Pharmacogenomics is a field of study that uses DNA testing to determine which medicines are most compatible with a person's genes.

Tim Curry, the director of education for Mayo Clinic's Center of Individualized Medicine, said pharmacogenomics helps researchers better fit many aspects of drug transcription to the patient.

"Sometimes (pharmacogenomics is) how fast it builds up in your system, or how fast it's broken down," he said. "Sometimes it talks about how easy it is for a drug that needs to be activated by the body.

"Sometimes it talks about the receptors within the body that the drug actually binds to, to have its effect. Sometimes it talks about the transporters that transport it into the cells that it needs to be there. And in other cases, it's regarding some really severe adverse effects that you might have a genetic predisposition to.

"If you wanted to get one tagline as to what the ultimate goal here is, it's one that we use all the time," Curry said. "We want to find the right drug, at the right dose, at the right time. For the right patient."

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Tests and research

Currently, Mayo is testing the use of pharmacogenomics to guide patients' drug treatment, Curry said. If there is good evidence for changing the dosing of a drug, or avoiding its use completely, having that information in the medical record could be useful, he added.

Another research project, the RIGHT 10K Study, is inputting gene information from 10,000 people into the medical record, including genes related to opioids and other medications.

When it comes to pain medications — opioids in particular — pharmacogenomics can help researchers predict which medications the body might "clear" faster and which might build up in the body, Curry said. This allows doctors to adjust the dosing of a medication for best results, or find another medication that "might be more appropriate."

Halena Gazelka is a member of the anesthesiology who specializes in pain medicine. She is also the chairwoman of the Mayo Clinic Opioid Stewardship program.

Gazelka said genetic testing could be more helpful than a family history, in some cases.

"So much of that is anecdotal, this is a much more specific way of testing than using patient reports," she said. "Patients' report of their family history does not always tell us why it occurred, and if we had specific genetic targets or understanding, that would be much more specific and applicable."

However, Curry noted that many things affect a drug's efficacy — genes are one variable, but other medications, kidney function, size and weight and sex all have a strong effect.

Prevent addiction?

Currently, pharmacogenomics aren't widely used to predict opioid addiction. There are known genetic markers which could indicate alcohol or nicotine addiction, Gazelka and Curry said, but there are so many factors that contribute to addiction that it is difficult to separate genetic links from environmental links.

Some studies have used questionnaires and genetic testing together to predict, fairly accurately, whether a patient might have trouble with either moderate or severe opioid addiction, Gazelka said.

"So that might be useful in a couple of ways," she said. "One would be if I were really worried that a patient were going to have a high risk of addiction, I may try to decrease that therapy for them or find a different therapy for them. Or I might feel better treating a patient who doesn't have that high of a risk."

While pharmacogenomics are "exciting and may be very helpful for this in the future," Gazelka said that because of the time and expense of testing, the Opioid Stewardship program will continue to limit the environmental factors of addiction, like access to drugs because of overprescription, in order to help unravel the opioid epidemic.

"I think one of the issues with considering genetics and genomics for the realm of addiction is that we already know that if we alter environmental factors, we can decrease the risk of addiction," Gazelka said. "So in other words, we know that patients who receive larger prescriptions, who receive longer prescriptions, who stay longer on pain medications when they're prescribed, have a higher risk of addiction. We know that access to these drugs is what leads to patients becoming addicted. We already know that we can reduce environmental factors and there's a lot of work to be done in that area. We need to reduce the amount of pills and drugs available in the circulation and in the society that are available for diversion."

"It's not like our genes have changed over the last 20 years," Curry said. "I think ultimately, what we're trying to do is not so much treat, but prevent. That's where applying the right drug at the right dose may be important, but equally as important is limiting, as Dr. Gazelka is doing in her efforts - making sure we limit the number of medications that people have, the number of doses of a drug, so they just don't have as much to take and share, or to be sold."

Growing collaboration

While pharmacogenomics may not be a miracle fix for the opioid epidemic, Curry hopes that it could prove useful in the future.

"One of the things you're seeing right now is that in general, there is a growing collaboration between clinicians and researchers, because it's now starting to get to the point where it can be used in patient care," Curry said. "And that's when you start to see advances. And so we all know there's a critical need for more research in this area. I think we were all kind of caught by surprise ... about the whole opioid epidemic in general. It kind of came up on us in a way that we didn't realize. And so in many ways, we're just now starting to see the push to get the research to where we really understand how we can put all of this stuff together."

"Certainly, studying things is interesting, it's exciting to researchers who discover things, but really, where they become clinically useful is where the rubber meets the road and where we really impact patient care," Gazelka said. "And so we're excited about the research Dr. Curry and his colleagues are sharing ... because in the future, we anticipate being able to care for our patients in even improved ways over what we're doing today."