[DRAFT] The Endocannabinoid System – Ch 8: Chronic Pain & The ECS

Introduction

Chronic pain affects more than 100 million people and costs an estimated 635 billion dollars per year. On top of that, chronic pain treatment is difficult and many pharmacological options only work in a subset of patients. In response to the ongoing opioid crisis, which claimed ~42,000 lives in 2016 in the US, many patients have turned to cannabis as an alternative medication for their pain management. According to recent meta-analyses, cannabis is a promising analgesic for many chronic pain conditions. In the US, medical cannabis legislation is associated with 25% fewer opioid overdose deaths in states with medical cannabis laws compared to those without. Other studies of medical cannabis users in the US, Canada, and Israel have found similar results, with users reporting improved pain, a better quality of life, decreased opioid use, and in some cases, the direct substitution of Cannabis for opioids and other medications.

Literature

Researchers from the University of Michigan Medical School conducted an online survey to study how cannabis affects medical patients’ pain management, health, and pain medication use. In addition, they examined whether and how these parameters were affected by concomitant recreational use and duration of use. Of the 1,321 participants, ~80% reported substituting cannabis for traditional pain medications (53% for opioids and 22% for benzodiazepines), citing fewer side effects and better symptom management as their rationale. Medical users were older, less likely to drink alcohol, and more likely to be taking opioids than users with a combined recreational-medical history. Compared to novice users, experienced users were more likely to be male, take no concomitant pain medications, and report improved health with use.

Meanwhile, a systematic review by McGill University, the University Medical Center of Göttingen, the Technical University of Munich, and the hospital of Saarbrücken in Germany evaluated the efficacy, acceptability, and safety of cannabis-based medicines for chronic pain management. Their results showed that there are inconsistent findings on the efficacy of cannabinoids in neuropathic pain and painful spasms in multiple sclerosis. Furthermore, they found inconsistent results on the tolerability and safety of cannabis-based medicines for any chronic pain.

Limitations

Current studies describing the efficiency of cannabis-based medicines in chronic pain show several limitations.

• In the study by the University of Michigan Medical School, the cross-sectional design impeded them to examine changes over time, thus, they were forced to make inferences based on retrospective self-report data.
• They were also unable to know how many people were informed about their survey via the various recruitment methods, so they could not accurately estimate the response rate.
• Finally, they did not analyze administration routes, cannabinoid preferences, or cannabinoid content of products that might be related to medication substitution.

Conclusion

Cannabis-based medicines undoubtedly enrich the possibilities of drug treatment for chronic pain conditions. However, as with any analgesic, cannabis might not be adequate for some individuals due to its risk of abuse and lack of therapeutic response. Currently, studies can’t agree upon a preferred cannabis-based medicine for chronic pain. It has been debated that the scarcity of high-quality evidence reflects the hardship in conducting cannabis research due to government regulations on medical and recreational use. Regardless, it’s still a health worker’s responsibility to continue pursuing therapeutical evidences that meets the standard of 21st-century clinical care.