A Comprehensive Review of Cannabinoids for Difficult-to-Treat Pain | Research

The takeaway

Multiple randomized trials demonstrated cannabinoid efficacy and safety for neuropathic, cancer, and inflammatory pain, with Sativex approved in Canada for MS pain and cancer pain.

Read this if you have chronic pain and want a thorough overview of the clinical evidence for cannabinoid treatments.

Sativex approved for MS neuropathic pain (2005) and cancer pain (2007) in Canada

What the researchers found

This review by Ethan Russo comprehensively covered the evidence for cannabinoid use in pain management as of 2008.

Sativex (THC:CBD oromucosal spray) had been approved in Canada for MS central neuropathic pain (2005) and intractable cancer pain (2007). The US FDA had approved an Investigational New Drug application for advanced cancer pain trials in 2006.

The review covered multiple mechanisms of cannabinoid analgesia: endocannabinoid system modulation, non-receptor mechanisms, anti-inflammatory effects, and synergy with opioids. Clinical trial evidence supported efficacy in central and peripheral neuropathic pain, rheumatoid arthritis, and cancer pain.

Adverse effects were generally well tolerated, and the adjunctive use of cannabinoids alongside existing pain treatments showed "great promise." The review positioned cannabinoids as complementary additions to the pain medicine toolkit rather than standalone treatments.

Why it matters

This review captured the state of cannabinoid pain research at a time when the first cannabinoid medicines were receiving regulatory approval. It provided a comprehensive evidence-based framework that influenced clinical practice and further research.

The numbers in context

Sativex approved in Canada: MS neuropathic pain (2005), cancer pain (2007). US FDA IND approved for cancer pain (2006). Multiple RCTs demonstrated safety and efficacy across pain types.

How the study worked

Comprehensive narrative review of endocannabinoid system biology, non-receptor analgesic mechanisms, and randomized clinical trials of cannabinoids for pain.

What this study cannot tell us

Narrative review without systematic methodology. Many trials were industry-sponsored. Long-term safety data was limited. The evidence was strongest for neuropathic pain, with less robust data for other pain types.

How to read the evidence

This is a comprehensive review by a leading researcher, drawing on multiple RCTs, providing strong evidence for cannabinoid analgesia in certain pain conditions.

When this study was published

Published in 2008. The evidence base has continued to grow, and several additional countries have approved cannabinoid medicines for pain.

The bigger picture

This review helped establish cannabinoids as legitimate analgesics in mainstream pain medicine. The emphasis on adjunctive use alongside existing treatments anticipated the current paradigm of multimodal pain management.

Questions still open

How do cannabinoids compare head-to-head with established neuropathic pain drugs? Can cannabinoid analgesics meaningfully reduce opioid requirements in clinical practice?

Common questions

What types of pain respond best to cannabinoids?

Based on this review, the strongest evidence was for neuropathic pain (nerve pain), followed by cancer pain and inflammatory pain (like rheumatoid arthritis). Evidence for acute pain or postoperative pain was more limited.

Are cannabinoid pain medications available in the US?

As of this review (2008), dronabinol and nabilone were approved in the US but not specifically for pain. Sativex had FDA IND approval for cancer pain trials. Medical cannabis was available in some states.

Read the original research

Cannabinoids in the management of difficult to treat pain.

Therapeutics and clinical risk management, 4(1), 245-59

View on PubMed ↗

Citation

Russo, Ethan B. (2008). Cannabinoids in the management of difficult to treat pain.. Therapeutics and clinical risk management, 4(1), 245-59.