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

The effects of a brand-specific, hemp-derived cannabidiol product on physiological, biochemical, and psychometric outcomes in healthy adults: a double-blind, randomized clinical trial

BACKGROUND

Cannabidiol (CBD) is a non-psychoactive phyto-cannabinoid derived from the Cannabis sativa plant. CBD exhibits various interactions at receptor sites, prompting the research of its potential anti-inflammatory, immunomodulatory, psychological, and pain-relieving effects. This study aimed to investigate the physiological, biochemical, and psychometric effects of a brand-specific, hemp-derived CBD product in healthy adults over a 12-week observation period.

METHODS

54 healthy males and females (age = 25 ± 7y; BMI = 24.82 ± 3.25 kg/m2) recruited from a large Southeastern University completed the study. Participants arrived at the laboratory after > 8 h of fasting, and > 48 h without alcohol consumption and vigorous exercise. Following baseline measurements (height, weight, blood pressure, electrocardiogram (ECG), and blood work), participants were stratified by sex and randomized to either CBD or placebo groups. Products were administered double-blinded, with both given in liquid form containing medium-chain triglyceride oil, while the CBD product specifically contained 50 mg/mL of CBD. Participants were instructed to consume 1 mL of their product twice daily and were given enough product to last until their next laboratory visit. Data were collected at baseline and on days 30 ± 3, 60 ± 3, and 90 ± 3. Blood was drawn for analysis of immune and inflammatory biomarkers. Chronic pain among participants was calculated using urine samples according to the foundational pain index (FPI). Self-reported psychometric questionnaires were utilized (Cohen's Perceived Stress Scale, Pittsburgh Sleep Quality Index, Profile of Mood States,10-item Likert scale for perceived pain) to assess stress, sleep quality, mood state, and body discomfort. To determine overall wellbeing, participants completed a daily survey indicating if they missed work or school due to illness. Change from baseline was calculated for each measure, and mixed effects models were used to determine differences between groups over time while adjusting for baseline values (α = 0.05). Data are presented as mean ± standard deviation.

RESULTS

There were no Group-by-Time interactions or Group or Time main effects for immune or inflammatory biomarkers (p > 0.05). Analyses revealed no Group-by-Time interactions or main effects observed for perceived stress, sleep quality, overall mood disturbance, and all the profile of mood state subscales (p > 0.05), except "vigor-activity." A Time main effect was found for the sub-score for "vigor-activity" (p = 0.007; Pre CBD = 19.5 ± 5.2, Post CBD = 17.3 ± 5.3; Pre PL = 19.0 ± 5.7, Post PL = 17.9 ± 7.1), which decreased from Visit 3 to Visit 4 (p = 0.025) and from Visit 3 to Visit 5 (p = 0.014). There was a Group main effect for FPI (p = 0.028; Pre CBD = 11.9 ± 14.4, Post CBD = 8.8 ± 10.9; Pre PL = 9.0 ± 14.2, Post PL = 12.9 ± 11.5), indicating that the placebo group had greater increases in pain over the intervention compared to the CBD group. No significant differences were found between groups in the incidence and prevalence of "colds or flus" (p > 0.05).

DISCUSSION

CBD was safe and well tolerated in healthy adults. These findings show pain was lower in the CBD group, suggesting a potentially positive effect for consumption of CBD. "Vigor-activity" decreased across the intervention, which may be a confounding effect of the academic semester. While the dosage chosen was safe, more research may be warranted using higher doses as these may be needed to observe further therapeutic effects in healthy populations.

Clinical Benefits and Safety of Medical Cannabis Products: A Narrative Review on Natural Extracts

Interest in medical cannabis and cannabis-based medicinal products (CBMPs) has increased greatly in recent years. Two cannabinoids are of principal importance; delta-9-tetrahydrocannabinol (∆9-THC), the primary psychoactive component, and also cannabidiol (CBD), considered non-intoxicating. Each has distinct mechanisms of action and different therapeutic potentials. CBMPs differ in their ∆9-THC and CBD components; predominantly ∆9-THC, balanced formulations with equivalent ∆9-THC and CBD elements, and CBD-predominant products. In this narrative review, we evaluate the published evidence for the clinical benefits of CBMPs and overall benefits in well-being. We also review the overall safety profile and discuss the potential for dependence with CBMPs. Evidence can be drawn from a wide range of randomized and other controlled studies and from observational real-world studies. Most data from observational registry studies are supportive of ∆9-THC-based products (∆9-THC-predominant or balanced CBMPs) in the management of chronic neuropathic pain. Balanced products are also effective in reducing spasticity in multiple sclerosis. Most CBMPs show benefit in providing symptomatic benefits in reducing anxiety, nausea, and in improving sleep, but the place of specific products is more subtle, and choice guided by specific circumstances. Symptomatic improvements are accompanied by improved quality of life and well-being. Safety data indicate that CBMPs are generally well tolerated in most patients without specific contraindications. The majority of adverse effects are non-serious, and transient; most are principally associated with ∆9-THC and are dose-dependent. In contrast to recreational cannabis use, there is little evidence from clinical studies that CBMPs have any potential for dependence.

Cannabinoids for Acute Pain Management: Approaches and Rationale

PURPOSE OF THE REVIEW

Acute pain management remains a challenge and postoperative pain is often undermanaged despite many available treatment options, also including cannabinoids.

RECENT FINDINGS

In the light of the opioid epidemic, there has been growing interest in alternative care bundles for pain management, including cannabinoids as potential treatment to decrease opioid prescribing. Despite the lack of solid evidence on the efficacy of cannabinoids, their use among patients with pain, including those using opioids, is currently increasing. This use is supported by data suggesting that cannabinoids could potentially contribute to a better pain management and to a reduction in opioid doses while maintaining effective analgesia with minimum side effects. The scientific basis for supporting the use of cannabis is extensive, although it does not necessarily translate into relevant clinical outcomes. The use of cannabinoids in acute pain did not always consistently show statistically significant results in improving acute pain. Large randomized, controlled trials evaluating diverse cannabis extracts are needed in different clinical pain populations to determine safety and efficacy.

Cannabinoid Analgesia in Postoperative Pain Management: From Molecular Mechanisms to Clinical Reality

Postoperative pain (POP) is a challenging clinical phenomenon that affects the majority of surgical patients and demands effective management to mitigate adverse outcomes such as persistent pain. The primary goal of POP management is to alleviate suffering and facilitate a seamless return to normal function for the patient. Despite compelling evidence of its drawbacks, opioid analgesia remains the basis of POP treatment. Novel therapeutic approaches rely on multimodal analgesia, integrating different pharmacological strategies to optimize efficacy while minimizing adverse effects. The recognition of the imperative role of the endocannabinoid system in pain regulation has prompted the investigation of cannabinoid compounds as a new therapeutic avenue. Cannabinoids may serve as adjuvants, enhancing the analgesic effects of other drugs and potentially replacing or at least reducing the dependence on other long-term analgesics in pain management. This narrative review succinctly summarizes pertinent information on the molecular mechanisms, clinical therapeutic benefits, and considerations associated with the plausible use of various cannabinoid compounds in treating POP. According to the available evidence, cannabinoid compounds modulate specific molecular mechanisms intimately involved in POP. However, only two of the eleven clinical trials that evaluated the efficacy of different cannabinoid interventions showed positive results.

Narrative bias ("spin") is common in randomised trials and systematic reviews of cannabinoids for pain

ABSTRACT

We define narrative bias as a tendency to interpret information as part of a larger story or pattern, regardless of whether the facts support the full narrative. Narrative bias in title and abstract means that results reported in the title and abstract of an article are done so in a way that could distort their interpretation and mislead readers who had not read the whole article. Narrative bias is often referred to as "spin." It is prevalent in abstracts of scientific papers and is impactful because abstracts are often the only part of an article read. We found no extant narrative bias instrument suitable for exploring both efficacy and safety statements in randomized trials and systematic reviews of pain. We constructed a 6-point instrument with clear instructions and tested it on randomised trials and systematic reviews of cannabinoids and cannabis-based medicines for pain, with updated searches to April 2021. The instrument detected moderate or severe narrative bias in the title and abstract of 24% (8 of 34) of randomised controlled trials and 17% (11 of 64) of systematic reviews; narrative bias for efficacy and safety occurred equally. There was no significant or meaningful association between narrative bias and study characteristics in correlation or cluster analyses. Bias was always in favour of the experimental cannabinoid or cannabis-based medicine. Put simply, reading title and abstract only could give an incorrect impression of efficacy or safety in about 1 in 5 papers reporting on these products.

