The State of Synthetic Cannabinoid Medications for the Treatment of Pain

Synthetic cannabinoids are compounds made in the laboratory to structurally and functionally mimic phytocannabinoids from the Cannabis sativa L. plant, including delta-9-tetrahydrocannabinol (THC). Synthetic cannabinoids (SCs) can signal via the classical endogenous cannabinoid system (ECS) and the greater endocannabidiome network, highlighting their signalling complexity and far-reaching effects. Dronabinol and nabilone, which mimic THC signalling, have been approved by the Food and Drug Administration (FDA) for treating nausea associated with cancer chemotherapy and/or acquired immunodeficiency syndrome (AIDS). However, there is ongoing interest in these two drugs as potential analgesics for a variety of other clinical conditions, including neuropathic pain, spasticity-related pain, and nociplastic pain syndromes including fibromyalgia, osteoarthritis, and postoperative pain, among others. In this review, we highlight the signalling mechanisms of FDA-approved synthetic cannabinoids, discuss key clinical trials that investigate their analgesic potential, and illustrate challenges faced when bringing synthetic cannabinoids to the clinic.

Efficacy of cannabinoids compared to the current standard treatments on symptom relief in persons with multiple sclerosis (CANSEP trial): study protocol for a randomized clinical trial

Background

Multiple sclerosis (MS) is an inflammatory and degenerative disease of the central nervous system. More than 90,000 Canadians are affected; a cure is yet to be found. Available treatments to manage the disease course are only partially effective. For many years, persons with MS (PwMS) have used cannabis to relax, to reduce pain and spasticity, or to improve sleep and daily functioning, despite the lack of scientific evidence on the efficacy of specific cannabinoids [i.e., tetrahydrocannabinol (THC) and cannabidiol (CBD)] on these MS symptoms. The purpose of this clinical trial is to assess the effectiveness of different doses of these cannabinoids, alone or combined, on spasticity relief, compared to placebo. Moreover, we aim to determine which treatment is best effective to address other key MS conditions.

Methods

A double-blinded, randomized, factorial, placebo-controlled trial will be performed. We intend to include up to 250 PwMS aged over 21 recruited from the Centre hospitalier de l'Université de Montréal MS Clinic. PwMS will be randomly assigned on a 1:1:1:1 ratio to one of the trial arms: THC alone, CBD alone, THC/CBD combination, or placebo, using stratified blocked randomization, with random blocks within each stratum. The primary outcome is a self-assessment of spasticity using the mean Numeric Rating Scale score over 7 days. The main outcome will be the difference in this score at 4 weeks compared to baseline. Secondary outcomes include assessments of spasticity as measured by a clinician, pain, fatigue, sleep, bowel, bladder, and sexual dysfunction, restless legs syndrome, mental health, quality of life, mobility, cognitive functioning, and adverse events. Treatment responders are eligible for a 12-week extension phase, using the same treatment allocation and assessments.

Discussion

Previous clinical studies examined the efficacy of cannabis-based medicines in PwMS, mostly using products with 1:1 THC/CBD ratio. The major barrier to effectively use cannabis in real-world clinical settings is the lack of evidence on benefits of specific cannabinoids and information on possible related risks. The CANSEP study will contribute to overcome these limitations and identify the risks and benefits of cannabis-based treatments in PwMS.

Clinical trial registration

ClinicalTrials.Gov, NCT05092191.

Phytocannabinoids for the Treatment of Neuropathic Pain: A Scoping Review of Randomised Controlled Trials Published Between 2012 and 2023

PURPOSE OF REVIEW

Neuropathic pain (NP) remains a challenge to treat, with 50% of patients experiencing limited efficacy from current treatments. Medicinal cannabis, which contains tetrahydrocannabinol (THC), cannabidiol (CBD) and other minor cannabinoids, is garnering attention as an alternative treatment for NP. This paper reviews the clinical evidence for phytocannabinoid treatment of NP.

RECENT FINDINGS

Seventeen randomised controlled trials (RCT) were identified for inclusion in this review. Of these, ten studies using phytocannabinoid preparations containing THC alone had the most evidence for pain relief. Four studies investigating THC/CBD combinations showed some reductions in pain scores, although not all findings were statistically significant, whereas studies investigating CBD (two studies) or cannabidivarin (one study) showed no analgesic effect over placebo. However, CBD studies were of small sample size when compared to other studies in the review and short duration. Results for treatment of diabetic peripheral neuropathy patients with THC showed better improvements over those for NP induced by chemotherapy and multiple sclerosis, with these trials using vaporised whole plant cannabis. This formulation may have trace amounts of other minor cannabinoids, compared with synthetic cannabinoids such as dronabinol or nabilone that were investigated in other studies. This review provides an overview of RCTs that have investigated phytocannabinoid use for the treatment of NP. There appears to be evidence to necessitate further high quality RCTs into novel formulations of phytocannabinoids for the treatment of NP.

Pharmacological and Non-pharmacological Approaches for the Management of Neuropathic Pain in Multiple Sclerosis

Multiple sclerosis is a chronic inflammatory disease that affects the central nervous system and can cause various types of pain including ongoing extremity pain, Lhermitte's phenomenon, trigeminal neuralgia, and mixed pain. Neuropathic pain is a major concern for individuals with multiple sclerosis as it is directly linked to myelin damage in the central nervous system and the management of neuropathic pain in multiple sclerosis is challenging as the options available have limited efficacy and can cause unpleasant side effects. The literature search was conducted across two databases, PubMed, and Google Scholar. Eligible studies included clinical trials, observational studies, meta-analyses, systematic reviews, and narrative reviews. The objective of this article is to provide an overview of literature on pharmacological and non-pharmacological strategies employed in the management of neuropathic pain in multiple sclerosis. Pharmacological options include cannabinoids, muscle relaxants (tizanidine, baclofen, dantrolene), anticonvulsants (benzodiazepines, gabapentin, phenytoin, carbamazepine, lamotrigine), antidepressants (duloxetine, venlafaxine, tricyclic antidepressants), opioids (naltrexone), and botulinum toxin variants, which have evidence from various clinical trials. Non-pharmacological approaches for trigeminal neuralgia may include neurosurgical methods. Non-invasive methods, physical therapy, and psychotherapy (cognitive behavioral therapy, acceptance and commitment therapy and mindfulness-based stress reduction) may be recommended for patients with neuropathic pain in multiple sclerosis. The choice of treatment depends on the severity and type of pain as well as other factors, such as patient preferences and comorbidities. There is a pressing need for healthcare professionals and researchers to prioritize the development of better strategies for managing multiple sclerosis-induced neuropathic pain.

IUPHAR review: Navigating the role of preclinical models in pain research

Chronic pain is a complex and challenging medical condition that affects millions of people worldwide. Understanding the underlying mechanisms of chronic pain is a key goal of preclinical pain research so that more effective treatment strategies can be developed. In this review, we explore nociception, pain, and the multifaceted factors that lead to chronic pain by focusing on preclinical models. We provide a detailed look into inflammatory and neuropathic pain models and discuss the most used animal models for studying the mechanisms behind these conditions. Additionally, we emphasize the vital role of these preclinical models in developing new pain-relief drugs, focusing on biologics and the therapeutic potential of NMDA and cannabinoid receptor antagonists. We also discuss the challenges of TRPV1 modulation for pain treatment, the clinical failures of neurokinin (NK)- 1 receptor antagonists, and the partial success story of Ziconotide to provide valuable lessons for preclinical pain models. Finally, we highlight the overall success and limitations of current treatments for chronic pain while providing critical insights into the development of more effective therapies to alleviate the burden of chronic pain.

Medicinal Plants for the Treatment of Neuropathic Pain: A Review of Randomized Controlled Trials

Neuropathic pain is a disabling condition caused by various diseases and can profoundly impact the quality of life. Unfortunately, current treatments often do not produce complete amelioration and can be associated with potential side effects. Recently, herbal drugs have garnered more attention as an alternative or a complementary treatment. In this article, we summarized the results of randomized clinical trials to evaluate the effects of various phytomedicines on neuropathic pain. In addition, we discussed their main bioactive components and potential mechanisms of action to provide a better view of the application of herbal drugs for treating neuropathic pain.

Cannabis and Cannabinoids in the Perioperative Period

Cannabis use is increasingly common, and with a growing number of jurisdictions implementing legalization frameworks, it is likely that providers will encounter more patients who use cannabis. Therefore, it is important for providers to understand the implications of cannabis use and practical considerations for the perioperative period. Cannabis affects multiple organ systems and may influence intraoperative anesthesia, as well as postoperative pain management. The effects of cannabis and key anesthetic considerations are reviewed here.

Characterizing cannabis use in a sample of adults with multiple sclerosis and chronic pain: An observational study

BACKGROUND

Although cannabis has become an increasingly common method for pain management among people with multiple sclerosis (PwMS), there is a dearth of knowledge regarding the types of cannabis products used as well as the characteristics of cannabis users. The current study aimed to (1) describe the prevalence of cannabis use and the routes of administration of cannabis products in adults with an existing chronic pain condition and MS, (2) to examine differences in demographic and disease-related variables between cannabis users and non-users, and (3) to examine differences between cannabis users and non-users in pain-related variables, including pain intensity, pain interference, neuropathic pain, pain medication use, and pain-related coping.

