NEW STUDY CASTS DOUBT ON MEDICAL MARIJUANA

As Canada moves ahead with legalization of marijuana for medicinal
purposes, new research is casting doubt on its usefulness for pain relief.

Cannabinoids (cannabis in pill or injectable form) are no more effective
than traditional painkillers, according to a study published in Friday's
edition of the British Medical Journal.

Even when cannabinoids do work effectively, such as in controlling the
nausea and vomiting related to chemotherapy, they have potentially serious
side effects that should limit their use, a second group of researchers
reported.

But Dr. Mary Lynch, director of research at the pain management unit of
QEII Health Sciences Centre in Halifax, said the research should be
interpreted cautiously and should not cast doubt on Canada's medicinal
marijuana program.

"The bottom line is that there is not enough human research to draw any
significant conclusions," she said in an interview. "Overall, I'm very
enthusiastic about the future of cannabinoids, but there is a lot of work
to be done in improving the drugs."

Dr. Lynch, who heads the Canadian Consortium for the Investigation of
Cannabinoids in Human Therapeutics, praised Canada's approach to medicinal
marijuana, and said it will help make the country a world leader in
cannabinoids research.

"This country is taking a humane, reasonable, compassionate approach by
approving the use of cannabis in specific conditions while we await the
results of further research," she said. "And, at the same time, the
government is funding cannabinoids research."

In the newly-published study, Dr. Fiona Campbell, a pain management
consultant at Queen's Medical Centre in Nottingham, England, said that, at
present, there is "insufficient evidence to support the introduction of
cannabinoids into widespread clinical practice for pain management."

She said that, at best, a single dose of cannabis is the equivalent of
taking 60 milligrams of codeine, "which rates poorly in relative efficacy."
Further, the higher the dose, the greater the side effects.

In particular, Dr. Campbell and her team identified cannabis as having a
depressant effect on the central nervous system, and adverse psychological
effects such as panic attacks and paranoia. A synthetic version of the
active ingredient in marijuana, THC (tetrahydrocannabinol), is used to
manufacture cannabinoids in pill and injectable forms.

The research is not original, but an analysis of material that has already
been published. The team looked at nine different trials in which
cannabinoids were used on patients with cancer pain, chronic pain and
post-operative pain. Dr. Campbell noted that only 222 patients were
involved in all the studies combined, underlining the dearth of human
research. None of the research involved patients who smoked cannabis
because none was conducted.

The second study, also published in today's edition of the British Medical
Journal, looked at the effectiveness of cannabis for controlling
chemotherapy-induced nausea and vomiting.

Dr. Martin Tramer of the department of anesthesiology of the Hopitaux
(CIRCUFLEX O) Universitaires in Geneva, analyzed the results of 30
different studies.

He found that cannabinoids, in both pill and injectable form, worked very
well for some patients. But the study also noted a number of troublesome
side effects ranging from dizziness to low blood pressure.

Dr. Tramer said that patients treated with cannabinoids were five times
more likely to discontinue treatment than those taking more traditional
anti-nausea drugs.

"Potentially serious adverse effects, even when taken short term orally or
intramuscularly, are likely to limit the widespread use," he said.

Again, none of the studies involved patients who smoked cannabis.

In Canada, only two cannabinoids have been approved as prescription drugs,
both of them for patients with chemotherapy-related nausea.

In an editorial published in the journal, Dr. Eija Kalso, head of the pain
clinic at Helsinki University Hospital, said that, at this time,
cannabinoids "clearly lose the battle in both efficacy and safety with the
competitors."

But he too highlighted the potential of cannabinoids, and said much more
research needs to be done on humans. Researchers are excited about the
drugs because cannabinoids exist naturally in the body and they have shown
dramatic results in animals -- including arresting tumour growth and
controlling chronic pain.

Earlier this week, the federal government released the regulations related
to medicinal use of marijuana. They require, among other things, that users
obtain a photo identification and that doctors approve an application for
use of cannabis.

The Canadian Medical Association objects strongly to the new legislation,
saying that marijuana has not been subjected to the rigorous pre-market
testing that other drugs must undergo.

Dr. Hugh Scully, past president of the CMA, said there is lack of
comprehensive and credible scientific evidence on the benefits, and risks,
of medicinal marijuana.

"We acknowledge the unique requirements of those individuals suffering from
a terminal illness or chronic disease for which conventional therapies have
not been effective," he said. "However, the CMA believes that it is
premature for Health Canada to expand broadly the medicinal use of
marijuana before there is adequate scientific support."

When the U.S. Institute of Medicine studied the pros and cons of medical
marijuana use in 1999, it concluded that the "future of cannibinoid drugs
lies not in smoked marijuana, but in chemically-defined drugs."

Supporters of medical marijuana dismissed those arguments, noting that
there is much anecdotal evidence about the benefits of the drug and
stressing that the regulations allow marijuana to be used only by people
who are expected to die within 12 months; those with chronic medical
conditions such as AIDS and multiple sclerosis; and those with serious
medical conditions who can't find relief in any other way.