The following is a summary from the 42nd Annual Scientific Meeting of the Australian Pain Society, which took place from April 10-13 in Hobart, Tasmania. This year, the Meeting featured a new item on the program—a debate. The inaugural debate focused on whether medicinal cannabis is the next opioid crisis. The evidence (or lack thereof) for medicinal cannabis use in the pain sector was discussed, with unique insights from political and consumer perspectives in addition those provided from clinicians and researchers. Read on to see how the debate played out.

The use of medicinal cannabis for chronic pain is a hotly debated topic and has been so for several years. Locally, the use of medicinal cannabis made headlines again in February when Australian basketball great Lauren Jackson hinted at making a surprise comeback from retirement.

Jackson represented Australia in four Olympics but was unable to compete at the 2016 Rio games due to an anterior cruciate ligament (ACL) injury. Since her retirement, Jackson has advocated for medicinal cannabis use for chronic pain based on her own experiences post-injury. Obtaining an exemption to continue using medicinal cannabis while competing was a key for Jackson’s comeback plans.

But is medicinal cannabis the next opioid crisis waiting to happen?

Current usage exceeds evidence base

Professor Iain McGregor, Academic Director for the Lambert Initiative for Cannabinoid Therapeutics at the University of Sydney, opened the debate by discussing the performance of medicinal cannabis since its prescription as an unregistered medication was legislated in late 2016.

Prof Iain McGregor at the podium, Prof Mark Hutchinson seated

McGregor highlighted there had been over 240,000 medicinal cannabis product prescriptions for 90,000 patients, with the majority of these occurring in the last two years. Most prescriptions (over 60%) were for chronic pain; more than all other indications combined—including anxiety and sleep.

Approximately 4,000 prescribers—mostly GPs—have issued a prescription for one of the more than 240 products available for prescription. It was here that McGregor delivered the first punch of the debate, citing that 4% of medicinal cannabis prescribers were “naughty” members of the Faculty of Pain Medicine (FPM). Prescribing cannabinoid products for chronic non-cancer pain outside of a registered clinical trial goes against Faculty recommendations on this matter.

McGregor went on to cite data from the recently completed but unpublished Cannabis as Medicine Survey 2020. Of the more than 1,600 respondents who had used cannabis—illicit or prescribed—for medical reasons in the past 12 months, over 80% reported their condition as much better or very much better due to cannabis use.

But it isn’t just patients who support the use of medical cannabis. In another recent survey of Australian GPs, McGregor highlighted that more than half of the 505 respondents supported the prescription of medicinal cannabis. However, GPs felt medicinal cannabis should only be available for certain patient groups and lacked confidence in discussing its use with their patients.

Attendees were reminded of the “grotesque carnage” caused by opioids as McGregor moved onto describe the associations between prescribing and harms for both opioids and medicinal cannabis. Although a similar number of people used an opioid or cannabis in 2016/17—approximately three million people each—the number of hospitalisations, emergency department visits, and deaths related to opioids were far higher than that of cannabis. But McGregor didn’t shy away from discussing the side effects of medicinal cannabis—such as dizziness, vertigo, and increased appetite—nor that the quality of published evidence for medicinal cannabis is poor.

McGregor concluded by reminding the audience that in 2015 numerous families were facing criminal charges for using medicinal cannabis to treat their severely epileptic children, despite the remarkable therapeutic benefits the treatment was having. But today, these products have been legalised. Furthermore, they are also subsidised as part of the Pharmaceutical Benefits Scheme. McGregor predicts a similar path for the use of cannabis for pain.

Learning from past mistakes

Associate Professor Mick Vagg, Director of Pain Matrix, provided the opposing view. Vagg emphasised the need to look at the learnings from the opioid crisis to help determine whether the medical cannabis movement should be handled in the same way.

Vagg didn’t deny that too many opioids are prescribed within Australia. Rather, he asked the audience to consider the multitude of GPs who can’t access proper pain management such as personalised cognitive behavioural therapy. Vagg described how many GPs are put between a rock and a hard place when faced with the choice of prescribing low-value therapies such as opioids.

Like McGregor, Vagg discussed the lack of quality research regarding the use of medical cannabis for pain. Citing evidence from a recent randomised, placebo-controlled crossover study, Vagg highlighted that an 800mg dose of cannabidiol did not affect pain, hyperalgesia, or allodynia in healthy volunteers during an experimentally induced model of acute pain. This dose far exceeds what would typically be prescribed to patients. Vagg is concerned about the lack of effect despite the large dose, and questioned why it should be used for neuropathic pain when efficacy it yet to be demonstrated?

A/Prof Mick Vagg at the podium, seated L to R: Prof Mark Hutchinson and Prof Iain McGregor

The lack of data regarding the effects of long-term medical cannabis use was also highlighted. Adverse effects of cannabis include anxiety, suicidal tendencies, and psychotic symptoms. This could cause issues for the many patients with pain who are prescribed tricyclic antidepressants. There is a known interaction that will and does occur when taking these medications concurrently, but it is unclear whether the antidepressant dose needs to be raised or lowered when using cannabis.