Phytocannabinoids: Exploring Pharmacological Profiles and Their Impact on Therapeutical Use

Phytocannabinoids, a diverse group of naturally occurring compounds extracted from the Cannabis plant, have attracted interest due to their potential pharmacological effects and medicinal uses. This comprehensive review presents the intricate pharmacological profiles of phytocannabinoids while exploring the diverse impacts these substances have on biological systems. From the more than one hundred cannabinoids which were identified in the Cannabis plant so far, cannabidiol (CBD) and tetrahydrocannabinol (THC) are two of the most extensively studied phytocannabinoids. CBD is a non-psychoactive compound, which exhibits potential anti-inflammatory, neuroprotective, and anxiolytic properties, making it a promising candidate for a wide array of medical conditions. THC, known for its psychoactive effects, possesses analgesic and antiemetic properties, contributing to its therapeutic potential. In addition to THC and CBD, a wide range of additional phytocannabinoids have shown intriguing pharmacological effects, including cannabichromene (CBC), cannabigerol (CBG), and cannabinol (CBN). The endocannabinoid system, made up of the enzymes involved in the production and breakdown of endocannabinoids, cannabinoid receptors (CB1 and CB2), and endogenous ligands (endocannabinoids), is essential for preserving homeostasis in several physiological processes. Beyond their effects on the endocannabinoid system, phytocannabinoids are studied for their ability to modify ion channels, neurotransmitter receptors, and anti-oxidative pathways. The complex interaction between phytocannabinoids and biological systems offers hope for novel treatment approaches and lays the groundwork for further developments in the field of cannabinoid-based medicine. This review summarizes the state of the field, points out information gaps, and emphasizes the need for more studies to fully realize the therapeutic potential of phytocannabinoids.

Marijuana Use, Vaping, and Preoperative Anesthetic and Surgical Considerations in Clinical Practice

In recent years, marijuana and vaping have acquired widespread popularity, with millions of people using them for a variety of reasons, including recreational purposes. However, these practices have often overlooked the implications on surgery and the preoperative anesthesia considerations. Marijuana can influence a patient's response to anesthesia, alter postoperative pain management, and increase the risk of complications, whereas vaping can have negative effects on the respiratory system and hinder the body's ability to recover after surgery.

Danish dog owners' use and the perceived effect of unlicensed cannabis products in dogs

The interest in the use of medical cannabis has increased in recent years in both human and veterinary fields. In Denmark, there are no veterinary-licensed medical cannabis or cannabinoid supplements, and it is illegal to prescribe or sell cannabinoids intended for the treatment of veterinary patients. This study aimed to explore the unlicensed cannabinoid use in Danish dogs, by questioning dog owners about usage, indication for use, way of purchase, and their perceived effect of the cannabinoid treatment. An anonymous online survey was distributed via social media. The total number of respondents were 2,002, of which 38% indicated using or having administered cannabinoids to their dog. The majority of the respondents confirming the use of cannabinoids (93%) had used cannabidiol drops/oil and only few (4%) reported using Δ9-tetrahydrocannabinol-based products. Most owners (67%) purchased the products online. The three most common indications for use were pain alleviation, behavioural issues, and allergy. When asked about the respondent-perceived effect the majority reported a good or very good effect. The indication with the highest percentage of owner-perceived positive effect (77%) was pain alleviation. This study shows that, despite no licensed veterinary cannabinoid products being available in Denmark, dog owners do supplement their dogs with cannabinoids and the majority of these perceive that the treatment had a positive effect. This supports the need for more evidence-based knowledge in veterinary cannabinoid therapy.

Medical Cannabis Use and Its Impact on Health Among Older Adults: Recent Research Findings and Future Directions

Purpose of Review

With the rapidly changing landscape of state level legalization of cannabis, older adults have become one of the fastest growing populations seeking medical cannabis (MC). However, research evidence on the risks and benefits of MC use in this population remains limited. This review aims to synthesize recent literature on the impacts of MC use in older adults and identify critical knowledge gaps to be addressed in future research.

Recent Findings

Recent literature showed that older adults often face financial and/or educational barriers and stigma associated with MC access. Emerging data showed that MC may have therapeutic effects on symptoms of conditions such as chronic pain, insomnia, anxiety/depression, dementia, nausea, and vomiting. However, available evidence is inconsistent and tends to rely on self-report and uncontrolled studies. While some adverse events associated with MC use were reported, it is generally well tolerated in older adults. Neurocognitive and psychological consequences and cardiovascular risks have been reported but again only in limited studies with inconsistent findings.

Summary

There is a need for more systematic and rigorous research on MC in older adults to determine its safety and efficacy. Research on dosing procedures and product characteristics, as well as how these may impact health outcomes, is crucial. More consistent evidence is needed to inform policy changes and patient/physician education to minimize potential risks and optimize benefits among older adults seeking MC as an alternative treatment.

The holistic effects of medical cannabis compared to opioids on pain experience in Finnish patients with chronic pain

BACKGROUND

Medical cannabis (MC) is increasingly used for chronic pain, but it is unclear how it aids in pain management. Previous literature suggests that MC could holistically alter the pain experience instead of only targeting pain intensity. However, this hypothesis has not been previously systematically tested.

METHOD

A retrospective internet survey was used in a sample of Finnish chronic pain patients (40 MC users and 161 opioid users). The patients evaluated statements describing positive and negative phenomenological effects of the medicine. The two groups were propensity score matched to control for possible confounding factors.

RESULTS

Exploratory factor analysis revealed three experience factors: Negative Side Effects, Positive Holistic Effects, and Positive Emotional Effects. The MC group (matched n = 39) received higher scores than the opioid group (matched n = 39) in Positive Emotional Effects with large effect size (Rank-Biserial Correlation RBC = .71, p < .001), and in Holistic Positive Effects with medium effect size (RBC = .47, p < .001), with no difference in Negative Side Effects (p = .13). MC and opioids were perceived as equally efficacious in reducing pain intensity. Ratings of individual statements were exploratively examined in a post hoc analysis.

CONCLUSION

MC and opioids were perceived to be equally efficacious in reducing pain intensity, but MC additionally positively affected broader pain-related factors such as emotion, functionality, and overall sense of wellbeing. This supports the hypothesis that MC alleviates pain through holistically altering the pain experience.

Cannabis constituents for chronic neuropathic pain; reconciling the clinical and animal evidence

Chronic neuropathic pain is a debilitating pain syndrome caused by damage to the nervous system that is poorly served by current medications. Given these problems, clinical studies have pursued extracts of the plant Cannabis sativa as alternative treatments for this condition. The vast majority of these studies have examined cannabinoids which contain the psychoactive constituent delta-9-tetrahydrocannabinol (THC). While there have been some positive findings, meta-analyses of this clinical work indicates that this effectiveness is limited and hampered by side-effects. This review focuses on how recent preclinical studies have predicted the clinical limitations of THC-containing cannabis extracts, and importantly, point to how they might be improved. This work highlights the importance of targeting channels and receptors other than cannabinoid CB1 receptors which mediate many of the side-effects of cannabis.

Evaluating the impact of cannabinoids on sleep health and pain in patients with chronic neuropathic pain: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Chronic neuropathic pain is often debilitating and can have a significant impact on sleep health and quality of life. There is limited information on the impact of cannabinoids on sleep health when treating neuropathic pain.

OBJECTIVE

The objectives of this systematic review and meta-analysis were to determine the effect of cannabinoids on sleep quality, pain intensity, and patient impression of treatment efficacy in patients with neuropathic pain.

EVIDENCE REVIEW

Nine available medical literature databases were searched for randomized controlled trials comparing synthetic and natural cannabinoids to placebo in patients with neuropathic pain syndromes. Data on validated tools for sleep quality, pain intensity, patients' global impression of change (PGIC), and incidence of adverse effects of cannabinoids were extracted and synthesized.

