Source: BBC News Online 2000-11-09
A breakthrough by scientists promises to revolutionise the treatment of pain caused by nerve damage as a result of surgery, injury or illness. This type of neuropathic pain has proved extremely difficult to treat because drugs cannot easily be targeted to the damaged area.
A team of US and UK researchers is developing a way to deliver painkillers directly to the damaged areas in smaller doses and with fewer side effects. The work has been carried out by an international team of scientists from the University of California in Los Angeles and Cambridge University in England.
They have developed a way to exploit the body's own transport mechanism within nerves - known as axonal transport. Using this technique it has been possible to deliver painkilling drugs directly to affected areas by transporting them along specifically targeted groups of nerves, effectively heading off pain impulses before they reach the brain.
Currently painkillers are delivered into the bloodstream where they travel around the patient's system and impact on all parts of the body, rather than just on the affected areas. This has meant that treatment of nervous system disorders has often been hindered because it has proved impossible to get sufficient levels of painkilling drugs directly to the precise site of injury without causing unwanted side effects.
Researcher Dr Aaron Filler, a UCLA neurosurgeon, said the new method could mean that one shot administered during surgery could alleviate the pain sensations a patient would normally feel for several days. There would also be none of the side effects associated with current painkilling treatments such as nausea, drowsiness and impaired breathing.
Dr Filler said. "The way it works makes this the first truly 21st century medication. These results are expected to lead to dozens of new medications that will solve difficult drug delivery problems in the treatment of conditions as varied as stroke, Alzheimer's disease, shingles and herpes."
The researchers used the technique to give painkilling injections to rats. They found that in a single injection there was a 50% reduction in the hypersensitivity to pain that lasted up to four days. Dr Filler said: "To achieve a similar effect by the current drugs would require more than 300 times the amount of painkiller given in multiple doses."
Clinical trials using axonal transport to treat neuropathic pain will begin in early 2002. The results of the research were presented at a conference of the Society for Neuroscience.