Pubdate: Wed, 30 Jan 2002
Source: Kingston Whig-Standard (CN ON)
Copyright: 2002 The Kingston Whig-Standard
Contact:  http://www.kingstonwhigstandard.com/
Details: http://www.mapinc.org/media/224
Author: Jennifer Pritchett

BREAKTHROUGH IN PAINKILLING

NEWS - Researchers at Queen's University have made a discovery that could 
lead to safer and more effective use of morphine and other painkillers.

Their groundbreaking research, which could change the way people suffering 
from chronic diseases deal with severe pain, will appear next month in the 
Journal of Pharmacology and Experimental Therapeutics.

Dr. Khem Jhamandas, who headed the research at Queen's, said his team found 
that small doses of drugs known as opioid antagonists - normally used to 
block the toxic effects of opioids such as morphine - can actually enhance 
painkilling action.

Their surprising finding also showed that the combination of small amounts 
of opioids and opioid antagonists stopped the development of a tolerance to 
morphine, and in cases where tolerance had already developed, it was 
actually reversed.

The experiments conducted at Queen's reveal that in cases where tolerance 
had developed, the effectiveness of morphine was restored to between 80 and 
90 per cent of the original dose.

"When we received the results from the first experiment, I couldn't believe 
it," said Jhamandas, who works in Queen's Department of Pharmacology and 
Toxicology.

"Everything we knew up to that point indicated it shouldn't work. One would 
not think to combine a morphine antagonist with morphine in small doses."

Both types of drugs act on opioid receptors which are located on nerve 
cells that transmit pain signals. When activated by morphine, these 
receptors will powerfully suppress pain.

Combining an opioid "agonist" such as morphine with its antagonist - in 
this case, the drug naltrexone - is a radical approach that was sparked by 
scientific literature that suggests morphine and other opioids have both 
stimulatory and depressant effects, said Jhamandas.

Funded by the Canadian Institutes of Health Research, the study could lead 
to the development of more effective painkilling drugs that require lower 
dosages, have fewer side-effects and remain effective with repeated use. 
The study's results are particularly exciting for patients with chronic 
illnesses that require long-term use of these drugs to control their pain. 
The discovery could also lead to the development of drugs to treat 
neuropathic pain, which results from nerve injury and doesn't respond well 
to opioids.

"This is exciting because there are so many potent chemicals in the brain 
that can influence pain, and we're just beginning to comprehend their 
functions and their promise for yielding treatments providing optimal pain 
relief," said Jhamandas.

"In understanding how pain transmissions occur, we're learning the biology 
of pain with the objective of making drugs that will work better."

Jhamandas said he isn't sure when clinical trials will begin on the 
discovery, but he's sure there will be interest in the finding. "Clinical 
trials will have to be done to support our claim," he added.

The Queen's study was conducted by a multidisciplinary research team 
composed of Jhamandas and graduate students Kelly Powell and Noura 
Abul-Husn from the pharmacology and toxicology department, as well as Asha 
Jhamandas, Mary Olmstead and Richard Benninger from the psychology department.
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