FINDINGS

Of the 3491 studies screened, eight randomized controlled trials satisfied the inclusion criteria for this review. Analyses were performed using R -4.1.2. using the metafor package and are interpreted using alpha=0.05 as the threshold for statistical significance. Validated measures for sleep health were not used in most studies. Meta-analysis of data from six studies showed that cannabinoids were associated with a significant improvement in sleep quality (standardized mean difference (SMD): 0.40; 95% CI: 0.19 to -0.61, 95% prediction interval (PI): -0.12 to 0.88, p-value=0.002, I2=55.26, τ2=0.05, Q-statistic=16.72, GRADE: moderate certainty). Meta-analysis of data from eight studies showed a significant reduction in daily pain scores in the cannabinoid (CB) group (SMD: -0.55, 95% CI:-0.69 to -0.19, 95% PI: -1.51 to 0.39, p=0.003, I2=82.49, τ2=0.20, Q-statistic=47.69, GRADE: moderate certainty). However, sleep health and analgesic benefits were associated with a higher likelihood of experiencing daytime somnolence, nausea, and dizziness.

CONCLUSIONS

Cannabinoids have a role in treating chronic neuropathic pain as evidenced by significant improvements in sleep quality, pain intensity, and PGIC. More research is needed to comprehensively evaluate the impact of cannabinoids on sleep health and analgesic efficacy.

PROSPERO REGISTRATION NUMBER

CRD42017074255.

Predictors of perceived symptom change with acute cannabis use for mental health conditions in a naturalistic sample: A machine learning approach

BACKGROUND

Despite limited clinical evidence of its efficacy, cannabis use has been commonly reported for the management of various mental health concerns in naturalistic field studies. The aim of the current study was to use machine learning methods to investigate predictors of perceived symptom change across various mental health symptoms with acute cannabis use in a large naturalistic sample.

METHODS

Data from 68,819 unique observations of cannabis use from 1307 individuals using cannabis to manage mental health symptoms were analyzed. Data were extracted from Strainprint®, a mobile app that allows users to monitor their cannabis use for therapeutic purposes. Machine learning models were employed to predict self-perceived symptom change after cannabis use, and SHapley Additive exPlanations (SHAP) value plots were used to assess feature importance of individual predictors in the model. Interaction effects of symptom severity pre-scores of anxiety, depression, insomnia, and gender were also examined.

RESULTS

The factors that were most strongly associated with perceived symptom change following acute cannabis use were pre-symptom severity, age, gender, and the ratio of CBD to THC. Further examination on the impact of baseline severity for the most commonly reported symptoms revealed distinct responses, with cannabis being reported to more likely benefit individuals with lower pre-symptom severity for depression, and higher pre-symptom severity for insomnia. Responses to cannabis use also differed between genders.

CONCLUSIONS

Findings from this study highlight the importance of several factors in predicting perceived symptom change with acute cannabis use for mental health symptom management. Mental health profiles and baseline symptom severity may play a large role in perceived responses to cannabis. Distinct response patterns were also noted across commonly reported mental health symptoms, emphasizing the need for placebo-controlled cannabis trials for specific user profiles.

Medicinal cannabis for Australian patients with chronic refractory pain including arthritis

Objectives

To examine the tolerability and effectiveness of medicinal cannabis prescribed to patients for chronic, refractory pain, with a subset analysis on arthritis.

Methods

This was an interim analysis of the CA Clinics Observational Study investigating self-reported adverse events (AEs) and changes in health-related quality of life (HRQoL) outcomes over time after commencing medicinal cannabis. Patients were prescribed medicinal cannabis by a medical practitioner, containing various ratios of Δ9-tetrahydrocannabinol (THC) and/or cannabidiol (CBD).

Results

The overall chronic pain cohort, and specifically the balanced CBD:THC products, were associated with significantly reduced pain intensity scores (p = 0.003, p = 0.025), with 22% of patients reporting a clinically meaningful reduction in pain intensity. Patients in the arthritis subset (n = 199) reported significantly reduced pain intensity scores (p = 0.005) overall, and specifically for those taking CBD-only (p = 0.018) and balanced products (p = 0.005). Other HRQoL outcomes, including pain interference and pain impact scores were significantly improved depending on the CBD:THC ratio. Products that contained a balanced ratio of CBD:THC were associated with improvements in the most number of PROMIS-29 domains. Approximately half (n = 364; 51%) of the chronic pain cohort experienced at least one AE, the most common being dry mouth (24%), somnolence (19%) or fatigue (12%). These findings were similar in the arthritis subset.

Discussion

Medicinal cannabis was observed to improve pain intensity scores and HRQoL outcomes in patients with chronic, refractory pain, providing real-world insights into medicinal cannabis' therapeutic potential.

Medical Cannabis in Hand Surgery: A Review of the Current Evidence

Acute and chronic pain management remains an ongoing challenge for hand surgeons. This has been compounded by the ongoing opioid epidemic in the United States. With the increasing legalization of medical and recreational cannabis throughout the United States and other countries, previous societal stigmas about this substance keep evolving, and recognition of medical cannabis as an opioid-sparing pain management alternative is growing. A review of the current literature demonstrates a strong interest from patients regarding the use of medical cannabis for pain control. Current evidence demonstrates its efficacy and safety for chronic musculoskeletal and neuropathic pain. However, definitive conclusions regarding the efficacy of cannabis for pain control in hand and upper extremity conditions require continued investigation. The purpose of this article is to provide a general review of the mechanism of medical cannabis and a scoping review of the current evidence for its efficacy, safety, and potential applicability in hand and upper extremity conditions.

Cys-loop receptors on cannabinoids: All high?

Endocannabinoids (eCBS) are endogenously derived lipid signaling molecules that serve as tissue hormones and interact with multiple targets, mostly within the endocannabinoid system (ECS). The ECS is a highly conserved regulatory system involved in homeostatic regulation, organ formation, and immunomodulation of chordates. The term “cannabinoid” evolved from the distinctive class of plant compounds found in Cannabis sativa, an ancient herb, due to their action on CB1 and CB2 receptors. CB1/2 receptors are the primary targets for eCBs, but their effects are not limited to the ECS. Due to the high interest and extensive research on the ECS, knowledge on its constituents and physiological role is substantial and still growing. Crosstalk and multiple targeting of molecules are common features of endogenous and plant compounds. Cannabimimetic molecules can be divided according to their origin, natural or synthetic, including phytocannabinoids (pCB’s) or synthetic cannabinoids (sCB’s). The endocannabinoid system (ECS) consists of receptors, transporters, enzymes, and signaling molecules. In this review, we focus on the effects of cannabinoids on Cys-loop receptors. Cys-loop receptors belong to the class of membrane-bound pentameric ligand gated ion channels, each family comprising multiple subunits. Mammalians possess GABA type A receptors (GABAAR), glycine receptors (GlyR), serotonin receptors type 3 (5-HT3R), and nicotinic acetylcholine receptors (nAChR). Several studies have shown different modulatory effects of CBs on multiple members of the Cys-loop receptor family. We highlight the existing knowledge, especially on subunits and protein domains with conserved binding sites for CBs and their possible pharmacological and physiological role in epilepsy and in chronic pain. We further discuss the potential for cannabinoids as first line treatments in epilepsy, chronic pain and other neuropsychiatric conditions, indicated by their polypharmacology and therapeutic profile.

