Inhaled Cannabis for Chronic Neuropathic Pain: A Meta-analysis of Individual Patient Data

Cannabinoids in neuropathic pain treatment: pharmacological insights and clinical outcomes from recent trials

Neuropathic pain, a complex and often devastating condition, poses significant challenges for its effective management. Despite promising research on various cannabis formulations and delivery methods for neuropathic pain, significant gaps remain in our knowledge. While inhaled cannabis shows analgesic effects and alternative delivery methods may improve bioavailability, oral formulations have yielded mixed results, often limited by small sample sizes and placebo effects. Therefore, further research is essential to optimize cannabis formulations, identify responder profiles to tailor treatments effectively, and, most critically, confirm the long-term safety and efficacy of cannabis-based therapies in managing NP. This review article aims to provide a comprehensive analysis of the therapeutic potential of cannabis-based medicines, with a particular focus on cannabinoids. This review, though not systematic, examines 11 clinical studies, specifically Randomised Clinical Trials) published from 2014 to 2024, highlighting the efficacy of numerous cannabis formulations, in alleviating neuropathic pain. Key findings show that cannabinoids can reduce pain perception, improve patient quality of life, and mitigate other symptoms associated with neuropathic pain. The synergistic effects of tetrahydrocannabinol and cannabidiol are discussed, emphasizing their ability to enhance analgesic effects, while potentially reducing the psychoactive side effects of tetrahydrocannabinol. This review emphasizes the importance of the personalized approach to improve therapeutic outcomes. Limitations of the existing research focusing on cannabis for neuropathic pain are limited by heterogeneity, lack of standardization, small sample sizes, and reliance on subjective outcomes, impacting the reliability and generalizability of findings. However, this exhaustive review aims to inform clinicians and researchers about the evolving role of cannabis in contemporary pain management strategies, illustrating the diverse pharmacological profiles of cannabinoids and their potential as adjunct therapies for neuropathic pain management.

Cannabinoids in Chronic Pain Management: A Review of the History, Efficacy, Applications, and Risks

Background/Objectives: Chronic pain remains a pervasive and challenging public health issue, often resistant to conventional treatments such as opioids, which carry substantial risks of dependency and adverse effects. Cannabinoids, bioactive compounds derived from the Cannabis sativa plant and their synthetic analogs, have emerged as a potential alternative for pain management, leveraging their interaction with the endocannabinoid system to modulate pain and inflammation. Methods: The current, evolving literature regarding the history, efficacy, applications, and safety of cannabinoids in the treatment of chronic pain was reviewed and summarized to provide the most current review of cannabinoids. Results: Evidence suggests that cannabinoids provide moderate efficacy in managing neuropathic pain, fibromyalgia, cancer-related pain, and multiple sclerosis-related spasticity. Patient-reported outcomes further indicate widespread perceptions of cannabinoids as a safer alternative to opioids, with potential opioid-sparing effects. However, the quality of existing evidence is limited by small sample sizes and methodological inconsistencies. Regulatory barriers, including the classification of cannabis as a Schedule I substance in the United States, continue to hinder robust research and clinical integration. Moreover, the risks associated with cannabinoids, such as psychiatric effects, addiction potential, and drug interactions, necessitate cautious application. Conclusions: Cannabinoids represent a promising, albeit complex, alternative for chronic pain management, particularly given the limitations and risks of traditional therapies such as opioids. However, significant deficiencies remain in the research. While smaller trials and systematic reviews indicate therapeutic potential, the quality of evidence is often low due to limited sample sizes, short study durations, and methodological inconsistencies. Large-scale, randomized controlled trials with long-term follow-up are urgently needed to confirm efficacy and safety across diverse patient populations and pain etiologies.

Cannabis Use and Self-Reported Bothersome Symptoms in People with HIV

Objective

While cannabis use is common among people with HIV (PWH), there have been few studies examining the association of use with health outcomes among PWH. We aimed to evaluate the association between cannabis use and bothersome physical and mental health symptoms using both self-report and a direct biomarker for cannabis use.

Method

The Medications, Alcohol and Substance use in HIV Study (MASH) is a cross-cohort study focused on polypharmacy and substance use among PWH. Participants were enrolled from October 2018 to May 2022 in the Swiss HIV Cohort Study (SHCS), Kaiser Permanente Northern California (KPNC) HIV Cohort, and 7 sites (Atlanta, GA; Bronx, NY; Washington, DC; Houston, TX; Los Angeles, CA; New York, NY; and Nashville, TN) in the Veterans Aging Cohort Study - HIV (VACS-HIV). Participants submitted self-reported information on the presence/absence of symptoms in the prior 4 weeks, along with bothersome level, using the HIV Symptom Index, which is comprised of 20 symptoms commonly reported in PWH, including fatigue, diarrhea, fever, anxiety, and weight loss, among others. Concurrent self-reported substance use information was also collected, and participants provided nail clippings to be tested for cannabis use. We used logistic regression models, adjusted for age, sex, race/ethnicity, and cohort, to examine associations of self-report and biomarker-identified cannabis use with self-reported bothersome symptoms.

Results

The analytic sample included 1,226 PWH who were predominantly male (85%), non-white (64%), with an average age of 57 years; 20% tested positive for cannabis use, and 23% reported recent cannabis use. Agreement between self-report and biomarker cannabis use was substantial (agreement 89%, kappa = 0.67). Put together, 27% either reported cannabis use or tested positive. Of the 20 symptoms included in the HIV Symptom Index, 19 were more prevalent at a bothersome level among those with cannabis use compared to those without. In adjusted models, the patterns of association remained for both self-reported and biomarker-confirmed cannabis use, and they were particularly substantial for memory, depression, anxiety, and nausea.

Conclusions

Cannabis use was common among PWH and was associated with a number of bothersome symptoms. While cannabis use may be used to treat loss of appetite, nausea/vomiting, and weight loss, the associations of cannabis use with depression, anxiety, and memory loss are concerning and deserve investigation.

ART26.12, a novel fatty acid-binding protein 5 inhibitor, shows efficacy in multiple preclinical neuropathy models

BACKGROUND

Painful neuropathy is a pathological condition caused by numerous factors including diabetes, chemotherapy or cancer. ART26.12 is a novel fatty acid-binding protein 5 inhibitor, which our group showed could prevent and treat persistent pain in a preclinical model of oxaliplatin-induced peripheral neuropathy.

METHODS

In the current study, the efficacy of orally dosed ART26.12 was tested in multiple neuropathy models of different aetiology. Paw withdrawal threshold to von Frey monofilaments and latency to escape a cold plate were used as measurements of mechanical and cold sensitivity.

