NATIONAL HARBOR, MD – Use of pharmacogenetic testing could be the key to increasing the effectivweness of opioids in certain patients and the overall effectiveness of therapies and treatments for chronic pain, according to Dr. Anita Gupta.
“Pharmacogenetic testing may help determine if genetic variations [can] impact the metabolism of certain medications [and] lead to unexpected outcomes, such as lack of efficacy or increased or unexpected toxicity,” explained Dr. Gupta of Drexel University in Philadelphia, citing earlier research by another investigator (Clin J Pain. 2010 Jan;26 Suppl 10:S16-20), which found that pharmacogenetic testing can help identify patients who are more likely to respond to opioid treatment, exactly which opioids would produce the most favorable responses, which patients would be at higher risks for opioid-related adverse events and drug interactions, and which patients would require higher-than-average opioid doses.
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“In the near future, pharmacogenetic approaches may be implemented to best predict which medicine from the outset may be most appropriate for an individual – the therapy with the most sustained efficacy and the best side effect profile,” the investigators wrote, adding that in current clinical practice, each patient is effectively his own analgesic trial as providers try to hit a moving target as to which and how much opioid treatment is effective for each patient’s needs.
Dr. Gupta also briefly discussed findings from a similar study (Pharmacogenomics. 2009 Jul;10[7]:1157-67), in which the investigators concluded that genotyping drugs could lead to “increased efficiency in proper drug selection, dose optimization, and minimization of adverse drug reactions to improve patient outcome and safety.”
Furthermore, the study “clearly demonstrated a relationship between oxycodone steady-state drug concentrations and pain relief,” and called for more large-scale studies in order to confirm these findings and focus pain management therapy on pharmacogenetics for prescribing opioids.
The need for opioid optimization is very real, Dr. Gupta said at the annual meeting of the American Academy on Pain Medicine. According to findings from another study, about 33% of patients who take antidepressants experience little to no efficacy (Am J Psychiatry. 2006 Nov;163[11]:1905-17). The study examined long-term treatment outcomes as part of the Sequenced Treatment Alternatives to Relieve Depression (STAR*D) trial, and found that “those who required more treatment steps had higher relapse rates during the naturalistic follow-up phase,” concluding that “development of more broadly effective treatments [is] needed.”
However, questions linger as to the practical applications of pharmacogenetics, even if the science is widely accepted, Dr. Gupta said. Among the questions that still need to be answered are whether pharmacogenetic testing is reliable, whether providers will be ready and willing to use the information given to them via such testing, whether insurance companies will cover the costs of these tests, and whether tailor-made medicine can lead to discrimination or ethnic biases in treatment.
“We’re at a place where medicine is changing, and it’s an exciting time,” Dr. Gupta noted, pointing to the Human Genome Project as a tool that can be used to help with pharmacogenetics moving forward. “We have so much data overwhelming us, but the future is bright [for] patients and clinicians to improve outcomes.”
Dr. Gupta reported that she receives consulting fees from Millenium Labs.