The Pharmacogenetics of Cannabis in the Treatment of Chronic Pain

Background: The increase in the medical use of cannabis has revealed a number of beneficial effects, a variety of adverse side effects and great inter-individual variability. Association studies connecting consumption, addiction and side effects related to recreational cannabis use have led to the identification of several polymorphic genes that may play a role in the pharmacodynamics and pharmacokinetics of cannabis. Method: In total, 600 patients treated with cannabis were genotyped for several candidate polymorphic genes (single-nucleotide polymorphism; SNP), encoding receptors CNR1 and TRPV1; for the ABCB1 transporter; for biotransformation, bioactivation and biosynthesis; and CYP3A4, COMT and UGT2B7 conjugation. Results: Three polymorphic genes (ABCB1, TRPV1 and UGT2B7) were identified as being significantly associated with decline in pain after treatment with cannabis. Patients simultaneously carrying the most favourable allele combinations showed a greater reduction (polygenic effect) in pain compared to those with a less favourable combination. Considering genotype combinations, we could group patients into good responders, intermediate responders and poor or non-responders. Results suggest that genetic makeup is, at the moment, a significant predictive factor of the variability in response to cannabis. Conclusions: This study proves, for the first time, that certain polymorphic candidate genes may be associated with cannabis effects, both in terms of pain management and side effects, including therapy dropout. Significance: Our attention to pharmacogenetics began in 2008, with the publication of a first study on the association between genetic polymorphisms and morphine action in pain relief. The study we are presenting is the first observational study conducted on a large number of patients involving several polymorphic candidate genes. The data obtained suggest that genetic makeup can be a predictive factor in the response to cannabis therapy and that more extensive and planned studies are needed for the opening of new scenarios for the personalization of cannabis therapy.

Systematic Review and Meta-analysis Seem to Indicate that Cannabinoids for Chronic Primary Pain Treatment Have Limited Benefit

INTRODUCTION

The IASP ICD-11 chronic primary pain (CPP) definition includes 19 different painful conditions. In recent years, interest in the potential role of cannabinoids in the management of CPP has increased, since they demonstrated a possible efficacy in treating pain, especially in secondary pain conditions. However, limited evidence is available for patients with CPP. The aim of this systematic review and meta-analysis is to evaluate the efficacy and safety of cannabinoid administration in CPP.

METHODS

PubMed, EMBASE, and Cochrane Library were searched form the beginning up to 31 October 2021 to retrieve published articles of randomized controlled trials (RCTs) or observational, retrospective or prospective, studies, investigating cannabinoids in CPP. The study screening process was completed during November 2021. The primary outcome was pain reduction by means of the visual analogue scale (VAS). Secondary outcomes were quality of life by means of the fibromyalgia impact questionnaire (FIQ) or other available scales, appetite, anxiety, depression, and sleep by means of any available scales. Safety was assessed with the reporting of serious adverse events (SAE) and discontinuation due to adverse events. Risk of bias was assessed. The weighted generic inverse variance method and Mantel-Haenszel method were used to estimate the mean difference (MD) and odds ratios (OR) with 95% confidence intervals (CI) for continuous and dichotomous outcomes, respectively. For outcome measures reported with different scales (pain, anxiety, depression), we used the standardized MD (SMD) as the effect measure and then converted it into units of the VAS scale for pain, the Beck Anxiety Inventory (BAI) for anxiety, and the Beck Depression Inventory (BDI) for depression. Summary of findings was produced using GRADEproGDT.

RESULTS

From 3007 identified records, we included eight articles reporting the results of eight different RCTs (four parallel and four crossover studies; seven compared to placebo and one to amitriptyline), with a total population of 240 patients. VAS pain reduction was non-significant for cannabinoids against placebo (MD = - 0.64; 95% CI - 1.30 to 0.02) or amitriptyline (MD = - 0.19; 95% CI - 0.58 to 0.19). More than 4 weeks cannabinoid treatment significantly reduced pain compared to placebo in parallel studies with more than 4 weeks of treatment duration (MD = - 1.28; 95% CI - 2.33 to - 0.22). Differences for the FIQ (MD = - 21.69; 95% CI - 46.20 to 2.82), BAI (MD = - 2.32; 95% CI - 7.99 to 3.08), and BDI (MD = 2.32; 95% CI - 1.71 to 6.35) were non-significant, likewise for discontinuation due to adverse events (OR = 2.15; 95% CI 0.44-10.65), when comparing cannabinoids to placebo. The quality of the evidence was generally low mainly as a result of imprecision and risk of bias.

CONCLUSION

Cannabinoid treatment in patients with CPP had limited benefit on pain relief; however, it might improve pain with long-term administration.

Systematic reviews of randomized controlled trials of cannabinoid products in chronic pain conditions and for symptoms associated with multiple sclerosis: what do they tell us?

INTRODUCTION

: To investigate whether published systematic reviews of randomized controlled trials provide sufficient clarity to inform prescribing of cannabinoid products aimed for medicinal use, we examined their features and findings in two well-researched areas: chronic cancer/noncancer pain and multiple sclerosis (MS)-related symptoms.

AREAS COVERED

: Structured searches from January 2011 to 2 February 2021 identified 31 systematic reviews (with/without meta-analyses) that met the inclusion criteria. Support for the efficacy of cannabinoids was minimal in cancer pain, and somewhat stronger in noncancer (especially neuropathic) pain and MS spasticity. All systematic reviews and most meta-analyses grouped cannabinoid products together without appropriate consideration of their differential attributes (active constituent(s), concentration/strength, dosage forms, administration route), dosing regimens or treatment durations. Patient populations and efficacy outcome measures were inhomogeneous, particularly for studies in noncancer pain and MS. Separate results for specific cannabinoid formulations were rarely provided.

EXPERT OPINION

: The therapeutic effect of cannabinoids, as already demonstrated for some products, is not reflected clearly in the current range of systematic reviews and meta-analyses in chronic pain and MS. To truly inform evidence-based practice, future publications should aim to present results by individual product from well-conducted clinical trials using appropriate and homogeneous outcome measures in well-defined patient populations.

The Role of Cannabis, Cannabidiol and Other Cannabinoids in Chronic Pain. The Perspective of Physicians

Currently, there is a renewed interest in treatments with medical cannabis and cannabinoids. Based on an increasing number of publications over the last decades that permitted new insights into mechanisms, efficacy and safety of cannabinoids, the use of cannabinergic medications is authorised in an increasing number of European and non-European countries. The alleviation of chronic, painful conditions is, since thousands of years, one of the primary reasons for the use of cannabis. Depending on the country, a wide range of medicinal cannabis preparations are available:ranging from defined cultivars of medical cannabis, mainly varying in their THC:CBD ratio, that are inhaled or taken as whole plant extracts,to highly purified single cannabinoids, such as delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD),or mixtures of two enriched extracts, standardised to a 1:1 ratio of THC:CBD (nabiximols). Although conflicting opinions continue to exist, the majority of reviews in the past concluded that medical cannabis and cannabinoids play a significant role in the management of pain. Surprisingly, systematic studies to date do not support an "entourage effect" of the other plant constituents of cannabis (mainly terpenoids) in treatment of chronic pain. An emerging cannabinoid is CBD which is the only cannabinergic medication available at present that does not cause the typical "cannabis high"; it is not a "controlled substance". However, despite years of research, there is either no study or no well-conducted, head-to-head, comparison available between different cannabis cultivars, between pure cannabinoids, and between pure cannabinoids and extracts. It remains unanswered which is the optimal treatment approach.

A Systematic Review on Cannabinoids for Neuropathic Pain Administered by Routes Other than Oral or Inhalation

The use of cannabis and cannabinoid products for the treatment of neuropathic pain is a growing area of research. This type of pain has a high prevalence, limited response to available therapies and high social and economic costs. Systemic cannabinoid-based therapies have shown some unwanted side effects. Alternative routes of administration in the treatment of neuropathic pain may provide better acceptance for the treatment of multiple pathologies associated with neuropathic pain. To examine the efficacy, tolerability, and safety of cannabinoids (individualized formulations, phytocannabinoids, and synthetics) administered by routes other than oral or inhalation compared to placebo and/or conventional medications in the management of neuropathic pain. This systematic review of the literature reveals a lack of clinical research investigating cannabis by routes other than oral and inhalation as a potential treatment for neuropathic pain and highlights the need for further investigation with well-designed clinical trials. There is a significant lack of evidence indicating that cannabinoids administered by routes other than oral or inhaled may be an effective alternative, with better tolerance and safety in the treatment of neuropathic pain. Higher quality, long-term, randomized controlled trials are needed to examine whether cannabinoids administered by routes other than inhalation and oral routes may have a role in the treatment of neuropathic pain.