METHODS

Secondary analysis of baseline data from participants with multiple sclerosis (MS) and chronic pain (N = 242) enrolled in an RCT comparing mindfulness-based cognitive therapy (MBCT), cognitive-behavioral therapy (CBT), and usual care for chronic pain. Statistical methods included t-tests, Mann-Whitney tests, chi-square tests, and Fisher's exact tests to assess for differences in demographic, disease-related, and pain-related variables between cannabis users and non-users.

RESULTS

Of the 242 participants included in the sample, 65 (27%) reported the use of cannabis for pain management. The most common route of administration was oil/tincture (reported by 42% of cannabis users), followed by vaped (22%) and edible (17%) products. Cannabis users were slightly younger than non-users (Medage 51.0 vs 55.0, p = .019) and reported higher median pain intensity scores (6.0 vs 5.0, p = .022), higher median pain interference scores (5.9 vs 5.4, p = .027), and higher median levels of neuropathic pain (20.0 vs 16.0, p = .001).

CONCLUSIONS

The current study identified factors that may intersect with cannabis use for pain management and adds to our current knowledge of the types of cannabis products used by PwMS. Future research should continue to investigate trends in cannabis use for pain management, especially as the legality and availability of products continue to shift. Additionally, longitudinal studies are needed to examine the effects of cannabis use on pain-related outcomes over time.

What's your cup of tea? The role of herbal compounds in the management of multiple sclerosis

Multiple Sclerosis (MS) is a chronic, inflammatory, neurodegenerative disease that is characterized by a complex etiology. Efforts towards the management of MS have long been directed towards symptomatic relief, as well as the use of immune-modulatory, disease modifying therapies; however, inconsistent treatment responses still prevail, increasing the risk for disease progression. While a great deal of research attempted to unravel the complexity of treatment responses in light of epigenetic variability, parallel efforts in the direction of alternative medicine may be as paramount. Herbal compounds have long been regarded as safe and versatile options for aiding in various disorders, including neurodegenerative conditions like MS. Numerous studies have taken interest in a myriad of herbal plants for their potential benefit in alleviating some of the most common MS symptoms such as spasticity and fatigue, delaying the progression of the disease, as well as influencing the overall quality of life for MS patients. This review aims to provide a comprehensive overview of recent clinical studies examining the effects of various herbal plants on different aspects of MS, in an attempt to shed light on an important tool for aiding in the management of this complex and multifactorial disease.

Cannabis and Cannabinoids in Multiple Sclerosis: From Experimental Models to Clinical Practice-A Review

BACKGROUND

As far as 80% of people diagnosed with multiple sclerosis (MS) experience disabling symptoms in the course of the disease, such as spasticity and neuropathic pain. As first-line symptomatic therapy is associated with important adverse reactions, cannabinoids have become increasingly popular among patients with MS. This review intends to provide an overview of the evidence of the role of cannabinoids in treating symptoms related to MS and to encourage further research on this matter.

AREAS OF UNCERTAINTY

To date, the evidence supporting the role of cannabis and its derivatives in alleviating the MS-related symptoms comes only from studies on experimental models of demyelination. To the best of our knowledge, relatively few clinical trials inquired about the therapeutic effects of cannabinoids on patients with MS, with variable results.

DATA SOURCES

We conducted a literature search through PubMed and Google Scholar from the beginning until 2022. We included articles in English describing the latest findings regarding the endocannabinoid system, the pharmacology of cannabinoids, and their therapeutic purpose in MS.

RESULTS

Evidence from preclinical studies showed that cannabinoids can limit the demyelination process, promote remyelination, and have anti-inflammatory properties by reducing immune cell infiltration of the central nervous system in mice with experimental autoimmune encephalomyelitis. Moreover, it has been established that experimental autoimmune encephalomyelitis mice treated with cannabinoids experienced a significant reduction of symptoms and slowing of the disease progression. Given the complexity of human immune and nervous systems, cannabinoids did not have the anticipated effects on human subjects. However, data obtained from clinical trials showed some beneficial results of cannabinoids as a single or as add-on therapy in reducing the spasticity and pain related to MS.

CONCLUSION

Considering their various mechanisms of action and good tolerability, cannabinoids remain an interesting therapy for spasticity and chronic pain related to MS.

Combination pharmacotherapy for the treatment of neuropathic pain in adults: systematic review and meta-analysis

ABSTRACT

Neuropathic pain causes substantial morbidity and healthcare utilization. Monotherapy with antidepressants or anticonvulsants often fails to provide relief. Combining different drugs sometimes provides improved analgesia and/or tolerability. More than half of patients receive 2 or more analgesics, and combination trials continue to emerge. This review comprehensively searched CENTRAL, MEDLINE, and EMBASE for relevant trials. Included studies are double-blind randomized controlled trials evaluating combinations of 2 or more drugs vs placebo or at least one monotherapy in adults with neuropathic pain. Outcomes included measures of efficacy and adverse effects. Risk of bias was assessed. Meta-analyses compared combination to monotherapy wherever 2 or more similar studies were available. Forty studies (4741 participants) were included. Studies were heterogenous with respect to various characteristics, including dose titration methods and administration (ie, simultaneous vs sequential) of the combination. Few combinations involved a nonsedating drug, and several methodological problems were identified. For opioid-antidepressant, opioid-gabapentinoid, and gabapentinoid-antidepressant combinations, meta-analyses failed to demonstrate superiority over both monotherapies. In general, adverse event profiles were not substantially different for combination therapy compared with monotherapy. Despite widespread use and a growing number of trials, convincing evidence has not yet emerged to suggest superiority of any combination over its respective monotherapies. Therefore, implementing combination therapy-as second- or third-line treatment-in situations where monotherapy is insufficient, should involve closely monitored individual dosing trials to confirm safety and overall added benefit. Further research is needed, including trials of combinations involving nonsedating agents, and to identify clinical settings and specific combinations that safely provide added benefit.

Cannabinoids versus placebo for pain: A systematic review with meta-analysis and Trial Sequential Analysis

OBJECTIVES

To assess the benefits and harms of cannabinoids in participants with pain.

DESIGN

Systematic review of randomised clinical trials with meta-analysis, Trial Sequential Analysis, and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

DATA SOURCES

The Cochrane Library, MEDLINE, Embase, Science Citation Index, and BIOSIS.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Published and unpublished randomised clinical trials comparing cannabinoids versus placebo in participants with any type of pain.

MAIN OUTCOME MEASURES

All-cause mortality, pain, adverse events, quality of life, cannabinoid dependence, psychosis, and quality of sleep.

RESULTS

We included 65 randomised placebo-controlled clinical trials enrolling 7017 participants. Fifty-nine of the trials and all outcome results were at high risk of bias. Meta-analysis and Trial Sequential Analysis showed no evidence of a difference between cannabinoids versus placebo on all-cause mortality (RR 1.20; 98% CI 0.85 to 1.67; P = 0.22). Meta-analyses and Trial Sequential Analysis showed that cannabinoids neither reduced acute pain (mean difference numerical rating scale (NRS) 0.52; 98% CI -0.40 to 1.43; P = 0.19) or cancer pain (mean difference NRS -0.13; 98% CI -0.33 to 0.06; P = 0.1) nor improved quality of life (mean difference -1.38; 98% CI -11.81 to 9.04; P = 0.33). Meta-analyses and Trial Sequential Analysis showed that cannabinoids reduced chronic pain (mean difference NRS -0.43; 98% CI -0.72 to -0.15; P = 0.0004) and improved quality of sleep (mean difference -0.42; 95% CI -0.65 to -0.20; P = 0.0003). However, both effect sizes were below our predefined minimal important differences. Meta-analysis and Trial Sequential Analysis indicated that cannabinoids increased the risk of non-serious adverse events (RR 1.20; 95% CI 1.15 to 1.25; P < 0.001) but not serious adverse events (RR 1.18; 98% CI 0.95 to 1.45; P = 0.07). None of the included trials reported on cannabinoid dependence or psychosis.

CONCLUSIONS

Cannabinoids reduced chronic pain and improved quality of sleep, but the effect sizes are of questionable importance. Cannabinoids had no effects on acute pain or cancer pain and increased the risks of non-serious adverse events. The harmful effects of cannabinoids for pain seem to outweigh the potential benefits.

