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EDITIONS
Panorama Tuesday, 6 November, 2001, 11:54 GMT
Philip Robson on cannabis trials
Philip Robson
Philip Robson on cannabis trials

The legalisation of cannabis for medicinal use has moved a step closer following promising results in trials. Philip Robson, Medical Director of the trial, answered your questions in a live forum. Click on the link below to watch the discussion.

Video56K


Highlights of the interview:


Newshost:

Alan Mason, Carlisle: Excellent programme, but I'm a little worried it was more of a commercial for GW Pharmaceuticals than an attempt to put right the horrendous folly of cannabis prohibition. We don't need years of pseudo-science and government licensing procedures. Just give us the herb and let us get on with it, whether for medicinal, recreational or spiritual purposes. Why is there a need for the involvement of pharmaceutical companies?


Philip Robson:

I think we should separate the question of a medicine and a recreational drug. Let's talk about cannabis as a medicine. The problem with the herb that is available on the street is its unpredictability, its lack of purity, its lack of quality control - quite apart from the fact it happens to be illegal and that is a point that is a separate issue. But the fact is, as it is at the moment, is that what is available to people who wish to use cannabis for medicinal purposes, the plant is very non-standardised and very inconvenient to use and of course you have to smoke it too, which many people don't want to do.


Newshost:

But what are you actually doing to standardise it? Why is the pharmaceutical product, as you see it, so very different?


Philip Robson:

Well, you start off with a completely standardised genetic material - that is the plant, the horticulture, the gardening if you like - you standardise the actual plant itself and then you instigate very carefully validated extraction procedures - checking, analysing - all away along the line so that you are absolutely certain of the consistency of the product that you end up with.

Cannabis too is full of potentially useful constituents as well as not very useful constituents. So we would wish to separate out the ones that are likely to be useful for particular conditions and make sure that they are represented in the medicine in an exact amount. Then there is the delivery system - smoking is really a non-starter for a medicine as many people don't want to smoke anyway but even if they did, smoking itself carries a whole raft of risks - so we have to devise better ways to give the drug.


Newshost:

So the plants themselves - and I have seen them in your greenhouse in a place I am not allowed to mention - but they are chemically different strains?


Philip Robson:

They are. They are unique strains. It would of course presumably be possible to hit on those strains by chance but there is no chance in the procedure. One studies the horticultural history of the different types of plant and blends the best strains together to end up with the best possible plant for the particular purpose.


Newshost:

And some of the strains you have got there are different to others - some of them can get you high, some of them can't get you high, some of them contain different cannabanoid chemicals in different balances and the street stuff of course can contain additives of an unpleasant nature.


Philip Robson:

This is the problem of course - criminals don't have quality control high on their agenda. Unfortunately, if you want to buy street cannabis you are in the hands of criminals along the line there. So you are right, the inconsistency is there but also the possibility that additional substances may be added to alter the effect of the material itself.


Newshost:

Simon Scutt, Hayling Island, UK: I am motor neurone disease sufferer and have had very positive results from smoking cannabis but suffer from chest complaints as a result from smoking it. I would like to take the spray form as soon as possible. Is it likely that this may happen in the very near future?


Philip Robson:

Not in the very near future. In the programme we have been looking really at the start of this process. We have been seeing the very, very encouraging material from the pilot studies. We now are embarking, and have embarked, on the larger scale trials which will convince regulators, politicians and other people - and sceptics, I hope, in the medical field that there really is something in these medicines. That is the point at which we can actually look to get this stuff available on prescription. So not immediately, but certainly in the pretty near future


Newshost:

So you are not going to make the special kind of spray you are working on available before the drug actually comes onto the market - presuming it does?


Philip Robson:

We will of course be expanding the research so many more patients will get involved in the research and receive the spray as part of the research programme - but no, it is not going to be possible to make that available until we have actually got licenses to do so.