Cannabis, cannabinoids, and cannabis-based medicines: future research directions for analgesia

The use of cannabis spans thousands of years and encompasses almost all dimensions of the human experience, including consumption for recreational, religious, social, and medicinal purposes. Its use in the management of pain has been anecdotally described for millennia. However, an evidence base has only developed over the last 100 years, with an explosion in research occurring in the last 20-30 years, as more states in the USA as well as countries worldwide have legalized and encouraged its use in pain management. Pain remains one of the most common reasons for individuals deciding to use cannabis medicinally. However, cannabis remains illegal at the federal level in the USA and in most countries of the world, making it difficult to advance quality research on its efficacy for pain treatment. Nonetheless, new products derived both from the cannabis plant and the chemistry laboratory are being developed for use as analgesics. This review examines the current landscape of cannabinoids research and future research directions in the management of pain.

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.

From a Symptom-Based to a Mechanism-Based Pharmacotherapeutic Treatment in Complex Regional Pain Syndrome

Complex regional pain syndrome (CRPS) is a debilitating painful condition of a distal extremity that can develop after tissue damage. CRPS is thought to be a multimechanism syndrome and ideally the most prominent mechanism(s) should be targeted by drugs in an individually tailored manner. This review gives an overview of the action and evidence of current and future pharmacotherapeutic options for CRPS. The available options are grouped in four categories by their therapeutic actions on the CRPS mechanisms, i.e. inflammation, central sensitisation, vasomotor disturbances and motor disturbances. More knowledge about the underlying mechanisms of CRPS helps to specifically target important CRPS mechanisms. In the future, objective biomarkers could potentially aid in selecting appropriate mechanism-based drugs in order to increase the effectiveness of CRPS treatment. Using this approach, current and future pharmacotherapeutic options for CRPS should be studied in multicentre trials to prove their efficacy. The ultimate goal is to shift the symptom-based selection of therapy into a mechanism-based selection of therapy in CRPS.

Medical marijuana knowledge and attitudes amongst internal medicine residents

BACKGROUND

Mounting evidence suggests the safety and efficacy of medical marijuana (MM) in treating chronic ailments, including chronic pain, epilepsy, and anorexia. Despite incremental use of medical and recreational cannabinoids, current limited evidence shows generalized unpreparedness of medical providers to discuss or recommend these substances to their patients. Herein, the present study aims to examine internal medicine residents' knowledge of marijuana and their attitude towards its medical use.

METHODS

This is a descriptive cross-sectional study. A survey with 12 standardized queries was created and distributed among the internal medicine residents from Mount Sinai Morningside-West (MSMW) program from July 2020 to December 2020. Participants included preliminary and categorical residents from post-graduate years one to three. The survey consisted of self-assessment of residents' knowledge on the indication, contraindication, adverse effects of MM.

RESULTS

Eighty-six (59%) out of 145 residents completed the questionnaire. Despite most trainees (70%) having considered certifying the use of MM for their patients, over 90% reported none to little knowledge on its use. Approximately 80% of the surveyed residents expressed willingness to receive an appropriate educational curriculum.

CONCLUSION

To the best of our knowledge, this is the first study that indicated a critical lack of medical marijuana-related knowledge in surveyed internal medicine residents. In a population with growing cannabis consumption, physician training on the indication, toxicity, and drug interaction of cannabinoids is warranted.

Pharmacologic and Non-Pharmacologic Treatments for Chronic Pain Used by Patients with Pain, HIV, and Depression

The objective of this study was to understand pain treatment utilization, perceived efficacy, and differences in utilization by gender, clinic site, chronicity of pain, pain severity, and depression severity among people living with HIV (PLWH), chronic pain, and elevated depression symptoms. Participants included 187 PLWH at three HIV clinics in the U.S. Overall, 85% of participants reported taking a pain medication. One quarter (25%) reported non-pharmacological professional treatments for pain (e.g., massage, physical therapy), 60% reported mind-body treatments, including exercise, meditation, and yoga, and 62% reported other non-pharmacological self-administered treatments (e.g., heat/cold). Most pain treatments were considered "slightly helpful" or "moderately helpful." Non-pharmacological self-administered treatments were more commonly used among women than men and among individuals with constant vs. intermittent pain. Further research is needed to evaluate the efficacy of the preferred analgesic modalities of PLWH.

Opioid Use in Patients With Cervical Cancer at Two Urban Medical Centers

Purpose

Patients with cervical cancer are at high risk for opioid use. This study aimed to characterize opioid prescribing patterns at 2 urban hospitals.

Methods and Materials

Data from patients with cervical cancer treated with curative intent from 2011 to 2018 were retrospectively collected. Women with unrelated chronic opioid use before diagnosis, persistent/recurrent disease at 3 months after initiation of treatment, or initiation of opioids >6 months after treatment were excluded. Demographics, disease characteristics, treatment, and outpatient prescription practices were collected. Endpoints included duration of opioid use ≥6 and ≥12 months.

Results

There were 106 women included, of whom 83% received definitive radiation. Most patients (n = 91, 85.8%) received outpatient opioids. Most common timing of prescriptions were before cancer therapy (35.9%), postprocedure (26.4%), and during radiation therapy (17.0%). Median duration was 3 (interquartile range, 1-11) months; 35.2% of these patients received opioids ≥6 months and 22% received opioids ≥12 months. Greater International Federation of Gynaecology and Obstetrics (FIGO) stage, recurrent/residual disease, initiation of opioids before treatment, history of depression or anxiety, and use of gabapentin or steroids were associated with long-term opioid use.

Conclusions

Most patients were prescribed outpatient opioids, many of whom used opioids for 12 months. Improvement in provider communication and education, increased posttreatment monitoring, and further evaluation of nonopioid therapies are needed in this patient population to reduce long-term opioid use.

Associations of Healthcare Service Utilization With Cannabis Use Status, Use Reasons, and Use Characteristics Among Those Age 50 and Older

Cannabis use has increased steadily among older adults, and they are a significant proportion of medical cannabis users. Using 2015-2019 National Survey on Drug Use and Health data (n = 44,007 age 50+), we examined whether the numbers of emergency department (ED) visits and nights hospitalized are associated with cannabis use status, use reason (nonmedical-only, medical-only, and medical and nonmedical), and use characteristics. Past-year users had higher rates of any ED visit (30.0%) and hospitalization (14.7%) than prior-to-past-year users and never users. However, negative binomial regression models showed that past-year users did not differ from never users on numbers of ED visits and nights hospitalized, although they had more ED visits than prior-to-past-year users (IRR = 1.21, 95% CI = 1.10-1.34). Medical-only users had more ED visits (IRR = 1.38, 95% CI = 1.02-1.88) than nonmedical-only users. Cannabis use and use characteristics were not associated with nights hospitalized. The study findings provide insights into older cannabis users' healthcare utilization.

Geographical variation in hospitalization for psychosis associated with cannabis use and cannabis legalization in the United States: Submit to: Psychiatry Research

The 2017 National Inpatient Sample database was utilized to investigate the association between cannabis legalization in the United States and hospitalizations for psychosis associated with cannabis use. We compared the odds of hospital discharges for psychosis associated with cannabis use in adults between the Pacific census division (where most states legalized recreational cannabis use) and other divisions using multivariable logistic regression, adjusting for confounders. We calculated a score for each census division representing cannabis legality as the population-weighted sum of state scores: 1=illegal or cannabidiol/low potency cannabis; 2= medical marijuana; and 3=recreational and medical marijuana legalized. Pearson's correlation coefficients (r) quantified the relationship between scores and the proportion of hospitalizations with psychosis associated with cannabis. In 2017, there were an estimated 129,070 hospital discharges for psychosis associated with cannabis use. The Pacific census division had significantly higher odds of discharges than other divisions (adjusted odds ratio 1.55; 95% confidence interval 1.25 - 1.93). There was a significant correlation between the cannabis legality score and proportion of hospital discharges for psychosis associated with cannabis use (r = 0.67, p<0.05). In conclusion, we observed a higher proportion of hospital discharges for psychosis associated with cannabis use in areas with more liberal cannabis legalization laws.

