Primary studies included in this systematic review

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Primary study

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Journal The journal of pain : official journal of the American Pain Society
Year 2015
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A randomized, double-blinded, placebo controlled crossover study was conducted in 16 patients with painful diabetic peripheral neuropathy to assess the short-term efficacy and tolerability of inhaled cannabis. In a crossover design, each participant was exposed to 4 single dosing sessions of placebo or to low (1% tetrahydrocannabinol [THC]), medium (4% THC), or high (7% THC) doses of cannabis. Baseline spontaneous pain, evoked pain, and cognitive testing were performed. Subjects were then administered aerosolized cannabis or placebo and the pain intensity and subjective “highness” score was measured at 5, 15, 30, 45, and 60 minutes and then every 30 minutes for an additional 3 hours. Cognitive testing was performed at 5 and 30 minutes and then every 30 minutes for an additional 3 hours. The primary analysis compared differences in spontaneous pain over time between doses using linear mixed effects models. There was a significant difference in spontaneous pain scores between doses (<i>P</i> &lt; .001). Specific significant comparisons were placebo versus low, medium, and high doses (<i>P</i> = .031, .04, and &lt;.001, respectively) and high versus low and medium doses (both <i>P</i> &lt; .001). There was a significant effect of the high dose on foam brush and von Frey evoked pain (both <i>P</i> &lt; .001). There was a significant negative effect (impaired performance) of the high dose on 2 of the 3 neuropsychological tests (Paced Auditory Serial Addition Test, Trail Making Test Part B. PERSPECTIVE: This small, short-term, placebo-controlled trial of inhaled cannabis demonstrated a dose-dependent reduction in diabetic peripheral neuropathy pain in patients with treatment-refractory pain. This adds preliminary evidence to support further research on the efficacy of the cannabinoids in neuropathic pain. (PsycInfo Database Record (c) 2022 APA, all rights reserved)

Primary study

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Journal Journal of neurology
Year 2015
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Despite the proven efficacy of Sativex(®) (9-delta-tetrahydrocannabinol plus cannabidiol) oromucosal spray in reducing spasticity symptoms in multiple sclerosis (MS), little is known about the neurophysiological correlates of such effects. The aim of the study was to investigate the effects of Sativex on neurophysiological measures of spasticity (H/M ratio) and corticospinal excitability in patients with progressive MS. This was a randomized, double-blind, placebo-controlled, crossover study. Consecutive subjects with progressive MS and lower limb spasticity referred to our center were randomized to 4 weeks' treatment (including 2 weeks' titration) with Sativex or placebo, with crossover after a 2-week washout. Clinical and neurophysiological measures (H/M ratio and cortical excitability) of spasticity were assessed. The H/M ratio was the primary outcome, with sample size calculation of 40 patients. Of 44 recruited patients, 34 were analyzed due to 6 drop-outs and 4 exclusions, which lowered the power of the study to show differences between treatments. Neurophysiological measures did not differ significantly according to treatment and did not correlate significantly with clinical response. Response on the modified Ashworth scale (at least 20 % improvement) was significantly more frequent after Sativex than placebo (50 vs 23.5 %; p = 0.041; McNemar). Side effects did not differ significantly according to treatment. Our findings confirm the clinical benefit of Sativex on MS spasticity. The lack of corresponding changes in corticospinal excitability and on the monosynaptic component, of the stretch reflex, although in a limited sample size, points to the involvement of other spinal and supraspinal mechanisms in the physiopathology of spasticity in progressive MS.

