24.4% had been prescribed at least one drug that, according to genetic guidelines, should have been substituted with an alternative or adjusted in dosage.
Nonetheless, the research did not ascertain whether patients faced side effects or whether their medications were less effective due to their genetic profiles.
Dr. Philip Empey, who is the senior author and an associate professor at the University of Pittsburgh School of Pharmacy, states that understanding a patient’s genetic makeup could minimize the trial-and-error approach often seen in medicine.
“I believe any advancements we can make to accurately predict what the most effective medications and optimal doses are will significantly reduce that trial-and-error process,” he explained.
A pharmacist organizes medications at a Vancouver pharmacy in October 2022. Genetic variations can influence how patients react to specific drugs, potentially leading physicians to modify the dosage or choose a different medication. (Darryl Dyck/The Canadian Press)
Identifying the appropriate medication
Omeprazole and pantoprazole for acid reflux, as well as atorvastatin for cholesterol, were among the frequently prescribed medications to participants whose genetic profiles suggested treatment modifications.
Empey mentions that certain genetic variations might heighten the risk of muscle issues when patients use statins like atorvastatin, which are intended to lower the chances of heart attacks or strokes.
This information could assist healthcare providers in selecting alternate medications or adjusting the treatment approach.
“It enables clinicians to make more informed choices, such as, ‘Perhaps that cholesterol medication isn’t the best option. Maybe we should start at a lower dose, or monitor for specific adverse effects more closely,'” Empey remarked.
In some cases, the stakes can be even higher.
For instance, specialists consulted by CBC News indicate that genetic testing can identify patients who may not respond effectively to clopidogrel (Plavix), a drug employed to prevent blood clots following cardiac stenting, enabling doctors to opt for a different treatment.
Dr. James Kennedy leads the Tanenbaum Centre for Pharmacogenetics at Toronto’s Centre for Addiction and Mental Health. He states that genetic testing can aid physicians in determining suitable medications, but other factors such as diet, lifestyle, and existing medications also need to be considered. (CBC)
A guide, not an assurance
Dr. James Kennedy, who directs the Tanenbaum Centre for Pharmacogenetics at Toronto’s Centre for Addiction and Mental Health (CAMH), remarked that the findings of the study were not unexpected, but he was particularly impressed by the genetic diversity and representation of individuals of African descent.
His team has conducted genetic tests for around 11,000 patients, many of whom had previously tried two or three antidepressants without achieving satisfactory outcomes.
Kennedy points out that approximately 8% to 10% of individuals metabolize certain commonly prescribed antidepressants at an unusually slow rate, which can lead to medication accumulation and potential side effects.
He emphasizes that genetic testing is particularly beneficial for patients who have faced challenges with multiple medications.
However, he cautions that DNA testing alone cannot determine how a patient will respond to a specific medication. Other medications the patient is using, their smoking habits, and dietary factors must also be taken into account.
“We say, ‘Here’s your genetic profile, here are some tendencies you might have, and now let’s discuss all the other factors that must be considered before making a final decision,'” he explained.
A 2023 European clinical trial mentioned in the study found that conducting genetic testing prior to prescribing certain medications minimized adverse drug reactions. However, implementing routine testing in Canada poses significant challenges.
A researcher at the University of Calgary holds a diagnostic kit used for identifying genetic variations in February 2024. While such testing has the potential to assist doctors in personalizing medications, costs and practical obstacles have restricted its broad adoption in Canada. (Jeff McIntosh/The Canadian Press)
The reasons behind limited testing in Canada
Dr. Jacob Udell, a cardiologist in Toronto, found the study impressive, particularly due to the genetic diversity of its participants. However, he noted that very few healthcare providers in Canada or the United States routinely screen patients for genetic variations that could influence drug metabolism.
“This is definitely not something that frontline clinicians consider regularly,” he stated.
Udell explained that for many medical conditions, a physician can prescribe a medication, observe the patient’s reaction, and make necessary adjustments without significant risks. This approach may be more pragmatic than routinely screening for genetic variations.
He also questioned whether widespread testing should be prioritized when Canada’s healthcare system is already facing challenges in delivering more fundamental services.
“We’re primarily focused on ensuring everyone has access to a family doctor,” he remarked.
In addition to the expense of the tests, Udell mentioned that healthcare providers would need access to genetic test results and the ability to interpret them accurately.
Empey concurred, stating that making genetic testing standard practice would necessitate substantial investments in training, infrastructure, and new systems for sharing results among healthcare providers.
“The scientific basis is strong for many medications. The real challenge regarding implementation is more about economic factors, procedural aspects, and educational needs,” he stated.
For the time being, Empey advises patients to inquire with their healthcare providers or pharmacists about the potential benefits of genetic testing and to share any relevant results.
Udell cautioned that private testing may become increasingly available for those who can afford it, “but this won’t assist those who cannot afford the testing.”