A narrative review of molecular mechanism and therapeutic effect of Cannabidiol (CBD)

Cannabidiol (CBD) is an abundant non-psychoactive phytocannabinoid in Cannabis extracts which has high affinity on a series of receptors, including type 1 cannabinoid receptor (CB1), type 2 cannabinoid receptor (CB2), GPR55, transient receptor potential vanilloid (TRPV), and peroxisome proliferator-activated receptor gamma (PPARγ). By modulating the activities of these receptors, CBD exhibits multiple therapeutic effects, including neuroprotective, antiepileptic, anxiolytic, antipsychotic, anti-inflammatory, analgesic and anti-cancer properties. CBD could also be applied to treat or prevent COVID-19 and its complications. Here, we provide a narrative review of CBD's applications in human diseases: from mechanism of action to clinical trials.

UK Medical Cannabis registry: an analysis of clinical outcomes of medicinal cannabis therapy for chronic pain conditions

OBJECTIVES

To explore pain-specific, general health-related quality of life (HRQoL), and safety outcomes of chronic pain patients prescribed cannabis-based medicinal products (CBMPs).

METHODS

A case series was performed using patients with chronic pain from the UK Medical Cannabis Registry. Primary outcomes were changes in Brief Pain Inventory short-form (BPI), Short-form McGill Pain Questionnaire-2 (SF-MPQ-2), Visual Analogue Scale-Pain (VAS), General Anxiety Disorder-7 (GAD-7), Sleep Quality Scale (SQS), and EQ-5D-5L, at 1, 3, and 6 months from baseline. Statistical significance was defined at p-value<0.050.

RESULTS

190 patients were included. Median initial Δ⁹-tetrahydrocannabinol and cannabidiol daily doses were 2.0mg (range:0.0-442.0mg) and 20.0mg (range:0.0-188.0mg) respectively. Significant improvements were observed within BPI, SF-MPQ-2, GAD-7, SQS, EQ-5D-5 L index, and VAS measures at all timepoints (p<0.050). Seventy-five adverse events (39.47%) were reported, of which 37 (19.47%) were rated as mild, 23 (12.11%) as moderate, and 14 (7.37%) as severe. Nausea (n=11; 5.8%) was the most frequent adverse event.

CONCLUSION

An association was identified between patients with chronic pain prescribed CBMPs and improvements in pain-specific and general HRQoL outcomes. Most adverse events were mild to moderate in severity, indicating CBMPs were well tolerated. Inherent limitations of study design limit its overall applicability.

Efficacy and safety of therapeutic use of cannabis derivatives and their synthetic analogs: Overview of systematic reviews

The debate on the use of cannabinoids for therapeutic purposes is constantly on the rise. This overview aimed to map the evidence on the therapeutic effects of cannabis derivatives and their synthetic analogs. Systematic reviews (SRs) of randomized trials were identified through a comprehensive search in several databases, and their methodological quality were evaluated with AMSTAR-2. The results for main outcomes are presented, prioritizing those from updated and better quality SRs. Finally, 68 SRs, addressing 37 different health conditions, were included. The methodological quality was high for eight SRs. The evidence certainty (GRADE) for the effects of cannabinoids is not high for any of the outcomes identified. Evidence certainty was moderate for the following: (a) cannabidiol appears to be beneficial for quality of life but increases the risk of adverse events in ulcerative colitis; (b) cannabinoids in general appear to have no clinically important benefit for chronic non-oncologic pain, spasticity-related pain in multiple sclerosis, or for acute post-operative pain; (c) cannabinoids in general appear to have a benefit in reducing chemotherapy-related nausea and vomiting. For all other outcomes from remaining comparisons, the evidence certainty was low, very low, or not evaluated, which prevents recommendations for or against their routine use.

Pain Management Strategies in Rheumatoid Arthritis: A Narrative Review

Rheumatoid Arthritis (RA) is a systemic autoimmune disease characterized by chronic inflammation and progressive deterioration of the joints, which generates pain and stiffness. The origin of this pain is multifactorial, with inflammation, secondary osteoarthritis, as well as central and peripheral sensitization playing important roles in the development. Up to 90.4% of RA patients visit a health professional for severe pain, and despite new therapies and sophisticated treatments, there are a limited number of options for analgesic management. We conducted a narrative review using the Medline and Pubmed search engines for articles in English and Spanish between 2000 and 2021, with the keywords "pain," "rheumatoid arthritis," "non-steroidal anti-inflammatory drugs" (NSAIDs), "opioids," "glucocorticoids," "disease modifying antirheumatic drugs" (DMARDs), "neuromodulators," "antidepressants," and "cannabinoids." The articles describing epidemiology, pathophysiological considerations and current treatments were selected after a screening process carried out by the authors. It was found that DMARDs are the fundamental basis of treatment, since the main mechanism of pain in this entity is inflammation. Nonetheless, a significant number of patients continue to have pain despite optimal treatment. The available evidence for pain management in RA is scarce, however, medications such as NSAIDs, topical capsaicin, weak opioids, and treatments such as joint infiltrations or surgical management, play an important role in its management. We believe more research efforts are needed to optimize analgesic treatment recommendations, however, based on the current existing evidence, we propose a stepwise algorithm in order to properly approach these cases.

Key PointsRA is a systemic autoimmune disease characterized by chronic inflammation, in which the main symptom is pain.Pain in RA is multifactorial, with inflammation, secondary osteoarthritis, as well as central and peripheral sensitization playing determining roles.DMARDs are the mainstay of RA treatment, although many patients continue to experience pain despite optimal management.Medications such as glucocorticoids, NSAIDs, topical capsaicin, and weak opioids are key elements when achieving analgesia in RA.Other pharmacological groups such as neuromodulators, antidepressants, muscle relaxants and cannabinoids currently do not have enough evidence to be recommended.

Cannabinoid Formulations and Delivery Systems: Current and Future Options to Treat Pain

The field of Cannabis sativa L. research for medical purposes has been rapidly advancing in recent decades and a growing body of evidence suggests that phytocannabinoids are beneficial for a range of conditions. At the same time impressing development has been observed for formulations and delivery systems expanding the potential use of cannabinoids as an effective medical therapy. The objective of this review is to present the most recent results from pharmaceutical companies and research groups investigating methods to improve cannabinoid bioavailability and to clearly establish its therapeutic efficacy, dose ranges, safety and also improve the patient compliance. Particular focus is the application of cannabinoids in pain treatment, describing the principal cannabinoids employed, the most promising delivery systems for each administration routes and updating the clinical evaluations. To offer the reader a wider view, this review discusses the formulation starting from galenic preparation up to nanotechnology approaches, showing advantages, limits, requirements needed. Furthermore, the most recent clinical data and meta-analysis for cannabinoids used in different pain management are summarized, evaluating their real effectiveness, in order also to spare opioids and improve patients' quality of life. Promising evidence for pain treatments and for other important pathologies are also reviewed as likely future directions for cannabinoids formulations.

Clinical Outcome Data of First Cohort of Chronic Pain Patients Treated With Cannabis-Based Sublingual Oils in the United Kingdom: Analysis From the UK Medical Cannabis Registry

Cannabis-based medicinal products (CBMPs) are an emerging therapeutic option in the management of primary chronic pain, using the role of the endocannabinoid system in modulating central and peripheral pain processes. Despite promising preclinical data, there is a paucity of high-quality evidence to support the use of CBMPs for chronic pain. This study aimed to investigate the health-related quality-of-life outcomes of patients with chronic pain who were prescribed CBMP oil preparations (Adven, Curaleaf International, Guernsey, UK). This study is a case series of patients from the UK Medical Cannabis Registry, who were treated with CBMP oils for an indication of chronic pain. The primary outcomes were the changes in Brief Pain Inventory short form, Short-Form McGill Pain Questionnaire-2, Visual Analog Scale Pain, General Anxiety Disorder-7, Sleep Quality Scale, and EQ-5D-5L, at 1, 3, and 6 months. One hundred ten patients were included. Significant improvements in Sleep Quality Scale, EQ-5D-5L pain and discomfort subscale, and Brief Pain Inventory Interference Subscale (P < .05) at 1, 3, and 6 months were demonstrated. There were no notable differences between cannabis-naïve and previous cannabis users in quality-of-life outcomes. The adverse event incidence was 30.0%, with most (n = 58; 92.1%) adverse events being mild or moderate in intensity. Treatment of chronic pain with Adven CBMP oils was associated with an improvement in pain-specific outcomes, health-related quality of life, and self-reported sleep quality. Relative safety was demonstrated over medium-term prescribed use. While these findings must be treated with caution considering the limitations of study design, they can inform future clinical trials.

