Importance of the field: In recent times, our knowledge of cannabinoids and the endocannabinoid system has greatly advanced. With expanding knowledge, synthetic cannabinoids - including nabilone, dronabinol and a combination of synthetic Delta9-THC and cannabidiol - have been developed and tested for benefit in a variety of therapeutic indications.
Areas covered in this review: The aim of this article is to provide a summative review of the vast amount of clinical trial data now available on these agents.
What the reader will gain: To locate clinical trials for review, a literature search was performed using PubMed between the dates of 25 May and 30 June 2009. Search parameters were set to isolate only human randomized controlled trials (RCTs) published between 1990 and 2009. Keywords consistently used for each search include: cannabinoids, marijuana, THC, nabilone and dronabinol. Preferential selection was given to the best-designed trials, focusing on placebo-controlled, double-blind RCTs with the largest patient populations, if available.
Take home message: As efficacy and tolerability of these agents remain questionable, it is important that cannabinoids not be considered 'first-line' therapies for conditions for which there are more supported and better-tolerated agents. Instead, these agents could be considered in a situation of treatment failure with standard therapies or as adjunctive agents where appropriate.