RESULTS

ART26.12 (25 and 50 mg/kg BID), dosed prior to the induction of paclitaxel-induced peripheral neuropathy (PIPN), reversed mechanical allodynia induced by paclitaxel in both male and female rats, and ART26.12 (50 mg/kg BID) prevented the induction of PIPN in female rats. ART26.12 (50 mg/kg BID) also had a protective effect on body weight in the PIPN model. ART26.12 (25 and 100 mg/kg BID) reversed mechanical allodynia when treating established streptozotocin-induced diabetic neuropathy in male rats. In a model of breast cancer-induced bone pain in female rats, ART26.12 (100 mg/kg BID) reversed mechanical allodynia within 1 h of dosing. In the same model, ART26.12 (25 mg/kg BID) reversed mechanical allodynia from day 4 of treatment.

CONCLUSION

Overall, these preclinical data suggest that ART26.12 is a safe and efficacious therapeutic drug for continued development towards the prevention and treatment of peripheral neuropathy.

SIGNIFICANCE STATEMENT

This work now shows that ART26.12, a novel and selective inhibitor of FABP5, can prevent and treat multiple preclinical models of peripheral neuropathy. Given its excellent safety profile, further work is warranted to develop ART26.12 as a potential therapeutic tool for pain management.

The comparative effectiveness of medicinal cannabis for chronic pain versus prescription medication treatment

ABSTRACT

Reviews of the effectiveness of medicinal cannabis for chronic pain vary in their conclusions. IASP has identified that a key missing evidence in this debate is data from observational cohort studies, analyzed with comparative effectiveness methods. In a medically supervised context to the use of marijuana for chronic pain, we identified 440 patients certified for medical marijuana by pain specialists in a single healthcare system. They were characterized by a battery of patient-reported outcomes stored electronically in the University of Pittsburgh Patient Outcomes Repository for Treatment (PORT). At 3 months, 38.6% were responders, based on clinically meaningful improvements in pain, function, or global impression of change, and maintained this response at 6 months. In the 157 patients who were coprescribed opioids, at 6 months there was a mean 39.3% decrease in morphine milligram equivalents (P < 0.05 for the difference vs baseline). In addition, 8114 patients treated in the same pain clinics with prescription pain medications instead (nonopioid or opioid) during the same timeframe were selected from PORT as a control group for comparison. They had a 34.9% rate of response at 3 months. Using the causal inference method of stratified modeling, logistic regression revealed an odds ratio of 2.6 in favor of medical marijuana vs medication treatment (P < 0.01). Potential harms data were not available in the PORT registry. Medical marijuana was comparatively more effective than prescription medications for the treatment of chronic pain at 3 months, although the populations compared were slightly different.

The endocannabinoid system in the brain undergoes long-lasting changes following neuropathic pain

The endocannabinoid system (ECS), which is composed of endocannabinoids (eCBs), cannabinoid receptors (CBRs), and associated signaling molecules, has been identified within the brain. In neuropathic pain animal models and patients, long-lasting alterations in the ECS have been observed. These changes of neurons and glial cells in the ECS contribute to the modulation of neuropathic pain. Intervention strategies such as the activation of CBRs, the enhancement of hydrolytic enzyme function, and the inhibition of synthetizing enzymes typically alleviate neuropathic pain through CBR-dependent mechanisms. Additionally, emotions such as fear, anxiety, and depression are frequently experienced with neuropathic pain. Exogenous cannabinoids can mitigate these mood disorders via CBR signaling pathways. Therefore, the targeting of long-lasting ECS alterations represents a potential therapeutic approach for both neuropathic pain and emotional disorders. In this review, the long-lasting variations in neurons and glial cells in the ECS related to neuropathic pain and the accompanying emotional comorbidities are elucidated. Furthermore, the cellular and molecular mechanisms underlying synaptic plasticity and neural circuit activities in the brain are reviewed.

Medicinal Cannabis and the Intestinal Microbiome

Historically, the multiple uses of cannabis as a medicine, food, and for recreational purposes as a psychoactive drug span several centuries. The various components of the plant (i.e., seeds, roots, leaves and flowers) have been utilized to alleviate symptoms of inflammation and pain (e.g., osteoarthritis, rheumatoid arthritis), mood disorders such as anxiety, and intestinal problems such as nausea, vomiting, abdominal pain and diarrhea. It has been established that the intestinal microbiota progresses neurological, endocrine, and immunological network effects through the gut-microbiota-brain axis, serving as a bilateral communication pathway between the central and enteric nervous systems. An expanding body of clinical evidence emphasizes that the endocannabinoid system has a fundamental connection in regulating immune responses. This is exemplified by its pivotal role in intestinal metabolic and immunity equilibrium and intestinal barrier integrity. This neuromodulator system responds to internal and external environmental signals while also serving as a homeostatic effector system, participating in a reciprocal association with the intestinal microbiota. We advance an exogenous cannabinoid-intestinal microbiota-endocannabinoid system axis potentiated by the intestinal microbiome and medicinal cannabinoids supporting the mechanism of action of the endocannabinoid system. An integrative medicine model of patient care is advanced that may provide patients with beneficial health outcomes when prescribed medicinal cannabis.

Research and Clinical Practice Involving the Use of Cannabis Products, with Emphasis on Cannabidiol: A Narrative Review

BACKGROUND

Emerging evidence supports cannabidiol (CBD) as a promising therapeutic compound for various health conditions, despite its approval as a medication (product for medical purposes) remaining restricted to a limited range of clinical indications. Simultaneously, the regulation of cannabis-derived products for medicinal and recreational use has expanded their global market availability to meet local community demands. This scenario presents a complex challenge for clinicians, researchers, and industry, as the global appeal of therapeutic uses of CBD is growing more rapidly than the scientific evidence supporting its safety and effectiveness.

OUTCOMES

A narrative review was conducted to discuss the best evidence regarding the pharmacological profile of CBD, its efficacy, and safety within the context of regulation and perspectives on the development of new cannabinoid-based drugs. Key articles addressing the various facets of this issue were selected for comprehensive analysis.

CONCLUSIONS

Clinicians and researchers may face unique challenges in understanding the pharmacological profile of CBD and the prospects for developing its clinical indications, given the heterogeneity of clinical terminologies and the quality and composition of cannabis-based medical products available on the market. More basic and clinical research that complies with regulatory agencies' testing guidelines, such as good manufacturing practices (GMPs), good laboratory practices (GLPs), and good clinical practices (GCPs), is needed to obtain approval for CBD or any other cannabinoid as a therapeutic for broader clinical indications.

