NO CUT-AND-DRIED CONCLUSIONS IN THE GREAT CANNABIS DEBATE

The plant known as Cannabis sativa has been used in various forms as a
painkiller for at least 5,000 years. But it has only recently been
recognised by the scientific community as the source of a set of more than
60 related chemicals called cannabinoids.

In November the British Medical Association issued a report, of which I
was a contributing author, calling for more clinical studies of
cannabinoids as medicines. It was a welcome sign that the establishment
was beginning to take the issue seriously.

The BMA is not advocating smoking dope, which is carcinogenic because of
the tars produced when it is lit, but there are nevertheless strong
arguments for allowing some of its constituent chemicals to be used in
medical treatment.

The best known of these chemicals is delta-9- tetrahydrocannabinol (THC),
to which most of the known pharmacological properties of cannabis,
including its effects on mood and perception, can be attributed.

For many years its precise mode of action remained a mystery, but all this
changed recently with two discoveries: first, that our body contain
specialised sites (cannabinoid receptors) that mandate many of the effects
of THC, and, second, that our tissues can produce their own cannabinoids
that interact with these receptors to control the release of chemical
messengers in the body.

Two cannabinoids - THC, also known as dronabinol, and nabilone - are
already used clinically in this country and elsewhere to suppress nausea
and vomiting provoked by cancer chemotherapy. in the United States,
doctors can alco prescribe THC to boost the appetite of AIDS patients and
so reduce loss of body weight.

It is likely that cannabis and individual cannabinoids would also be
effective in relieving the muscle spasms, pain and bladder dysfunction of
multiple sclerosis and spinal injury, in managing other types of pain and
in treating glaucoma and bronchial asthma.

A few British doctors prescribe nabilone for multiple sclerosis or chronic
pain, despite the fact that it is not licensed for these purposes.

The evidence supporting such use, based on anecdotal, pharmacological and
clinical data, is particularly promising. Seven trials, albeit with rather
small numbers of patients, have shown that cannabis, THC or nabilone can
reduce the intensity of at least some symptoms, particularly muscle
spasm, pain and bladder dysfunction.

THC has also been shown to be effective in an animal version of MS.
Results from other trials, as well as from animal studies, lend further
support to the claim that THC relieves pain.

Meanwhile, a survey that I conducted with colleagues recently found that
among 112 MS pateints who use cannabis - illegally under current laws -
almost all listed multiple benefits. Improvements included a reduction in
muscle spasms when falling asleep (96.5 per cent), decreased spasms when
waking at night (93.2 per cent), relief from pain in the legs at night
(92.3 per cent), from arm or head tremors (90.7 per cent) and from
depression (90.6 per cent).

While many find such data convincing, others would like to see larger,
more extensive clinical trials.

It is this approach that the BMA recommended in the recently published
report 'Therapeutic uses of Cannabis', concluding that patient groups,
pharmaceutical companies and the Department of Health should jointly
encourage properly conducted clinical trials to evaluate the further
potential therapeutic uses of cannabis - alone or in combination with
other drugs. We at Aberdeen intend to carry out such a trial if we can
obtain funding.

Meanwhile it must be remembered that some of the effects of cannabis and
THC are potentially hazardous. Among the possible problems are increased
heart rate and altered hormone release, and evidence that cannabis can
induce psychosis in individuals predisposed to schizophrenia.

But although cannabis is carcinogenic when smoked, it is effective by
other routes, and data strongly suggest it is not strongly addictive.
There is no pharmacological evidence that cannabis use leads to the taking
of other illegal drugs.

Evidence that cannabis and cannabinoids can produce adverse effects should
not rule out their use as medicines, as these effects are no worse than
those of some prescribed drugs.

It can now be prescribed in Italy as well as in Arizona and California
(according to state laws). It could also be prescribed in this country
until 1971, and in 1968 a government advisory committee concluded in its
report to the Home Office (the Wootton report): "Preparations of cannabis
and its derivatives should continue to be available on prescription for
purposes of medical treatment and research".

There is no doubt that further research into the medicinal properties of
cannabis and cannabinoids is needed. We also need to develop better ways
of administering it, possibly as suppositories.

As all this will take considerable time, a strong case can be made for
allowing doctors to prescribe cannabis, nabilone or dronabinol for
disorders such as MS and spinal injury. This would seem preferable to the
present state of affairs where many patients who in all other ways appear
to be law-abiding citizens feel so strongly that they need the medical
benefits of cannabis that they are prepared to risk punishment.

They have no medical supervision and no knowledge of its potency and
pedigree, which could mean inadvertently taking in pathogenic organisms,
microbial toxins, other drugs or even pesticides.

But with dronabinol and nabilone unlicensed in Britain for anything other
than treating chemotherapy-induced nausea and vomiting, many patients have
no option but to seek out cannabis as the only such drug available to them.