New cannabis-like drugs could block pain without affecting brain, says study

September 12th, 2008

A new type of drug could alleviate pain in a similar way to cannabis without affecting the brain, according to a new study published in the journal Pain on Monday 15 September.

The research demonstrates for the first time that cannabinoid receptors called CB2, which can be activated by cannabis use, are present in human sensory nerves in the peripheral nervous system, but are not present in a normal human brain.

Drugs which activate the CB2 receptors are able to block pain by stopping pain signals being transmitted in human sensory nerves, according to the study, led by researchers from Imperial College London.

Previous studies have mainly focused on the other receptor activated by cannabis use, known as CB1, which was believed to be the primary receptor involved in pain relief. However, as CB1 receptors are found in the brain, taking drugs which activate these receptors can lead to side-effects, such as drowsiness, dependence and psychosis, and also recreational abuse.

The new research indicates that drugs targeting CB2 receptors offer a new way of treating pain in clinical conditions where there are currently few effective or safe treatments, such as chronic pain caused by osteoarthritis and pain from nerve damage. It could also provide an alternative treatment for acute pain, such as that experienced following surgical operations.

The new study showed that CB2 receptors work to block pain with a mechanism similar to the one which opiate receptors use when activated by the powerful painkilling drug morphine. They hope that drugs which target CB2 might provide an alternative to morphine, which can have serious side effects such as dependency, nausea and vomiting.

Praveen Anand, Professor of Clinical Neurology and Principal Investigator of the study from the Division of Neurosciences and Mental Health at Imperial College London, said: "Although cannabis is probably best known as an illegal recreational drug, people have used it for medicinal purposes for centuries. Queen Victoria used it in tea to help with her period pains, and people with a variety of conditions say that it helps alleviate their symptoms.

"Our new study is very promising because it suggests that we could alleviate pain by targeting the cannabinoid receptor CB2 without causing the kinds of side-effects we associate with people using cannabis itself."

The researchers reached their conclusions after studying human sensory nerve cells in culture with CB2 receptor compounds provided by GlaxoSmithKline, and also injured nerves from patients with chronic pain.

The researchers are now planning to conduct clinical trials of drugs which target CB2 in patients with chronic pain at Imperial College Healthcare NHS Trust, which has integrated with Imperial College London to form the UK's first Academic Health Science Centre.

Source: Imperial College London

• Keys1337 - Sep 12, 2008
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  These results obviously must be false, the federal government says there are absolutely no medical uses for marijuana, so these CB2 receptors must be a dead end. These UK scientists could have saves their time and money by just checking with the Feds first.
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• TopherT - Sep 12, 2008
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  Drowsiness, dependence and psychosis? Sounds like someone's drinking the kool-aid on the government's drug war propaganda. Are we such an up tight society that we can't simply allow people who need this pain relief to get high as well? We've got little problem pumping people full of chemotherapy drugs that make them feel terrible. Whats wrong with drugs that have a side effect of making you feel good?
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• TJ_alberta - Sep 12, 2008
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  Tropher: a choice would be good. If you simply want to be rid of the pain AND get some work done / drive / use power tools -- you are probably better off by taking a pass on the recreational side effects.
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• podizzle - Sep 12, 2008
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  dont you know there's no money in this highly dangerous illegal substance everyone should just take their ssri and be happy they are making phizer money. /sarcasm
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• deatopmg - Sep 13, 2008
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  BEWARE!; THis article is likely a release by Sanofi in the public opinion war to get their un-approved, dangerous drug Rimonabant approved by the FDA for uses other than as a diet-aid. Drug companies will stoop to any, ANY level to recoup/make money.
  for more on this see;
  http://articles.m...ource=nl
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• deatopmg - Sep 13, 2008
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  Sorry! The Sanofi drug is a CB1 inhibitor whereas the GSK drug is a CB2 inhibitor, but the issues are the same. Remember how the COX2 inhibitors were the best thing since sliced bread and turned out to be toxic? We could be seeing the same thing here.
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• nevrknw - Sep 13, 2008
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  keys1337 do you really think the federal goverment did all these studies... they didnt and id rather be taking a natural pain killer than anything in chemical form
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• VPXL - Oct 05, 2008
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  Years ago they we sure heroin had no side efect such as addiction.. Honestly, i have many doubts about this study.
  
  www.fdadrugstore.org - my favorite web site
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