Cannabinoids in neuroinflammatory disorders: Focusing on multiple sclerosis, Parkinsons, and Alzheimers diseases

The medicinal properties of cannabis and cannabinoid-derivative are entirely investigated and known. In addition, the identification of psychotropic plant cannabinoids has led to more studies regarding the cannabinoid system and its therapeutic features in the treatment and management of clinical symptoms of neuroinflammatory disorders, such as multiple sclerosis (MS), Parkinsons disease (PD), and Alzheimers disease (AD). In fact, cannabinoid agonists are able to control and regulate inflammatory responses. In contrast to the cannabinoid receptor type 1 (CB1) and its unwanted adverse effects, the cannabinoid receptor type 2 (CB2) and its ligands hold promise for new and effective therapeutic approaches. So far, some successes have been achieved in this field. This review will discuss an outline of the endocannabinoid system's involvement in neuroinflammatory disorders. Moreover, the pharmacological efficacy of different natural and synthetic preparations of phytocannabinoids acting on cannabinoid receptors, particularly in MS, PD, and AD, will be updated. Also, the reasons for targeting CB2 for neurodegeneration will be explained.

Perceived Efficacy, Reduced Prescription Drug Use, and Minimal Side Effects of Cannabis in Patients with Chronic Orthopedic Pain

Introduction: Although cannabis is widely used for the treatment of chronic pain, most research relies on patient self-report and few studies have objectively quantified its efficacy and side effects. Extant inventories for measuring cannabis use were not designed to capture the medically relevant features of cannabis use, but rather were designed to detect problematic use or cannabis use disorder. Thus, we sought to capture the medically relevant features of cannabis use in a population of patients with orthopedic pain and pair these data with objective measures of pain and prescription drug use. Materials and Methods: In this prospective observational study, orthopedic pain patients were enrolled in Pennsylvania's medical cannabis program by their treating pain management physician, received cannabis education from their physician at the time of certification, and purchased products from state-licensed cannabis retailers. Results: Medical cannabis use was associated with clinical improvements in pain, function, and quality of life with reductions in prescription drug use; 73% either ceased or decreased opioid consumption and 31% discontinued benzodiazepines. Importantly, 52% of patients did not experience intoxication as a side effect of cannabis therapy. Significant clinical benefits of cannabis occurred within 3 months of initiating cannabis therapy and plateaued at the subsequent follow-ups. Conclusions: This work provides a direct relationship between the initiation of cannabis therapy and objectively fewer opioid and benzodiazepine prescriptions. Our work also identifies specific subpopulations of patients for whom cannabis may be most efficacious in reducing opioid consumption, and it highlights the importance of both physician involvement and patient self-titration in symptom management with cannabis.

Medical cannabinoids: a pharmacology-based systematic review and meta-analysis for all relevant medical indications

BACKGROUND

Medical cannabinoids differ in their pharmacology and may have different treatment effects. We aimed to conduct a pharmacology-based systematic review (SR) and meta-analyses of medical cannabinoids for efficacy, retention and adverse events.

METHODS

We systematically reviewed (registered at PROSPERO: CRD42021229932) eight databases for randomized controlled trials (RCTs) of dronabinol, nabilone, cannabidiol and nabiximols for chronic pain, spasticity, nausea /vomiting, appetite, ALS, irritable bowel syndrome, MS, Chorea Huntington, epilepsy, dystonia, Parkinsonism, glaucoma, ADHD, anorexia nervosa, anxiety, dementia, depression, schizophrenia, PTSD, sleeping disorders, SUD and Tourette. Main outcomes and measures included patient-relevant/disease-specific outcomes, retention and adverse events. Data were calculated as standardized mean difference (SMD) and ORs with confidence intervals (CI) via random effects. Evidence quality was assessed by the Cochrane Risk of Bias and GRADE tools.

RESULTS

In total, 152 RCTs (12,123 participants) were analysed according to the type of the cannabinoid, outcome and comparator used, resulting in 84 comparisons. Significant therapeutic effects of medical cannabinoids show a large variability in the grade of evidence that depends on the type of cannabinoid. CBD has a significant therapeutic effect for epilepsy (SMD - 0.5[CI - 0.62, - 0.38] high grade) and Parkinsonism (- 0.41[CI - 0.75, - 0.08] moderate grade). There is moderate evidence for dronabinol for chronic pain (- 0.31[CI - 0.46, - 0.15]), appetite (- 0.51[CI - 0.87, - 0.15]) and Tourette (- 1.01[CI - 1.58, - 0.44]) and moderate evidence for nabiximols on chronic pain (- 0.25[- 0.37, - 0.14]), spasticity (- 0.36[CI - 0.54, - 0.19]), sleep (- 0.24[CI - 0.35, - 0.14]) and SUDs (- 0.48[CI - 0.92, - 0.04]). All other significant therapeutic effects have either low, very low, or even no grade of evidence. Cannabinoids produce different adverse events, and there is low to moderate grade of evidence for this conclusion depending on the type of cannabinoid.

CONCLUSIONS

Cannabinoids are effective therapeutics for several medical indications if their specific pharmacological properties are considered. We suggest that future systematic studies in the cannabinoid field should be based upon their specific pharmacology.

Cannabis-Based Products for Chronic Pain : A Systematic Review

BACKGROUND

Contemporary data are needed about the utility of cannabinoids in chronic pain.

PURPOSE

To evaluate the benefits and harms of cannabinoids for chronic pain.

DATA SOURCES

Ovid MEDLINE, PsycINFO, EMBASE, the Cochrane Library, and Scopus to January 2022.

STUDY SELECTION

English-language, randomized, placebo-controlled trials and cohort studies (≥1 month duration) of cannabinoids for chronic pain.

DATA EXTRACTION

Data abstraction, risk of bias, and strength of evidence assessments were dually reviewed. Cannabinoids were categorized by THC-to-CBD ratio (high, comparable, or low) and source (synthetic, extract or purified, or whole plant).

DATA SYNTHESIS

Eighteen randomized, placebo-controlled trials (n = 1740) and 7 cohort studies (n = 13 095) assessed cannabinoids. Studies were primarily short term (1 to 6 months); 56% enrolled patients with neuropathic pain, with 3% to 89% female patients. Synthetic products with high THC-to-CBD ratios (>98% THC) may be associated with moderate improvement in pain severity and response (≥30% improvement) and an increased risk for sedation and are probably associated with a large increased risk for dizziness. Extracted products with high THC-to-CBD ratios (range, 3:1 to 47:1) may be associated with large increased risk for study withdrawal due to adverse events and dizziness. Sublingual spray with comparable THC-to-CBD ratio (1.1:1) probably is associated with small improvement in pain severity and overall function and may be associated with large increased risk for dizziness and sedation and moderate increased risk for nausea. Evidence for other products and outcomes, including longer-term harms, were not reported or were insufficient.

LIMITATION

Variation in interventions; lack of study details, including unclear availability in the United States; and inadequate evidence for some products.

CONCLUSION

Oral, synthetic cannabis products with high THC-to-CBD ratios and sublingual, extracted cannabis products with comparable THC-to-CBD ratios may be associated with short-term improvements in chronic pain and increased risk for dizziness and sedation. Studies are needed on long-term outcomes and further evaluation of product formulation effects.

PRIMARY FUNDING SOURCE

Agency for Healthcare Research and Quality, U.S. Department of Health and Human Services. (PROSPERO: CRD42021229579).

Cannabis and cannabinoids for symptomatic treatment for people with multiple sclerosis

BACKGROUND

Spasticity and chronic neuropathic pain are common and serious symptoms in people with multiple sclerosis (MS). These symptoms increase with disease progression and lead to worsening disability, impaired activities of daily living and quality of life. Anti-spasticity medications and analgesics are of limited benefit or poorly tolerated. Cannabinoids may reduce spasticity and pain in people with MS. Demand for symptomatic treatment with cannabinoids is high. A thorough understanding of the current body of evidence regarding benefits and harms of these drugs is required.

OBJECTIVES

To assess benefit and harms of cannabinoids, including synthetic, or herbal and plant-derived cannabinoids, for reducing symptoms for adults with MS.

SEARCH METHODS

We searched the following databases from inception to December 2021: MEDLINE, Embase, the Cochrane Central Register of Controlled Trials (CENTRAL, the Cochrane Library), CINAHL (EBSCO host), LILACS, the Physiotherapy Evidence Database (PEDro), the World Health Organisation International Clinical Trials Registry Platform, the US National Institutes of Health clinical trial register, the European Union Clinical Trials Register, the International Association for Cannabinoid Medicines databank. We hand searched citation lists of included studies and relevant reviews.

SELECTION CRITERIA

We included randomised parallel or cross-over trials (RCTs) evaluating any cannabinoid (including herbal Cannabis, Cannabis flowers, plant-based cannabinoids, or synthetic cannabinoids) irrespective of dose, route, frequency, or duration of use for adults with MS.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methodology. To assess bias in included studies, we used the Cochrane Risk of bias 2 tool for parallel RCTs and crossover trials. We rated the certainty of evidence using the GRADE approach for the following outcomes: reduction of 30% in the spasticity Numeric Rating Scale, pain relief of 50% or greater in the Numeric Rating Scale-Pain Intensity, much or very much improvement in the Patient Global Impression of Change (PGIC), Health-Related Quality of Life (HRQoL), withdrawals due to adverse events (AEs) (tolerability), serious adverse events (SAEs), nervous system disorders, psychiatric disorders, physical dependence.