High-Performance Liquid Chromatography with DAD Detection for the Determination of Cannabinoids in Commercial Veterinary CBD Oil

The study highlights the need for quality control in evaluating medicinal plant products, especially CBD oils, before market release. Due to varying regulatory requirements, product labeling can sometimes be misleading, especially regarding cannabinoid concentrations such as CBD and THC. This research focused on developing a validated high-performance liquid chromatography (HPLC) method for accurately identifying and quantifying key cannabinoids in Commercial Veterinary CBD Oil. The main compounds identified included Cannabidivarin (CBDV), Cannabidiolic Acid (CBD-A), Cannabigerolic Acid (CBG-A), Cannabigerol (CBG), Cannabidiol (CBD), Tetrahydrocannabivarin (THCV), Cannabinol (CBN), ∆9-Tetrahydrocannabinol (d9-THC) ∆8-Tetrahydrocannabinol (d8-THC), Cannabicyclol (CBL), Cannabichromene (CBC), and Tetrahydrocannabinolic Acid (THCA), determined in line with the International Conference on Harmonization's (ICH) guidelines. The method was validated for linearity, accuracy, precision, limit of detection (LOD), and limit of quantitation (LOQ). It was determined to be linear, with a correlation coefficient (R²) > 0.999. The LOD and LOQ values calculated from the calibration curve ranged from 0.05 to 0.13 and 0.50 to 0.61 µg/mL, respectively. The method also exhibited acceptable precision, with relative standard deviation values lower than or equal to 2%. The method's accuracy was assessed through recovery percentages and fell within an acceptable range of 98-102 if the RSD was 2%. This study's rigorous methodology and comprehensive findings significantly contribute to cannabinoid analysis. This validated protocol was used to analyze cannabinoids in 14 commercial veterinary CBD oil products from the Republic of North Macedonia. The performance parameters demonstrated that the method is reliable for quantitatively measuring cannabinoids in CBD oil. The analysis showed that the cannabinoid levels in the products were consistent with the manufacturers' declared specifications, with no significant discrepancies in labeling.

Cannabidiol Increases Psychotropic Effects and Plasma Concentrations of Δ9-Tetrahydrocannabinol Without Improving Its Analgesic Properties

Cannabidiol (CBD), the main non-intoxicating compound in cannabis, has been hypothesized to reduce the adverse effects of Δ9-tetrahydrocannabinol (THC), the main psychoactive and analgesic component of cannabis. This clinical trial investigated the hypothesis that CBD counteracts the adverse effects of THC and thereby potentially improves the tolerability of cannabis as an analgesic. A randomized, double-blind, placebo-controlled, five-way cross-over trial was performed in 37 healthy volunteers. On each visit, a double-placebo, THC 9 mg with placebo CBD, or THC 9 mg with 10, 30, or 450 mg CBD was administered orally. Psychoactive and analgesic effects were quantified using standardized test batteries. Pharmacokinetic sampling was performed. Data were analyzed using mixed-effects model. Co-administration of 450 mg CBD did not reduce, but instead significantly increased subjective, psychomotor, cognitive, and autonomous effects of THC (e.g., VAS "Feeling High" by 60.5% (95% CI: 12.7%, 128.5%, P < 0.01)), whereas THC effects with 10 and 30 mg CBD were not significantly different from THC alone. CBD did not significantly enhance THC analgesia at any dose level. Administration of 450 mg CBD significantly increased AUClast of THC (AUClast ratio: 2.18, 95% CI: 1.54, 3.08, P < 0.0001) and 11-OH-THC (AUClast ratio: 6.24, 95% CI: 4.27, 9.12, P < 0.0001) compared with THC alone, and 30 mg CBD significantly increased AUClast of 11-OH-THC (AUClast ratio: 1.89, 95% CI: 1.30, 2.77, P = 0.0013), and of THC (AUClast ratio: 1.44, 95% CI: 1.01, 2.04, P = 0.0446). Present findings do not support the use of CBD to reduce adverse effects of oral THC or enhance THC analgesia.

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.

Edible cannabis for chronic low back pain: associations with pain, mood, and intoxication

Introduction

Cannabis, commonly known for both therapeutic and intoxicating effects, is gaining accessibility on legal markets and traction as a potential alternative therapy for pain mediation, particularly in those suffering from chronic low back pain. However, the effectiveness in this population of legal market forms of cannabis, particularly commonly used edibles, is unknown.

Methods

Therefore, this study utilized a naturalistic prospective design where participants with chronic low back pain with intentions to initiate cannabis use for treatment were recruited and self-selected edible cannabis products containing varying amounts of delta- 9 tetrahydrocannabinol (THC) and cannabidiol (CBD). Products were categorized as CBD-dominant, THC-dominant, or combined THC and CBD (THC + CBD).

Results

249 participants [140 female (56.62%), mean (SD) age of 46.30 (16.02), 90% White] were tracked over 2 weeks of ad libitum use and assessed during a naturalistic acute cannabis administration session on changes in pain, mood, and subjective drug effects. During acute administration, a significant correlation between THC dose and short-term pain relief was found, suggesting that higher THC doses were associated with greater pain reduction (p < .05). In addition, THC was associated with higher levels of subjective cannabis drug effects (p < .001), regardless of whether CBD was also in the edible product. Acute CBD dose was primarily associated with short-term tension relief (p < .05); however, there were no associations between CBD dose and acute pain. Over the 2-week ad libitum administration period results suggested pain reductions across participants using all forms of cannabis. However, trends suggested that more frequent use of CBD-dominant edible cannabis may be associated with greater reductions in perceived pain over the 2-week observation period (p = .07).

Discussion

These findings support the short-term analgesic effects of THC and anxiolytic effects of CBD and further suggest that orally-administered THC and CBD should continue to be evaluated for the potential to provide both acute and extended relief from chronic low back pain.

Clinical Trial Registration

https://clinicaltrials.gov/study/NCT03522324?locStr=Boulder,%20CO&country=United%20States&state=Colorado&city=Boulder&cond=chronic%20low%20back%20pain&intr=Cannabis&rank=1, identifier NCT03522324.

The Efficacy of Cannabis in Oncology Patient Care and Its Anti-Tumor Effects

As the legalization of medical cannabis expands across several countries, interest in its potential advantages among cancer patients and caregivers is burgeoning. However, patients seeking to integrate cannabis into their treatment often encounter frustration when their oncologists lack adequate information to offer guidance. This knowledge gap is exacerbated by the scarcity of published literature on the benefits of medical cannabis, leaving oncologists reliant on evidence-based data disheartened. This comprehensive narrative article, tailored for both clinicians and patients, endeavors to bridge these informational voids. It synthesizes cannabis history, pharmacology, and physiology and focuses on addressing various symptoms prevalent in cancer care, including insomnia, nausea and vomiting, appetite issues, pain management, and potential anti-cancer effects. Furthermore, by delving into the potential mechanisms of action and exploring their relevance in cancer treatment, this article aims to shed light on the potential benefits and effects of cannabis in oncology.