Medication overuse headache in patients with chronic migraine using cannabis: A case-referent study

OBJECTIVE

To examine whether cannabis use predicts medication overuse headache (MOH) in patients with chronic migraine (CM).

METHODS

Electronic chart review was conducted by combining the terms "CM," "medication overuse," "cannabis," "cannabidiol," and "tetrahydrocannabinol" for patients seen at our headache clinics from 2015 to 2019. Of 729 charts consecutively screened, 368 met our inclusion criteria, that is, adult patients with CM with ≥1-year CM duration. The following variables were extracted from the included patient charts: MOH diagnosis, age, sex, migraine frequency, current CM duration, current cannabis use duration, overused acute migraine medications, current MOH duration, and types of cannabis products used. Logistic regression was used to identify variables predicting MOH while controlling for remaining predictors. Agglomerative hierarchical clustering (AHC) was conducted to explore natural clusters using all predictor variables.

RESULTS

There were 212 patients with CM and MOH (cases; median age 43 years, interquartile range [IQR] 33-54; 177 [83%] females) and 156 patients with CM without MOH (referents; median age 40 years, IQR 31-49; 130 [83%] females). MOH was present in 81% (122/150) of current cannabis users compared with 41% (90/218) in those without cannabis use-adjusted odds ratio 6.3 (95% CI: 3.56 to 11.1, p < 0.0001). Current cannabis use was significantly associated with opioid use (Spearman's rho 0.26, p < 0.0001). Both current cannabis use (rho 0.40, p < 0.0001) and opioid use (rho 0.36, p < 0.0001) were significantly associated with MOH. Similarly, AHC revealed two major natural clusters. Cluster I patients featured 9.3 times higher current cannabis use, 9.2 times higher current opioid use, and 1.8 times higher MOH burden than those in Cluster II (p < 0.0001).

CONCLUSION

Cannabis use was significantly associated with increased prevalence of MOH in CM. Bidirectional cannabis-opioid association was observed-use of one was associated with use of the other. Advising patients with CM and MOH to reduce cannabis use may help treat MOH effectively.

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.

Consensus recommendations on dosing and administration of medical cannabis to treat chronic pain: results of a modified Delphi process

BACKGROUND

Globally, medical cannabis legalization has increased in recent years and medical cannabis is commonly used to treat chronic pain. However, there are few randomized control trials studying medical cannabis indicating expert guidance on how to dose and administer medical cannabis safely and effectively is needed.

METHODS

Using a multistage modified Delphi process, twenty global experts across nine countries developed consensus-based recommendations on how to dose and administer medical cannabis in patients with chronic pain.

RESULTS

There was consensus that medical cannabis may be considered for patients experiencing neuropathic, inflammatory, nociplastic, and mixed pain. Three treatment protocols were developed. A routine protocol where the clinician initiates the patient on a CBD-predominant variety at a dose of 5 mg CBD twice daily and titrates the CBD-predominant dose by 10 mg every 2 to 3 days until the patient reaches their goals, or up to 40 mg/day. At a CBD-predominant dose of 40 mg/day, clinicians may consider adding THC at 2.5 mg and titrate by 2.5 mg every 2 to 7 days until a maximum daily dose of 40 mg/day of THC. A conservative protocol where the clinician initiates the patient on a CBD-predominant variety at a dose of 5 mg once daily and titrates the CBD-predominant dose by 10 mg every 2 to 3 days until the patient reaches their goals, or up to 40 mg/day. At a CBD-predominant dose of 40 mg/day, clinicians may consider adding THC at 1 mg/day and titrate by 1 mg every 7 days until a maximum daily dose of 40 mg/day of THC. A rapid protocol where the clinician initiates the patient on a balanced THC:CBD variety at 2.5-5 mg of each cannabinoid once or twice daily and titrates by 2.5-5 mg of each cannabinoid every 2 to 3 days until the patient reaches his/her goals or to a maximum THC dose of 40 mg/day.

CONCLUSIONS

In summary, using a modified Delphi process, expert consensus-based recommendations were developed on how to dose and administer medical cannabis for the treatment of patients with chronic pain.

Cannabis and orofacial pain: a systematic review

The naturally occurring cannabis plant has played an established role in pain management throughout recorded history. However, in recent years, both natural and synthetic cannabis-based products for medicinal use (CBPM) have gained increasing worldwide attention due to growing evidence supporting their use in alleviating chronic inflammatory and neuropathic pain associated with an array of conditions. In view of these products' growing popularity in both the medical and commercial fields, we carried out a systematic review to ascertain the effects of cannabis and its synthetically derived products on orofacial pain and inflammation. The application of topical dermal cannabidiol formulation has shown positive findings such as reducing pain and improving muscle function in patients suffering from myofascial pain. Conversely, two orally-administered synthetic cannabinoid receptor agonists (AZD1940 and GW842166) failed to demonstrate significant analgesic effects following surgical third molar removal. There is a paucity of literature pertaining to the effects of cannabis-based products in the orofacial region; however, there is a wealth of high-quality evidence supporting their use for treating chronic nociceptive and neuropathic pain conditions in other areas. Further research is warranted to explore and substantiate the therapeutic role of CBPMs in the context of orofacial pain and inflammation. As evidence supporting their use expands, healthcare professionals should pay close attention to outcomes and changes to legislation that may impact and potentially benefit their patients.

Nabiximols in Chronic Neuropathic Pain: A Meta-Analysis of Randomized Placebo-Controlled Trials

OBJECTIVE

Pooled analysis of nabiximols and placebo in randomized controlled studies (RCTs) of chronic neuropathic pain.

DESIGN

Systematic review and meta-analysis.

METHODS

A systematic literature search was conducted to identify double-blind placebo-controlled RCTs of nabiximols for chronic neuropathic pain. The clinical endpoint of interest was change from baseline in mean pain score on 11-point numerical rating scales. Mean difference (MD) and standardized mean difference (SMD, Hedges' g) were calculated using fixed effect (FE) and random effects (RE) models. Strength of evidence was assessed using the Cochrane Grading of Recommendations Assessment, Development and Evaluation (GRADE) tool. Risk of bias was assessed using the revised Cochrane risk-of-bias tool (RoB 2).

RESULTS

Nine RCTs with 1289 participants were included. Quality of evidence (GRADE) was moderate. One study had a high risk of bias (RoB 2) and five had some concerns. For the pooled endpoint of change from baseline in mean pain score, nabiximols was superior to placebo, with a MD of -0.40 (95% confidence interval [CI]: -.59 to -.21; FE, P < .0001) or -0.44 (95% CI: -.70 to -.19; RE, P = .0006). A SMD of -0.21 (95% CI: -.32 to -.10; FE) or -0.26 (95% CI: -.42 to -.10; RE) indicated an incremental benefit over background analgesia. Results in favor of nabiximols were maintained in sensitivity analyses.

CONCLUSIONS

Nabiximols was superior to placebo for reduction of chronic neuropathic pain, with a small effect size. Larger RCTs designed to assess the effect of nabiximols in neuropathic pain are required to reach more definitive conclusions.

Recreational Cannabis Use Before and After Legalization in Women With Pelvic Pain

OBJECTIVE

To evaluate the prevalence and characteristics of recreational cannabis use in women with pelvic pain, and to examine the influence of cannabis legalization on these parameters.

METHODS

We conducted a retrospective analysis of a prospective registry of women with self-reported moderate-to-severe pelvic pain referred to a tertiary care clinic in Vancouver, Canada, 2013-2019. We excluded patients aged 18 years or younger and those with unknown data on cannabis use. Demographic, clinical, and validated questionnaire data were extracted for two main analyses: 1) comparison of current cannabis users with current nonusers, and 2) comparison of current cannabis users who entered the registry before cannabis legalization (October 17, 2018) with those who entered the registry on or after legalization.

