The simple new medication test that could save your life… and when to ask your doctor for it

A simple cheek swab test could help doctors pinpoint the right medication for their patients and avoid debilitating side effects that can persist for years.

There are hundreds of FDA-approved psychiatric drugs available. And while they have been approved for safety and efficacy, their effects vary widely from person to person, leading to a slow, often frustrating trial-and-error process of finding the right medication and dose.

Up to half of patients with depression do not respond to their first antidepressant, and adverse reactions ranging from nausea to worsened depression and suicidal thoughts result in thousands of emergency visits annually.

Subtle differences in a person’s genetic blueprint can fundamentally alter how their body processes medications, explaining why a drug that helps one person may be ineffective for another.

To help prevent unwanted reactions, a doctor can perform a pharmacogenetic (PGx) test. They would swab the inside of a patient’s cheek and send the sample to a lab where technicians can analyze specific key genes to identify variants that might influence how the medication works. Doctors typically receive the results within two to four weeks. 

‘Finding out how your body metabolizes different medications can affect whether a medication may be more likely to produce side effects…’ Dr Ashwini Nadkarni, an assistant professor of psychiatry at Harvard Medical School, told the Daily Mail.

‘This allows a treater to be able to adjust medication dosing – or even choose specific medications versus others – to treat mental health disorders.’

Still, this testing is rare, with fewer than one in 10 patients getting it done. The process is most common for those taking medications with a documented risk of gene interaction such as antidepressants, antipsychotics, certain heart drugs, specific chemotherapy drugs and antiretroviral medications for HIV.

The cost of PGx testing varies. While Medicare or Medicaid enrollees may not incur any fees, those with other types of health insurance could face an out-of-pocket cost of up to $330. 

Ultimately, PGx tests reveal how quickly or slowly a patient’s body breaks down a medication. 

A high metabolization speed could clear the drug from the body before it has a chance to take effect. But if metabolization is too slow, the drug could build up to dangerously high levels in the bloodstream, increasing the risk of severe side effects such as serotonin syndrome, which causes confusion, agitation, rapid heart rate, high blood pressure, dilated pupils and muscle rigidity.

Dr Nadkarni told the Daily Mail that PGx testing often provides a report categorizing medications into different groups.

The first group includes medications that can be used as directed (there were no variants revealed that would impact how a patient’s body processes those specific drugs).

The second group includes drugs that have a moderate gene-drug interaction (suggesting a potential need for a dose adjustment or increased monitoring). 

The third group includes medications with a significant gene-drug interaction (the patient’s genetic makeup indicates a high risk of the drug being ineffective or causing severe reactions).

Everyone has genes that hold the blueprint for building specific enzymes – the molecules that break down medications in the liver. 

The production of these enzymes determines how certain drugs interact with the body – like the potency of pain relievers and required dosage of blood thinners.

For example, variations in the CYP2C19 gene directly control how quickly Zoloft (sertraline) is metabolized.

Meanwhile, genetic variations in the CYP2D6 gene control the metabolism of Prozac.

An analysis of two million patient records in 2021 found that 63 percent of adults and nearly a third of children received ibuprofen, anti-nausea medication, pain relievers and other common drugs – the effectiveness of which is known to be directly influenced by genetics.

A Brazilian woman, Jacqueline Gmack, developed a life-threatening reaction to the ibuprofen she took for menstrual cramps. She was diagnosed with Stevens-Johnson Syndrome (SJS), a rare condition where the body’s immune system attacks its own skin and mucous membranes.

The reaction caused her skin to blister and detach, leading to a 17-day medically induced coma. The damage to her eyes was severe and permanent. Despite more than 24 surgeries, she lost 60 percent of her vision.

Her severe SJS was likely due to a predisposing genetic factor, experts have said. 

Another drug seen to cause devastating effects in some people is the asthma medication montelukast (marketed as Singulair). 

Harrison Sellick of Melbourne, Australia, began taking montelukast at age two. Over the next three years, he developed severe behavioral problems and suicidal thoughts. His mother reported that at just five years old, he attempted to take his own life and frequently made comments about death and self-loathing. 

In 2021, researchers in Japan found montelukast interacts with a network of specific human genes known to be involved in mood disorders.

Yet despite its potential, PGx testing is not yet common in healthcare. 

In one survey led by Dr Peter Schwartz and an Indiana University team, only four of the 31 people asked recognized the terms ‘pharmacogenomics’ or ‘PGx’ and were able to give an acceptable definition of it. After being told what it is, just 10 of the 31 knew they had undergone this sort of testing.

Researchers have said the most significant barrier to the widespread use of PGx testing is an educational gap. 

‘In short, healthcare professionals have to do a better job of educating patients about PGx, especially as it becomes more and more a part of everyday practice,’ Dr Schwartz said.

Studies consistently show that while 80 to 90 percent of healthcare providers acknowledge the value of PGx when doling out prescriptions, only 10 to 20 percent feel adequately trained or confident enough to apply it.