WHY THE GP MAY OFFER YOU CANNABIS

Sufferers of MS have long campaigned for the drug to be legal for medicinal
uses. Their goal may be in sight. By Jerome Burne

Once we only smoked it to get high; now it looks set to be a valued
addition to the medicine cabinet. The announcement last week that marijuana
might reduce stroke damage and protect against Alzheimer's is just the
latest in a string of beneficial effects, recently uncovered by
researchers. And there is undoubtedly more to come. Marijuana contains a
rich cocktail of chemicals whose functions are only just being unravelled.
Already research into its mechanisms has led to the discovery of a
neurotransmitter system in the brain that was totally unexpected.

"What we have found so far suggests that cannabis could form the basis for
an entirely new approach to pain," says Professor Howard Field of the
University of California, San Francisco. In Britain Dr Geoffrey Guy,
recently granted the first Home Office licence to grow and research
cannabis, also believes that we have only just begun to tap its possible
uses. "The next condition that is going to benefit is epileptic seizures,"
he predicts.

Until recently it was impossible to get funding to study cannabis unless
you wanted to show how dangerous it was. But about 18 months ago, there was
a sea change in the American research establishment's attitude, after the
residents of California and Arizona voted to legalise marijuana for medical
purposes.

The prestigious Institute of Medicine of the National Academy of Sciences
performed a U-turn and began an investigation into the claims that
marijuana was beneficial for a remarkable range of disorders, including
glaucoma, pain, muscle spasm in Multiple Sclerosis and loss of appetite in
AIDS patients. As a result cannabinoids - the chemicals in the plant that
affect particular cells in the brain - have become a hot topic. In two
weeks' time (July 23 to 25) an international conference in France on
cannabinoids will be discussing why marijuana is emerging as such a panacea.

Meanwhile, in this country the BMA has thrown its considerable weight
behind a campaign for the medical use of marijuana. This has encouraged the
Home Office to grant Dr Guy his licence to grow marijuana for the purpose
of research at a secret location in southern England and to run clinical
trials. What he's discovered so far should change your way of looking at
the humble joint for ever.

"Marijuana contains about 400 active chemicals," says Dr Guy, founder of GW
Pharmaceuticals. "The conventional drug company approach to medicinal
plants is to extract a single active ingredient, which in this case is
generally assumed to be one known as THC, but this is very short-sighted."

In evidence he recently presented to the House of Lords Committee on
cannabis Dr Guy explained that THC - "the one that gets you high" was just
one of 60 cannabinoids that can affect receptors in the brain. "In addition
to them, the plant's essential oils have a range of valuable properties -
anti-fungal, anti-bacterial and antiinflammatory." Despite all this potent
activity, cannabis has the startlingly unusual property of being incredibly
safe. The difference between a therapeutic dose and a deadly one is 40,000.
By comparison, the figure for aspirin is 25, while morphine is 50.

For now, Dr Guy is looking at the cannabinoids, particularly CBD, the one
found to protect the brain after a stroke by mopping up dangerous free
radicals. He believes it will also be useful in treating epileptic
seizures. "It's only in the past year that we have been able to separate it
from its close relative CBC, so now we can begin to study it properly."

But one of the most dramatic medicinal effects of cannabis is the way it
stops the pain of muscle spasms that come with MS, against which
conventional opiate-based painkillers are useless. Literally a few puffs on
a joint can bring relief. "This is startling in pharmacological terms,"
says Dr Guy. "No other painkillers work that fast or at such low doses."
The latest American research into where cannabinoids work in the brain is
beginning to unravel what's going on.

For over 20 years we've known that the brain has its own pain-control
system that uses natural chemicals called endorphins. Morphine is a
painkiller because it taps into that system. There are other systems, such
as the one based on serotonin, controlling mood. Now it turns out there is
a system that cannabinoids can manipulate.

"We now know there are two sorts of cannabinoid receptor - CB1 and CB2",
says Professor Steven Childers of Wake Forest University school of medicine
in Winston Salem, New Connecticut. "CB1 is found all over the brain while
CB2 is found in the body, especially in the immune system. No one would
ever have predicted that receptors for marijuana would exist in such high
quantities."

What's revealing is where these receptors are found in the brain. "Motor
systems are packed with them," Childers continues. "This may partly explain
why cannabis is said to help with the muscle spasms of Multiple Sclerosis."

But it is pain control that is creating the most excitement. And all this
may have a decisive effect on the wider drug culture. Increasingly, proper
trials are showing that whole plant extracts are as effective, with fewer
side effects than the synthesised "active ingredient". If Dr Guy's trials
come up with the results, that could lead to a big change in the sort of
pills we are prescribed. And that's really heavy, man.