Pubdate: Mon, 30 Aug 2010
Source: Vancouver Sun (CN BC)
Copyright: 2010 The Vancouver Sun
Contact: http://www.canada.com/vancouversun/letters.html
Website: http://www.canada.com/vancouversun/
Details: http://www.mapinc.org/media/477
Author: Sharon Kirkey, Postmedia News
Note: Download the study at http://mapinc.org/url/t4KIh82X
Bookmark: http://www.mapinc.org/mmj.htm (Cannabis - Medicinal)

CANNABIS CUTS PAIN, WITH NO HIGH

Treatment Also Improved Mood, Helped Patients Sleep

Briefly inhaling cannabis just 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 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 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 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 ten 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
Centre for Research on Pain 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.

"Through no fault of the surgeon's, it's impossible to do an operation
without cutting through some nerves," Ware said. "For some people, for
some reason, even after the tissue has healed they have persistent
pain at the site of the operation.

"All of these were very refractory, very difficult pain problems to
resolve. Any improvement in pain was quite remarkable.

"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 "administrations" of cannabis, 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. "Street users have access to
cannabis that can be anywhere from 15 to 20 per cent THC."

"When we started the study there was no evidence this was effective,"
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.

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

The study appears in the Canadian Medical Association Journal.
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MAP posted-by: Richard Lake