Cannabidiol and pain

Chronic pain presents significant personal, psychological, and socioeconomic hurdles, impacting over 30% of adults worldwide and substantially contributing to disability. Unfortunately, current pharmacotherapy often proves inadequate, leaving fewer than 70% of patients with relief. This shortfall has sparked a drive to seek alternative treatments offering superior safety and efficacy profiles. Cannabinoid-based pharmaceuticals, notably cannabidiol (CBD), hold promise in pain management, driven by their natural origins, versatility, and reduced risk of addiction. As we navigate the opioid crisis, ongoing research plunges into CBD's therapeutic potential, buoyed by animal studies revealing its pain-relieving prowess through various system tweaks. However, the efficacy of cannabis in chronic pain management remains a contentious and stigmatized issue. The International Association for the Study of Pain (IASP) presently refrains from endorsing cannabinoid use for pain relief. Nevertheless, evidence indicates their potential in alleviating cancer-related, neuropathic, arthritis, and musculoskeletal pain, necessitating further investigation. Crucially, our comprehension of CBD's role in pain management is a journey still unfolding, with animal studies illustrating its analgesic effects through interactions with the endocannabinoid, inflammatory, and nociceptive systems. As the plot thickens, it's clear: the saga of chronic pain and CBD's potential offers a compelling narrative ripe for further exploration and understanding.

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.

Oncology: What You May Have Missed in 2023

Advances in oncology treatment methods have improved outcomes and quality of life for patients with cancer. However, care of these patients can be complex, and the contribution of physicians from different specialties is crucial. This article highlights important publications from 2023 on topics across a wide spectrum relating to the management of oncology patients. The literature was screened for significant new evidence that is relevant to internal medicine specialists and subspecialists whose focus is not oncology. Two articles address the importance of social interventions targeting end-of-life care for low-income and minority patients and the well-being of caregivers. Two additional articles address screening considerations in patients at risk for colorectal and lung cancer. Two more articles address safe use of hormone-related therapies to treat symptoms of menopause and prevent disease recurrence or progression in patients diagnosed with noninvasive breast neoplasia. Finally, several articles were included on topics related to COVID-19 vaccination in patients with cancer, use of cannabinoids for cancer pain control, chronic autoimmune adverse effects related to use of immune checkpoint inhibitors, and the incidence of second primary neoplasms.

Cannabidiol induces systemic analgesia through activation of the PI3Kγ/nNOS/NO/KATP signaling pathway in neuropathic mice. A KATP channel S-nitrosylation-dependent mechanism

BACKGROUND

Cannabidiol (CBD) is the second most abundant pharmacologically active component present in Cannabis sp. Unlike Δ-9-tetrahydrocannabinol (THC), it has no psychotomimetic effects and has recently received significant interest from the scientific community due to its potential to treat anxiety and epilepsy. CBD has excellent anti-inflammatory potential and can be used to treat some types of inflammatory and neuropathic pain. In this context, the present study aimed to evaluate the analgesic mechanism of cannabidiol administered systemically for the treatment of neuropathic pain and determine the endogenous mechanisms involved with this analgesia.

METHODS

Neuropathic pain was induced by sciatic nerve constriction surgery, and the nociceptive threshold was measured using the paw compression test in mice.

RESULTS

CBD produced dose-dependent antinociception after intraperitoneal injection. Selective inhibition of PI3Kγ dose-dependently reversed CBD-induced antinociception. Selective inhibition of nNOS enzymes reversed the antinociception induced by CBD, while selective inhibition of iNOS and eNOS did not alter this antinociception. However, the inhibition of cGMP production by guanylyl cyclase did not alter CBD-mediated antinociception, but selective blockade of ATP-sensitive K+ channels dose-dependently reversed CBD-induced antinociception. Inhibition of S-nitrosylation dose-dependently and completely reversed CBD-mediated antinociception.

CONCLUSION

Cannabidiol has an antinociceptive effect when administered systemically and this effect is mediated by the activation of PI3Kγ as well as by nitric oxide and subsequent direct S-nitrosylation of KATP channels on peripheral nociceptors.

Overview: Chronic Pain and Cannabis-Based Medicines

Chronic pain is primarily conceptualized as a disease in its own right when it is associated with emotional distress and functional impairment. Pathophysiologically, dysfunction of the cortico-mesolimbic connectome is of major importance, with overlapping signals in the nociceptive and stress systems. The endocannabinoid system plays an important role in the central processing of nociceptive signals and regulates the central stress response. Clinically, there is moderate evidence that cannabis-based medicines (CBM) can contribute to a significant reduction in pain, especially the associated pain affect, and improvement in physical function and sleep quality in a proportion of patients with chronic pain. The analgesic effect appears to be largely independent of the cause of pain. In this context, CBM preferentially regulates stress-associated pain processing.

Pierre M, Belle-Isle L, Gagnon M, Bevan S, Sanchez T, Arlt S, Monahan-Ellison M, O'Hara J, Boivin M, Costiniuk C. Clinical Practice Guidelines for Cannabis and Cannabinoid-Based Medicines in the Management of Chronic Pain and Co-Occurring Conditions

Background: One in five individuals live with chronic pain globally, which often co-occurs with sleep problems, anxiety, depression, and substance use disorders. Although these conditions are commonly managed with cannabinoid-based medicines (CBM), health care providers report lack of information on the risks, benefits, and appropriate use of CBM for therapeutic purposes. Aims: We present these clinical practice guidelines to help clinicians and patients navigate appropriate CBM use in the management of chronic pain and co-occurring conditions. Materials and Methods: We conducted a systematic review of studies investigating the use of CBM for the treatment of chronic pain. Articles were dually reviewed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Clinical recommendations were developed based on available evidence from the review. Values and preferences and practical tips have also been provided to support clinical application. The GRADE system was used to rate the strength of recommendations and quality of evidence. Results: From our literature search, 70 articles met inclusion criteria and were utilized in guideline development, including 19 systematic reviews and 51 original research studies. Research typically demonstrates moderate benefit of CBM in chronic pain management. There is also evidence for efficacy of CBM in the management of comorbidities, including sleep problems, anxiety, appetite suppression, and for managing symptoms in some chronic conditions associated with pain including HIV, multiple sclerosis, fibromyalgia, and arthritis. Conclusions: All patients considering CBM should be educated on risks and adverse events. Patients and clinicians should work collaboratively to identify appropriate dosing, titration, and administration routes for each individual. Systematic Review Registration: PROSPERO no. 135886.