Newshost:

Gill Brown, Saffron Walden, UK: It is frequently said in the arguments against cannabis use (and with relation to drug testing) that cannabis remains in the system for up to 3 months. Doesn't this make a nonsense of the placebo trial, as if the placebo is received after the cannabis treatment, the cannabis could still be having an effect on the patient?


Philip Robson:

I think that is a very important point. It is certainly true that many of the constituents of cannabis do hang around in the fat stores of the body for a very, very long time indeed but they are only in tiny quantities there for much of that time.

It is quite true that if you were to smoke a single cannabis cigarette right now, you may well test positive in a urine screen three or four weeks later. But that doesn't mean you are still stoned after three or four weeks.


Newshost:

This is the sort of thing that makes testing for people who are driving after taking cannabis quite difficult. They may have it in the blood stream but you don't know if they are still high.


Philip Robson:

Quite so. It is a very good point but for most of the symptoms that we are looking at, such as pain, the effect seems to be relatively short-lived - by that I mean a few hours - even though there is this small residual amount in the body.

Other symptoms though, such as stasisity, may have a cumulative effective and so the questioner is making a very important point, we have to design the trials to allow sufficient time between treatments for the active part of the medicine to disappear before the placebo is evaluated.


Newshost:

Avril Herbert, Wales: For those of us with primary progressive MS, which affects muscle tone in the legs particularly, exercise is essential to maintain tone. Would cannabis inhibit the necessary energy for exercise?


Philip Robson:

No, it shouldn't do. The whole key here is getting the dose exactly right for each individual. The response to cannabis varies tremendously from one person to another and recreational users recognise that as well. So it very difficult to say for a group of people what is the right dose. The right dose has to be determined for that particular individual and of course as with any medicine, it is the balance of the beneficial effects against the unwanted effects. For every medicine there are unwanted effects and cannabis is no exception to that. So for most people though, that threshold of useful symptom relieve is different from the threshold for intoxication. So you can actually get the symptom relief at a level of dose that doesn't make you stoned.


Newshost:

I don't think she is asking if she would be intoxicated so much as if she would be sluggish, apathetic, wouldn't want to get out of the house, wouldn't want to take any exercise.


Philip Robson:

If that happened I would regard it as an overdose. So one could scale back the dose that was being taken so that that didn't happen.


Newshost:

Quite difficult for some ill people to tell of course what's an overdose, what's feeling apathetic.


Philip Robson:

It is a value judgement for each individual, I think you are right. Some people are going to enjoy feeling slightly relaxed and slightly intoxicated. But the vast majority of people that I have come across with multiple sclerosis and serious diseases such as that really don't want that at all. They want to get on with their lives and remain completely sharp and as you know that's just a question of adjusting the dose very carefully.


Newshost:

Sue Smith, Harrow, UK: How many MS people took part in this particular trial? Presumably, the patients on the trial also noted a number of other "side effects" that were down to being on cannabis - the programme didn't seem to note any of these. Were there any?


Philip Robson:

I think it is well recognised that cannabis-derived medicines are associated with a number of unwanted effects. But what we find and what appears from the literature is that these symptoms are generally well tolerated by patients. They are experienced more often early in the treatment and perhaps disappear after they have been on the drug for a while. But it is a balance of the positive and negative effects of the drug and getting that balance right is the key.


Newshost:

You are talking about things like dry mouth, maybe mild nausea but you are not talking about - at least in the trials - anything that would be in any sense morbid or pathological?


Philip Robson:

No. One of the things that we can learn from the recreational use of cannabis is that in terms of acute toxicity - that is to say fatal overdoses - cannabis is incredibly safe. So what we are talking about by and large are those relatively minor side effects.


Newshost:

You say relatively minor but you are also carrying out long-term cancer checks I believe, so you can't be that sure.


Philip Robson:

At this stage we can't assume anything because although this is a drug, as many people have pointed out, which has a 5,000 year history of use by humans, the amount of really carefully gathered scientific information about it is relatively limited in humans. There's an awful lot of animal research on cannabis and its derivatives but the amount of human research that is available to us is pretty limited.


Newshost:

So you've still got some way to go?


