MARIJUANA MAY MAKE SOME PAIN WORSE: STUDY

By David Wylie, Canwest News Service

(CNS) - Marijuana's painkilling properties are being called into
question by research that suggests the drug can amplify and prolong
pain in some cases, rather than relieve it.

A study in the current issue of Science suggests prescribing
marijuana for pain relief, which is legal in several countries
including Canada, may be counter-productive.

Experiments with rodents and humans found that a group of compounds
that includes cannabinoids, the active ingredients in marijuana, can
interfere with the body's mechanisms to stop pain signals from
reaching the brain.

"If you had a toothache, you probably wouldn't want to treat it with
marijuana, because you could actually make it worse," said University
of Texas Prof. Volker Neugebauer, a study author.

"For more pathological conditions like neuropathic pain, where the
problem is a dysfunction within the nerves themselves and a
subsequent disturbance throughout the nervous system that's not
confined to the pain system, marijuana may be beneficial."

Researchers from the U.S., Switzerland, Hungary, Japan, Germany,
France and Venezuela collaborated on the new research. They found
endocannabinoids in the spinal cord suppress the body's ability to
put "the brakes" on pain signals, leaving pain with a straight road
to the brain.

"In the spinal cord there's a balance of systems that control what
information, including information about pain, is transmitted to the
brain," said Neugebauer. "Excitatory systems act like a car's
accelerator, and inhibitory ones act like the brakes. What we found
is that in the spinal cord, endocannabinoids can disable the brakes."
He said the study raises questions about marijuana's power to relieve
acute pain because endocannabinoids and the cannabinoids in marijuana
are very similar.