Pubdate: Mon, 30 Aug 2010
Source: Ottawa Citizen (CN ON)
Copyright: 2010 The Ottawa Citizen
Contact: http://www.canada.com/ottawacitizen/letters.html
Website: http://www.canada.com/ottawacitizen/
Details: http://www.mapinc.org/media/326
Author: Sharon Kirkey, Postmedia News
Cited: http://www.cmaj.ca/cgi/rapidpdf/cmaj.091414v1

MARIJUANA CAN REDUCE PAIN WITHOUT HIGH: STUDY

Trial Participants Reported Better Sleep, Less Anxiety At Low
Doses

Briefly inhaling cannabis three times a day eases a kind of chronic
pain that affects tens of thousands of Canadians -- without making
them high -- Montreal researchers are reporting.

The new study, the first clinical trial in the world to allow patients
to take marijuana home with them and "self-dose," found that for
people with neuropathic pain -- a common and dreaded condition that
causes electric, stabbing pain -- smoking cannabis reduced pain,
improved mood and helped them sleep.

Three different potencies (2.5 per cent, six per cent and 9.4 per
cent) of THC, the active ingredient in marijuana, were tested against
a placebo, or "dummy" cannabis in 21 patients with neuropathic pain,
none of whom had responded to standard treatments.

Participants inhaled a single dose through a pipe three times daily
for five days, followed by a nine-day "washout" period. They were
instructed to inhale for five seconds while the cannabis was lit, hold
the smoke in their lungs for 10 seconds, and then exhale.

Pain was measured on an 11- point scale ranging from "no pain" to
"worst pain possible."

Patients reported less pain, better sleep and less anxiety when they
were smoking the highest concentration of THC, compared with the placebo.

It wasn't a massive reduction in pain: The average daily pain
intensity was 5.4 with 9.4 per cent THC, versus 6.1 with the placebo.

"But the patients that we were recruiting had to be patients that had
tried and failed all other conventional treatments," said lead author
Dr. Mark Ware, director of clinical research at the Alan Edwards Pain
Management Unit at the McGill University Health Centre.

Neuropathic pain -- which is caused by damage to nerves -- affects as
much as two per cent of the population. The Montreal study involved
patients with post-trauma or post-surgical pain -- radiating pain from
prolapsed discs, for example, or burning pain from an incision.

"We're not going to argue that smoked cannabis is the be-all and
end-all of pain management," Ware said.

"It simply opens the door to the fact that cannabinoids may be an
additional tool in the physician's tool box, along with other
medications and other non-pharmacological approaches."

During the study, "psychoactive effects" were rare:

After more than 1,000 different "administrations" of cannabis over the
course of the study, people reported feeling "high" on only three occasions.

Ware said it's possible their plasma levels of THC didn't reach the
levels found with recreational smokers.

"When we started the study, there was no evidence this was effective,"
said Ware. Three other trials have since been completed, two that were
restricted to neuropathic pain in patients with HIV.

"Now it's clear that smoked cannabis does have analgesic properties,"
Ware said. "The question now is, where do we go with that?"

His team is just concluding another study on the long-term safety
issues.

"Chronic pain isn't a life-threatening disorder," he said. "If
patients use cannabis, they may use it for many years. We want to know
what the long-term safety issues are. Are there other ways of
administering this drug that doesn't require smoking?"

Some prescription sprays and medications are now available that
contain cannabinoids. Cannabinoids bind to receptors in the brain that
play a role in modulating pain.

The study, which appears in the latest issue of the Canadian Medical
Association Journal, comes as more than 5,000 health professionals
from across Canada and the world gather in Montreal this week for the
13th World Congress on Pain. 
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MAP posted-by: Jo-D