JACKSONVILLE, Fla. — For Linda Armstrong, the pain started 25 years ago with a truck going 45 miles an hour. It left her with severe neurological and brain injuries.
On a scale of one to 10, she said, “There are days when it’s 10. I mean you literally can’t move.”
Like millions of Americans, she was prescribed opioids -- Vicodin, Dilaudid, Percocet – but the pain persisted.
“I would get some relief, but nothing that ever really made me functional,” she said, "and it always made me nauseous.”
Armstrong’s lackluster response to pain medications had been a reality since she was a child. Once, getting a cavity filled, she recalls, “I had to have 10 shots for one filling because it just would not numb.”
Her resistance to drugs was simply anecdotal until she visited her doctor in October. Under new Centers for Disease Control and Prevention guidelines, doctors test opioid patients both for the presence of illegal drugs, and to ensure they are taking – and not selling – their pain meds.
Her test? Completely negative. There were no drugs of any type in my system.”
Initially, her doctor wrote it off as a fluke.
“When it happened a second time,” Armstrong explained, her doctor said “‘Linda we have to talk about this.’”
She took another test – this time going so far as to take pills while her doctor watched. She even got her hair tested.
Still: Negative.
Fortunately, Armstrong has had the same doctor since the mid-'90s, and rather than doubting her, she worked to help get answers. She ordered a genetic test, which revealed significant abnormalities -- including in an enzyme called CYP2d6, which metabolizes opioids.
The test revealed something researchers in the field of pharmacogenomics know, but few patients do. “People do not respond to drugs in the same way,” explains Standford University researcher Dr. Russ Altman in a Ted Talk. “Some people get no pain relief at all.”
Armstrong’s genetic test showed she was a hyper-metabolizer of opioids – an issue that creates problems beyond pain. As Altman says, there are only two things a doctor can think when a patient complains they aren’t getting relief from opioids.
“I could think this person is a CYPD2d6 non-responder, or I could think this is a trouble-making drug-seeker who wants something stronger,” Altman said. “Most doctors think the latter.”
Armstrong’s case is dramatic but not unusual. Dr Liewei Wang at Mayo Clinic in Rochester, Minn., is a leading researcher in pharmacogenomics – research into the interaction of genes and drugs. She says 99 percent of people have at least one genetic variant that affects drug response. “Response is variable, and in some cases not desirable.”
Genetic testing can “predict who may or may not respond,” she said, “and for those who don’t respond -- are there alternative therapies?”
In some cases, the wrong drug can be fatal. Already, hospitals like UF Health test cardiac patients before surgery for a gene that complicates blood clotting.
And some fields, like oncology and psychiatry, routinely use genetic tests to prescribe drugs. But most patients aren’t aware such tests even exist.
Jacksonville Pharmacist Todd Troxell believes genetic testing is the key to more effective prescribing. “When you go get your glasses we don’t just say, ‘pick something up and go home.’ We get your prescription,” he says. “You can’t see out of my glasses.”
After looking at Armstrong’s test, Troxell was able to steer her to a different pain medication that is working. “I could tell from what she had on her report she wasn’t going to be able to take certain medications.”
Troxell would like to see genetic testing more widely available -- and comprehensible. Companies focused on translating dense genetic code into pharmaceutical recommendations were effectively shut down by the FDA in 2018. The agency worried the tests could “pose significant public health concerns as inaccurate test results could impact the decision-making of healthcare providers and patients in ways that are seriously detrimental to patient health.”
The agency walked that back slightly earlier this year, creating a Table of Pharmacogenetic Associations, which lists gene-drug interactions the agency believes are based on “sufficient scientific evidence based on published literature.”
For now, a genetic test needs to be ordered by a physician, who may or may not be able to interpret the code. And genetics remains just one element that doctors and patients should consider, including age, weight and environmental factors.
But patients like Armstrong say breaking the genetic code shouldn’t be a secret – it could literally spare them a lifetime of pain. Given the chance early on, she said, “I would have had that test done in a heartbeat.”