MAIN RESULTS

We included 25 RCTs with 3763 participants of whom 2290 received cannabinoids. Age ranged from 18 to 60 years, and between 50% and 88% participants across the studies were female.  The included studies were 3 to 48 weeks long and compared nabiximols, an oromucosal spray with a plant derived equal (1:1) combination of tetrahydrocannabinol (THC) and cannabidiol (CBD) (13 studies), synthetic cannabinoids mimicking THC (7 studies), an oral THC extract of Cannabis sativa (2 studies), inhaled herbal Cannabis (1 study) against placebo. One study compared dronabinol, THC extract of Cannabis sativa and placebo, one compared inhaled herbal Cannabis, dronabinol and placebo. We identified eight ongoing studies. Critical outcomes • Spasticity: nabiximols probably increases the number of people who report an important reduction of perceived severity of spasticity compared with placebo (odds ratio (OR) 2.51, 95% confidence interval (CI) 1.56 to 4.04; 5 RCTs, 1143 participants; I2 = 67%; moderate-certainty evidence). The absolute effect was 216 more people (95% CI 99 more to 332 more) per 1000 reporting benefit with cannabinoids than with placebo. • Chronic neuropathic pain: we found only one small trial that measured the number of participants reporting substantial pain relief with a synthetic cannabinoid compared with placebo (OR 4.23, 95% CI 1.11 to 16.17; 1 study, 48 participants; very low-certainty evidence). We are uncertain whether cannabinoids reduce chronic neuropathic pain intensity. • Treatment discontinuation due to AEs: cannabinoids may increase slightly the number of participants who discontinue treatment compared with placebo (OR 2.41, 95% CI 1.51 to 3.84; 21 studies, 3110 participants; I² = 17%; low-certainty evidence); the absolute effect is 39 more people (95% CI 15 more to 76 more) per 1000 people. Important outcomes • PGIC: cannabinoids probably increase the number of people who report 'very much' or 'much' improvement in health status compared with placebo (OR 1.80, 95% CI 1.37 to 2.36; 8 studies, 1215 participants; I² = 0%; moderate-certainty evidence). The absolute effect is 113 more people (95% CI 57 more to 175 more) per 1000 people reporting improvement. • HRQoL: cannabinoids may have little to no effect on HRQoL (SMD -0.08, 95% CI -0.17 to 0.02; 8 studies, 1942 participants; I2 = 0%; low-certainty evidence); • SAEs: cannabinoids may result in little to no difference in the number of participants who have SAEs compared with placebo (OR 1.38, 95% CI 0.96 to 1.99; 20 studies, 3124 participants; I² = 0%; low-certainty evidence); • AEs of the nervous system: cannabinoids may increase nervous system disorders compared with placebo (OR 2.61, 95% CI 1.53 to 4.44; 7 studies, 1154 participants; I² = 63%; low-certainty evidence); • Psychiatric disorders: cannabinoids may increase psychiatric disorders compared with placebo (OR 1.94, 95% CI 1.31 to 2.88; 6 studies, 1122 participants; I² = 0%; low-certainty evidence); • Drug tolerance: the evidence is very uncertain about the effect of cannabinoids on drug tolerance (OR 3.07, 95% CI 0.12 to 75.95; 2 studies, 458 participants; very low-certainty evidence).

AUTHORS' CONCLUSIONS

Compared with placebo, nabiximols probably reduces the severity of spasticity in the short-term in people with MS. We are uncertain about the effect on chronic neurological pain and health-related quality of life. Cannabinoids may increase slightly treatment discontinuation due to AEs, nervous system and psychiatric disorders compared with placebo. We are uncertain about the effect on drug tolerance. The overall certainty of evidence is limited by short-term duration of the included studies.

The Efficacy of Cannabis on Multiple Sclerosis-Related Symptoms

Multiple sclerosis (MS) is known as an autoimmune disease that damages the neurons in the central nervous system. MS is characterized by its most common symptoms of spasticity, muscle spasms, neuropathic pain, tremors, bladder dysfunction, dysarthria, and some intellectual problems, including memory disturbances. Several clinical studies have been conducted to investigate the effects of cannabis on the relief of these symptoms in MS patients. The efficacy of Cannabis sativa (C. Sativa) in the management of MS outcomes such as spasticity, pain, tremors, ataxia, bladder functions, sleep, quality of life, and adverse effects were assessed in this review. Most clinical studies showed the positive effects of cannabinoids with their different routes of administration, such as oromucosal spray and oral form, in reducing most MS symptoms. The oromucosal spray Nabiximols demonstrated an improvement in reducing MS spasticity, pain, and quality of life with a tolerated adverse effect. Oral cannabinoids are significantly effective for treating MS pain and spasticity, while the other symptoms indicate slight improvement and the evidence is quite inconsistent. Oromucosal spray and oral cannabis are mainly used for treating patients with MS and have positive effects on treating the most common symptoms of MS, such as pain and spasticity, whereas the other MS symptoms indicated slight improvement, for which further studies are needed.

Central Neuropathic Pain Syndromes: Current and Emerging Pharmacological Strategies

Central neuropathic pain is caused by a disease or lesion of the brain or spinal cord. It is difficult to predict which patients will develop central pain syndromes after a central nervous system injury, but depending on the etiology, lifetime prevalence may be greater than 50%. The resulting pain is often highly distressing and difficult to treat, with no specific treatment guidelines currently available. This narrative review discusses mechanisms contributing to central neuropathic pain, and focuses on pharmacological approaches for managing common central neuropathic pain conditions such as central post-stroke pain, spinal cord injury-related pain, and multiple sclerosis-related neuropathic pain. Tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors, and gabapentinoids have some evidence for efficacy in central neuropathic pain. Medications from other pharmacologic classes may also provide pain relief, but current evidence is limited. Certain non-pharmacologic approaches, neuromodulation in particular, may be helpful in refractory cases. Emerging data suggest that modulating the primary afferent input may open new horizons for the treatment of central neuropathic pain. For most patients, effective treatment will likely require a multimodal therapy approach.

Dorsal Column Stimulation and Cannabinoids in the Treatment of Chronic Nociceptive and Neuropathic Pain: a Review of the Clinical and Pre-clinical Data

PURPOSE OF REVIEW

The main objective of this review is to appraise the literature on the role of spinal cord stimulation (SCS), cannabinoid therapy, as well as SCS and cannabinoid combination therapy for the management of chronic neuropathic and nociceptive pain. Current research suggests that SCS reduces pain and increases functional status in carefully selected patients with minimal side effects.

RECENT FINDINGS

As cannabinoid-based medications become a topic of increasing interest in pain management, data remains limited regarding the clinical efficacy of cannabinoids for pain relief. Furthermore, from a mechanistic perspective, although various pain treatment modalities utilize overlapping pain-signaling pathways, clarifying whether cannabinoids work synergistically with SCS via shared mechanisms remains to be determined. In considering secondary outcomes, the current literature suggests cannabinoids improve quality of life, specifically sleep quality, and that SCS decreases opioid consumption, increases functional capacity, and decreases long-term healthcare costs. These findings, along with the high safety profiles of SCS and cannabinoids overall, incentivize further exploration of cannabinoids as an adjunctive therapy to SCS in the treatment of neuropathic and nociceptive pain.

The Effectiveness of Cannabis and Cannabis Derivatives in Treating Lower Back Pain in the Aged Population: A Systematic Review

BACKGROUND/AIMS

Cannabis is increasingly used in the management of pain, though minimal research exists to support its use since approval. Reduction in stigma has led to a growing interest in pharmaceutical cannabinoids as a possible treatment for lower back pain (LBP). The objective of this review was to assess the role and efficacy of cannabis and its derivatives in the management of LBP and compile global data related to the role of cannabis in the management of LBP in an aging population.

METHODS

A systematic review was conducted using predetermined keywords by 3 independent researchers. Predetermined inclusion and exclusion criteria were applied, and 23 articles were selected for further analysis.

RESULTS

Studies identified both significant and insignificant impacts of cannabis on LBP. Contradicting evidence was noted on the role of cannabis in the management of anxiety and insomnia, 2 common comorbidities with LBP. The existing literature suggests that cannabis may be used in the management of LBP and comorbid symptoms.

CONCLUSIONS

Further research is needed to consider cannabis as an independent management option. There is a lack of evidence pertaining to the benefits of cannabis in an aged population, and thus, additional research is warranted to support its use in the aged population.

