Painkillers Could Lengthen Chronic Pain, Study



Addiction to narcotic painkillers has long been an enemy of public health, but the problems attached to opioid abuse don’t end there.

According to a new research, drugs that are supposed to offer pain relief can actually make an individual even more sensitive to pain over time. This effect is known as hyperalgesia.

The new study, conducted by scientists from University of Colorado Boulder (CU-Boulder), analyzed the long-term effects of opioid treatment in lab rats; the experiments focused specifically on morphine.

Co-author of the study Peter Grace, a neuroscientist at the university, says that even though too few papers have been written on the association between opioid and pre-existing pain, they have been trying to connect hyperalgesia to the effects of opioids on the immune system.

For the experiments, Grace’s team used a rat model to imitate chronic nerve pain found in humans. This condition is often experienced by stroke patients, as well as those who have undergone traumatic nerve injury or nerve damage caused by diabetes.

After causing nerve injury in some of the lab rats, researchers waited for ten days before starting morphine treatment on half of them for five days. For the following three months, Grace and his team periodically measured the rats’ threshold of pain.

After six weeks, injured lab rats that were not treated with morphine had the same sensitivity to pain as the uninjured rats. But when it came to morphine-treated lab rats, their threshold of pain was much lower.

It took at least 12 weeks before the rats in the morphine group returned to the same pain sensitivity threshold as the other rats. Consequently, it seems that opioids can paradoxically cause an increase in chronic.

Grace suggests that, according to the findings, increasing opioid prescriptions in humans could also be a contributor to chronic pain. The treatment is, in fact, part of the problem – also making it worse.

Therefore, making the decision to take oxycodone, morphine, and other opioids for the short-term could have very bad consequences, increasing pain, and making it last longer.

The results of the study were featured in the journal PNAS.
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