Cannabis is the source of some 60 or so compounds called cannabinoids. One of the most important of these is called THC, responsible for producing the effects people are after when they take it for recreational purposes and also, in a way unfortunately, the constituent that may be helpful in treating some of the symptoms of M.S.
THC is one of two cannabinoid drugs licenced in the western world for use clinically. It is licenced in the USA to suppress nausea and vomiting produced by anti-cancer drugs, and as an appetite stimulant particularly for AIDs patients.
The other drug is Nabilone, not found naturally in Cannabis but produced in the laboratory. It has very similar properties to THC but is a bit more potent. It is licenced in the UK also to suppress nausea and vomiting.
Cannabinoids have a very precise and specific mode of action in the body. They key in with receptors found in nerves, the brain and spinal cord, altering the function of our nervous system by effecting how cells communicate. There are many receptors some of which are involved with the control of movement, with memory, and with perception of pain. There is some evidence that cannabis related compounds can reduce the release of inflammation producing chemicals.
It is thought Cannabinoids may help conditions such as disorders of cognition, learning and memory, mood disorders, disorders of movement, muscle tone, chronic pain, bronchial asthma, glaucoma and disorders of the immune system.
So what evidence is there for carrying out clinical trials?
There have been five clinical trials in the past and overall the results are encouraging showing that Cannabinoids produced improvements in spasticity, painful spasticity, in head and neck tremor, in intention tremor and handwriting performance.
These trials were carried out using THC, Cannabis itself and Nabilone. They were not large trials and to convince the Department of Health and the Home Office it is necessary to carry out larger trials.
However, important information came from these trials. One important point is that the best dosage of the same drug is different for different people. It is easy to stray from an ineffective dose to a dose with unpleasant side-effect. It may be that self administration using a puffer device (as for asthma) would allow people to find their own dosage levels. This will be quite a challenge to get the dosage right for a trial.
Very recently a survey was carried out in USA and UK. involving 112 people. This was the first questionnaire on Cannabis use and M.S. and was an anecdotal survey of the perceived effects of smoking cannabis (not a trial).
A full report on this study is available from the Centre.
The results showed that from 97% to 30% of the subjects reported cannabis improved either as “much better” or “a little better” many of their M.S. symptoms, particularly; improved sleep, pain relief, relief of bladder problems, muscle spasm and constipation.
The people surveyed have specific therapeutic reasons for smoking cannabis.
But there are many questions to be asked. Are the claims true? Or is it just a placebo effect? What type of M.S. patients will most benefit? Should one give Cannabis which is a mixture of some 60 or so chemicals, or should we use a single cannabinoid, or a mixture of 2 or 3 cannabinoids? What dosage should people take and how should it be taken? Would you build up a tolerance to the drug? Are any unwanted side effects acceptable? In a good drug the advantages outweigh the bad.
So what are the side effects if taking cannabis?
Cannabis can sometimes induce schizophrenia-like symptoms in people. Clinicians would evaluate someone’s family history for a predisposition. The heart rate is elevated so people with problems like angina should be careful. Reproductive hormones seem to be suppressed. Pregnant women should avoid taking cannabis related compounds – this applies to most drugs. The immune function is suppressed but this has not given rise to problems with AIDs patients. Withdrawal symptoms are mild and flu-like. There is no evidence for developing a craving. Exceptions are people who use cannabis as a crutch. People who take it for it’s mood altering qualities should avoid it. When smoked cannabis is carcinogenic but not if eaten or taken as tea. Minor symptoms such as dizziness, sedation, dry mouth, blurred vision and mental clouding have all been reported. Practically every centrally acting drug has commonly got these side effects.
If a trial goes ahead it would be M.S. specific, probably looking in particular at its therapeutic effects on pain, particularly in spasticity.
It is very slow progress getting trials underway. The next application for a trial can be made in February 98 (applications can be made once a year only).
The M.S. Society, the Government, the BMA and other influential groups are keen to look at the possibilities of a trial which is encouraging. Now we need to design one suitable. Evaluating the effects has to be able to prove that it works therapeutically – anecdotal evidence is not enough.
If the trial does go ahead people would probably be on the drug for say a month, then a month on the placebo. People would also be asked to keep a diary to record any other effects or benefits they feel. If you would like to be included in a future trial please speak to a neurologist. He or she will pass on your name and you will be contacted direct, should a trial go ahead.