The medical cannabis industry has come a long way over the last two decades, with countries and jurisdictions around the world opening up legal avenues to patient access. Cannabis-based medicines are now available to millions of people for a multitude of conditions, thanks to evolving public opinion, advances in medical research, and patient and clinician testimonies. However, there remains a vital need for acceptable evidence in order to accumulate high-quality evidence and accelerate patient access to these potentially life-saving medicines.

In November 2018, the UK government announced that cannabis was to be rescheduled, from schedule 1 to schedule 2, of the Misuse of Drugs Act. This simple move was to make medical cannabis available to patients who were yet to find an effective treatment option for a number of conditions. Thousands – and maybe millions – of patients and family members were filled with hope. But, it soon became clear that significant red tape around the industry was set to drastically limit the potential of this landmark moment.

Medical Cannabis Regulation in the UK

Understandably, many patients and advocates were disappointed to discover the continued restrictions to medical cannabis access. Firstly, only clinicians that are specialists in the specific indication – whether epilepsy, multiple sclerosis, or chronic pain – are able to write a prescription for medical cannabis. Secondly, recommendations for the use of these products remains limited to just three conditions: certain forms of epilepsy, spasticity associated with multiple sclerosis, and chemotherapy-induced nausea and vomiting. As a result NHS prescriptions have been extremely limited, with the vast majority of patients left to access the medicines through private clinics.

The truth is, despite thousands of years of cannabis use – both for medicinal and recreational purposes – the global prohibition of the plant during the most significant period of scientific development in history, has left an enormous gap in clinical research into the potential benefits and risks associated with the use of medical cannabis treatments.

The Importance of Clinical Trials

For decades, successful clinical trials – and particularly, randomised controlled clinical trials – have often been the required standard for the approval of ‘new’ medicines. This process allows clinicians and governments to be confident in the favourable benefit-risk profile of pharmaceutical drugs (though, arguably, this has not always been effective).

Clinical trials have undoubtedly been one of the most important contributors to medical development since the first one was carried out way back in 1747. They allow us to not only discover and test the potential of new medicines, but also to identify “new ways to detect, diagnose, and reduce the chance of developing the disease.”

Randomised Controlled Trials – The Gold Standard?

While there are a number of study designs for clinical trials, the randomised controlled trial (RCT) is largely considered the ‘gold standard’. The structure of these trials is pretty self-explanatory: participants are randomised into treatment groups and given one of two or more clinical interventions in a controlled setting. This allows researchers to more effectively compare the effects of each intervention.

RCTs are designed to prevent selection bias, assigning participants randomly, so that any difference in outcome can only be explained by the treatment used.

Medical Cannabis and Clinical Trials

As mentioned above, prohibition significantly limited the number of clinical trials that assessed medical cannabis. Research has, however, been on the rise over the last few decades. In fact, the EU Clinical Trials Register currently displays over 40,000 cannabis clinical trials in the European Union alone. Nonetheless, lawmakers and many physicians continue to claim limited evidence as the primary reason for restricted access to cannabis medicines. So, why is this?

As already touched upon, RCTs are overwhelmingly considered the gold standard for medical research – and understandably so. However, many healthcare specialists and and researchers argue that this form of research may not be suitable for all kinds of medicines – including medical cannabis.

An unsuitable measure of efficacy?

The vast majority of medications approved following randomised controlled trials are pharmaceutically developed drugs. In many cases, these are carefully constructed formulations – or even singular chemicals – that can be meticulously reproduced. Cannabis, however, contains a vast amount of active ingredients – many of which have proven therapeutic properties all of their own. Research indicates that many of these properties may be enhanced when delivered in combination with other cannabis compounds (known as the Entourage Effect). This can often make it difficult to determine the exact efficacy of this multi-profile plant.

Furthermore, many patients who benefit from medical cannabis treatments suffer from multiple pathologies, which often would exclude them from RCTs. Some argue that this narrows the relevance of RCTs in the context of medical cannabis and other therapies like it. In answer to this discrepancy, there has been a recent uptick in the collection of real-world evidence, through UK patient registries like Project Twenty21 and the UK Medical Cannabis Registry. These registries assess patient- and clinician-reported outcomes of medical cannabis patients undergoing treatment for a large variety of conditions. It is hoped that the observational evidence collected through these projects, and others like it, will – alongside clinical trials – help to further patient access to medical cannabis in the UK.

Clinical trials – whether RCTs or not – undoubtedly remain an extremely important part of medical development. While it may not always be ideal, for now, medical cannabis will need to continue to jump through the hoops of these research requirements if access is to be expanded.