Special Edition 2021

REVIEWS

REVIEWS

©Rolf Schulten/Buchcover/Photononstop

Medical cannabis in chronic pain An option for some types of pain, while awaiting further evaluation

● In three randomised trials in a total of 686 patients with multiple sclerosis, the oromucosal spray containing a mixture of standardised Can- nabis sativa extracts was more effective than pla- cebo in relieving painful muscle spasms for about 10% of patients. ● Adverse effects were common in the clinical trials, and were consistent with those known to occur with recreational cannabis use, primarily dizziness and psychiatric disorders. Many drug interactions are foreseeable with cannabinoids. ● Withdrawal symptoms have been observed in newborns exposed to cannabis in utero. A poten- tial long-term effect on neuropsychological devel- opment after in utero exposure has not been ruled out. Cannabinoids pass into breast milk in consid- erable quantities. ● In practice, the adverse effects of cannabis are quite well known, except in pregnancy. They are frequent and sometimes severe, but reversible. Despite little evidence of their efficacy, cannabis-­ derived drugs sometimes appear to be an option to consider to produce a feeling of wellbeing in patients with neuropathic pain, cancer pain or spasticity-related pain. Rev Prescrire 2021; 41 (448): 116-121 Full review (5 pages) available to subscribers at english.prescrire.org ▶ Translated from Rev Prescrire February 2021 Volume 41 N° 448 • Pages 116-121

ABSTRACT

● France has announced the start of an experimen- tal programme in 2021 involving the use of medical cannabis for certain painful conditions. How effect- ive are cannabis and its derivatives in these situ- ations?And what are their adverse effects?To answer these questions, we reviewed the available evidence using the standard Prescrire methodology . ● The main cannabis-derived substances that have been evaluated in these situations are: a mix- ture of standardised Cannabis sativa extracts, con- taining delta-9-tetrahydrocannabinol ( THC ) and cannabidiol ; THC or preparations containing THC ; and the synthetic THC analogue nabilone . ● In an analysis of 16 double-blind randomised trials, including a total of 1750 adults with neuro- pathic pain, the analgesic effect of the cannabis derivatives evaluated appeared to be tangibly superior to placebo in only about 5% of treated patients. Possible publication bias reduces the strength of this evidence. ● The mixture of standardised Cannabis sativa extracts in oromucosal spray form has been evalu- ated in five double-blind randomised trials in a total of 1539 patients with cancer-related pain. No anal- gesic effect beyond that of a placebo was found.

Prescrire Int • May 2021

P rescrire I nternational S pecial E dition 2021 • P age 13