Philip Robson:

Absolutely.


Newshost:

It's too early to be triumphal in any sense.


Philip Robson:

Very much so. I was a little disturbed to see descriptions in the press in response to the programme referring to miracle drug, wonder drug - we have to keep in this perspective. This seems to be a medicine which is incredibly useful for people who haven't had very much luck with the standard medicines. But to talk about wonder drugs and miracle cures is really way over the top at this stage.


Newshost:

Chris Ayres, Birmingham, UK: Do you think it will ever be possible to effectively extract the "high" of cannabis intake without losing its medicinal qualities?


Philip Robson:

It depends on which medical conditions you are talking about. I think that it is going to be possible in the arena, for example, of inflammatory disorders, because a number of the constituents of cannabis, which seem to have great potential in treating inflammation, don't get you high. There is this particular receptor that part of the plant interacts with that is responsible for the intoxicating effect and some of the potential that cannabis constituents have is unrelated to that. But unfortunately in the sort of conditions that we are looking at, at the moment - chronic pain, multiple sclerosis, spasms and bladder problems - that particular receptor does seem to be a key therapeutic target. We are talking about this constituent that everyone is familiar with - THC - that is the main psycho-active component of cannabis - but it is also quite an important component of the therapeutic package for some of these conditions and in those conditions intoxication is always going to be a possibility if you overdo it. But I come back to the point, that there are separate thresholds for the intoxication effect and the therapeutic effect. So for most people a useful therapeutic effect can be obtained without having to take that extra step and get stoned.


Newshost:

Sean, Devon, UK: I noticed that there is a definite divide being made between the intended effect of medicinal relief and being "high". Do you employ special growing techniques to amplify the medicinal benefits while muting the psychoactive "side effects"? Or is the distinction only in the dose? If there is no way to completely divorce the medicinal benefits and the psycho-active "side effects" then could it be that they are one and the same?

You suggested that one of the therapeutic receptors may be the same as the intoxicating receptor, does that mean that the therapeutic effect and the intoxicating effect could, to a question of degree, actually be the same effect?


Philip Robson:

I think that's a very interesting point although I think the answer is no. They do seem to be separable.


Newshost:

Well you would say that wouldn't you?


Philip Robson:

No, I don't really feel I have an axe to grind here because if the medicine is effective and the level of intoxication doesn't reach a sufficient level to interfere with people's ability to carry out the complicated tasks that they have to - in other words that they are not actually subjectively stoned - then perhaps it doesn't matter. But I am giving you my scientific opinion which is that it seems to be separable in terms of symptoms like, for example, bladder-related problems or spasticity. These do seem to be decoupled, to some extent, from the psycho-active effects. So, at this stage, it is just a matter of opinion but my opinion is that these are separable. But your questioner is absolutely right - for these conditions, the same receptor is being targeted as would be targeted if you wanted to get high.


Newshost:

But some of the trial plants I saw in the greenhouses were high in CBD which, I think, is not intoxicating as opposed to THC. Does that mean that they don't work?


Philip Robson:

No. The role of CBD - we have a lot to find out about that yet - but it certainly seems to have some very, very useful characteristics all on its own. I have mentioned the anti-inflammatory effects and there are some other useful effects within the cells. But I think the other useful aspect that it has is that it may well modulate the effects of THC - such as the intoxication and it may help the breakdown of the metabolism of THC in a useful way too. In other words, the sum of the two seems to be rather more than the individual contribution of the separate parts.


Newshost:

Rosalind Brown, Carlisle: I suffer with MS and I am very interested in taking part in a trial for pain relief using cannabis. How do I go about this?


Philip Robson:

We are concentrating at the moment on a fairly small cluster of controlled trials in order to try to nail a particular use for cannabis and then we can expand further. That doesn't mean to say that in the course of the next year we won't be starting some new studies. But I think the best way to register for that is to, if possible, go online to the website and request a patient questionnaire and we can then get your questioner onto the database and it will be from the database that we will try and draw the initial patients for the study.

Cannabis from the chemist

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