Potency trends of cannabis in Jamaica during the period of 2014 to 2020

Reports suggest that cannabis potency has dramatically increased over the last decade in the USA and Europe. Cannabinoids are the terpeno-phenolic compounds found in the cannabis plant and are responsible for its pharmacological activity. The two most prominent cannabinoids are delta-9-tetrahydrocannabinol (Δ9 THC) and cannabidiol (CBD). Cannabis potency is measured not only by the Δ9 THC levels but also by the ratio of Δ9 THC to other non-psychoactive cannabinoids, namely, CBD. Cannabis use was decriminalized in Jamaica in 2015, which opened the gates for the creation of a regulated medical cannabis industry in the country. To date, there is no information available on the potency of cannabis in Jamaica. In this study, the cannabinoid content of Jamaican-grown cannabis was examined over the period 2014-2020. Two hundred ninety-nine herbal cannabis samples were received from 12 parishes across the island, and the levels of the major cannabinoids were determined using gas chromatography-mass spectrometry. There was a significant increase (p < 0.05) in the median total THC levels of cannabis samples tested between 2014 (1.1%) and 2020 (10.2%). The highest median THC was detected in the central parish of Manchester (21.1%). During the period, THC/CBD ratios increased from 2.1 (2014) to 194.1 (2020), and there was a corresponding increase in the percent freshness of samples (CBN/THC ratios <0.013). The data show that a significant increase in the potency of locally grown cannabis has occurred in Jamaica during the last decade.

Tetrahydrocannabinol and Cannabidiol for Pain Treatment-An Update on the Evidence

In light of the current International Association for the Study of Pain (IASP) clinical practice guidelines (CPGs) and the European Society for Medical Oncology (ESMO) guidelines, the topic of cannabinoids in relation to pain remains controversial, with insufficient research presently available. Cannabinoids are an attractive pain management option due to their synergistic effects when administered with opioids, thereby also limiting the extent of respiratory depression. On their own, however, cannabinoids have been shown to have the potential to relieve specific subtypes of chronic pain in adults, although controversies remain. Among these subtypes are neuropathic, musculoskeletal, cancer, and geriatric pain. Another interesting feature is their effectiveness in chemotherapy-induced peripheral neuropathy (CIPN). Analgesic benefits are hypothesized to extend to HIV-associated neuropathic pain, as well as to lower back pain in the elderly. The aim of this article is to provide an up-to-date review of the existing preclinical as well as clinical studies, along with relevant systematic reviews addressing the roles of various types of cannabinoids in neuropathic pain settings. The impact of cannabinoids in chronic cancer pain and in non-cancer conditions, such as multiple sclerosis and headaches, are all discussed, as well as novel techniques of administration and relevant mechanisms of action.

Cannabinoids, Endocannabinoids, and Synthetic Cannabimimetic Molecules in Neuromuscular Disorders

Neuromuscular disorders (NMDs) encompass a large heterogeneous group of hereditary and acquired diseases primarily affecting motor neurons, peripheral nerves, and the skeletal muscle system. The symptoms of NMDs may vary depending on the specific condition, but some of the most common ones include muscle weakness, pain, paresthesias, and hyporeflexia, as well as difficulties with swallowing and breathing. NMDs are currently untreatable. Therapeutic options include symptomatic and experimental medications aimed at delaying and alleviating symptoms, in some cases supplemented by surgical and physical interventions. To address this unmet medical need, ongoing research is being conducted on new treatments, including studies on medical cannabis, endocannabinoids, and related molecules with cannabimimetic properties. In this context, a significant amount of knowledge about the safety and effectiveness of cannabinoids in NMDs has been obtained from studies involving patients with multiple sclerosis experiencing pain and spasticity. In recent decades, numerous other preclinical and clinical studies have been conducted to determine the potential benefits of cannabinoids in NMDs. This review article aims to summarize and provide an unbiased point of view on the current knowledge about the use of cannabinoids, endocannabinoids, and synthetic analogs in NMDs, drawing from an array of compelling studies.

[Cannabis use in adolescents : Narrative Review and Position paper of the "Addiction Disorders in Adolescents" task force of the Austrian Society for Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy (ÖGKJP)]

BACKGROUND

Cannabis is the illegal drug most frequently used by Minors in Austria. Due to the gradual decriminalization and legalization that has taken place in many European countries in recent years, the ÖGKJP would like to take a balanced and scientifically based stand on the complex issue of cannabis use and abuse among young people.

METHODS

The authors searched the medline for current studies using searches tailored to each specific subtopic. Furthermore, recognized compendiums were quoted.

RESULTS

While occasional recreational use of cannabis in adults with completed brain maturation and no risk profile for mental disorders is likely to be relatively harmless, early initiation of use with regular use and the increasingly available, highly potent cannabis varieties can lead to explicit and sometimes irreversible neurocognitive brain dysfunction.

CONCLUSION

Legalisation of cannabis consumption for minors needs to be objected to due to the risks of the expected damage in the area of brain development. At the same time, however, it is important to establish sensible legal regulations in order to be able to adequately counteract the fact that over 30% of all European young people occasionally consume cannabis. We are also clearly recommending to not criminalize cannabis users and provide necessary support to vulnerable and addicted cannabis users.

Cannabinoid CB1 Receptor Expression and Localization in the Dorsal Horn of Male and Female Rat and Human Spinal Cord

Background

Preclinical and clinical evidence suggests that cannabis has potential analgesic properties. However, cannabinoid receptor expression and localization within spinal cord pain processing circuits remain to be characterized across sex and species.

Aims

We aimed to investigate the differential expression of the cannabinoid type 1 (CB1) receptor across dorsal horn laminae and cell populations in male and female adult rats and humans.

Methods

To investigate and quantify CB1 receptor expression in the spinal dorsal horn across species, we refined immunohistochemical procedures for successful rat and human fixed tissue staining and confocal imaging. Immunohistochemical results were complemented with analysis of CB1 gene (CNR1) expression within rodent and human dorsal horn using single-cell/nuclei RNA sequencing data sets.

Results

We found that CB1 was preferentially localized to the neuropil within the superficial dorsal horn of both rats and humans, with CB1 somatic staining across dorsal horn laminae. CB1 receptor immunoreactivity was significantly higher in the superficial dorsal horn compared to the deeper dorsal horn laminae for both rats and humans, which was conserved across sex. Interestingly, we found that CB1 immunoreactivity was not primarily localized to peptidergic afferents in rats and humans and that CNR1 (CB1) but not CNR2 (CB2) was robustly expressed in dorsal horn neuron subpopulations of both rodents and humans.

Conclusions

The conserved preferential expression of CB1 receptors in the superficial dorsal horn in male and female rodents and humans has significant implications for understanding the roles of this cannabinoid receptor in spinal mechanisms of nociception and analgesia.

Perceptions and Preoccupations of Patients and Physicians Regarding Use of Medical Cannabis as an Intervention Against Chronic Musculoskeletal Pain: Results from a Qualitative Study

Objective

Explore perceptions and preoccupations regarding use of medical cannabis against chronic musculoskeletal pain, among patients and physicians.

Design

Qualitative study using interviews with patients and physicians, based on the Theory of Planned Behavior (TPB).

Setting

The study was conducted in Quebec, Canada, in spring 2020.