Combination Therapy for Neuropathic Pain: A Review of Recent Evidence

Pharmacological treatment is not very effective for neuropathic pain (NP). A progressive decrease in the estimated effect of NP drugs has been reported, giving rise to an increase in the use of the multimodal analgesic approach. We performed a new independent review to assess whether more and better-quality evidence has become available since the last systematic review. We evaluated the efficacy, tolerability, and safety of double-blinded randomized controlled trials involving only adult participants and comparing combination therapy (CT: ≥2 drugs) with a placebo and/or at least one other comparator with an NP indication. The primary outcome assessed was the proportion of participants reporting ≥50% pain reductions from baseline. The secondary outcome assessed was the proportion of drop-outs due to treatment-emergent adverse events. After removing duplicates, 2323 citations were screened, with 164 articles assessed for eligibility, from which 16 were included for qualitative analysis. From the latter, only five lasted for at least 12 weeks and only six complied with the required data for complete analysis. CT has been adopted for years without robust evidence. Efforts have been made to achieve better-quality evidence, but the quality has not improved over the years. In this regard, guidelines for NP should attempt to make recommendations about CT research, prioritizing which combinations to analyze.

Cannabis and pain: a scoping review

For centuries, cannabis has been used with many different purposes, including medicinal use, usually bypassing any formal approval process. However, during the last decade, interest in cannabis in medicine has been increasing, and several countries, including the United States and Canada, have produced their own legislation about marihuana and cannabis-based medicines. Because of this, interest in research has been increasing and evidence about its medical effects is becoming necessary. We conducted a review examining the evidence of cannabis in pain. Cannabis had been shown to be useful in acute and chronic pain, however recently, these results have been controverted. Within the different types of chronic pain, it has a weak evidence for neuropathic, rheumatic pain, and headache, modest evidence for multiple sclerosis related pain, and as adjuvant therapy in cancer pain. There is no strong evidence to recommend cannabis in order to decrease opioids in patients with chronic use. Even though cannabis-based medications appear to be mostly safe, mild adverse effects are common; somnolence, sedation, amnesia, euphoric mood, hyperhidrosis, paranoia, and confusion may limit the use of cannabis in clinical practice. Risks have not been systematically analyzed. Special concern arises on how adverse effect might affect vulnerable population such as elderly patients. More research is needed in order to evaluate benefits and risks, as well as the ideal administration route and dosages. As cannabis use increases in several countries, answers to these questions might be coming soon.

Cannabinoids in Neurology - Position paper from Scientific Departments from Brazilian Academy of Neurology

Cannabinoids comprehend endocannabinoids, phytocannabinoids, and synthetic cannabinoids, with actions both in the central and peripherical nervous systems. A considerable amount of publications have been made in recent years, although cannabis has been known for over a thousand years. Scientific Departments from the Brazilian Academy of Neurology described evidence for medical use in their areas. Literature is constantly changing, and possible new evidence can emerge in the next days or months. Prescription of these substances must be discussed with patients and their families, with knowledge about adverse events and their efficacy.

Sex Differences in Tolerance to Delta-9-Tetrahydrocannabinol in Mice With Cisplatin-Evoked Chronic Neuropathic Pain

Tolerance to the pain-relieving effects of cannabinoids limits the therapeutic potential of these drugs in patients with chronic pain. Recent preclinical research with rodents and clinical studies in humans has suggested important differences between males and females in the development of tolerance to cannabinoids. Our previous work found that male mice expressing a desensitization resistant form (S426A/S430A) of the type 1 cannabinoid receptor (CB₁R) show delayed tolerance and increased sensitivity to the antinociceptive effects of delta-9-tetrahydrocannabinol (∆⁹-THC). Sex differences in tolerance have been reported in rodent models with females acquiring tolerance to ∆⁹-THC faster than males. However, it remains unknown whether the S426A/S430A mutation alters analgesic tolerance to ∆⁹-THC in mice with chemotherapy-evoked chronic neuropathic pain, and also whether this tolerance might be different between males and females. Male and female S426A/S430A mutant and wild-type littermates were made neuropathic using four once-weekly injections of 5 mg/kg cisplatin and subsequently assessed for tolerance to the anti-allodynic effects of 6 and/or 10 mg/kg ∆⁹-THC. Females acquired tolerance to the anti-allodynic effects of both 6 and 10 mg/kg ∆⁹-THC faster than males. In contrast, the S426A/S430A mutation did not alter tolerance to ∆⁹-THC in either male or female mice. The anti-allodynic effects of ∆⁹-THC were blocked following pretreatment with the CB₁R antagonist, rimonabant, and partially blocked following pretreatment with the CB₂R inverse agonist, SR144528. Our results show that disruption of the GRK/β-arrestin-2 pathway of desensitization did not affect sensitivity and/or tolerance to ∆⁹-THC in a chronic pain model of neuropathy.

Therapeutic Attributes of Endocannabinoid System against Neuro-Inflammatory Autoimmune Disorders

In humans, various sites like cannabinoid receptors (CBR) having a binding affinity with cannabinoids are distributed on the surface of different cell types, where endocannabinoids (ECs) and derivatives of fatty acid can bind. The binding of these substance(s) triggers the activation of specific receptors required for various physiological functions, including pain sensation, memory, and appetite. The ECs and CBR perform multiple functions via the cannabinoid receptor 1 (CB1); cannabinoid receptor 2 (CB2), having a key effect in restraining neurotransmitters and the arrangement of cytokines. The role of cannabinoids in the immune system is illustrated because of their immunosuppressive characteristics. These characteristics include inhibition of leucocyte proliferation, T cells apoptosis, and induction of macrophages along with reduced pro-inflammatory cytokines secretion. The review seeks to discuss the functional relationship between the endocannabinoid system (ECS) and anti-tumor characteristics of cannabinoids in various cancers. The therapeutic potential of cannabinoids for cancer-both in vivo and in vitro clinical trials-has also been highlighted and reported to be effective in mice models in arthritis for the inflammation reduction, neuropathic pain, positive effect in multiple sclerosis and type-1 diabetes mellitus, and found beneficial for treating in various cancers. In human models, such studies are limited; thereby, further research is indispensable in this field to get a conclusive outcome. Therefore, in autoimmune disorders, therapeutic cannabinoids can serve as promising immunosuppressive and anti-fibrotic agents.

Pharmacotherapeutic Options for Managing Neuropathic Pain: A Systematic Review and Meta-Analysis

Despite an increasing number of available therapies, the treatment of neuropathic pain remains a major issue. Systematic reviews and meta-analyses indicate that only a minority of patients with neuropathic pain have an adequate response to pharmacological treatment and that most drugs have dose-limiting side effects. We conducted a systematic review and meta-analysis of randomised controlled trials published in the last five years. We searched for relevant papers within PubMed, EMBASE, the Cochrane Database of Systematic Reviews, and the Clinical Trials database (ClinicalTrials.gov). Two authors independently selected studies for inclusion, data extraction, and bias assessment. We identified 39 randomised controlled trials and included 16 in the meta-analysis. Trial outcomes were generally modest even for first-line drugs such as tricyclic antidepressants, serotonin-noradrenaline reuptake inhibitors, and gabapentinoids. Many drugs acting on new pain targets are currently under development. Clinical data are currently available for sodium channel isoform-specific antagonists, anti-nerve growth factor molecules, and fatty acid amide hydrolase inhibitors.

Cannabis for Chronic Pain: A Rapid Systematic Review of Randomized Control Trials

BACKGROUND

The high prevalence of inadequately managed chronic pain indicates the need for alternative and multimodal treatment options. Use of cannabinoids in medicine is becoming a growing area of interest, specifically in the context of chronic pain. The efficacy of cannabinoids for the treatment of chronic pain is not well established.

AIMS

The objectives of this rapid systematic literature review are to summarize the efficacy and secondary effects of cannabinoids for chronic pain management.

DESIGN

Rapid systematic review of randomized control trials.

PARTICIPANTS

Individuals with chronic pain (n = 1352).

METHODS

Embase, Cochrane, PubMed, and CINAHL databases were searched. Inclusion criteria included cannabis of any formulation used to treat chronic pain of any origin.

RESULTS

Thirteen randomized controlled trials met the inclusion criteria. Five demonstrated moderate analgesic effects of cannabis for chronic pain, and eight concluded there were no significant impacts on pain in the cannabis-treated group versus the control group.

CONCLUSIONS

Evidence on the efficacy of cannabinoids for chronic pain shows patient-perceived benefit but inconsistent other treatment effects. These findings indicate cannabinoids may have a modest analgesic effect for chronic neuropathic pain conditions, and that the use of cannabinoids is relatively safe, with few severe adverse events. This review concludes that cannabinoids may have a potential role in chronic pain management. Inconsistent evidence on the efficacy of cannabis to treat chronic pain indicates the need for more studies on a larger scale. Clinicians should draw on available evidence and consider cannabinoids as a potential approach to chronic pain management.

Cannabinoid-Based Medicines and Multiple Sclerosis

The emerging role of the endocannabinoid system (ECS) in the control of symptoms and disease progression in multiple sclerosis (MS) has been highlighted by recent studies. MS is a chronic, immune-mediated, and demyelinating disorder of the central nervous system with no cure so far. It is widely reported that cannabinoids might be used to control MS symptoms and that they also might exert neuroprotective effects and slow down disease progression. The aim of this chapter is to give an overview of the main endogenous and synthetic cannabinoids used for the symptomatic amelioration of MS and their beneficial outcomes, providing new possible perspectives for the treatment of this disease.

