MARIJUANA EFFECTIVE FOR PAIN RELIEF, STUDY FINDS

Smoking pot can make some of the pain go away, without the patient
getting high.

The finding comes from what researchers in Montreal believe to be the
first outpatient clinical trial of smoked cannabis, involving 21
people with chronic neuropathic pain.

The results, which included improvements in mood and sleep, were
published Monday in the Canadian Medical Association Journal.

Dr. Mark Ware and colleagues at McGill University and McGill
University Health Centre got the ball rolling for the study almost a
decade ago, but found it was a long road to get all the necessary
approvals and import a convincing marijuana placebo from the United
States.

But they plowed ahead, supported by a grant from the Canadian
Institute for Health Research, because they felt it was important to
generate some scientific data.

Marijuana is illegal in Canada but can be used medicinally in some
circumstances. In 2001, Health Canada brought in marijuana medical
access regulations outlining conditions for possessing, producing and
using the herb for medical purposes.

Despite the years that have passed, "the debate rages on about medical
marijuana," Ware said.

"We hear this a lot from policy makers and from regulatory colleges,
especially here in Canada ... there is very little evidence, and many
of them aren't aware of any evidence that smoked cannabis has any
medical value."

Marijuana with potencies of 2.5 per cent, six per cent and 9.4 per
cent of the active ingredient THC were obtained from Prairie Plant
Systems, the company that was given a government contract 10 years ago
to produce a safe, standardized supply of marijuana.

A placebo came from the U.S., where an alcohol extraction process was
used to remove the active ingredient, and the herb was reconstituted
so it looked like a green leafy material, Ware said.

There was a lot of paperwork and back-and-forth.

"Importing cannabis from the United States is not a trivial issue in
this environment," Ware noted.

Patients were given a special pipe bought on the Internet and
25-milligram capsules of a substance to put in the pipe and light. The
smoke was to be inhaled once - three times a day for five days - and
patients didn't know whether they were getting a placebo or one of
three different potencies of active drug.

Participants used each strength of marijuana product for five days,
separated by nine days of washout without cannabis.

"They would inhale that in a slow, smooth, single inhalation, hold
their breath for 10 seconds," then exhale slowly, Ware said.

The first dose was in the hospital, under observation.

"Even with this kind of fixed dosing and limited exposure, we were
able to show in a blinded fashion that the patients did obtain some
analgesia, improvements in sleep quality and on one of the subscales
of the quality-of-life measure, we found that the anxiety was mildly
improved as well," Ware said.

"This may help in developing policy, or improving policy, or improving
doctors' willingness to consider this as an approach when all else has
failed."

Side-effects - the euphoria associated with smoking pot - were "very,
very rare," Ware said.

"I think because the doses we used were very low," he
explained.

"The plasma levels which we found, and which are reported in the
trial, show levels of THC in the blood of around ... 40 to 50
nanograms per millilitre in the plasma. And we know that recreational
users hit blood levels of around 100 and 150 nanograms per
millilitre."

Prairie Plant Systems now offers medical marijuana that is 12 per cent
THC, Ware observed.

"So would we get better results if we had slightly higher THC levels,
would we get better results if the patients could use it for longer
periods, or if they could use it more frequently during the day?" he
asked. "I think these are questions that we can't answer."

Prof. Henry McQuay, who works at a pain relief unit in Oxford, U.K.,
wrote a commentary in the journal, saying that the researchers should
be congratulated for tackling the project given that the regulatory
hurdles "must have been a nightmare."

"The big picture here is a political one in a way, where Canada has
decided to legalize medicinal use of cannabis in this arena, but many
other countries have not," he said in an interview.

"It's another brick in that wall, that says here's evidence that some
people do indeed show some pain-relieving benefit from smoking cannabis."

Dr. Igor Grant, director of the Center for Medicinal Cannabis Research
at the University of California in San Diego, said the finding is
consistent with data reported from his centre, "and basically shows
that there is a beneficial effect of smoked cannabis on neuropathic
pain."

"The potencies we have typically used have been around four per cent
and as high as seven per cent, so that (9.4 per cent) is a higher
potency than we're experienced with," he said.

"But in reading the article, it seems like the patients tolerated it
reasonably well."

Neuropathic pain is a bit different than the pain of a broken leg, for
instance, and is a more chronic, burning, unpleasant sensation, he
explained.

"Many patients don't respond completely to existing treatments, and so
it's useful to have another agent ... available, and I think there's
good evidence now cannabis may represent one of those additional agents."

The researchers say more studies are needed using higher potencies of
marijuana, longer duration and flexible dosing to see if pain levels
can be reduced even further.

Grant remarked that smoke inhalation raises several issues, and his
centre is completing two studies on pain using a vaporization form of
cannabis.

"People who are non-smokers may have difficulty tolerating it
(smoke)," he said. "Secondly, there's the issue of second-hand smoke,
which people may not like."

There are also the side-effects of smoking, and practical issues, such
as concerns about lighting up in a hospital where there are oxygen
tanks, he added.