Subjects

We included 27 adult patients and 11 physicians (GPs, anesthesiologists, psychiatrists, and a rheumatologist); the mean age of patients was 48.2 years; 59.3% of patients and 36.4% of physicians were women; 59.3% of patients used no medical cannabis at the time of study; 45.5% of physicians had never authorized it.

Methods

Semi-structured interviews were conducted, transcribed and for the qualitative analysis codes were developed in a hybrid, inductive and deductive approach. Guided by the TPB, facilitators and barriers, perceived benefits and harms, and perceived norms that may influence cannabis use or authorization were documented.

Results

Although medical cannabis is an interesting avenue for the relief of chronic musculoskeletal pain, doctors and patients agreed that it remained a last line option, due to the lack of scientific evidence regarding its safety and efficacy. The norms surrounding medical cannabis also play an important role in the social and professional acceptance of this therapeutic option.

Conclusion

Medical cannabis is seen as a last line option among interventions in the management of chronic pain, and attitudes and prior experiences play a role in the decision to use it. Study results may contribute to improved shared decision making between patients and physicians regarding this option.

Therapeutic Potential of Cannabis: A Comprehensive Review of Current and Future Applications

Historically, cannabis has been valued for its pain-relieving, anti-inflammatory, and calming properties. Ancient civilizations like the Egyptians, Greeks, and Chinese medicines recognized their therapeutic potential. The discovery of the endocannabinoid system, which interacts with cannabis phytoconstituents, has scientifically explained how cannabis affects the human immune system, including the central nervous system (CNS). This review explores the evolving world of cannabis-based treatments, spotlighting its diverse applications. By researching current research and clinical studies, we probe into how cannabinoids like Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) help to manage conditions ranging from chronic pain, persistent inflammation, cancer, inflammatory bowel disease, and neurological disorders to even viral diseases such as Human Immunodeficiency virus (HIV), SARS-CoV-2. and the emerging monkeypox. The long-term recreational use of cannabis can develop into cannabis use disorder (CUD), and therefore, understanding the factors contributing to the development and maintenance of cannabis addiction, including genetic predisposition, neurobiological mechanisms, and environmental influences, will be timely. Shedding light on the adverse impacts of CUD underscores the importance of early intervention, effective treatment approaches, and public health initiatives to address this complex issue in an evolving landscape of cannabis policies and perceptions.

Balancing risks and benefits of cannabis use: umbrella review of meta-analyses of randomised controlled trials and observational studies

OBJECTIVE

To systematically assess credibility and certainty of associations between cannabis, cannabinoids, and cannabis based medicines and human health, from observational studies and randomised controlled trials (RCTs).

DESIGN

Umbrella review.

DATA SOURCES

PubMed, PsychInfo, Embase, up to 9 February 2022.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Systematic reviews with meta-analyses of observational studies and RCTs that have reported on the efficacy and safety of cannabis, cannabinoids, or cannabis based medicines were included. Credibility was graded according to convincing, highly suggestive, suggestive, weak, or not significant (observational evidence), and by GRADE (Grading of Recommendations, Assessment, Development and Evaluations) (RCTs). Quality was assessed with AMSTAR 2 (A Measurement Tool to Assess Systematic Reviews 2). Sensitivity analyses were conducted.

RESULTS

101 meta-analyses were included (observational=50, RCTs=51) (AMSTAR 2 high 33, moderate 31, low 32, or critically low 5). From RCTs supported by high to moderate certainty, cannabis based medicines increased adverse events related to the central nervous system (equivalent odds ratio 2.84 (95% confidence interval 2.16 to 3.73)), psychological effects (3.07 (1.79 to 5.26)), and vision (3.00 (1.79 to 5.03)) in people with mixed conditions (GRADE=high), improved nausea/vomit, pain, spasticity, but increased psychiatric, gastrointestinal adverse events, and somnolence among others (GRADE=moderate). Cannabidiol improved 50% reduction of seizures (0.59 (0.38 to 0.92)) and seizure events (0.59 (0.36 to 0.96)) (GRADE=high), but increased pneumonia, gastrointestinal adverse events, and somnolence (GRADE=moderate). For chronic pain, cannabis based medicines or cannabinoids reduced pain by 30% (0.59 (0.37 to 0.93), GRADE=high), across different conditions (n=7), but increased psychological distress. For epilepsy, cannabidiol increased risk of diarrhoea (2.25 (1.33 to 3.81)), had no effect on sleep disruption (GRADE=high), reduced seizures across different populations and measures (n=7), improved global impression (n=2), quality of life, and increased risk of somnolence (GRADE=moderate). In the general population, cannabis worsened positive psychotic symptoms (5.21 (3.36 to 8.01)) and total psychiatric symptoms (7.49 (5.31 to 10.42)) (GRADE=high), negative psychotic symptoms, and cognition (n=11) (GRADE=moderate). In healthy people, cannabinoids improved pain threshold (0.74 (0.59 to 0.91)), unpleasantness (0.60 (0.41 to 0.88)) (GRADE=high). For inflammatory bowel disease, cannabinoids improved quality of life (0.34 (0.22 to 0.53) (GRADE=high). For multiple sclerosis, cannabinoids improved spasticity, pain, but increased risk of dizziness, dry mouth, nausea, somnolence (GRADE=moderate). For cancer, cannabinoids improved sleep disruption, but had gastrointestinal adverse events (n=2) (GRADE=moderate). Cannabis based medicines, cannabis, and cannabinoids resulted in poor tolerability across various conditions (GRADE=moderate). Evidence was convincing from observational studies (main and sensitivity analyses) in pregnant women, small for gestational age (1.61 (1.41 to 1.83)), low birth weight (1.43 (1.27 to 1.62)); in drivers, car crash (1.27 (1.21 to 1.34)); and in the general population, psychosis (1.71 (1.47 to 2.00)). Harmful effects were noted for additional neonatal outcomes, outcomes related to car crash, outcomes in the general population including psychotic symptoms, suicide attempt, depression, and mania, and impaired cognition in healthy cannabis users (all suggestive to highly suggestive).

CONCLUSIONS

Convincing or converging evidence supports avoidance of cannabis during adolescence and early adulthood, in people prone to or with mental health disorders, in pregnancy and before and while driving. Cannabidiol is effective in people with epilepsy. Cannabis based medicines are effective in people with multiple sclerosis, chronic pain, inflammatory bowel disease, and in palliative medicine but not without adverse events.

STUDY REGISTRATION

PROSPERO CRD42018093045.

FUNDING

None.

Interventions for treating pain and disability in adults with complex regional pain syndrome- an overview of systematic reviews

BACKGROUND

Complex regional pain syndrome (CRPS) is a chronic pain condition that usually occurs in a limb following trauma or surgery. It is characterised by persisting pain that is disproportionate in magnitude or duration to the typical course of pain after similar injury. There is currently no consensus regarding the optimal management of CRPS, although a broad range of interventions have been described and are commonly used. This is the first update of the original Cochrane review published in Issue 4, 2013.

