RESEARCH CASTS DOUBT ON CANNABIS BENEFITS

Setback for calls to license pot, as derivatives cause side effects
and prove less valuable than conventional drugs for pain relief.

Cannabis derivatives are neither as effective nor as safe as
conventional medicines for the relief of pain and prevention of
sickness during cancer drug treatment, according to two reviews of
existing evidence which will dismay those who hope to see marijuana
licensed as a medicine.

However, neither study focused on the possible benefit to people
suffering from multiple sclerosis. Cannabis derivatives are being
tested on substantial numbers of people with MS and other neuropathic
disorders as a result of sufferers' claims that smoking dope relieved
their symptoms and their pain.

Recently a House of Lords select committee urged the medicines
control agency to help speed up the process of licensing cannabis
derivatives. The MCA, however, has said it may require further tests
on the toxicity of one of the cannabinoids - the chemicals derived
from breaking down the whole plant.

The review published today in the British Medical Journal suggests
that cannabinoids do have an effect in pain and sickness relief, but
that it is not great, and it warns of serious side effects that
outweigh the benefits.

The authors acknowledge, however, that multiple sclerosis - where
there are few useful drugs - may be a special case. One trial,
examined during the review of pain control, showed not only that
people who smoked marijuana felt that their symptoms had improved,
but that their posture and balance measurably improved.

Fiona Campbell, from the pain management centre of the Queen's
medical centre in Nottingham, collaborated with colleagues in Oxford
and Switzerland to review all the trials that have been done into
cannabinoids for pain management. They found nine relevant and
acceptable studies, of which five related to cancer pain, two to
acute pain after surgery and two to chronic pain.

The researchers found that cannabinoids were no more effective than
codeine tablets in controlling pain. They depressed the nervous
system, which would limit their use. "Their widespread introduction
into clinical practice for pain management is therefore undesirable.
In acute postoperative pain they should not be used," the authors
said.

They and the team who reviewed the use of cannabinoids to prevent
sickness in people undergoing chemo therapy, or toxic drug treatment
for cancer, were alarmed by the side effects of the cannabinoids.
"Adverse effects associated with the cannabinoids were common and
sometimes severe in six of the eight trials that showed efficacy,"
said Dr Campbell and colleagues.

The result of the review of the chemotherapy studies was otherwise a
little more optimistic. Martin Tramer, an anaesthetist from the
University hospital of Geneva, Switzerland, and colleagues from the
Oxford Radcliffe hospital in the UK looked at the results of 30
trials published between 1975 and 1997. They found the cannabinoids
were slightly more effective than other drugs in preventing nausea
and vomiting, and the patients preferred them. But the researchers
said they caused so many damaging side effects that doctors would
have to think hard about using them.

Tony Moffat of the Royal Pharmaceutical Society, who is on the
steering committee for the trials of cannabinoids use in multiple
sclerosis and pain relief funded by the Medical Research Council,
said the papers were no reason to be dismayed; the trials had shown
there was some effect in terms of pain relief.

The MRC pain relief trials, which will begin next month, involve 400
patients who have had surgery in London hospitals. The multiple
sclerosis trial involves 660 patients and is based in Derriford
hospital, Plymouth. The first 20 patients have been treated with no
adverse effects.

A second set of trials is taking place, run by the commercial company
GW Pharmaceuticals, which has developed a spray from the entire
cannabis plant which is applied under the tongue. The company is
already claiming great success and says using the whole plant gets
better results than stripping it down to derivative cannabinoids.

"In the last 18 months GW has carried out clinical trials in 75
patients suffering from multiple sclerosis, spinal cord injury,
neuropathic pain, other intractable neurological conditions and
rheumatoid arthritis," said Philip Robson, the company's medical
director. "We are seeing clinically significant improvements in a
range of symptoms, including pain, muscle spasms, spasticity, bladder
symptoms, tremor and overall improvements in quality of life. In some
cases the improvement has been sufficient to transform lives."