Primary study

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Journal European journal of pain (London, England)
Year 2014
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BACKGROUND: Peripheral neuropathic pain (PNP) associated with allodynia poses a significant clinical challenge. The efficacy of Δ⁹‐tetrahydrocannabinol/cannabidiol (THC/CBD) oromucosal spray, a novel cannabinoid formulation, was investigated in this 15‐week randomized, double‐blind, placebo‐controlled parallel group study. METHODS: In total, 303 patients with PNP associated with allodynia were screened; 128 were randomized to THC/CBD spray and 118 to placebo, in addition to their current analgesic therapy. The co‐primary efficacy endpoints were the 30% responder rate in PNP 0–10 numerical rating scale (NRS) score and the mean change from baseline to the end of treatment in this score. Various key secondary measures of pain and functioning were also investigated. RESULTS: At the 30% responder level, there were statistically significant treatment differences in favour of THC/CBD spray in the full analysis (intention‐to‐treat) dataset [<i>p</i> = 0.034; 95% confidence interval (CI): 1.05–3.70]. There was also a reduction in mean PNP 0–10 NRS scores in both treatment groups that was numerically higher in the THC/CBD spray group, but which failed to reach statistical significance. Secondary measures of sleep quality 0–10 NRS score (<i>p</i> = 0.0072) and Subject Global Impression of Change (SGIC) (p = 0.023) also demonstrated statistically significant treatment differences in favour of THC/CBD spray treatment. CONCLUSIONS: These findings demonstrate that, in a meaningful proportion of otherwise treatment‐resistant patients, clinically important improvements in pain, sleep quality and SGIC of the severity of their condition are obtained with THC/CBD spray. THC/CBD spray was well tolerated and no new safety concerns were identified. (PsycInfo Database Record (c) 2022 APA, all rights reserved)

Primary study

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Journal Journal of Multiple Sclerosis
Year 2014
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OBJECTIVE: When Sativex® THC/CBD cannabinoid-based oromucosal spray was first approved as a prescription medicine for multiple sclerosis (MS) spasticity, there was some concern about its possible long-term impact on cognition and mood. The objective of this study was therefore to assess the long-term impact of Sativex on cognitive function and mood in MS patients with spasticity. METHODS: 121 patients were randomly assigned Sativex or placebo in a double-blind manner. Patients selfadministered treatment daily for 48 weeks while maintaining anti-spasticity therapy. The primary endpoint was the difference between treatments in Paced Auditory Serial Addition Test (PASAT) score from baseline to end of treatment. Secondary measures included Beck Depression Inventory-II (BDI-II), Subject-, Physician- and Caregiver Global Impression of Change, and Columbia-Suicide Severity Rating Scale. RESULTS: 62 patients were randomised to Sativex and 59 to placebo. There was no difference in the effect of Sativex on PASAT and BDI-II scores compared with placebo. Subject-, Physician- and Caregiver-rated improvements in spasticity with Sativex were all statistically significant. The mean daily dose of Sativex declined gradually to 6.4 sprays per day. CONCLUSION: Long-term treatment with Sativex was not associated with cognitive decline or significant changes in mood in this prone population sample. Sativex was efficacious and well tolerated across the study period and no new safety concerns were identified.

Primary study

Unclassified

Journal The journal of pain : official journal of the American Pain Society
Year 2013
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We conducted a double-blind, placebo-controlled, crossover study evaluating the analgesic efficacy of vaporized cannabis in subjects, the majority of whom were experiencing neuropathic pain despite traditional treatment. Thirty-nine patients with central and peripheral neuropathic pain underwent a standardized procedure for inhaling medium-dose (3.53%), low-dose (1.29%), or placebo cannabis with the primary outcome being visual analog scale pain intensity. Psychoactive side effects and neuropsychological performance were also evaluated. Mixed-effects regression models demonstrated an analgesic response to vaporized cannabis. There was no significant difference between the 2 active dose groups' results (<i>P</i> &gt; .7). The number needed to treat (NNT) to achieve 30% pain reduction was 3.2 for placebo versus low-dose, 2.9 for placebo versus medium-dose, and 25 for medium- versus low-dose. As these NNTs are comparable to those of traditional neuropathic pain medications, cannabis has analgesic efficacy with the low dose being as effective a pain reliever as the medium dose. Psychoactive effects were minimal and well tolerated, and neuropsychological effects were of limited duration and readily reversible within 1 to 2 hours. Vaporized cannabis, even at low doses, may present an effective option for patients with treatment-resistant neuropathic pain. PERSPECTIVE: The analgesia obtained from a low dose of delta-9-tetrahydrocannabinol (1.29%) in patients, most of whom were experiencing neuropathic pain despite conventional treatments, is a clinically significant outcome. In general, the effect sizes on cognitive testing were consistent with this minimal dose. As a result, one might not anticipate a significant impact on daily functioning. (PsycInfo Database Record (c) 2022 APA, all rights reserved)