OBJECTIVES

To summarise the evidence from Cochrane and non-Cochrane systematic reviews of the efficacy, effectiveness, and safety of any intervention used to reduce pain, disability, or both, in adults with CRPS.

METHODS

We identified Cochrane reviews and non-Cochrane reviews through a systematic search of Ovid MEDLINE, Ovid Embase, Cochrane Database of Systematic Reviews, CINAHL, PEDro, LILACS and Epistemonikos from inception to October 2022, with no language restrictions. We included systematic reviews of randomised controlled trials that included adults (≥18 years) diagnosed with CRPS, using any diagnostic criteria.  Two overview authors independently assessed eligibility, extracted data, and assessed the quality of the reviews and certainty of the evidence using the AMSTAR 2 and GRADE tools respectively. We extracted data for the primary outcomes pain, disability and adverse events, and the secondary outcomes quality of life, emotional well-being, and participants' ratings of satisfaction or improvement with treatment.  MAIN RESULTS: We included six Cochrane and 13 non-Cochrane systematic reviews in the previous version of this overview and five Cochrane and 12 non-Cochrane reviews in the current version. Using the AMSTAR 2 tool, we judged Cochrane reviews to have higher methodological quality than non-Cochrane reviews. The studies in the included reviews were typically small and mostly at high risk of bias or of low methodological quality. We found no high-certainty evidence for any comparison.  There was low-certainty evidence that bisphosphonates may reduce pain intensity post-intervention (standardised mean difference (SMD) -2.6, 95% confidence interval (CI) -1.8 to -3.4, P = 0.001; I2 = 81%; 4 trials, n = 181) and moderate-certainty evidence that they are probably associated with increased adverse events of any nature (risk ratio (RR) 2.10, 95% CI 1.27 to 3.47; number needed to treat for an additional harmful outcome (NNTH) 4.6, 95% CI 2.4 to 168.0; 4 trials, n = 181).  There was moderate-certainty evidence that lidocaine local anaesthetic sympathetic blockade probably does not reduce pain intensity compared with placebo, and low-certainty evidence that it may not reduce pain intensity compared with ultrasound of the stellate ganglion. No effect size was reported for either comparison. There was low-certainty evidence that topical dimethyl sulfoxide may not reduce pain intensity compared with oral N-acetylcysteine, but no effect size was reported. There was low-certainty evidence that continuous bupivacaine brachial plexus block may reduce pain intensity compared with continuous bupivacaine stellate ganglion block, but no effect size was reported. For a wide range of other commonly used interventions, the certainty in the evidence was very low and provides insufficient evidence to either support or refute their use. Comparisons with low- and very low-certainty evidence should be treated with substantial caution. We did not identify any RCT evidence for routinely used pharmacological interventions for CRPS such as tricyclic antidepressants or opioids.

AUTHORS' CONCLUSIONS

Despite a considerable increase in included evidence compared with the previous version of this overview, we identified no high-certainty evidence for the effectiveness of any therapy for CRPS. Until larger, high-quality trials are undertaken, formulating an evidence-based approach to managing CRPS will remain difficult. Current non-Cochrane systematic reviews of interventions for CRPS are of low methodological quality and should not be relied upon to provide an accurate and comprehensive summary of the evidence.

Cannabidiol for the Treatment of Brain Disorders: Therapeutic Potential and Routes of Administration

The use of cannabidiol (CBD) for treating brain disorders has gained increasing interest. While the mechanism of action of CBD in these conditions is still under investigation, CBD has been shown to affect numerous different drug targets in the brain that are involved in brain disorders. Here we review the preclinical and clinical evidence on the potential therapeutic use of CBD in treating various brain disorders. Moreover, we also examine various drug delivery approaches that have been applied to CBD. Due to the slow absorption and low bioavailability with the current oral CBD therapy, more efficient routes of administration to bypass hepatic metabolism, particularly pulmonary delivery, should be considered. Comparison of pharmacokinetic studies of different delivery routes highlight the advantages of intranasal and inhalation drug delivery over other routes of administration (oral, injection, sublingual, buccal, and transdermal) for treating brain disorders. These two routes of delivery, being non-invasive and able to achieve fast absorption and increase bioavailability, are attracting increasing interest for CBD applications, with more research and development expected in the near future.

Cannabinoids as a Potential Alternative to Opioids in the Management of Various Pain Subtypes: Benefits, Limitations, and Risks

INTRODUCTION

Pain is a global phenomenon encompassing many subtypes that include neuropathic, musculoskeletal, acute postoperative, cancer, and geriatric pain. Traditionally, opioids have been a mainstay pharmacological agent for managing many types of pain. However, opioids have been a subject of controversy with increased addiction, fatality rates, and cost burden on the US healthcare system. Cannabinoids have emerged as a potentially favorable alternative or adjunctive treatment for various types of acute and chronic pain. This narrative review seeks to describe the efficacy, risks, and benefits of cannabinoids as an adjunct or even potential replacement for opioids in the treatment of various subtypes of pain.

METHODS

In June of 2022, we performed a comprehensive search across multiple databases for English-language studies related to the use of cannabinoids in the treatment of various types pain: neuropathic pain, musculoskeletal pain, acute postoperative pain, cancer pain, and geriatric pain. Data from meta-analyses, systematic reviews, and randomized control trials (RCTs) were prioritized for reporting. We sought to focus our reported analysis on more recent literature as well as include older relevant studies with particularly notable findings.

RESULTS

There is conflicting evidence for the use of cannabinoids in the management of pain. While cannabinoids have shown efficacy in treating specific chronic pain subtypes such as neuropathic pain, fibromyalgia pain, and geriatric pain, they do not show as clear benefit in acute postoperative and the majority of musculoskeletal pain syndromes. Data trends towards cannabinoids having a positive effect in treating cancer pain, but results are not as conclusive. To date, there is a paucity of data comparing cannabinoids directly to opioids for pain relief. Overall, the side effects of cannabinoids appear to be relatively mild. However, there is still potential for addiction, altered brain development, psychiatric comorbidities, and drug-drug interactions.

CONCLUSION

Cannabinoids may be effective in specific subtypes of pain, but current evidence and guidelines do not yet support its use as the first-line treatment for any type of acute or chronic pain. Rather, it may be considered a good adjunct or alternative for patients who have failed more typical or conservative measures. Additional studies are needed with standardized forms of cannabinoids, route of delivery, and dosing for greater-powered analysis. Providers must weigh the individualized patient risks, benefits, and concurrent medication list in order to determine whether cannabinoids are appropriate for a patient's pain treatment plan.

