Chronic pain, poorly managed by conventional medicine, afflicts one in five Europeans, with a significant impact on the quality of life (QoL). Depression, anxiety, and sleep disorders are common results of chronic pain. A survey of chronic pain sufferers revealed that one-third had tried three or more prescription treatments but more than 50% only obtained pain relief one or two days a week, and 68% were in pain for ≥12 hours daily. Flowering buds, resinous exudates, and leaves of cannabis (Cannabis sativa, Cannabaceae) has been used for pain relief for centuries. Increased knowledge of the endocannabinoid system, preclinical, in vivo, and human studies indicate that cannabinoid agonists may act analgesic. Several systematic reviews and meta-analyses also support the use of cannabinoids for chronic pain.
The US National Academies of Sciences reported in 2017 that there is substantial evidence of cannabis’ efficacy in chronic pain in adults. Pain conditions reported to respond positively to cannabis therapies include neuropathic pain, pain or cancer, spasticity, acute pain, and other chronic pain syndromes. Use of medical cannabis is increasingly supported as an adjunct to or substitute for opiates in treating chronic pain, as cannabis may reduce their use and adverse effects (AEs), prevent the development of tolerance, and rekindle opiate sensitivity if prescribed doses become ineffective. Cannabis may thus also be useful in treating substance abuse. The authors investigated patterns of medical cannabis use and associated effects reported by patients with different types of chronic pain, using a patented strain of Dutch cannabis, Bedrocan, provided by the Dutch Ministry of Health (DMH) in the form of dried flower tops. This strain is standardized to provide 19% tetrahydrocannabinol (THC) and ≤1% cannabidiol (CBD).
This prospective, non-randomized, single-arm clinical trial was conducted in the Pain Therapy Unit of Santa Chiara University Hospital (Pisa, Tuscany, Italy) between November 2013 and September 2015. Willing patients diagnosed with a chronic pain condition who were 18 years of age or older, had chronic pain for over three months and inadequate or no response to conventional treatment, or adverse effects (AEs) that made conventional treatments intolerable, were enrolled. Pregnant and breast-feeding patients, those with certain heart conditions, and those with severe psychiatric or personality disorders including a history of substance abuse were excluded. Patients underwent psychological screening before enrollment to detect the latter exclusion criterion. At baseline and in follow-up phone calls after one, three, and six months and after one year, patients completed questionnaires evaluating psychopathological parameters of pain and its intensity, the effect on daily activities of living, and states of anxiety, depression, and emotional distress. The study agent was administered as a decoction, prepared by patients according to a method recommended by the Office of Medical Cannabis of the DMH and modified by the Department of Clinical Toxicology and Antidoping of the Local Health Authority of Tuscany, including the addition of milk or another lipid to the decoction or infusion. THC is fat-soluble and its administration with lipids substantially boosts bioavailability.
The study included 338 patients (66% women) averaging 60.9 ± 14 years of age (range 21-94 years) affected by pain of fibromyalgia (20%), radiculopathy (16%), headache (12%), arthritis (12%), various types of neuropathy (3%), or other conditions (37%). During the study period, 124 patients interrupted the cannabis therapy, 79 for lack of efficacy; 33%, AEs, especially sleepiness (30%) and mental confusion (25%). AEs ceased soon after cessation of cannabis. In 214 patients who completed the study and used the therapy for at least 12 months, the analysis found significant improvements in pain intensity, pain-related disability, anxiety, and depression compared to baseline (P < 0.001 for all). Differences between baseline values and data collected at follow-up points, separately analyzed, show differences in cannabis’s efficacy at different time points. For example, maximum benefits in pain intensity were mostly achieved within the first three months.
Psychological improvements continued throughout the study period, as did pain-related disability scores. While the observational nature of the study and its lack of a control or comparison arm prevent any conclusion that cannabis is more effective than other pain relievers, results suggest its value as a potential adjunct in most cases requiring opiates. Unfortunately, the authors did not track patients’ use of opiates or other pain remedies during the study. Notably, 38 patients dropped out because of prejudice against cannabis as a medicinal agent, while 87 reported being unable to obtain the study agent from pharmacies. The authors suggest bureaucratic barriers to the legal importation of Dutch cannabis by Italian pharmacies. In addition, 10 patients suspended treatment after one week because of the lack of immediate improvement. Randomized controlled trials are needed to better determine cannabis’s role in pain management. Limitations of this study include that an analysis of the actual decoction was not included. The information provided indicates very low decarboxylation to THC and limited recruitment of tetrahydrocannabinolic acid.
Poli P, Crestani F, Salvadori C, Valenti I, Sannino C. Medical cannabis in patients with chronic pain: effect on pain-relief, pain disability, and psychological aspects. A prospective non randomized single arm clinical trial. Clin Ter. May-June 2018;169(3):e102-e107 doi: 10.7417/T.2018.2062.