Purpose: The aim of this review was to assess the efficacy of cannabis preparations for relieving pain in patients with malignant diseases, through a systematic review of randomized controlled trials (RCTs), which were predominantly double-blind trials that compared cannabis preparation to a placebo.
Methods: An electronic search of all literature published until June 2017 was made in MEDLINE/PubMed, Embase, The Cochrane Controlled Trials Register and specific web pages devoted to cannabis.
Results: Fifteen of the 18 trials demonstrated a significant analgesic effect of cannabinoids as compared to placebo. The most commonly reported adverse effects were generally well tolerated, mild to moderate. The main side effects were drowsiness, nausea, vomiting and dry mouth. There is evidence that cannabinoids are safe and modestly effective in neuropathic pain and also for relieving pain in patients with malignant diseases. The proportion of "responders" (patients who at the end of 2 weeks of treatment reported =30% reduction in pain intensity on a scale of 0-10, which is considered to be clinically important) was 43% in comparison with placebo (21%).
Conclusion: The target dose for relieving pain in patients with malignant diseases is most likely about 10 actuations per day, which is about 27 mg tetrahydrocannabinol (THC) and 25 mg cannabidiol (CBD), and the highest approved recommended dose is 12 actuations per day (32 mg THC/30 mg CBD). Further large studies of cannabinoids in homogeneous populations are required.
The popular press has increasing information on the medical use of cannabinoids. This study looked at the use of cannabinoids for pain in patients with cancer. Like a recent meta-analysis (JAMA. 2015;313(24):2456-2473. doi:10.1001/jama.2015.6358) they found some data for cannabinoids in neuropathic pain. The emphasis of this article is nabiximols - an oromucosal cannabis-based spray combining a CB1 partial agonist (THC) with a cannabinoid system modulator (CBD). The article reviews a number of studies of this drug and its efficacy in cancer pain. While interesting there is not enough details to evaluate the methods of these studies. This spray is not available in the United States.
This review of cannabinoids in palliative care gives some up to date information on dosing, but again shows that more studies are needed.
This article does not give enough robust evidence to influence my clinical practice.