Opiates' side effects rooted in patients' genetics, study shows

June 20, 2012, Stanford University Medical Center

Genetics play a significant role in determining which patients will suffer the most from the disturbing side effects of opiates, commonly prescribed painkillers for severe to moderate pain, according to a new Stanford University School of Medicine study, which pinpoints nausea, slowed breathing and potential for addiction as heritable traits.

"One of the most hated of these opiates, nausea, is strongly inherited," said Martin Angst, MD, professor of anesthesia and one of two for the new study, which explores individual variations in the response to opiate use. The study will be published online June 20 in Anesthesiology. Genetics also play a likely role in determining which patients will suffer from itchiness and associated with the use of these powerful medications, which include , and .

"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," said Angst, director of the Stanford Human Pain Research Laboratory. "Our findings strongly encourage the use of downstream 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."

Treatment with opiates, also known as narcotics, is tricky because of this variability in drug response. Certain patients may require 10 times the amount of these to get the same level of pain relief as others. In fact, in some patients the occurrence of side effects may prevent the use of opioids for effectively alleviating pain. Side effects such as nausea or sedation can be debilitating to some, while nonexistent for others. Similarly, some patients can take medications for months with little addiction potential, while others are at risk within weeks.

Millions of U.S. patients are prescribed opiates for pain each year. A better understanding of the potential risk of side effects motivated the researchers to explore individual variation in pairs of identical and fraternal twins, Angst said. The study was prompted by past genetic studies in animals that have shown a strong genetic component in the response to opiates.

"We rely heavily on narcotics as the cornerstone medication for the relief of pain," said Angst. "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."

Researchers recruited 121 twin pairs for the randomized, double-blinded and placebo-controlled study. Pain sensitivity and analgesic response were measured by applying a heat probe and by immersing a hand in ice-cold water, both before and during an infusion of the opiate alfentanil, a short-acting painkiller prescribed by anesthesiologists. The team also compared individual variations in levels of sedation, mental acuity, respiratory depression, nausea, itch, and drug-liking/disliking — a surrogate measure of addiction potential — between identical twins, non-identical twins and non-related subjects. This provided an estimate of the extent to which variations in responses to opiates are inherited. For example, the finding that identical twins are more similar in their responses to opiates than non-identical twins suggested inheritance plays a significant role.

Heritability was found to account for 30 percent of the variability for respiratory depression, 59 percent of the variability for and 36 percent for drug disliking. Additionally, up to 38 percent for itchiness, 32 percent for dizziness and 26 percent for drug-liking could be due to heritable factors. An earlier study published by the same researchers in the March issue of Pain reported that genetics accounted for 60 percent of the variability in the effectiveness of opiates in relieving pain.

"Since side effects are common among patients who use opioid medications, it will be beneficial to use such research to help at-risk avoid serious, life-threatening complications," said David Clark, MD, PhD, professor of anesthesia and the other principal investigator for the study.

Explore further: Heroin addicts have higher pain sensitivity, even during treatment

Related Stories

Heroin addicts have higher pain sensitivity, even during treatment

April 25, 2012
(HealthDay) -- Heroin addicts often have an increased sensitivity to pain, and this sensitivity does not subside over the course of treatment with methadone or other opioids, new research finds.

Medical marijuana could help patients reduce pain with opiates, study finds

December 6, 2011
A UCSF study suggests patients with chronic pain may experience greater relief if their doctors add cannabinoids – the main ingredient in cannabis or medical marijuana – to an opiates-only treatment. The findings, ...

Reformulated imatinib eliminates morphine tolerance in lab studies

February 21, 2012
By reformulating the common cancer drug imatinib (Gleevec), researchers have eliminated morphine tolerance in rats – an important step toward improving the effectiveness of chronic pain management in patients, according ...

Recommended for you

Study looks at how newly discovered gene helps grow blood vessels

February 19, 2018
A new study published today found that a newly discovered gene helps grow blood vessels when it senses inadequate blood flow to tissues.

Scientists produce human intestinal lining that re-creates living tissue inside organ-chip

February 16, 2018
Investigators have demonstrated how cells of a human intestinal lining created outside an individual's body mirror living tissue when placed inside microengineered Intestine-Chips, opening the door to personalized testing ...

Data wave hits health care

February 16, 2018
Technology used by Facebook, Google and Amazon to turn spoken language into text, recognize faces and target advertising could help doctors fight one of the deadliest infections in American hospitals.

Researcher explains how statistics, neuroscience improve anesthesiology

February 16, 2018
It's intuitive that anesthesia operates in the brain, but the standard protocol among anesthesiologists when monitoring and dosing patients during surgery is to rely on indirect signs of arousal like movement, and changes ...

Team reports progress in pursuit of sickle cell cure

February 16, 2018
Scientists have successfully used gene editing to repair 20 to 40 percent of stem and progenitor cells taken from the peripheral blood of patients with sickle cell disease, according to Rice University bioengineer Gang Bao.

Appetite-controlling molecule could prevent 'rebound' weight gain after dieting

February 15, 2018
Scientists have revealed how mice control their appetite when under stress such as cold temperatures and starvation, according to a new study by Monash University and St Vincent's Institute in Melbourne. The results shed ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.