Cannabinoids in the management of difficult to treat pain Cannabinoids for treatment of spasticity and other symptoms related to multiple sclerosis (CAMS study): multicentre randomised placebo-controlled trial Are oral cannabinoids safe and effective in refractory neuropathic pain? A double-blind, placebo-controlled, crossover pilot trial with extension using an oral mucosal cannabinoid extract for treatment of chemotherapy-induced neuropathic pain.
This article review s recent research on cannabinoid analgesia via the endocannabinoid system and non-receptor mechanisms , as well as r and omized clinical trials employing cannabinoids in pain treatment .  Tetrahydrocannabinol ( THC , Marinol ® ) and nabilone ( Cesamet ® ) are currently approved in the United States and other countries , but not for pain indications . Other synthetic cannabinoids , such as ajulemic acid , are in development . Crude herbal cannabis remains illegal in most jurisdictions but is also under investigation . Sativex ® , a cannabis derived oromucosal spray containing equal proportions of THC ( partial CB1 receptor agonist ) and cannabidiol ( CBD , a non-euphoriant , anti-inflammatory analgesic with CB1 receptor antagonist and endocannabinoid modulating effects ) was approved in Canada in 2005 for treatment of central neuropathic pain in multiple sclerosis , and in 2007 for intractable cancer pain . Numerous r and omized clinical trials have demonstrated safety and efficacy for Sativex in central and peripheral neuropathic pain , rheumatoid arthritis and cancer pain . An Investigational New Drug application to conduct advanced clinical trials for cancer pain was approved by the US FDA in January 2006 . Cannabinoid analgesics have generally been well tolerated in clinical trials with acceptable adverse event profiles . Their adjunctive addition to the pharmacological armamentarium for treatment of pain shows great promise BACKGROUND Multiple sclerosis is associated with muscle stiffness , spasms , pain , and tremor . Much anecdotal evidence suggests that cannabinoids could help these symptoms . Our aim was to test the notion that cannabinoids have a beneficial effect on spasticity and other symptoms related to multiple sclerosis . METHODS We did a r and omised , placebo-controlled trial , to which we enrolled 667 patients with stable multiple sclerosis and muscle spasticity . 630 participants were treated at 33 UK centres with oral cannabis extract ( n=211 ) , Delta9-tetrahydrocannabinol ( Delta9-THC ; n=206 ) , or placebo ( n=213 ) . Trial duration was 15 weeks . Our primary outcome measure was change in overall spasticity scores , using the Ashworth scale . Analysis was by intention to treat . FINDINGS 611 of 630 patients were followed up for the primary endpoint . We noted no treatment effect of cannabinoids on the primary outcome ( p=0.40 ) . The estimated difference in mean reduction in total Ashworth score for participants taking cannabis extract compared with placebo was 0.32 ( 95 % CI -1.04 to 1.67 ) , and for those taking Delta9-THC versus placebo it was 0.94 ( -0.44 to 2.31 ) . There was evidence of a treatment effect on patient-reported spasticity and pain ( p=0.003 ) , with improvement in spasticity reported in 61 % ( n=121 , 95 % CI 54.6 - 68.2 ) , 60 % ( n=108 , 52.5 - 66.8 ) , and 46 % ( n=91 , 39.0 - 52.9 ) of participants on cannabis extract , Delta9-THC , and placebo , respectively . INTERPRETATION Treatment with cannabinoids did not have a beneficial effect on spasticity when assessed with the Ashworth scale . However , though there was a degree of unmasking among the patients in the active treatment groups , objective improvement in mobility and patients ' opinion of an improvement in pain suggest cannabinoids might be clinical ly useful Although cannabinoids have anti‐hyperalgesic effects in animal models of nerve injury , there are currently very few prospect i ve trials of the efficacy of cannabinoids in neuropathic pain in humans . This open label prospect i ve study investigated the safety , tolerability and analgesic benefit of oral Δ‐9‐tetrahydrocannabinol ( THC ) titrated to a maximal dosage of 25 mg/day in 8 consecutive patients with chronic refractory neuropathic pain .  Spontaneous ongoing and paroxysmal pain , allodynia and paresthesias were assessed . The sensory and affective components of pain using the McGill pain question naire , quality of life , mood , anxiety and functionality were also evaluated . Seven patients suffered from  side effects  necessitating premature arrest of the drug in 5 of them . THC ( mean dosage : 16.6 ± 6.5 mg/day ) did not induce any significant effects on ongoing and paroxysmal pain , allodynia , quality of life , anxiety/depression scores and functional impact of pain . These results do not support an overall benefit  of  THC in pain and quality of life in patients with refractory neuropathic pain CONTEXT Neuropathic pain caused by chemotherapy limits dosing and duration of potentially life-saving anti-cancer treatment and impairs quality of life . Chemotherapeutic neuropathy responds poorly to conventional treatments , and there is an urgent medical need for new treatments . Recent pre clinical studies demonstrate that cannabinoid agonists suppress established chemotherapy-evoked neuropathy . OBJECTIVES This was a pilot trial to begin to investigate a currently available cannabinoid agent , nabiximols ( oral mucosal spray containing cannabinoids ) , in the treatment of chemotherapy-induced neuropathic pain . METHODS A r and omized , placebo-controlled crossover pilot study was done in 16 patients with established chemotherapy-induced neuropathic pain . A 0 - 10 point numeric rating scale for pain intensity ( NRS-PI ) was used as the primary outcome measure . RESULTS When examining the whole group , there was no statistically significant difference between the treatment and the placebo groups on the NRS-PI . A responder analysis demonstrated that there were five participants who reported a two-point or greater reduction in pain that trended toward statistical significance and the number needed to treat was five . CONCLUSION Chemotherapy-induced neuropathic pain is particularly resistant to currently available treatments . This pilot trial found a number needed to treat of five and an average decrease of 2.6 on an 11-point NRS-PI in five " responders " ( as compared with a decrease of 0.6 with placebo ) and supports that it is worthwhile to study nabiximols in a full r and omized , placebo-controlled trial of chemotherapy-induced neuropathic pain
DISCUSSION Although cannabinoids are now being used to manage different pain conditions , the evidence for the clinical effects are unclear .
INTRODUCTION Pain is a frequent clinical symptom with significant impact on the patient 's well-being .
Therefore , adequate pain management is of utmost importance .
While cannabinoids have become a more popular alternative to traditional types of pain medication among patients , the quality of evidence supporting the use of cannabinoids has been question ed .
The beneficial and harmful effects of cannabinoids in patients with pain is unknown .
Accordingly , we aim to assess the efﬁcacy , tolerability and safety of cannabinoids ( herbal , plant-derived extracts and synthetic ) compared with placebo or no intervention for any type of pain .