RESULTS

Overall, 14.9% (509/3,426) of patients were classified as current cannabis users. Compared with nonusers, cannabis users were younger (P<.001), had lower levels of education (P<.001) and lower household income (P<.001), were taking opioids (P<.001), antiinflammatories (P=.003), neuromodulators (P=.020), and herbal medications (P<.001) more frequently. They had worse questionnaire scores for depression, anxiety, pain catastrophizing, quality of life, and pelvic pain severity (P<.001 for all). After cannabis legalization, prevalence of current cannabis use increased from 13.3% (366/2,760) to 21.5% (143/666) (P<.001). Compared with prelegalization, postlegalization users were associated with higher levels of education (P<.001), worse anxiety (P=.036), and worse pain catastrophizing (P<.001) scores. They were taking fewer antiinflammatories (P<.001), neuroleptics (P=.027) and daily opioids or narcotics (P=.026), but more herbal medications (P=.010).

CONCLUSION

Recreational cannabis use increased among patients with pelvic pain after legalization in Canada. Cannabis users had worse pain-related morbidities. Postlegalization, cannabis users were less likely to require daily opioids compared with cannabis users before legalization. The role, perceived benefits, and possible risks of cannabis for pelvic pain require further investigation.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT02911090.

A Multicriteria Decision Analysis Comparing Pharmacotherapy for Chronic Neuropathic Pain, Including Cannabinoids and Cannabis-Based Medical Products

Background:

Pharmacological management of chronic neuropathic pain (CNP) still represents a major clinical challenge. Collective harnessing of both the scientific evidence base and clinical experience (of clinicians and patients) can play a key role in informing treatment pathways and contribute to the debate on specific treatments (e.g., cannabinoids). A group of expert clinicians (pain specialists and psychiatrists), scientists, and patient representatives convened to assess the relative benefit–safety balance of 12 pharmacological treatments, including orally administered cannabinoids/cannabis-based medicinal products, for the treatment of CNP in adults.

Methods:

A decision conference provided the process of creating a multicriteria decision analysis (MCDA) model, in which the group collectively scored the drugs on 17 effect criteria relevant to benefits and safety and then weighted the criteria for their clinical relevance.

Findings:

Cannabis-based medicinal products consisting of tetrahydrocannabinol/cannabidiol (THC/CBD), in a 1:1 ratio, achieved the highest overall score, 79 (out of 100), followed by CBD dominant at 75, then THC dominant at 72. Duloxetine and the gabapentinoids scored in the 60s, amitriptyline, tramadol, and ibuprofen in the 50s, methadone and oxycodone in the 40s, and morphine and fentanyl in the 30s. Sensitivity analyses showed that even if the pain reduction and quality-of-life scores for THC/CBD and THC are halved, their benefit–safety balances remain better than those of the noncannabinoid drugs.

Interpretation:

The benefit–safety profiles for cannabinoids were higher than for other commonly used medications for CNP largely because they contribute more to quality of life and have a more favorable side effect profile. The results also reflect the shortcomings of alternative pharmacological treatments with respect to safety and mitigation of neuropathic pain symptoms. Further high-quality clinical trials and systematic comprehensive capture of clinical experience with cannabinoids is warranted. These results demonstrate once again the complexity and multimodal mechanisms underlying the clinical experience and impact of chronic pain.

Medical Cannabis for Chronic Noncancer Pain: A Systematic Review of Health Care Recommendations

Purpose

Medical cannabis for patients with chronic noncancer pain (CNCP) has been the focus of numerous health care recommendations. We conducted a systematic review to identify and summarize the currently available evidence-based recommendations.

Methods

We searched MEDLINE, EMBASE, PsycINFO, the Cochrane database of systematic reviews, and websites for clinical guidelines and recommendations. We summarized the type of the publications, developers, approach of health care recommendation development, year and country of publication, and conditions that were addressed. We categorized the direction and strength of each recommendation.

Results

We identified 12 eligible publications. Publication years ranged from 2007 to 2019; four (33.3%) of them were published in 2018. Canada ranked first for the number of publications (n = 4, 33.3%). Most (n = 11, 92%) of the included recommendations were based on both a systematic review of the best evidence and expert consensus. All the included publications provided a recommendation supporting medical cannabis for CNCP in general and for the specific conditions of neuropathic pain, chronic pain in people living with Human Immunodeficiency Virus (HIV), and chronic abdominal pain, with detailed information sharing and comprehensive consideration of a patient's own values and preferences.

Conclusion

Clinicians can attend to the guidance currently offered, being aware that only weak recommendations are available for medical cannabis in patients with CNCP, as a third- or fourth-line therapy. Detailed discussions with patients regarding the benefits in reducing pain and potential adverse effects are required before its prescription.

Median Nerve Stimulation as a Nonpharmacological Approach to Bypass Analgesic Tolerance to Morphine: A Proof-of-Concept Study in Mice

Analgesic tolerance to opioids contributes to the opioid crisis by increasing the quantity of opioids prescribed and consumed. Thus, there is a need to develop non-opioid-based pain-relieving regimens as well as strategies to circumvent opioid tolerance. Previously, we revealed a non-opioid analgesic mechanism induced by median nerve electrostimulation at the overlaying PC6 (Neiguan) acupoint (MNS-PC6). Here, we further examined the efficacy of MNS-PC6 in morphine-tolerant mice with neuropathic pain induced by chronic constriction injury (CCI) of the sciatic nerve. Daily treatments of MNS-PC6 (2 Hz, 2 mA), but not electrostimulation at a nonmedian nerve-innervated location, for a week post-CCI induction significantly suppressed established mechanical allodynia in CCI-mice in an orexin-1 (OX₁) and cannabinoid-1 (CB₁) receptor-dependent fashion. This antiallodynic effect induced by repeated MNS-PC6 was comparable to that induced by repeated gabapentin (50 mg/kg, i.p.) or single morphine (10 mg/kg, i.p.) treatments, but without tolerance, unlike repeated morphine-induced analgesia. Furthermore, single and repeated MNS-PC6 treatments remained fully effective in morphine-tolerant CCI-mice, also in an OX₁ and CB₁ receptor-dependent fashion. In CCI-mice receiving escalating doses of morphine for 21 days (10, 20 and 50 mg/kg), single and repeated MNS-PC6 treatments remained fully effective. Therefore, repeated MNS-PC6 treatments induce analgesia without tolerance, and retain efficacy in opioid-tolerant mice via a mechanism that involves OX₁ and CB₁ receptors. This study suggests that MNS-PC6 is an alternative pain management strategy that maybe useful for combatting the opioid epidemic, and opioid-tolerant patients receiving palliative care. PERSPECTIVE: Median nerve stimulation relieves neuropathic pain in mice without tolerance and retains efficacy even in mice with analgesic tolerance to escalating doses of morphine, via an opioid-independent, orexin-endocannabinoid-mediated mechanism. This study provides a proof of concept for utilizing peripheral nerve stimulating devices for pain management in opioid-tolerant patients.

Complex regional pain syndrome: An updated comprehensive review

Complex regional pain syndrome (CRPS) is a complex disorder that can have a significant impact on the quality of life of a person with this syndrome. The diagnosis and treatment of CRPS are often difficult as there is no one confirmatory test and no one definitive treatment. Currently, the most widely accepted clinical diagnostic criteria are the Budapest criteria, which were developed by expert consensus. Though no one single treatment has been found to be universally effective, early detection and an interdisciplinary approach to treatment appear to be key in treating CRPS. This review aims to present up-to-date clinical information regarding the diagnosis and management of CRPS and highlight the potential issues with diagnosis in the neurological population. Ultimately, more research is needed to identify the exact etiology of CRPS in order to help target appropriate therapies. In addition, more randomized controlled trials need to be performed in order to test new therapies or combinations of therapies, including pharmacological, interventional, and behavioral therapies, to determine the best treatment options for this potentially debilitating disorder.

Potential Pharmacokinetic Drug-Drug Interactions between Cannabinoids and Drugs Used for Chronic Pain

Choosing an appropriate treatment for chronic pain remains problematic, and despite the available medication for its treatment, still, many patients complain about pain and appeal to the use of cannabis derivatives for pain control. However, few data have been provided to clinicians about the pharmacokinetic drug-drug interactions of cannabinoids with other concomitant administered medications. Therefore, the aim of this brief review is to assess the interactions between cannabinoids and pain medication through drug transporters (ATP-binding cassette superfamily members) and/or metabolizing enzymes (cytochromes P450 and glucuronyl transferases).

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.