Medical cannabis for orthopaedic patients with chronic musculoskeletal pain: does evidence support its use?

The treatment of chronic, non-cancer musculoskeletal pain has become a topic growing interest as it is believed to be one of the reasons for the current opioid epidemic. The medicinal use of cannabis has a long history as a number of active compounds in cannabis have been shown to interact with the body's endocannabinoid system to reduce pain. This position paper provides a history on the evolution of cannabis, the science behind its therapeutic effects, and review of the evidence and current guideline recommendations on its use as a treatment for patients with chronic, non-cancer musculoskeletal pain. Results from systematic reviews have demonstrated a statistically significant reduction in chronic pain conditions with cannabinoids, compared with placebo, although the effects might be considered small and did not reach the minimally important difference. More adverse events were reported in the cannabinoid group than in the placebo group with longer than 2 weeks of treatment. There is a lack of evidence on dependence. With changes to policies, patients' perception has changed to be more positive toward the use of medical cannabis. Current recommendations from North America, Latin America, Europe, Australia and Iran support the use of medical cannabis for chronic, non-cancer pain. Based on the current evidence, it is our position that cannabinoids may be considered as an adjunctive therapy after recommended first- and second-line therapies have failed to provide sufficient efficacy or tolerability. Patients should consider the balance between the desirable and undesirable effects of taking cannabis for chronic pain, and comprehensively consider their own values and preferences, as well as cost-effectiveness factors, based on the information provided by their physician.

Pharmacotherapeutic Options for Managing Pain in Multiple Sclerosis

Pain is a major matter for patients with multiple sclerosis; treatment response is frequently inadequate, with a significant impact on quality of life. The estimated prevalence of pain in multiple sclerosis ranges widely (26-86%), and different subtypes of pain, mediated by specific pathophysiological mechanisms, are described. The aim of this narrative review, performed using a systematic search methodology, was to provide current, evidence-based, knowledge about the pharmacological treatment of the different kinds of pain in multiple sclerosis. We searched for relevant papers within PubMed, EMBASE, the Cochrane Database of Systematic Reviews, and the Clinical Trials database (ClinicalTrials.gov), considering publications up to November 2019. Two authors independently selected studies for inclusion, data extraction, and bias assessment. A total of 27 randomized controlled trials were identified, but in only a few cases, patients with different pain qualities were stratified. Following a mechanism-based approach, treatment of paroxysmal pain and painful tonic spasms should be based on sodium-channel blockers, whereas treatment of ongoing extremity pain should be based on gabapentinoids and antidepressants.

Analgesic Effects of Cannabinoids for Chronic Non-cancer Pain: a Systematic Review and Meta-Analysis with Meta-Regression

There is growing interest in using cannabinoids for chronic pain. We performed a systematic review and meta-analysis of randomized controlled trials to evaluate the analgesic efficacy and adverse effects of cannabinoids for chronic non-cancer pain. PubMed, EMBASE, Web of Science, Cochrane CENTRAL and clinicaltrials.gov were searched up to December 2018. Information on the type, dosage, route of administration, pain conditions, pain scores, and adverse events were extracted for qualitative analysis. Meta-analysis of analgesic efficacy was performed. Meta-regression was performed to compare the analgesic efficacy for different pain conditions (neuropathic versus non-neuropathic pain). Risk of bias was assessed by The Cochrane Risk of Bias tool, and the strength of the evidence was assessed using the Grade of Recommendations Assessment, Development, and Evaluation (GRADE) approach. Forty-three randomized controlled trials were included. Meta-analysis was performed for 33 studies that compared cannabinoids to placebo, and showed a mean pain score (scale 0-10) reduction of -0.70 (p < 0.001, random effect). Meta-regression showed that analgesic efficacy was similar for neuropathic and non-neuropathic pain (Difference = -0.14, p = 0.262). Inhaled, oral, and oromucosal administration all provided statistically significant, but small reduction in mean pain score (-0.97, -0.85, -0.45, all p < 0.001). Incidence of serious adverse events was rare, and non-serious adverse events were usually mild to moderate. Heterogeneity was moderate. The GRADE level of evidence was low to moderate. Pain intensity of chronic non-cancer patients was reduced by cannabinoids consumption, but effect sizes were small. Efficacy for neuropathic and non-neuropathic pain was similar.

Targeting Peripherally Restricted Cannabinoid Receptor 1, Cannabinoid Receptor 2, and Endocannabinoid-Degrading Enzymes for the Treatment of Neuropathic Pain Including Neuropathic Orofacial Pain

Neuropathic pain conditions including neuropathic orofacial pain (NOP) are difficult to treat. Contemporary therapeutic agents for neuropathic pain are often ineffective in relieving pain and are associated with various adverse effects. Finding new options for treating neuropathic pain is a major priority in pain-related research. Cannabinoid-based therapeutic strategies have emerged as promising new options. Cannabinoids mainly act on cannabinoid 1 (CB1) and 2 (CB2) receptors, and the former is widely distributed in the brain. The therapeutic significance of cannabinoids is masked by their adverse effects including sedation, motor impairment, addiction and cognitive impairment, which are thought to be mediated by CB1 receptors in the brain. Alternative approaches have been developed to overcome this problem by selectively targeting CB2 receptors, peripherally restricted CB1 receptors and endocannabinoids that may be locally synthesized on demand at sites where their actions are pertinent. Many preclinical studies have reported that these strategies are effective for treating neuropathic pain and produce no or minimal side effects. Recently, we observed that inhibition of degradation of a major endocannabinoid, 2-arachydonoylglycerol, can attenuate NOP following trigeminal nerve injury in mice. This review will discuss the above-mentioned alternative approaches that show potential for treating neuropathic pain including NOP.

Cannabinoids in Chronic Non-Cancer Pain: A Systematic Review and Meta-Analysis

Background:

For patients with chronic, non-cancer pain, traditional pain-relieving medications include opioids, which have shown benefits but are associated with increased risks of addiction and adverse effects. Medical cannabis has emerged as a treatment alternative for managing these patients and there has been a rise in the number of randomized clinical trials in recent years; therefore, a systematic review of the evidence was warranted.

Objective:

To analyze the evidence surrounding the benefits and harms of medical cannabinoids in the treatment of chronic, non-cancer-related pain.

Design:

Systematic review with meta-analysis.

Data sources:

Medline, Embase, CINAHL, SCOPUS, Google Scholar, and Cochrane Databases.

Eligibility criteria:

English language randomized clinical trials of cannabinoids for the treatment of chronic, non-cancer-related pain.

Data extraction and synthesis:

Study quality was assessed using the Cochrane risk of bias tool. All stages were conducted independently by a team of 6 reviewers. Data were pooled through meta-analysis with different durations of treatment (2 weeks, 2 months, 6 months) and stratified by route of administration (smoked, oromucosal, oral), conditions, and type of cannabinoids.

Main outcomes and measures:

Patient-reported pain and adverse events (AEs).

Results:

Thirty-six trials (4006 participants) were included, examining smoked cannabis (4 trials), oromucosal cannabis sprays (14 trials), and oral cannabinoids (18 trials). Compared with placebo, cannabinoids showed a significant reduction in pain which was greatest with treatment duration of 2 to 8 weeks (weighted mean difference on a 0-10 pain visual analogue scale −0.68, 95% confidence interval [CI], −0.96 to −0.40, I² = 8%, P < .00001; n = 16 trials). When stratified by route of administration, pain condition, and type of cannabinoids, oral cannabinoids had a larger reduction in pain compared with placebo relative to oromucosal and smoked formulations but the difference was not significant (P[interaction] > .05 in all the 3 durations of treatment); cannabinoids had a smaller reduction in pain due to multiple sclerosis compared with placebo relative to other neuropathic pain (P[interaction] = .05) within 2 weeks and the difference was not significant relative to pain due to rheumatic arthritis; nabilone had a greater reduction in pain compared with placebo relative to other types of cannabinoids longer than 2 weeks of treatment but the difference was not significant (P[interaction] > .05). Serious AEs were rare, and similar across the cannabinoid (74 out of 2176, 3.4%) and placebo groups (53 out of 1640, 3.2%). There was an increased risk of non-serious AEs with cannabinoids compared with placebo.

Conclusions:

There was moderate evidence to support cannabinoids in treating chronic, non-cancer pain at 2 weeks. Similar results were observed at later time points, but the confidence in effect is low. There is little evidence that cannabinoids increase the risk of experiencing serious AEs, although non-serious AEs may be common in the short-term period following use.

Cannabis-based medicines and the perioperative physician

The increasing availability of cannabis for both recreational and medicinal purposes means that anaesthetists will encounter an increasing number of patients taking cannabis-based medications. The existing evidence base is conflicted and incomplete regarding the indications, interactions and long-term effects of these substances. Globally, most doctors have had little education regarding the pharmacology of cannabis-based medicines, despite the endocannabinoid system being one of the most widespread in the human body. Much is unknown, and much is to be decided, including clarifying definitions and nomenclature, and therapeutic indications and dosing. Anaesthetists, Intensivists, Pain and Perioperative physicians will want to contribute to this evidence base and attempt to harness such therapeutic benefits in terms of pain relief and opiate-avoidance, anti-emesis and seizure control. We present a summary of the pharmacology of cannabis-based medicines including anaesthetic interactions and implications, to assist colleagues encountering these medicines in clinical practice.

