Are Opioid Side Effects Inherited?

Side effects from painkillers could be genetic and potentially detected before an adverse reaction

(RxWiki News) Painkillers are used to manage pain all the time, yet a lot of people have serious side effects. If opiate side effects are genetic, a test could help to determine who is at risk for an adverse reaction.

A recent study looked at twins to determine whether opiate side effects were inherited.

Not all side effects were purely genetic, but nausea was chief among the ones that were.

"Call your doctor immediately if you experience side effects."

Martin Angst, MD, professor of anesthesia and director of the Stanford University’s Human Pain Research Laboratory, and David Clark, MD, PhD, also a professor of anesthesia at Stanford University, teamed up to investigate whether genetics determine opiate side effects.

To determine genetic risk factors, Doctors Angst and Clark looked at 114 pairs of twins, 81 identical and 33 fraternal. A double-blind, placebo controlled study model was used to administer 100 ng/ml of the fast acting opiate, alfentanil.

Researchers tested the effects on the subjects through measures of pain sensitivity with a heat probe and ice cold water, respiratory depression, nausea, drug like/dislike, itch, sedation and dizziness.

Dr. Angst said, “One of the most hated side effects of these opiates, nausea, is strongly inherited. The study is a significant step forward in efforts to understand the basis of individual variability in response to opioids and to eventually personalize opioid treatment plans for patients.”

By comparing results of the identical twins, which share exact genetic and cellular makeup, to fraternal twins, who are as genetically different as single born siblings from the same set of parents, hereditary probabilities were measured.

Heritability in the identical twin group accounted for 30 percent of respiratory depression, 59 percent of nausea and 36 percent of drug disliking. Significant familial similarities in the fraternal twin group accounted for 29 percent of sedation, 32 percent of dizziness and 26 percent of drug liking.

“Our findings strongly encourage the use of downstream molecular genetics to identify patients who are more likely or less likely to benefit from these drugs—to help make decisions on how aggressive you want to be with treatment, how carefully you monitor patients and whether certain patients are suitable candidates for prolonged treatment.”

Concerned with addiction potential, Dr. Angst stated, “We rely heavily on narcotics as the cornerstone medication for the relief of pain. Yet we don’t know the answers to fundamental questions, such as why some people ‘like’ narcotics more than others—drug liking and disliking could be key in determining addiction potential.”

Dr. Clark added, “Since side effects are more common among patients who use opioid medications, it will be beneficial to use such research to help at-risk patients avoid serious, life-threatening complications.”

This study was published in the journal Anesthesiology, June 2012. No financial disclosures were made and no conflicts of interest were reported.

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Review Date: 
June 23, 2012