Scientists can now block heroin, morphine addiction; clinical trials possible within 18 months

August 14, 2012
This is concept art depicting addiction by Joshua Burton (School of Medical Sciences, University of Adelaide). Credit: Joshua Burton/University of Adelaide

In a major breakthrough, an international team of scientists has proven that addiction to morphine and heroin can be blocked, while at the same time increasing pain relief.

The team from the University of Adelaide and University of Colorado has discovered the key mechanism in the body's that amplifies addiction to .

Laboratory studies have shown that the drug (+)- (pronounced: PLUS nal-OX-own) will selectively block the immune-addiction response.

The results – which could eventually lead to new co-formulated drugs that assist patients with severe pain, as well as helping heroin users to kick the habit – will be published tomorrow in the Journal of Neuroscience.

"Our studies have shown conclusively that we can block addiction via the immune system of the brain, without targeting the brain's wiring," says the lead author of the study, Dr Mark Hutchinson, ARC Research Fellow in the University of Adelaide's School of Medical Sciences.

"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."

The team has focused its research efforts on the immune receptor known as Toll-Like receptor 4 (TLR4).

"Opioid drugs such as and bind to TLR4 in a similar way to the normal immune response to bacteria. The problem is that TLR4 then acts as an amplifier for addiction," Dr Hutchinson says.

"The drug (+)-naloxone automatically shuts down the addiction. It shuts down the need to take opioids, it cuts out behaviours 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."

Senior author Professor Linda Watkins, from the Center for Neuroscience at the University of Colorado Boulder, says: "This work fundamentally changes what we understand about opioids, reward and addiction. 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 , (+)-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 with morphine, so that patients who require relief for severe pain will not become addicted but still receive . This has the potential to lead to major advances in patient and palliative care," Professor Watkins says.

The researchers say clinical trials may be possible within the next 18 months.

Explore further: Study provides clues for designing new anti-addiction medications

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8 comments

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Tom_Hennessy
5 / 5 (1) Aug 14, 2012
Lecithin has been shown in the mouse to effectively block addiction to cocaine in mice.
"Soy phosphatidylcholine (SPC)"
"We propose that SPC can be useful as a selective inhibitor to suppress the TLR4-mediated inflammatory signaling"
Parsec
2.3 / 5 (3) Aug 14, 2012
Naloxone has been know to cause rapid detoxification of opioid addicts and has been used for decades as the primary treatment for opioid overdoses in ER's. It simply targets the opioid receptor sites and blocks them.

I do not understand how co-formulating a drug (morphine) with an antagonist that prevents the opioid from acting could actually cause an increase in pain relief. It 'should' cause the combination to be useless and have no effect.
Jeddy_Mctedder
1 / 5 (2) Aug 14, 2012
bullshit. this whole article reads like an advertisment and lack substance.
tadchem
1 / 5 (1) Aug 15, 2012
40-year old news. Naloxone has been used for decades to counter the effects of opiate overdose. This was one of the first applications for the drug, developed in the 1960s.
It is a standard item in OD kits used by emergency responders. Naloxone is usually injected IV for fastest action. The drug acts within a minute, and may last up to 45 minutes. It blocks the cellular receptors used by opioids and endorphins, rendering the drugs totally ineffective.
Kettricken
not rated yet Aug 15, 2012
Looks like Orexo in Sweden is working with such a drug since long time ago

CrossMan
5 / 5 (1) Aug 15, 2012
Naloxone and (plus)-Naloxone are different. (See e.g. Wikipedia.)
Iconoclast24601
not rated yet Aug 17, 2012
Singularity24601
not rated yet Aug 17, 2012
Theoretically, blocking the TLR4/dopamine pathway might only affect the the psychological component of opioid dependence but have no effect on the physiological component, which may be due to unrelated functional mu-opioid receptor down-regulation mechanisms. This may limit any impact in general medical or palliative care, save for psychiatric substance abuse settings.

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