Are cannabinoids an effective and safe treatment option in the management of pain? A qualitative systematic review

Objective To establish whether cannabis is an effective and safe treatment option in the management of pain. Design Systematic review of randomised controlled trials. Data sources Electronic databases Medline, Embase, Oxford Pain Database, an d Cochrane Library; references from identified papers; hand searches. Study selection Trials of cannabis given by any route of administration (ex perimental intervention) with any analgesic or placebo (control interventio n) in patients with acute, chronic non-malignant, or cancer pain. Outcomes examined were pain intensity scores, pain relief scores, and adverse effect s. Validity of trials was assessed independently with the Oxford score. Data extraction Independent data extraction; discrepancies resolved by cons ensus. Data synthesis 20 randomised controlled trials were identified, 11 of which were excluded. Of the 9 included trials (222 patients), 5 trials related t o cancer pain, 2 to chronic non-malignant pain, and 2 to acute postoperativ e pain. No randomised controlled trials evaluated cannabis; all tested acti ve substances were cannabinoids. Oral delta-9-tetrahydrocannabinol (THC) 5- 20 mg, an oral synthetic nitrogen analogue of THC 1 mg, and intramuscular l evonantradol 1.5-3 mg were about as effective as codeine 50-120 mg, and ora l benzopyranoperidine 2-4 mg was less effective than codeine 60-120 mg and no better than placebo. Adverse effects, most often psychotropic, were comm on. Conclusion Cannabinoids are no more effective than codeine in controlling p ain and have depressant effects on the central nervous system that limit th eir use. Their widespread introduction into clinical practice for pain mana gement is therefore undesirable. In acute postoperative pain they should no t be used. Before cannabinoids can be considered for treating spasticity an d neuropathic pain, further valid randomised controlled studies are needed.