Primary study

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Journal Journal of neurology
Year 2013
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Central neuropathic pain (CNP) occurs in many multiple sclerosis (MS) patients. The provision of adequate pain relief to these patients can very difficult. Here we report the first phase III placebo-controlled study of the efficacy of the endocannabinoid system modulator delta-9-tetrahydrocannabinol (THC)/cannabidiol (CBD) oromucosal spray (USAN name, nabiximols; Sativex, GW Pharmaceuticals, Salisbury, Wiltshire, UK), to alleviate CNP. Patients who had failed to gain adequate analgesia from existing medication were treated with THC/CBD spray or placebo as an add-on treatment, in a double-blind manner, for 14 weeks to investigate the efficacy of the medication in MS-induced neuropathic pain. This parallel-group phase of the study was then followed by an 18-week randomized-withdrawal study (14-week open-label treatment period plus a double-blind 4-week randomized-withdrawal phase) to investigate time to treatment failure and show maintenance of efficacy. A total of 339 patients were randomized to phase A (167 received THC/CBD spray and 172 received placebo). Of those who completed phase A, 58 entered the randomized-withdrawal phase. The primary endpoint of responder analysis at the 30 % level at week 14 of phase A of the study was not met, with 50 % of patients on THC/CBD spray classed as responders at the 30 % level compared to 45 % of patients on placebo (p = 0.234). However, an interim analysis at week 10 showed a statistically significant treatment difference in favor of THC/CBD spray at this time point (p = 0.046). During the randomized-withdrawal phase, the primary endpoint of time to treatment failure was statistically significant in favor of THC/CBD spray, with 57 % of patients receiving placebo failing treatment versus 24 % of patients from the THC/CBD spray group (p = 0.04). The mean change from baseline in Pain Numerical Rating Scale (NRS) (p = 0.028) and sleep quality NRS (p = 0.015) scores, both secondary endpoints in phase B, were also statistically significant compared to placebo, with estimated treatment differences of -0.79 and 0.99 points, respectively, in favor of THC/CBD spray treatment. The results of the current investigation were equivocal, with conflicting findings in the two phases of the study. While there were a large proportion of responders to THC/CBD spray treatment during the phase A double-blind period, the primary endpoint was not met due to a similarly large number of placebo responders. In contrast, there was a marked effect in phase B of the study, with an increased time to treatment failure in the THC/CBD spray group compared to placebo. These findings suggest that further studies are required to explore the full potential of THC/CBD spray in these patients.

Primary study

Unclassified

Journal The journal of pain : official journal of the American Pain Society
Year 2012
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Patients with advanced cancer who have pain that responds poorly to opioid therapy pose a clinical challenge. Nabiximols (Nabiximols is the US Adopted Name [USAN] for Sativex [GW Pharma Ltd, Wiltshire, UK], which does not yet have an INN), a novel cannabinoid formulation, is undergoing investigation as add-on therapy for this population. In a randomized, double-blind, placebo-controlled, graded-dose study, patients with advanced cancer and opioid-refractory pain received placebo or nabiximols at a low dose (1–4 sprays/day), medium dose (6–10 sprays/day), or high dose (11–16 sprays/day). Average pain, worst pain and sleep disruption were measured daily during 5 weeks of treatment; other questionnaires measured quality of life and mood. A total of 360 patients were randomized; 263 completed. There were no baseline differences across groups. The 30% responder rate primary analysis was not significant for nabiximols versus placebo (overall <i>P</i> = .59). A secondary continuous responder analysis of average daily pain from baseline to end of study demonstrated that the proportion of patients reporting analgesia was greater for nabiximols than placebo overall (<i>P</i> = .035), and specifically in the low-dose (<i>P</i> = .008) and medium-dose (<i>P</i> = .039) groups. In the low-dose group, results were similar for mean average pain (<i>P</i> = .006), mean worst pain (<i>P</i> = .011), and mean sleep disruption (<i>P</i> = .003).Other questionnaires showed no significant group differences. Adverse events were dose-related and only the high-dose group compared unfavorably with placebo. This study supports the efficacy and safety of nabiximols at the 2 lower-dose levels and provides important dose information for future trials. PERSPECTIVE: <i>Nabiximols, a novel cannabinoid formulation, may be a useful add-on analgesic for patients with opioid-refractory cancer pain. A randomized, double-blind, placebo-controlled, graded-dose study demonstrated efficacy and safety at low and medium doses</i>. (PsycInfo Database Record (c) 2021 APA, all rights reserved)

