14 August 2019

It’s time to get serious about medicinal cannabis

By Tom Chivers

“We’ve had a change in the laws,” says Gavin Sathianathan. “But that’s a necessary, not a sufficient, condition towards people getting access to cannabis medicines”.

More and more people are using cannabis as a medicine, both in the UK and abroad; and in the UK the rules have changed to allow doctors to prescribe it in certain circumstances. But there are challenges unique to cannabis that make it harder to research, market and prescribe: the usual model of getting a drug to patients, of clinical trials and regulation, hits hurdles with cannabis that you don’t see elsewhere.

Sathianathan is the CEO of a botanical medicines firm, Alta Flora, which makes cannabis-based drugs, among others. He is one of a new breed of cannabis producer who are trying to make the drug scientifically respectable, to put its medical use on an evidence-based foundation like that of other medicines. At the moment, it is often either seen by large parts of the medical establishment as medically useless, or held up by ageing hippies as a quasi-mystical panacea.

“Cannabis is complex, pharmacologically,” he says. “Traditionally, pharmaceuticals tend to be single molecules with a single target. Cannabis is a treasure chest of medicines”.

That makes it harder to study, says Harry Sumnall, Professor in Substance Use at Liverpool John Moores University. “There are some products that are extracts such as Sativex and Epidiolex”. They are drugs that reduce spasticity in multiple sclerosis patients, and reduce the frequency of epileptic seizures respectively. Sativex is already licensed. Epidiolex is approved by the FDA for the treatment of seizures associated with two rare and severe forms of epilepsy, Lennox-Gastaut syndrome and Dravet syndrome, and recently won a positive recommendation for marketing approval from a European Medicines Agency (EMA) panel. But they are specific chemicals, extracted and purified, and tested like any other drug.

Where it gets complex is with “whole-plant” herbal products:  flowers, or largely unrefined extracts such as oils. Many people who use, and derive benefit from, cannabis medicines use it in this form. “The plant contains hundreds of cannabinoids and other chemicals,” says Sumnall. “You see this end result, but what actually produced it? Was it the THC, the CBD, the whole product? Translating it to what your GP will prescribe is very difficult”. And the plants and their derivatives are not of standardised strength. “You can’t say ‘take two tablets a day and you’ll be fine’, because it’s so complex”.

Instead, argue some producers and scientists – David Nutt, the former chairman of the government’s Advisory Council on the Misuse of Drugs, among them –  we need to find a new regulatory framework for cannabis products, and new ways of testing them.

Elsewhere in the world, notably Australia and the USA, “we’re seeing a shift in the regulatory landscape to accepting real-world evidence,” says Adam James, the commercial director of Emerald Clinics, another medicinal cannabis firm. As well as randomised controlled trials (RCTs), the gold standard of medical trial, there is an increasing use of “post-market surveillance” – data collected from real-world patients who have been given the drug.

That is possible with cannabis in a way that it wouldn’t be with, say, some new chemotherapy drug for cancer, because regardless of whether it’s effective, cannabis has at least been shown to be relatively safe; there is little to no risk of acute reactions.

The problem is that regulators and professional bodies in the United Kingdom are understandably wary, although a lobby group, the Centre for Medicinal Cannabis, recently issued a report on how to gather and use this sort of evidence in the UK, using the Danish and Australian systems as examples.

Cannabis is usually a recreational drug; some of the people who push cannabis as a medicinal drug overstate its efficacy, claiming that it cures practically everything. “We believe there are significant therapeutic benefits, but we do it a disservice by calling it a wonder drug” says Diane Scott, CEO of the Jamaican Medical Cannabis Collective, another medicinal cannabis firm.

Those therapeutic benefits, she is keen to stress, are real for the millions of patients around the world using cannabis as medicine, but the hard medical evidence gathered via traditional means such as RCTs is, as yet, limited. But, if individuals prefer to use cannabis, instead of, for example, opioid-based medicines for some types of pain management, why shouldn’t they be able to? In fact, research teams at major universities in both Australia and Canada are investigating marijuana’s usefulness as a treatment for opioid addictions. (Government health agencies in both countries, as well as the USA have declared the opioid crisis public health emergencies.)

There is evidence of effectiveness in things like appetite stimulation in cancer patients, in pain relief, nausea reduction, and – as with Sativex and Epidiolex – in the reduction of some symptoms of MS and epilepsy.

In the UK, cannabis was moved last year from “schedule 1”, meaning it was considered to have no medical benefits at all, to “schedule 2”, which meant that doctors could prescribe it in certain circumstances.

But, says Sumnall, it is still very rarely prescribed. Partly, that’s a result of the difficulties of research that are specific to cannabis, and a reason why some people are calling for a change to the regulatory framework. In Britain, though, that may be a hard sell, says Sumnall. “We have the NHS, and the public pay for these products,” he says. “So the public needs to be confident that the money is being spent well”.

The National Institute for Health and Care Excellence (NICE), which licences drugs in the UK, relies on good-quality evidence. Many of the studies that so far exist into the effects of cannabis are of lower quality: the respected Cochrane Collaboration carried out a literature review of research into the use of cannabis for chronic neuropathic pain last year, and found no good-quality evidence at all.

Which is why some people push back against the idea that cannabis should be regulated differently. “The other argument, which I have time for,” says Sumnall, “is that if you’re presenting it as a medicine to treat quite serious diseases, then it should be subjected to the same rigorous tests as other potential medicines.” The evidence base in cannabis is “growing”, he says, and he agrees with Scott that there is good evidence in some areas, especially around nausea and some kinds of pain relief. “But patients on the grey and illicit markets are using it for a whole range of problems, anxiety, cancer, PTSD, and don’t have the high-quality evidence”. He is concerned about reducing the standard of evidence required.

Medicinal cannabis also has a PR problem, says James. It is too often seen as decriminalisation by stealth: recreational users getting signed off by a doctor to get access to weed. “That’s a problem in the system in the US,” he says, where a doctor grants you permission to use cannabis products, and then the staff at the dispensary provide it. The patient has complete agency over what product they take and how much. In Australia, where James works, “doctors write a specific script for a specific product”, as they would with any other medicine. The UK system is developing more along those lines, so stealthy recreational use is much less likely; but the US system is well known over here, so there is scepticism.

The UK will have to make some decisions on this in the near future. Many thousands of people self-medicate with street cannabis already, and recent high-profile cases such as Billy Caldwell have brought the matter to public attention.

There is a genuine tension between the need to make special provision for cannabis, given the unique challenges of testing and regulating it, and the need to make sure the NHS doesn’t waste money on unevidenced products. Other countries – notably Australia, Germany and Denmark – have successfully integrated cannabis into their medical systems; perhaps the UK can too.

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Tom Chivers is a freelance science writer and author of 'The AI Does Not Hate You: The Rationalists and Their Quest to Save the World'