Expert Panel to Review Use of Medical Cannabis

Peter Russell

Disclosures

June 19, 2018

A panel of clinical experts has been set up to consider the use of medicinal cannabis, the government has announced.

Home Office minister, Nick Hurd, told the Commons on Monday that the group, led by England's Chief Medical Officer Professor Dame Sally Davies, would advise ministers on any individual applications to prescribe the drug.

The decision follows the case of Billy Caldwell, 12, who was treated with cannabis oil in hospital after the Home Office granted a 20-day licence. His mother, Charlotte Caldwell, has said the drug reduced seizures for her son caused by severe epilepsy.

The oil contains a substance called tetrahydrocannabinol (THC), which is illegal in the UK but available in other countries.

We asked Dr Amir Englund, a post-doctoral researcher in psychopharmacology at the Institute of Psychiatry, Psychology and Neuroscience, King’s College London, to explain more about medical cannabis and whether it has a future in treating certain conditions.

Medscape News UK: In which health conditions can medical cannabis be of useful value?

Dr Englund: The term medical cannabis is extremely loosely used. There are several approved cannabis products at the moment. In the UK we have – I think – two that are currently licenced. One is Sativex [nabiximols, GW Pharmaceuticals], which is a combination spray which has cannabis's two most common compounds, which is THC and CBD [cannabidiol] on a one-to-one ratio, and that's an approved medicine to treat pain and spasticity in patients who have MS.

Then there is Nabilone [cannabinoid, Meda Pharmaceuticals], approved for use in relation to cancer treatment. And also, there's a THC tablet that was approved in the mid-80s called Marinol [dronabinol, Solvay] also used to treat nausea related to cancer treatment and as an appetite stimulant for HIV/AIDS.

Also, there's a new one on its way which is called Epidiolex, made by the same company that makes Sativex. Epidiolex is an oral liquid containing high doses of CBD and is made from plant extract that is purified. That's gone through extensive clinical trials now. It's been shown to be effective in rare forms of childhood epilepsies known as Dravet syndrome and Lennox-Gastaut. [1,2]

Medscape: There have been calls for more trials to establish the therapeutic value of medical cannabis. Have there already been good quality trials and what if anything have they established or not established?

Dr Englund: It depends on your definition of good quality trials. But, good enough to get a medicine approved? We have it for Sativex, we have it for Epidiolex, and also all the drugs like Marinol. They've been through clinical trials.

And then the waters start to muddy a bit because cannabis is a plant, and the example I like to give is tomatoes. Everyone knows what a tomato is but tomatoes can be very, very different: different flavours, big, small, different coloured ones, and similarly you can get cannabis that has a wide range of qualities.

Now, most of street cannabis is very strong THC cannabis but there are also cannabis varieties that only produce CBD and everything in between these two. And apart from THC and CBD it's estimated that the cannabis plant has 144 different cannabinoids – cannabis specific compounds – so cannabis is not a drug, it's a plant that contains many different drugs, and that complicates matters quite a lot because in medicine we are just used to one single compound being tested for one indication.

Medscape: In the case of Billy Caldwell, do you think the right decision has been made to grant a temporary exemption to receive this drug in a hospital environment?

Dr Englund: What I think we can do is trust the treating physicians and their judgement that the medication that has been prescribed has worked. And although we're in this regulatory limbo in which we know that that product which has been prescribed has not gone through normal clinical trials, there can be exemptions made if there's a clinical need according to the physician's judgement.

Medscape: The Home Office has announced an expert panel on how cases of medical cannabis are handled. Is that something you would welcome?

Dr Englund: The issue of medical cannabis is that for a lot of indications we don't have sufficient evidence of efficacy [apart from] the ones that I have mentioned: these rare forms of epilepsy, MS, and nausea related to cancer treatment.

There have been other academic studies to show that cannabis might help in other conditions as well, but that level of evidence isn't to the standard that the regulatory agencies require.

And also, because of poor incentives for the pharmaceutical industries to pursue medical cannabis, we don't have those trials done yet because cannabis is a naturally occurring plant and the compounds are also naturally occurring, so it's very difficult to patent products made from cannabis or the cannabis compounds themselves. So, we're kind of stuck in a Catch-22 situation where the studies that we need to be done to show that something is safe and effective and henceforth can be prescribed as a medicine are unlikely to happen because drug companies might not be interested in that.

I think having an expert panel to make a case-by-case judgement and make exemptions is definitely a good thing, and that might also be a way for more research to be done on these individual cases to build an evidence base that's currently lacking. 

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