New research suggests morphine may worsen pain and delay recovery. This is in contrast to the conventional idea that opioids, like morphine, are used in pain management.
ABC reports on findings that show opioid treatment for chronic nerve pain is harmful when used long-term. It was noted that the experiments were conducted on laboratory rats and any correlation of results in humans is yet to be determined.
Confirmed Findings In Delayed Recovery
The report from the "Proceedings of the National Academy of Sciences" stated that the five-day morphine treatment on rats prolonged recovery time by three months. The animals also bore more severe pain after treatment.
Doctor Peter Grace, who co-authored of the study, insists the treatment is likely a contributing factor to the problem. It has been established in previous studies that the immune system's glial cells are responsible for the release of neurotransmitters that stimulate pain neurons.
Grace said studies involving opioids showed the substance activates the same glial cells. The recent study hypothesizes that opioids enhance the pain that's supposed to be naturally stimulated in the tested rats.
Opioid-Induced Pain Sensitivity Confirmed in Humans
Scientists have established opioids can enhance sensitivity to pain in some people, in a condition called Opioid-Induced Hyperalgesia. The experiment has confirmed that the effects of the substances linger for weeks after the treatment has stopped.
The study involved surgery in rats, by stitching and squeezing the sciatic nerves that run down the hind legs. The pain is treated by either morphine or saline solution; rats that received saline solution had diminished response to the pain stimuli after a month, while rats treated with morphine only started recovering after two months.
Grace noted the experiment was exclusively conducted among male rats and results among female rats have yet to be confirmed. This is in consideration of how the genders experience pain differently. The tests also involve genetically-similar rats.
Science News reported it is possible people will have unique responses to pain during and after opioid treatment. "Clearly these data suggest that there may be a subset of people who might be in trouble," Grace said. Opioids are currently a common consideration in pain management.