Medical Use of Cannabinoids

Cannabinoid receptors, endocannabinoids and the enzymes responsible for their biosynthesis and degradation constitute the endocannabinoid system. In recent decades, the endocannabinoid system has attracted considerable interest as a potential therapeutic target in numerous pathological conditions. Its involvement in several physiological processes is well known, such as in energy balance, appetite stimulation, blood pressure, pain modulation, embryogenesis, nausea and vomiting control, memory, learning and immune response, among others, as well as in pathological conditions where it exerts a protective role in the development of certain disorders. As a result, it has been reported that changes in endocannabinoid levels may be related to neurological diseases such as Parkinson's disease, Huntington's disease, Alzheimer's disease and multiple sclerosis, as well as anorexia and irritable bowel syndrome. Alterations in the endocannabinoid system have also been associated with cancer, affecting the growth, migration and invasion of some tumours. Cannabinoids have been tested in several cancer types, including brain, breast and prostate cancers. Cannabinoids have shown promise as analgesics for the treatment of both inflammatory and neuropathic pain. There is also evidence for a role of the endocannabinoid system in the control of emotional states, and cannabinoids could prove useful in decreasing and palliating post-traumatic stress disorder symptoms and anxiolytic disorders. The role of the endocannabinoid system in addictions has also been examined, and cannabinoids have been postulated as alternative and co-adjuvant treatments in some abuse syndromes, mainly in ethanol and opioid abuses. The expression of the endocannabinoid system in the eye suggests that it could be a potential therapeutic target for eye diseases. Considering the importance of the endocannabinoid system and the therapeutic potential of cannabinoids in this vast number of medical conditions, several clinical studies with cannabinoid-based medications are ongoing. In addition, some cannabinoid-based medications have already been approved in various countries, including nabilone and dronabinol capsules for the treatment of nausea and vomiting associated with chemotherapy, dronabinol capsules for anorexia, an oral solution of dronabinol for both vomiting associated with chemotherapy and anorexia, a Δ⁹-tetrahydrocannabinol/cannabidiol oromucosal spray for pain related to cancer and for spasticity and pain associated with multiple sclerosis, and an oral solution of cannabidiol for Dravet and Lennox-Gastaut syndromes. Here, we review the available efficacy, safety and tolerability data for cannabinoids in a range of medical conditions.

Medicinal Properties of Cannabinoids, Terpenes, and Flavonoids in Cannabis, and Benefits in Migraine, Headache, and Pain: An Update on Current Evidence and Cannabis Science

BACKGROUND

Comprehensive literature reviews of historical perspectives and evidence supporting cannabis/cannabinoids in the treatment of pain, including migraine and headache, with associated neurobiological mechanisms of pain modulation have been well described. Most of the existing literature reports on the cannabinoids Δ⁹ -tetrahydrocannabinol (THC) and cannabidiol (CBD), or cannabis in general. There are many cannabis strains that vary widely in the composition of cannabinoids, terpenes, flavonoids, and other compounds. These components work synergistically to produce wide variations in benefits, side effects, and strain characteristics. Knowledge of the individual medicinal properties of the cannabinoids, terpenes, and flavonoids is necessary to cross-breed strains to obtain optimal standardized synergistic compositions. This will enable targeting individual symptoms and/or diseases, including migraine, headache, and pain.

OBJECTIVE

Review the medical literature for the use of cannabis/cannabinoids in the treatment of migraine, headache, facial pain, and other chronic pain syndromes, and for supporting evidence of a potential role in combatting the opioid epidemic. Review the medical literature involving major and minor cannabinoids, primary and secondary terpenes, and flavonoids that underlie the synergistic entourage effects of cannabis. Summarize the individual medicinal benefits of these substances, including analgesic and anti-inflammatory properties.

CONCLUSION

There is accumulating evidence for various therapeutic benefits of cannabis/cannabinoids, especially in the treatment of pain, which may also apply to the treatment of migraine and headache. There is also supporting evidence that cannabis may assist in opioid detoxification and weaning, thus making it a potential weapon in battling the opioid epidemic. Cannabis science is a rapidly evolving medical sector and industry with increasingly regulated production standards. Further research is anticipated to optimize breeding of strain-specific synergistic ratios of cannabinoids, terpenes, and other phytochemicals for predictable user effects, characteristics, and improved symptom and disease-targeted therapies.

Cannabinoids: Current and Future Options to Treat Chronic and Chemotherapy-Induced Neuropathic Pain

Increases in cancer diagnosis have tremendous negative impacts on patients and their families, and major societal and economic costs. The beneficial effect of chemotherapeutic agents on tumor suppression comes with major unwanted side effects such as weight and hair loss, nausea and vomiting, and neuropathic pain. Chemotherapy-induced peripheral neuropathy (CIPN), which can include both painful and non-painful symptoms, can persist 6 months or longer after the patient's last chemotherapeutic treatment. These peripheral sensory and motor deficits are poorly treated by our current analgesics with limited effectiveness. Therefore, the development of novel treatment strategies is an important preclinical research focus and an urgent need for patients. Approaches to prevent CIPN have yielded disappointing results since these compounds may interfere with the anti-tumor properties of chemotherapeutic agents. Nevertheless, the first (serotonin noradrenaline reuptake inhibitors [SNRIs], anticonvulsants, tricyclic antidepressants) and second (5% lidocaine patches, 8% capsaicin patches and weak opioids such as tramadol) lines of treatment for CIPN have shown some efficacy. The clinical challenge of CIPN management in cancer patients and the need to target novel therapies with long-term efficacy in alleviating CIPN are an ongoing focus of research. The endogenous cannabinoid system has shown great promise and efficacy in alleviating CIPN in preclinical and clinical studies. In this review, we will discuss the mechanisms through which the platinum, taxane, and vinca alkaloid classes of chemotherapeutics may produce CIPN and the potential therapeutic effect of drugs targeting the endocannabinoid system in preclinical and clinical studies, in addition to cannabinoid compounds diffuse mechanisms of action in alleviation of CIPN.

Nabilone for non-motor symptoms of Parkinson's disease: a randomized placebo-controlled, double-blind, parallel-group, enriched enrolment randomized withdrawal study (The NMS-Nab Study)

Although open-label observations report a positive effect of cannabinoids on non-motor symptoms (NMS) in Parkinson's disease (PD) patients, these effects remain to be investigated in a controlled trial for a broader use in NMS in PD patients. Therefore, we decided to design a proof-of-concept study to assess the synthetic cannabinoid nabilone for the treatment of NMS. We hypothesize that nabilone will improve NMS in patients with PD and have a favorable safety profile. The NMS-Nab Study is as a mono-centric phase II, randomized, placebo-controlled, double-blind, parallel-group, enriched enrollment withdrawal study. The primary efficacy criterion will be the change in Movement Disorders Society-Unified Parkinson's Disease-Rating Scale Part I score between baseline (i.e. randomization) and week 4. A total of 38 patients will have 80% power to detect a probability of 0.231 that an observation in the treatment group is less than an observation in the placebo group using a Wilcoxon rank-sum test with a 0.050 two-sided significance level assuming a true difference of 2.5 points between nabilone and placebo in the primary outcome measure and a standard deviation of the change of 2.4 points. The reduction of harm through an ineffective treatment, the possibility of individualized dosing, the reduction of sample size, and the possible evaluation of the influence of the placebo effect on efficacy outcomes justify this design for a single-centered placebo-controlled investigator-initiated trial of nabilone. This study should be the basis for further evaluations of long-term efficacy and safety of the use of cannabinoids in PD patients.

Review of Treatment for Central Spinal Neuropathic Pain and Its Effect on Quality of Life: Implications for Neuromyelitis Optica Spectrum Disorder

OBJECTIVES

Neuromyelitis optica spectrum disorder (NMOSD) causes disabling and persistent central neuropathic pain (NP). Because the pain syndrome in NMOSD is severe and often intractable to analgesic treatment, it interferes with quality of life in patients. No interventional trials have been published looking at response to interventions for pain in NMOSD. This is a synthesis of the literature surveying the impact on quality of life of interventions in all mechanisms of central spinal NP. This review has important implications for management of pain in NMOSD.

METHODS AND DATA SOURCES

A systematic database search was conducted using PubMed, Embase, and CINAHL Plus with keywords including "spinal cord," "quality of life," and "neuropathic pain" in an attempt to identify original research that targeted spinal NP treatment and used quality of life as an outcome measure. Both pharmacologic and nonpharmacologic treatments were sought out.

RESULTS

Twenty-one studies meeting our eligibility criteria were identified and evaluated, 13 using pharmacologic treatments and 8 using nonpharmacologic interventions. Overall, sample sizes were modest, and effects on decreasing pain and/or improving quality of life were suboptimal.

