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Morphine was used during the American Civil War as an anaesthetic and was given to wounded soldiers to take home as a treatment for pain. Although it helped during the campaign, at the end of the war 400,000 people had the "disease of the army", better known as morphine addiction.
Despite morphine not being used as liberally as it was 200 years ago, there are still many people in the world presently classified as morphine addicted.
However, help is on the way: new, non-addictive, effective painkillers are being developed to stop the threat of addiction. The new research comes from two University of Adelaide pharmacologists who have been working with one of the world's leading neuroscientists to formulate a compound to do just this.
Professor of Clinical Pharmacology at the University of Adelaide, Professor Paul Rolan, and postdoctoral fellow, Dr Mark Hutchinson, are part of a combined United States (US) and Australian research team that has revealed how opioid drugs such as morphine both relieves pain and also causes addiction.
The Adelaide scientists and senior colleagues at the University of Colorado in the US, including world pain expert Dr Linda Watkins, have isolated in animal models the effect morphine has on the brain's immune cells, known as glia and also on nerve cells (neurons).
Paul explained that glia cells heighten nerve pain such as sciatica by exciting neurons that transmit pain signals.
"While morphine deadens pain by acting at nerve synapses, it also activates glial cells, worsening the drug's side effects, such as drowsiness, tolerance and addiction," he said.
"We tested a new drug called AV411 that blocks morphine's effects on glia but not on neurons, resulting in effective pain relief without the side effects of addiction, which is really exciting."
AV411 is being developed by Avigen Inc., a Californian biopharmaceutical company that is sponsoring the collaborative research and currently, the drug is in clinical trials for neuropathic pain at the Royal Adelaide Hospital.
"Our research will be to study this molecule which is involved in opioid withdrawal, and preliminary tests show that by blocking morphine's effects on glial cells, it stops the drug cravings," said Paul.
"This new drug has the potential to help many people as although morphine is an excellent pain relief these types of opiates come with the potential for addiction or abuse"
These pre-clinical findings were reported at the annual meeting of the Society for Neuroscience in 2007, the world's largest organisation of scientists devoted to the study of the brain. The journal Science also published the findings.
The Director of the National Institute in Drug Abuse in the US, Dr Nora Volkow, was reported to say that the research helped to "pave the way toward developing new, potent, non-addictive medications".
In November 2007, Paul addressed the 10th International Conference on the Mechanisms and Treatment of Neuropathic pain held in Salt Lake City, Utah. He told delegates that the summary data showed that AV411 was "a promising non-opioid clinical candidate for chronic neuropathic pain."
Other US scientists involved in the research include Dr Steven Maier for the Department of Psychology and Centre for Neuroscience at the University of Colorado and postdoctoral fellow, Sondra Blond.
Author - Candy Gibson
Adelaidean - News from the University of Adelaide