A Canadian working group has conducted a literature review and has drawn up clinical practice guidelines for chronic pain management with cannabinoid-based therapies.
Globally, chronic pain is rather widespread, and most sufferers report long-lasting, moderate to severe symptoms. Furthermore, chronic pain often occurs with other conditions, such as insomnia, anxiety, depression and alcohol and opioid abuse disorders.
All these disorders are among the conditions most frequently treated with cannabinoid-based products.
A group of Canadian researchers, clinicians and patient organisations has conducted a review of the literature with the aim of developing clinical practice guidelines to support doctors and patients in the appropriate use of cannabinoids for the management of chronic non-cancer pain and co-occurring conditions.
The working group used 8 databases of scientific studies, selecting 70 papers published between 2001 and 2019, 51 original research studies and 19 systematic reviews, which were analysed separately to avoid redundancies.
Benefits and recommendations for practice
Of the systematic reviews analysed, most (12 out of 19) only included randomised controlled clinical trials.
In most reviews (14 out of 19), cannabinoids proved effective in reducing chronic pain in at least some contexts, for example neuropathic pain or multiple sclerosis-related pain. The 8 reviews assessed were considered to meet good quality standards; 7 of them indicated the benefits of cannabinoids in the treatment of chronic pain, although in some cases the analgesic effect was found to be moderate or mild.
Some reviews also analysed co-occurring conditions associated with chronic pain, providing substantially consistent results on the benefits regarding sleep issues and quality, while the results concerning efficacy for mood disorders, anxiety and depression were more heterogeneous.
The adverse events associated with cannabinoid use analysed in the systematic reviews, albeit common, were generally mild or moderately severe, and not always entirely attributable to cannabinoids, the most common ones being drowsiness, dizziness and dry mouth.
Among the selected original studies, 47 were considered relevant in terms of chronic pain management, 22 of which were randomised controlled trials – these studies involved over 11 thousand patients in total.
Following the analysis of the data, the working group drew up strong guidelines, based on moderate quality evidence from 38 studies, supporting the use of cannabinoid-based medicines, especially as a replacement or adjunctive treatment for chronic pain management, including central and peripheral neuropathic pain, with the aim of improving pain outcomes.
Strong recommendations were also made to support the therapeutic use of cannabinoids for certain conditions associated with chronic pain.
In the case of HIV, the recommendation concerns patients who have inadequate response to or experience adverse effects with other treatments.
In people with multiple sclerosis, cannabinoids are recommended, in addition to standard therapies, for the management of chronic pain, muscle spasms, and sleep disorders, when the response to other treatments is not adequate.
Similarly, the guidelines recommend the use of these medicines for patients with chronic pain due to arthritis, which does not respond adequately to other analgesic therapies.
Furthermore, cannabinoids are indicated as adjunctive treatment for the management of back pain and other chronic pain in fibromyalgia patients who do not have an adequate response to standard analgesics.
Cannabinoids are also considered useful to improve sleep and sleep deprivation symptoms in people with chronic pain who do not respond to or are intolerant to other pharmacological treatments.
With regard to loss of appetite associated with chronic pain, the use of THC-predominant cannabis has benefits compared to no treatment.
Lastly, the use of cannabinoid-based medicines as adjunctive therapy is indicated in patients with chronic pain to improve anxiety symptoms, when there is no response to non-pharmacological treatment.
Cannabinoids and opioids
Four of the analysed studies assessed specifically the efficacy of the combination of opioid analgesics and cannabis therapy for chronic pain, observing further pain reduction. Therefore, the guidelines recommend cannabinoid-based medicines as adjunctive treatment to opioids, for chronic pain management in people who have unsatisfactory analgesic effects from opioid treatment alone.
Furthermore, most participants in the analysed studies reduced the routine use of painkillers with the concomitant administration of cannabinoids and opioids, ensuring benefits also in terms of improved sleep, anxiety and mood, and prevention of opioid tolerance and dose escalation.
Therefore, according to the guidelines, therapy with cannabinoid-based medicines is recommended as an adjunctive treatment in patients who use moderate or high doses of opioids, for chronic pain management and to reduce opioid consumption, as well as for people who, regardless of the dose of opioids, do not achieve chronic pain management goals, or have adverse effects or risk factors.
Reference
Bell AD, MacCallum C, Margolese S, et al. Clinical practice guidelines for cannabis and cannabinoid-based medicines in the management of chronic pain and co-occurring conditions. Cannabis Cannabinoid Res. 2024 Apr;9(2):669-687.
