Article Text

other Versions

Efficacy of topical cannabinoids in the management of pain: a systematic review and meta-analysis of animal studies
  1. Lukas D Linde1,2,
  2. Carey M Ogryzlo1,
  3. Cassandra M Choles1,
  4. Brian E Cairns3 and
  5. John L K Kramer1,2
  1. 1International Collaboration on Repair Discoveries (ICORD), Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada
  2. 2Department of Anesthesiology, Pharmacology & Therapeutics, The University of British Columbia, Vancouver, British Columbia, Canada
  3. 3Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, British Columbia, Canada
  1. Correspondence to Dr Lukas D Linde, The University of British Columbia International Collaboration on Repair Discoveries, 818 W 10th Ave, Vancouver, BC V5Z 1M9, Canada; lukas.linde{at}ubc.ca

Abstract

Background/importance Cannabinoids are emerging as an alternative pain management option, preliminarily supported by preclinical and clinical studies. Unwanted side effects from oral or inhaled cannabinoids remain, however, a major barrier to widespread use. Peripherally acting cannabinoids (eg, topically applied) may circumvent these side effects while providing localized pain management.

Objective Our purpose was to systematically review the literature on the effectiveness of peripherally acting cannabinoids for pain management.

Evidence review We searched MEDLINE, EMBASE, CENTRAL, CINAHL, and PubMed databases. Included studies examined the effect of topical/peripherally administered cannabinoids on pain ratings in humans, as well as pain-related outcomes in animals (eg, paw withdrawal). Due to a lack of trials, human studies were summarized in a narrative synthesis. Separate meta-analyses were performed for animal studies using radiant tail flick or paw withdrawal outcomes.

Findings Our search yielded 1182 studies following removal of duplicates, with 46 studies (6 human, 40 animal) included. Human studies (one randomized controlled trial and five case studies/series) reported no adverse events to topical cannabinoids and preliminary evidence of decreased pain ratings. Animal studies reporting tail flick (5) (2.81, 95% CI 1.93 to 3.69, p<0.001) and mechanical withdrawal (11) (2.74, 95% CI 1.82 to 3.67, p<0.001) reported prolonged responses (analgesia) in peripheral cannabinoid groups compared with controls.

Conclusions Preclinical animal studies provided low-quality evidence for peripherally administered cannabinoids to provide regional, antinociceptive effects. The scarcity of high-quality human studies underscores the need to translate preclinical evidence into well-controlled human trials.

  • neurotransmitter agents
  • pain management
  • pain measurement
  • pharmacology

Data availability statement

All data relevant to the study are included in the article or uploaded as supplemental information. Our search protocol is available on PROSPERO (CRD42020155962) and all search strategies are available in supplemental materials.

Statistics from Altmetric.com

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.

Data availability statement

All data relevant to the study are included in the article or uploaded as supplemental information. Our search protocol is available on PROSPERO (CRD42020155962) and all search strategies are available in supplemental materials.

View Full Text

Footnotes

  • Contributors LDL—conceptualization, methodology, article screening, formal analysis, writing (original draft), writing (review and editing), software, and visualization. CMO—conceptualization, article screening, and writing (review and editing). CMC—article screening, quality assessments, formal analysis, and writing (review and editing). BEC—conceptualization and writing (review and editing). JLKK—conceptualization, writing (review and editing), supervision, resources, and project administration.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.