According to the scientists, from the University of Adelaide and the University of Colorado, they have identified the key mechanism in the body's immune system that intensifies addiction to these potentially harmful drugs.
After much research, the experts learned that the drug (+)-naloxone can selectively block this immune-addiction response.
This finding, published in the Journal of Neuroscience, is a huge breakthrough which could potentially even lead to new treatment drugs that could reduce the severe pain of users while kicking their habit.
Dr. Mark Hutchinson, lead author of the study and ARC Researcher at the University of Adelaide's School of Medical Sciences, explained:
"Our studies have shown conclusively that we can block addiction via the immune system of the brain, without targeting the brain's wiring. Both the central nervous system and the immune system play important roles in creating addiction, but our studies have shown we only need to block the immune response in the brain to prevent cravings for opioid drugs."
Opioid drugs interfere with normal brain activity which causes a reduction in pain. The drug binds to certain receptors in the brain called opiate receptors, causing the drug to act like naturally occurring opioids in the brain, such as endorphins. This not only reduces the person's pain but also gives them a euphoric feeling.
Opium and heroin are known as street opioid drugs, because they are not prescription drugs. Examples of prescription opioid drugs, which are sometimes used instead to get high, include:
"The drug (+)-naloxone automatically shuts down the addiction. It shuts down the need to take opioids, it cuts out behaviors associated with addiction, and the neurochemistry in the brain changes- dopamine, which is the chemical important for providing that sense of 'reward' from the drug, is no longer produced," he continued.
Senior author Professor Linda Watkins, from the Center for Neuroscience at the University of Colorado Boulder, revealed how their finding fundamentally changes previous knowledge on these drugs. "We've suspected for some years that TLR4 may be the key to blocking opioid addiction, but now we have the proof."
"The drug that we've used to block addiction, (+)-naloxone, is a non-opioid mirror image drug that was created by Dr Kenner Rice in the 1970s. We believe this will prove extremely useful as a co-formulated drug with morphine, so that patients who require relief for severe pain will not become addicted but still receive pain relief. This has the potential to lead to major advances in patient and palliative care."
Authors hope clinical trials will be possible within the next 18 months.
Written by Sarah Glynn