by Dr Richard Griffiths, Research Manager, Arthritis New Zealand

Our September 2020 edition of Joint Support (pages 6 and 7) included an overview of the benefits and risks associated with the medicinal use of cannabis and how cannabis, including its recreational form, may potentially help people with arthritis. It also provided a summary of what was happening with regards to New Zealand law and recreational cannabis in the build-up to the Cannabis Legalisation and Control Bill Referendum which was part of the 2020 New Zealand General Election. My article offers an update in this area of interest to our readers and some insights from a few recently published studies related to arthritis and cannabis.

Defining Cannabis

There are many different names for cannabis as well as the products associated with its medicinal use. While recreational cannabis is also known colloquially as “marijuana”, “weed” or “pot”, it is becoming increasingly common to hear the terms “CBD” or “cannabidiol” when people are talking about medicinal or medical cannabis. In an extremely informative episode of Professor David Hunter’s Joint Action podcast entitled ‘Why does my knee hurt’ (20th April 2020), Professor Hunter’s guest Dr. Jason McDougall, from Dalhousie University (Canada), offers a very useful definition of cannabis:

“Cannabis is a very complicated plant. There are hundreds and hundreds of different chemical entities that are in cannabis and we are only just scratching the surface of understanding what those different cannabinoids are and what they can do. The two main ones that are investigated are THC, which is tetrahydrocannabinol, and that’s the psychoactive part of cannabis, that’s the part that gives the feeling of euphoria and highs…. The other main component is cannabidiol or CBD and CBD is non-psychoactive. It can make you feel a little sleepy, but it doesn’t have that euphoric effect associated with it” (‘Why does my knee hurt’,, 20th April 2020).

In my article care is taken wherever possible to refer to either recreational or medicinal cannabis.

New Zealand Law and Recreational Cannabis – An Update

Close to three million votes were received in relation to the Cannabis Legalisation and Control Bill Referendum held on 17th October 2020. The Referendum asked voters the question, “Do you support the proposed Cannabis Legalisation and Control Bill?” Importantly, the Referendum was only in relation to recreational cannabis. While 50.7% of New Zealanders did not support the bill, 48.4% of voters selected “yes” when voting in the referendum. Although the result was extremely close, the fact that more people chose “no” means that recreational cannabis remains illegal in our country in 2021. The Government has also indicated that the referendum result means they will not pursue legalisation or decriminalisation of recreational cannabis at this time. Parties in favour of a law change are however continuing their advocacy efforts. The 2021 Parliamentary Drug Policy Symposium held very recently at Parliament on 12th and 13th May is one such notable example featuring speakers such as the Rt Hon Helen Clark, Dr Huhana Hickey and Professor Michael Baker.

Research Insights

In their 2017 article, ‘Is cannabis an effective treatment for joint pain’ published in Clinical and Experimental Rheumatology, Richard and Rachael Miller note that cannabis has been used in the treatment of pain and for other medical purposes for thousands of years in Asian countries. They also note that the 19th century saw cannabis introduced into the United States and Europe where it started to be widely utilised for its analgesic properties. While significant changes to cannabis’ legal status in the early 20th century limited its evaluation using modern scientific criteria, the past decade has seen greater acceptance through the increasing availability of medicinal cannabis but also the legalisation of recreational cannabis in countries such as Australia, Canada and the United States.

The body of literature that investigates the therapeutic potential of cannabis and cannabinoids in relation to different health conditions is vast and growing annually. The Office of Medicinal Cannabis in Victoria, Australia for example publishes quarterly updates on current international research which evaluates the therapeutic potential of medicinal cannabis. Their latest release in September 2020 for example provides interested readers 168 pages of references and references with abstracts in relation to areas such as palliative care, cancer, mental health and pain. There are eight papers that specifically discuss arthritis, including Melissa O’Brien and Jason McDougall’s 2018 paper published in Current Opinion in Pharmacology which is referenced below.

Is cannabis an effective treatment for joint pain? (R.J. Miller and R.E. Miller 2017) – Clinical and Experimental Rheumatology (S-59 – S-67)

  • The authors suggest that the preclinical and human data that exists “indicate that the use of cannabis should be taken seriously as a potential treatment of joint pain” (S-59).
  • They cite a 2015 survey of medical cannabis users aged 18 – 83 years in Arizona, USA (n=367) which revealed that 77% of patients with fibromyalgia and 62% of patients with osteoarthritis (OA) reported experiencing “a lot or almost complete overall pain relief”.
  • They also note that while significant preclinical data have highlighted the potential therapeutic benefits of smoked (or recreational) cannabis for pain relief in patients with OA, rheumatoid arthritis (RA), fibromyalgia and cancer, at the time of publication, no randomised controlled trials for smoked (or recreational) cannabis have been carried out for these conditions.
  • They conclude that large scale clinical trials involving recreational cannabis need to be conducted in the near future to explore its potential in the health arena.

Cannabis and joints: scientific evidence for the alleviation of osteoarthritis pain by cannabinoids (M. O’Brien and J.J. McDougall 2018) – Current Opinion in Pharmacology (40: 104-109)

  • The authors state that OA-related pain is one of the most common types of pain and that patients with OA often use medical cannabis to manage their symptoms.
  • Up to 60% of OA patients are not satisfied with their current pain management.
  • There is a “growing body of scientific evidence which supports the analgesic potential of cannabinoids to treat OA pain” (p.104).
  • Ongoing research indicates that the human body’s endocannabinoid system, which is one of our “natural analgesic systems”, is a “viable target for new OA therapies”.
  • Very few clinical trials investigating cannabinoids in OA patients have either been completed or are underway (at the time of publication).

Cannabis and Cannabinoids in the Treatment of Rheumatic Diseases (T. Gonen and H. Amital 2020) – Rambam Maimonides Medical Journal (Volume 11, Issue 1: 1-7)

  • This paper discusses the current literature relating to cannabis and cannabinoids as a treatment for rheumatic diseases and also considers fibromyalgia, RA and OA.
  • The authors cite results from a UK-based study published in 2006 which was the first controlled trial of cannabis-based medicines in the symptomatic treatment of RA in humans. The study showed that compared to a placebo being used, Sativex (a cannabis-based drug) was associated with significant improvements in sleep quality and pain at rest and pain on movement. Importantly, this study found no serious adverse effects in those participants in the active treatment group.
  • They conclude that the use of cannabis and cannabinoids as a form of pain relief in patients with chronic pain that comes from rheumatic diseases and especially fibromyalgia demonstrates “great potential”.
  • They do however caution that despite the evidence on this potential, the literature they reviewed on the use of cannabis as a treatment for chronic pain, in general, contains “conflicting reports”.

What Is Arthritis New Zealand Doing About Access To Medicinal Cannabis?

Arthritis New Zealand is looking at further research into the effectiveness of and access to medicinal cannabis. We will be discussing these issues with our medical advisors.

How Can You Help?

Tell us your experiences and thoughts about using or trying to access medicinal cannabis by taking part in a quick, 5-minute anonymous survey.

This survey will enable us to gain a better understanding of our consumers’ needs in relation to this type of medicine. Please be reassured that the type of cannabis we are asking you about is medicinal cannabis only which is legal in New Zealand and being increasingly prescribed by health professionals.  

If you have any questions or comments regarding this article or the survey, please send an email to Dr Griffiths by using the contact form below.

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