By Emily Ledger
Pain management is one of the most common reasons for the use of medical cannabis products. However, despite many jurisdictions – including Canada, Germany, and the Netherlands – now allowing the prescription of medical cannabis for this purpose, there remains little ‘high-quality’ evidence to support, or oppose its efficacy.
Madden et al. (2018) set out to review the evidence available in order to determine the efficacy of medical cannabis when employed in the management of various forms of musculoskeletal pain. The researchers analysed various studies that assessed the use of cannabinoids in the treatment of arthritis pain; back pain; postoperative pain; and trauma-related pain.
Pain Conditions and Treatment Options
It is estimated that up to 30% of the population may suffer from a non-cancer-related pain condition. As such a high percentage of people suffer from these conditions, the development of simple and safe therapies is an essential area of research.
This is particularly important as the therapeutic options for people with chronic pain are increasingly limited. There is a large population of chronic pain patients who are established on long-term opioids for chronic pain but may struggle to reduce or stop their opioids. This can expose them to significant harm, with some taking extremely high doses.
Additionally, long-term use of non-steroidal anti-inflammatory medications is associated with an increased risk of adverse cardiovascular outcomes and gut bleeding, particularly in older people. Evidence to support the prescribing of either medication in chronic pain is also limited.
Pain Conditions and Medical Cannabis
In recent years, the use of medical cannabis products has become more prevalent as a medical treatment option. Medical cannabis products contain cannabinoids as well as other compounds from the cannabis plant with a wide range of potential indications.
The most common cannabinoids used in medicines are cannabidiol (CBD) and tetrahydrocannabinol (THC). Cannabinoids are used on their own, or in conjunction, to treat pain by interacting with the human body’s own cannabinoid receptors, but also other pain receptor targets.
The Endocannabinoid System
The two main cannabinoid receptors are the CB1 and CB2 receptors. The CB1 receptors are found primarily within central and peripheral nervous systems. In comparison, CB2 receptors are highly concentrated in immune cells. The body produces its own cannabinoids which act at these receptors and together these are termed the endocannabinoid system.
Our understanding of the effects of cannabis on our health is continuously evolving due to the current wealth of research being undertaken globally. Whilst years of prohibition have harmed the utilisation of cannabis in drug discovery, it remains one of the world’s oldest utilised medicines and from this, we can draw a great deal about its safety.
Though evidence of the efficacy of cannabis is still debated, many laboratory and animal studies have demonstrated promising results. Studies in humans have also demonstrated the potential of cannabinoids as a therapy option for pain management. However, the majority of these trials have been small, making it difficult to draw extensive conclusions. Nevertheless, support for the use of cannabis medications is increasing amongst patients, governments and doctors.
A report in the USA assessed patients who use cannabis as a pain-management option. The report’s findings showed that 63% of patients reported complete or almost complete pain relief. In addition, 81% of those reported that they were able to decline their opioid use.
A Review of the Evidence
After systematically reviewing the current literature, the authors identified 118 studies which assessed the effect of medical cannabis on non-cancer-related musculoskeletal pain. These studies represented various conditions, including fibromyalgia (18); multiple sclerosis (71); spinal cord injury (19); and musculoskeletal (33).
Of these 118 studies, 85 (72%) demonstrated that cannabis was an effective treatment option for pain management. An additional 17 studies (14%) yielded mixed results, 11 (9%) that the treatment was ineffective, and the remaining 5 (4%) yielded inconclusive or unclear results.
These findings provide promising insight into the efficacy of cannabinoids in the management of pain across a variety of conditions. In relation to musculoskeletal, such as arthritis, postoperative pain, back pain, and trauma-related pain, there, unfortunately, is limited high-quality evidence.
The authors of the review conclude that a significant number of the total 118 studies were limited in quality. This was down to small sample sizes and a lack of control groups. However, despite the limited number of randomised controlled trials, the available literature suggests the potential efficacy of medical cannabis for pain management in a number of common conditions. Above all, the currently limited evidence highlights the need for continued research in the area.