Comment on: Cannabis-based medicines for chronic neuropathic pain in adults

Chronic neuropathic pain in adults: Are cannabis-based medicines effective, tolerable and safe compared to a placebo or conventional drugs?

Chronic neuropathic pain affects 6 -10% of the world population. It is difficult to treat as only a small percentage of patients has substantial benefit from the treatment and often adverse effects outweigh the benefits. Recent guidelines consider conventional analgesics such as paracetamol and non-steroidal anti-inflammatory drugs to be ineffective, while tend to be generally in agreement about the use of antidepressants and anticonvulsants. The role of opioids and cannabis-based drugs is under debate. Several products based on the cannabis plant (inhaled herbal cannabis, sprays or tablets containing active cannabis ingredients natural or synthetic) have been suggested as treatment for pain, including neuropathic pain. 
This Cochrane review summarizes the current evidence on the use of cannabis-based medicines for chronic neuropathic pain in adults, and in particular its efficacy, tolerability, and safety compared to placebo or conventional drugs. Ten studies compared an oromucosal spray with a plant-derived combination of tetrahydrocannabinol (THC) and cannabidiol (CBD) versus a placebo. Two compared herbal cannabis and THC plants derived, with a placebo. Two studies compared an artificial cannabinoid (nabilone) with a placebo and a painkiller (Dihydrocodeine), respectively. 
All cannabis-based medicines resulted more effective than placebo in reducing pain, sleep problems and psychological distress. Due to some methodological limitations, the quality of this evidence was rated from very low to moderate. Adverse events like somnolence, sedation, confusion and psychosis, may limit the clinical usefulness of this medicines. 
Comment by Francesco Agostini