Driving with medical cannabis in your system

ABC Radio Adelaide with Peter Goers

Peter Goers: Last year the Federal Government legalised the prescription of medicinal cannabis and earlier this year South Australia slashed red tape, allowing doctors to prescribe the treatment. Plans to allow medicinal cannabis users to drive in South Australia have been brought on by Kelly Vincent at the Dignity Party. Kelly Vincent had said the proposal would only apply if the motorist’s driving would not be impaired by the prescribed medical treatment. Today on Breakfast with David Bevan, Police Minister Peter Malinauskas spoke about his concerns regarding medicinal cannabis users on the roads.

[Excerpt of Peter Malinauskas].

Malinauskas: We’ve seen a spike in the number of people who are dying on our roads as a result of having drugs within their system including cannabis. It’s now getting to the point where more people are dying on our roads as a result of drug consumption than there are of drink driving this needs a response and hence the Government has opened up the act and making a number of changes I think that Kelly Vincent’s amendments to allow for medical cannabis to be consumed and then get behind the wheel of the car is done with good intention Kelly is sincerely trying to look out for the interests of those people that might be using medical cannabis, but I think that’s inconsistent with the objective of road safety. Our objective here is to make sure that people who get behind the wheel of a car have their brain operating in such a way that doesn’t cause a risk to everyone else on the road and we think what we know from a range of research around the world that any cannabis consumption or any consumption of cannabis that results in THC being in your system impairs your ability to drive and therefore you shouldn’t be getting behind the wheel of the car and putting every other road user at risk. [End excerpt]

Peter Goers: Associate Professor David Caldicott, you disagree with the Minister’s comments?

David Caldicott: Look, I think the most charitable thing to say is that he has been misinformed on the nature of the science. There is a big difference between having detectable THC in your bloodstream and being impaired by THC is perhaps the scariest element for many in cannabis it’s what recreational consumers frequently chase to get themselves high.

Peter Goers: So is the THC removed in medicinal cannabis?

David Caldicott: It really depends on what the medication is for. In fact there are preparations overseas which have a considerable quantity of THC because it provides a pharmaceutical benefit. There are preparations which contain no THC at all the other major constituent is a product called CBD for example if you were going to treat a child who had intractable epilepsy you might use a substance that had a high quantity of CBD. Interestingly one of the commercial products that are available for the treatment of epilepsy actually has a little bit of THC in it anyway. So a lot of the medicinal preparations still have THC in it because it seems that it works better that way.

Peter Goers: Kelly Vincent is saying that the proposal would only apply if the doctor said the motorists driving would be impaired by the prescribed medical treatment, so it’s up to the doctor to decide whether this would work. Do you agree with that?

David Caldicott: I think as far as road safety is concerned impairment is paramount. So if we can directly associate a THC level with the level of impairment people should not be allowed to drive, but a blanket ban just because THC can be detected, it’s a little bit facile if you look at what other countries are doing they’re quite sophisticated in their approach. A good idea would be like what was being proposed in Germany – you shouldn’t be driving when you start your medicinal cannabis because we don’t know how it’s going to affect you and you shouldn’t be driving when your dose gets changed, but once you’re stable on a dose and you can demonstrate that you’re not impaired why shouldn’t you drive?

Peter Goers: People are driving all the time on opiates and all these painkilling medications.

David Caldicott: Well that’s an excellent point we know for a fact these are definitely impairing and yet for reasons more to do with historical basis and tradition they’re not included in the roadside drug screening. They’re probably every bit as important, maybe even more important. What we see if you use some of the driving simulators and you look at recreational consumers there in fact is a tendency among recreational consumers to focus and drive more slowly. But there’s an equal number of reports to suggest that people who are under the influence and are actually impaired in fact drive slower. So there’s quite a lot of blanket statements in what your Police Minister seems to have said.

Peter Goers: how many drivers have died with only marijuana in their system? do we have any statistics for that?

David Caldicott: I would say that there probably have been deaths. What we know for a fact is that recreational cannabis that particularly our friends in South Australia are so enthusiastic about, it’s a very different beast to the nature of the drug that will be prescribed in the 1970s where they were running clinical trials of recreational cannabis in London older patients really did like the sensation of being high, so it’s quite a different product. What we do know is that if you for example combine your recreational drugs, THC and alcohol for example, or you combine a medicinal drug and THC you are far more likely to crash your car. So there is definitely some evidence that THC in combination to other drugs has as deleterious effect on your ability to make decisions. But there will probably be several more drugs up the chain before you got to THC which would be more dangerous as far as driving is concerned and of course the most obvious and most dangerous one of them all is alcohol.

Peter Goers: the accidents and deaths from marijuana would be infinitesimal compared with those from alcohol.

David Caldicott: Absolutely no doubt whatsoever.

Peter Goers: Michelle says someone with epilepsy has more chances of being in danger if they had an episode compared to the impairment of THC.

David Caldicott: It’s a very good point. There’s a colleague of mine who’s a health economist and he talks about a phenomenon known as the ‘net health benefit’. So really when you’re talking about these things you’ve got to weigh up what the benefit overall to society is rather than this drug can be detected in the bloodstream. The fact that they can be detected is merely a reflection of the sensitivity of tests that can be detecting. It says nothing about the impairment.

Peter Goers: Professor David Caldicott, is medicinal cannabis detectible in police drug driving tests?

David Caldicott: It would depend on the THC content. My understanding as the tests are evolving in Australia is that they’re still only testing for THC and so if you had a terminal illness, you had pain and anxiety associated with your mortality you might be prescribed a drug that had a reasonably high THC content

Peter Goers: Yes please, if not heroin. I knew of someone who was terminally ill with cancer and went to her grave on heroin and why not?

David Caldicott: heroin is still readily prescribeable in the United Kingdom.

Peter Goers: Thank you for that, David.

David Caldicott: there has come a time now where we have got beyond a generation of prohibition and more and more countries are realising that the issue of drugs is a significant one as far as health is concerned. So we need to sort of change the narrative a little bit; we need to have a discussion in the context of health and maybe not be quite as hysterical about the mortality side of drug consumption because that achieves nothing we’re running a course in Adelaide on medicinal cannabis it’s run out of the ANU and it’s supposed to be quite scientific and people, especially our opponents, would be more than welcomed to come along and quiz us on it.

Peter Goers: thank you.