CONCLUSIONS

This review provides researchers with a foundation from which to start a more thorough and thoughtful investigation into the management of NP in NMOSD and underscores the importance of including quality of life as a clinically meaningful outcome measure.

Toward a Shared-Care Model of Relapsing-Remitting Multiple Sclerosis: Role of the Primary Care Practitioner

The objective of this study was to develop a shared-care model to enable primary-care physicians to participate more fully in meeting the complex, multidisciplinary healthcare needs of patients with multiple sclerosis (MS).

DESIGN

The design consisted of development of consensus recommendations and a shared-care algorithm.

PARTICIPANTS

A working group of 11 Canadian neurologists involved in the management of patients with MS were included in this study.

MAIN MESSAGE

The clinical management of patients with multiple sclerosis is increasing in complexity as new disease-modifying therapies (DMTs) become available, and ongoing safety monitoring is required. A shared-care model that includes primary care physicians is needed. Primary care physicians can assist in the early detection of MS of individuals presenting with neurological symptoms. Additional key roles for family physicians are health promotion, symptom management, and safety and relapse monitoring of DMT-treated patients. General principles of health promotion include counseling MS patients on maintaining a healthy lifestyle; performing standard screening measures; and identifying and treating comorbidities. Of particular importance are depression and anxiety, which occur in >20% of MS patients. Standard work-ups and treatments are needed for common MS-related symptoms, such as fatigue, pain, bladder dysfunction, sexual dysfunction, spasticity, and sleep disorders. Ongoing safety monitoring is required for patients receiving specific DMTs. Multiple sclerosis medications are generally contraindicated during pregnancy, and patients should be counseled to practice effective contraception.

CONCLUSIONS

Multiple sclerosis is a complex, disabling illness, which, similar to other chronic diseases, requires ongoing multidisciplinary care to meet the evolving needs of patients throughout the clinical course. Family physicians can play an invaluable role in maintaining general health, managing MS-related symptoms and comorbidities, monitoring for treatment-related adverse effects and MS relapses, and coordinating allied health services to ensure continuity of care to meet the complex and evolving needs of MS patients through the disease course. RÉSUMÉ: Élaborer un modèle de soins partagés dans les cas de sclérose en plaques récurrente-rémittente. Objectif: Élaborer un modèle de soins partagés afin de permettre aux médecins de première ligne de mieux répondre aux besoins complexes et multidisciplinaires de patients atteints de la sclérose en plaques (SP). Conception : Recommandations résultant d'un consensus et élaboration d'un algorithme en matière de soins partagés.

PARTICIPANTS

Un groupe de travail formé de onze neurologues canadiens impliqués dans la prise en charge de patients atteints de la SP. Message-clé : La prise en charge clinique de patients atteints de la SP est de plus en plus complexe dans la mesure où des médicaments modificateurs de l'évolution de la maladie (MMSP) deviennent accessibles et où un suivi permanent en matière de sécurité est nécessaire. Soulignons aussi qu'un modèle de soins partagés incluant les médecins de première ligne est nécessaire. Ces professionnels peuvent permettre un dépistage plus rapide de la SP chez des individus présentant des symptômes neurologiques. Ils peuvent aussi jouer un rôle de premier plan en matière de promotion de la santé, de soulagement des symptômes et de suivi de patients traités avec des MMSP en ce qui a trait à leur sécurité et à de possibles rechutes. Parmi les principes généraux de promotion de la santé, on peut inclure les suivants : offrir aux patients atteints de la SP des conseils leur permettant de maintenir de saines habitudes de vie ; adopter des mesures de dépistage standards ; identifier et traiter les comorbidités. À cet égard, l'anxiété et la dépression sont d'une importance particulière et sont fréquemment signalées (> 20 %) chez les patients atteints de SP. Des démarches d'investigation et des traitements standards sont nécessaires dans le cas des symptômes courants reliés à la SP, par exemple de la fatigue, des douleurs, une dysfonction vésicale, des dysfonctions sexuelles, de la spasticité et des troubles du sommeil. On l'a dit, un suivi permanent s'impose dans le cas de patients bénéficiant d'un traitement spécifique avec des MMSP. Les médicaments associés à la SP sont généralement contre-indiqués durant la grossesse de sorte qu'on devrait conseiller aux patients d'adopter des méthodes de contraception efficaces.

CONCLUSIONS

La SP est une maladie complexe et invalidante qui, à l'instar d'autres maladies chroniques, exige des soins multidisciplinaires continus afin de répondre, en lien avec un tableau clinique précis, aux besoins en constante évolution des patients. Les médecins de première ligne peuvent jouer un rôle irremplaçable à plusieurs égards : dans le maintien d'une bonne santé ; le suivi et le soulagement des symptômes et des comorbidités reliés à la SP ; le suivi des rechutes et des effets indésirables associés aux traitements. N'oublions pas non plus la coordination des services paramédicaux afin d'assurer, durant l'évolution de la SP, une continuité des soins répondant aux besoins complexes et en constante évolution des patients atteints de cette maladie.

Assessment of Efficacy and Tolerability of Medicinal Cannabinoids in Patients With Multiple Sclerosis: A Systematic Review and Meta-analysis

IMPORTANCE

Cannabinoids have antispastic and analgesic effects; however, their role in the treatment of multiple sclerosis (MS) symptoms is not well defined.

OBJECTIVE

To conduct a systematic review and meta-analysis to assess the efficacy and tolerability of medicinal cannabinoids compared with placebo in the symptomatic treatment of patients with MS.

DATA SOURCES

MEDLINE and the Cochrane Library Plus up to July 26, 2016. No restrictions were applied. The search was completed with information from ClinicalTrials.gov.

STUDY SELECTION

Randomized, double-blind, and placebo-controlled trials evaluating the effect of medicinal cannabinoids by oral or oromucosal route of administration on the symptoms of spasticity, pain, or bladder dysfunction in adult patients with MS.

DATA EXTRACTION AND SYNTHESIS

The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guidelines were followed. Effect sizes were calculated as standardized mean difference (SMD) for efficacy, and rate ratio (RR) for tolerability. Within each study, those SMDs evaluating the same outcome were combined before the meta-analysis to obtain a single value per outcome and study. Pooling of the studies was performed on an intention-to-treat basis by means of random-effect meta-analysis.

MAIN OUTCOMES AND MEASURES

Spasticity (on the Ashworth and Modified Ashworth scales and subjective), pain, bladder dysfunction, adverse events, and withdrawals due to adverse events.

RESULTS

Seventeen selected trials including 3161 patients were analyzed. Significant findings for the efficacy of cannabinoids vs placebo were SMD = -0.25 SD (95% CI, -0.38 to -0.13 SD) for spasticity (subjective patient assessment data), -0.17 SD (95% CI, -0.31 to -0.03 SD) for pain, and -0.11 SD (95% CI, -0.22 to -0.0008 SD) for bladder dysfunction. Results favored cannabinoids. Findings for tolerability were RR = 1.72 patient-years (95% CI, 1.46-2.02 patient-years) in the total adverse events analysis and 2.95 patient-years (95% CI, 2.14-4.07 patient-years) in withdrawals due to adverse events. Results described a higher risk for cannabinoids. The serious adverse events meta-analysis showed no statistical significance.

CONCLUSIONS AND RELEVANCE

The results suggest a limited efficacy of cannabinoids for the treatment of spasticity, pain, and bladder dysfunction in patients with MS. Therapy using these drugs can be considered as safe.

TRIAL REGISTRATION

PROSPERO Identifier: CRD42014015391.

Traditional Uses of Cannabinoids and New Perspectives in the Treatment of Multiple Sclerosis

Recent findings highlight the emerging role of the endocannabinoid system in the control of symptoms and disease progression in multiple sclerosis (MS). MS is a chronic, immune-mediated, demyelinating disorder of the central nervous system with no cure so far. It is widely reported in the literature that cannabinoids might be used to control MS symptoms and that they also might exert neuroprotective effects and slow down disease progression. This review aims to give an overview of the principal cannabinoids (synthetic and endogenous) used for the symptomatic amelioration of MS and their beneficial outcomes, providing new potentially possible perspectives for the treatment of this disease.

Therapeutic applications of cannabinoids

The psychoactive property of cannabinoids is well known and there has been a continuous controversy regarding the usage of these compounds for therapeutic purposes all over the world. Their use for medical and research purposes are restricted in various countries. However, their utility as medications should not be overshadowed by its negative physiological activities. This review article is focused on the therapeutic potential and applications of phytocannabinoids and endocannabinoids. We further highlights their mode of action, overall effects on physiology, various in vitro and in vivo studies that have been done so far and the extent to which these compounds can be useful in different disease conditions such as cancer, Alzheimer's disease, multiple sclerosis, pain, inflammation, glaucoma and many others. Thus, this work is an attempt to make the readers understand the positive implications of these compounds and indicates the significant developments of utilizing cannabinoids as therapeutic agents.