Another area concerning Vagg is the advertising and regulation of medicinal products. In recent times advertisements for medical cannabis have gathered the second-highest number of complaints to the TGA, behind only fake COVID cures. He felt there was reckless promotion in the absence of both safety and efficacy data, and poor regulation of advertising.

Vagg concluded by stating the pain community was being “the right amount of sceptical” about medical cannabis and warned of being sucked in by confirmation bias. He acknowledged the anecdotes about cannabis being useful as a last resort treatment for pain but reminded the audience of the importance of finding the evidence for a new treatment before deciding it works, not the other way around.

What’s in a name?

Following the debate, McGregor and Vagg were joined on stage by the Honourable Ruth Forrest MLC (Independent Member for Murchison, Tasmania) and Ms Allison Park (consumer representative) for a panel debate led by facilitator Professor Mark Hutchinson.

Panel debate: L to R: Ms Allison Park, Hon Ruth Forrest MLC, A/Prof Mick Vagg and Prof Iain McGregor

Hutchinson also posed the question of whether more specific naming conventions for medical cannabis products—such as moving away from the word ‘cannabis’—would benefit things. The panel had mixed views on this suggestion.

Vagg was indifferent to what current or potential products were called, provided they were safe and effective. Forrest and Park didn’t think changing the name would influence consumers who were in favour of the product nor fool naysayers who were opposed to its use. In contrast, McGregor felt changing the cannabis name would have an effect, claiming a similar process had occurred for “marijuana”, which is now rarely used in scientific discourse.

Hutchinson then asked the panel to think about the scale of the problem. Specifically, given the large number of people affected by pain, what is the problem if some people benefit from medical cannabis, and these individuals can be identified?

Vagg felt the issue came down to the individual cost of benefiting from a particular treatment and whether they could get similar benefits elsewhere for the same cost. He pointed to the use of neuromodulation for pain as an example of the need to demonstrate products and treatments are safe and effective. While neuromodulation systems are highly expensive and are associated with a risk of infection, they are carefully introduced into practice if the benefits and harms are carefully monitored through rigorous monitoring.

McGregor addressed the role of patients in this discussion, citing surveys from the Lambert Initiative where cannabis users reported great benefits with next to no side effects. Forrest also touched on the patient issue, emphasising the need for informed consent with new treatments. This requires prescribers to have a good understanding of the benefits and risks. Forrest felt the only way to get to the point where prescribers were fully informed was through testing these products in randomised controlled trials—to which Vagg was very quick to jump in and remind everyone this was the position of the FPM.

Finally, Hutchinson asked the panel for a one word answer on whether we would still be having this debate a decade down the track. Forrest and Vagg suspected yes, Park hoped not, and McGregor cheekily responded with “psilocybin”—possibly implying that the debate will have moved onto other treatments. 

The debate and panel discussion certainly provided the Australian pain community with much to think about. It will be interesting to see these conversations continue to unfold at future meetings.  

Lincoln Tracy is a postdoctoral research fellow in the School of Public Health and Preventive Medicine at Monash University and freelance writer from Melbourne, Australia. He is a member of the Australian Pain Society and enthusiastic conference attendee. You can follow him on Twitter (@lincolntracy) or check out some of his other writing on his website.

Related reading

Dieterle M, Zurbriggen L, Mauermann E, et al. Pain response to cannabidiol in opioid-induced hyperalgesia, acute nociceptive pain, and allodynia using a model mimicking acute pain in healthy adults in a randomized trial (CANAB II) [published online ahead of print, 2022 Jan 24]. Pain. doi:10.1097/j.pain.0000000000002591

Fisher E, Moore RA, Fogarty AE, et al. Cannabinoids, cannabis, and cannabis-based medicine for pain management: a systematic review of randomised controlled trials. Pain. 2021;162(Suppl 1):S45-S66. doi:10.1097/j.pain.0000000000001929

Karanges EA, Suraev A, Elias N, Manocha R, McGregor IS. Knowledge and attitudes of Australian general practitioners towards medicinal cannabis: a cross-sectional survey. BMJ Open. 2018;8(7):e022101. doi:10.1136/bmjopen-2018-022101

Lintzeris N, Mills L, Suraev A, et al. Medical cannabis use in the Australian community following introduction of legal access: the 2018-2019 Online Cross-Sectional Cannabis as Medicine Survey (CAMS-18). Harm Reduct J. 2020;17(1):37. doi:10.1186/s12954-020-00377-0

Mohiuddin M, Blyth FM, Degenhardt L, et al. General risks of harm with cannabinoids, cannabis, and cannabis-based medicine possibly relevant to patients receiving these for pain management: an overview of systematic reviews. Pain. 2021;162(Suppl 1):S80-S96. doi:10.1097/j.pain.0000000000002000

Schneider T, Zurbriggen L, Dieterle M, et al. Pain response to cannabidiol in induced acute nociceptive pain, allodynia, and hyperalgesia by using a model mimicking acute pain in healthy adults in a randomized trial (CANAB I). Pain. 2022;163(1):e62-e71. doi:10.1097/j.pain.0000000000002310

About Australian Pain Society

The Australian Pain Society is a multidisciplinary body aiming to relieve pain and related suffering through leadership in clinical practice, education, research and public advocacy.

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