Primary study

Unclassified

Journal Journal of neurology, neurosurgery, and psychiatry
Year 2012
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OBJECTIVE: Multiple sclerosis (MS) is associated with chronic symptoms, including muscle stiffness, spasms, pain and insomnia. Here we report the results of the Multiple Sclerosis and Extract of Cannabis (MUSEC) study that aimed to substantiate the patient based findings of previous studies. Patients and methods: Patients with stable MS at 22 UK centres were randomised to oral cannabis extract (CE) (N = 144) or placebo (N = 135), stratified by centre, walking ability and use of antispastic medication. This double blind, placebo controlled, phase III study had a screening period, a 2 week dose titration phase from 5 mg to a maximum of 25 mg of tetrahydrocannabinol daily and a 10 week maintenance phase. The primary outcome measure was a category rating scale (CRS) measuring patient reported change in muscle stiffness from baseline. Further CRSs assessed body pain, spasms and sleep quality. Three validated MS specific patient reported outcome measures assessed aspects of spasticity, physical and psychological impact, and walking ability. RESULTS: The rate of relief from muscle stiffness after 12 weeks was almost twice as high with CE than with placebo (29.4% vs 15.7%; OR 2.26; 95% CI 1.24 to 4.13; p = 0.004, one sided). Similar results were found after 4 weeks and 8 weeks, and also for all further CRSs. Results from the MS scales supported these findings. CONCLUSION: The study met its primary objective to demonstrate the superiority of CE over placebo in the treatment of muscle stiffness in MS. This was supported by results for secondary efficacy variables. Adverse events in participants treated with CE were consistent with the known side effects of cannabinoids. No new safety concerns were observed. (PsycInfo Database Record (c) 2022 APA, all rights reserved)

Primary study

Unclassified

Journal CMAJ : Canadian Medical Association journal = journal de l'Association medicale canadienne
Year 2012
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BACKGROUND: Spasticity is a common and poorly controlled symptom of multiple sclerosis. Our objective was to determine the short-term effect of smoked cannabis on this symptom. METHODS: We conducted a placebo-controlled, crossover trial involving adult patients with multiple sclerosis and spasticity. We recruited participants from a regional clinic or by referral from specialists. We randomly assigned participants to either the intervention (smoked cannabis, once daily for three days) or control (identical placebo cigarettes, once daily for three days). Each participant was assessed daily before and after treatment. After a washout interval of 11 days, participants crossed over to the opposite group. Our primary outcome was change in spasticity as measured by patient score on the modified Ashworth scale. Our secondary outcomes included patients’ perception of pain (as measured using a visual analogue scale), a timed walk and changes in cognitive function (as measured by patient performance on the Paced Auditory Serial Addition Test), in addition to ratings of fatigue. RESULTS: Thirty-seven participants were randomized at the start of the study, 30 of whom completed the trial. Treatment with smoked cannabis resulted in a reduction in patient scores on the modified Ashworth scale by an average of 2.74 points more than placebo (<i>p</i> &lt; 0.0001). In addition, treatment reduced pain scores on a visual analogue scale by an average of 5.28 points more than placebo (<i>p</i> = 0.008). Scores for the timed walk did not differ significantly between treatment and placebo (<i>p</i> = 0.2). Scores on the Paced Auditory Serial Addition Test decreased by 8.67 points more with treatment than with placebo (<i>p</i> = 0.003). No serious adverse events occurred during the trial. INTERPRETATION: Smoked cannabis was superior to placebo in symptom and pain reduction in participants with treatment-resistant spasticity. Future studies should examine whether different doses can result in similar beneficial effects with less cognitive impact. (PsycInfo Database Record (c) 2024 APA, all rights reserved)

Primary study

Unclassified

Journal Diabetes care
Year 2010
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OBJECTIVE - To assess the efficacy of Sativex, a cannabis-based medicinal extract, as adjuvant treatment in painful diabetic peripheral neuropathy (DPN). RESEARCH DESIGN AND METHODS - In this randomized controlled trial, 30 subjects with painful DPN received daily Sativex or placebo. The primary outcome measure was change in mean daily pain scores, and secondary outcome measures included quality-of-life assessments. RESULTS - There was significant improvement in pain scores in both groups, but mean change between groups was not significant. There were no significant differences in secondary outcome measures. Patients with depression had significantly greater baseline pain scores that improved regardless of intervention. CONCLUSIONS - This first-ever trial assessing the efficacy of cannabis has shown it to be no more efficacious than placebo in painful DPN. Depression was a major confounder and may have important implications for future trials on painful DPN. © 2010 by the American Diabetes Association.