The Efficacy and Safety of the Use of Cannabis Products in the Management of Pain: A Systematic Review

Introduction: The medical applications of cannabis have generated controversy among experts. The main point of conflict is the evaluation of the expected therapeutic benefit compared to the side effects of its use. Aim: To determine whether cannabis is an effective and safe treatment option in the management of pain. Method: A systematic review was made of randomized controlled trials on the medical use of cannabis. Studies were retrieved from the electronic databases: Medline, Embase, Oxford Pain Database and Cochrane Library. The induction criterion was referral for use of a cannabis product as a therapeutic intervention for pain management (given by any route of administration), compared with any other analgesic drug or placebo (control intervention) in patients with acute, chronic non-malignant or cancer pain. The study results were examined according to the pain intensity scores. Of 20 randomized controlled trials identified, 11 were excluded, giving for review 9 studies (222 patients in total), 5 of which investigated cancer pain management, 2 chronic non-malignant pain and 2 postoperative pain. In all studies, the active substances tested were cannabinoids. Results: Delta-9- tetrahydrocannabinol (THC) 520 mg, the synthetic analogue of nitrogen THC 1 mg, and intramuscular levonantradol 1.53 mg were almost as effective as codeine 50-120 mg. Oral benzopyran pyridine 24 mg was less effective than codeine 60-120 mg and no more effective than placebo. Conclusions: Cannabinoids are no more effective than codeine in controlling pain and have a sedative effect on the central nervous system that limits their use. Their widespread introduction into clinical practice for pain management (cancer, chronic non-malignant, or postoperative pain), is therefore not recommended.