Specialized or Ubiquitous? The Scope of Current PGx Testing
“Above all, do no harm” - the modern physician's creed. But certain therapies, such as high-dose opioid pain treatment, do carry a risk of harm, especially given the wide variability of patient responsiveness. Recently, Practical Pain Management published an article by Dr. Forest Tennant which establishes a correlation between patient response variability and genetic variants in the CYP450 enzymes, suggesting genetic testing could be used to create safer and more effective pain therapies.
In response, Dr. Michael Brennan of The Pain Center, Fairfield, Connecticut, wrote in support of this pharmacogenomic testing, but cautioned that physicians must proceed with an empiric approach, carefully considering when and where to apply this new tool. One question seemed particularly timely: “What would the benefits of widespread clinical use of pharmacogenomics testing be outside of the pain clinic?”
Opioid narcotics are not the only drug to be processed by the CYP450 super-family of enzymes – more than half of the top 200 commonly prescribed drugs are metabolized by this system. This includes many other narrow-range drugs such as blood thinners, anti-psychotic and anti-depressive medications, and various chemo-therapies, all of which typically require what Dr. Brennan calls N-of-one (i.e. trial and error) approaches. The benefit is that a single genetic test can be used across these disparate fields – a patient’s genome will not change between sub-specialties. Furthermore, the same test can also be used to predict reactions to or refine the dosage of more common drugs, improving patient well-being.
We would argue that this ability to predict risk in multiple settings and treatments concurrently is the benefit of widespread clinical use of pharmacogenomic testing and is a key component in personalized medicine. This pre-treatment testing has the potential to seriously reduce the incidence of adverse drug reactions and reduce overall risk of medical treatment.