Role of the gut-brain axis in HIV and drug abuse-mediated neuroinflammation

Drug abuse and related disorders are a global public health crisis affecting millions, but to date, limited treatment options are available. Abused drugs include but are not limited to opioids, cocaine, nicotine, methamphetamine, and alcohol. Drug abuse and human immunodeficiency virus-1/acquired immune deficiency syndrome (HIV-1/AIDS) are inextricably linked. Extensive research has been done to understand the effect of prolonged drug use on neuronal signaling networks and gut microbiota. Recently, there has been rising interest in exploring the interactions between the central nervous system and the gut microbiome. This review summarizes the existing research that points toward the potential role of the gut microbiome in the pathogenesis of HIV-1-linked drug abuse and subsequent neuroinflammation and neurodegenerative disorders. Preclinical data about gut dysbiosis as a consequence of drug abuse in the context of HIV-1 has been discussed in detail, along with its implications in various neurodegenerative disorders. Understanding this interplay will help elucidate the etiology and progression of drug abuse-induced neurodegenerative disorders. This will consequently be beneficial in developing possible interventions and therapeutic options for these drug abuse-related disorders.

Assessment of clinical outcomes of medicinal cannabis therapy for depression: analysis from the UK Medical Cannabis Registry

BACKGROUND

Although pre-clinical experiments associate cannabinoids with reduced depressive symptoms, there is a paucity of clinical evidence. This study aims to analyze the health-related quality of life changes and safety outcomes in patients prescribed cannabis-based medicinal products (CBMPs) for depression.

METHODS

A series of uncontrolled cases from the UK Medical Cannabis Registry were analyzed. The primary outcomes were changes from baseline in the Patient Health Questionnaire-9 (PHQ-9), Generalized Anxiety Disorder-7 (GAD-7), Sleep Quality Scale (SQS), and EQ-5D-5 L at 1, 3, and 6 months. Secondary outcomes included adverse events incidence.

RESULTS

129 patients were identified for inclusion. Median PHQ-9 at baseline was 16.0 (IQR: 9.0-21.0). There were reductions in PHQ-9 at 1-month (median: 8.0; IQR: 4.0-14.0; p < 0.001), 3-months (7.0; 2.3-12.8; p < 0.001), and 6-months (7.0; 2.0-9.5; p < 0.001). Improvements were also observed in GAD-7, SQS, and EQ-5D-5L Index Value at 1, 3, and 6 months (p < 0.050). 153 (118.6%) adverse events were recorded by 14.0% (n = 18) of participants, 87% (n = 133) of which were mild or moderate.

CONCLUSION

CBMP treatment was associated with reductions in depression severity at 1, 3, and 6 months. Limitations of the study design mean that a causal relationship cannot be proven. This analysis provides insights for further study within clinical trial settings.

“Flower Power”: Controlled Inhalation of THC-Predominant Cannabis Flos Improves Health-Related Quality of Life and Symptoms of Chronic Pain and Anxiety in Eligible UK Patients

In November 2018, the UK’s Home Office established a legal route for eligible patients to be prescribed cannabis-based products for medicinal use in humans (CBPMs) as unlicensed medicines. These include liquid cannabis extracts for oral administration (“oils”) and dried flowers for inhalation (“flos”). Smoking of CBPMs is expressly prohibited. To date, THC-predominant cannabis flowers remain the most prescribed CBPMs in project Twenty21 (T21), the first multi-center, prospective, observational UK cannabis patient registry. This observational, prospective data review analyzes patient-reported outcome measures (PROMS) collected by T21 associated with the inhalation of KHIRON 20/1, the most prescribed CBPM in the project. PROMS collected at baseline and at subsequent 3-month follow-up included health-related quality of life (HRQoL), general mood, and sleep. Condition-specific measures of illness severity were performed with the Brief Pain Inventory Short Form (BPI-SF) and the Generalized Anxiety Disorder 7-Item Scale (GAD-7). Participants (N = 344) were mostly males (77.6%, average age = 38.3) diagnosed mainly with chronic pain (50.9%) and anxiety-related disorders (25.3%). Inhalation of KHIRON 20/1 was associated with a marked increase in self-reported HRQoL, general mood, and sleep (N = 344; p < 0.001). Condition-specific assessments showed significant improvements in pain severity (T = 6.67; p < 0.001) and interference (T = 7.19; p < 0.001) in patients using KHIRON 20/1 for chronic pain (N = 174). Similar results were found for patients diagnosed with anxiety-related disorders (N = 107; T = 12.9; p < 0.001). Our results indicate that controlled inhalation of pharmaceutical grade, THC-predominant cannabis flos is associated with a significant improvement in patient-reported pain scores, mood, anxiety, sleep disturbances and overall HRQoL in a treatment-resistant clinical population.

"Flower Power": Controlled Inhalation of THC-Predominant Cannabis Flos Improves Health-Related Quality of Life and Symptoms of Chronic Pain and Anxiety in Eligible UK Patients

In November 2018, the UK’s Home Office established a legal route for eligible patients to be prescribed cannabis-based products for medicinal use in humans (CBPMs) as unlicensed medicines. These include liquid cannabis extracts for oral administration (“oils”) and dried flowers for inhalation (“flos”). Smoking of CBPMs is expressly prohibited. To date, THC-predominant cannabis flowers remain the most prescribed CBPMs in project Twenty21 (T21), the first multi-center, prospective, observational UK cannabis patient registry. This observational, prospective data review analyzes patient-reported outcome measures (PROMS) collected by T21 associated with the inhalation of KHIRON 20/1, the most prescribed CBPM in the project. PROMS collected at baseline and at subsequent 3-month follow-up included health-related quality of life (HRQoL), general mood, and sleep. Condition-specific measures of illness severity were performed with the Brief Pain Inventory Short Form (BPI-SF) and the Generalized Anxiety Disorder 7-Item Scale (GAD-7). Participants (N = 344) were mostly males (77.6%, average age = 38.3) diagnosed mainly with chronic pain (50.9%) and anxiety-related disorders (25.3%). Inhalation of KHIRON 20/1 was associated with a marked increase in self-reported HRQoL, general mood, and sleep (N = 344; p < 0.001). Condition-specific assessments showed significant improvements in pain severity (T = 6.67; p < 0.001) and interference (T = 7.19; p < 0.001) in patients using KHIRON 20/1 for chronic pain (N = 174). Similar results were found for patients diagnosed with anxiety-related disorders (N = 107; T = 12.9; p < 0.001). Our results indicate that controlled inhalation of pharmaceutical grade, THC-predominant cannabis flos is associated with a significant improvement in patient-reported pain scores, mood, anxiety, sleep disturbances and overall HRQoL in a treatment-resistant clinical population.

Lenalidomide, bortezomib and dexamethasone induction therapy for the treatment of newly diagnosed multiple myeloma: a practical review

For patients with newly diagnosed multiple myeloma, survival outcomes continue to improve significantly: however, nearly all patients will relapse following induction treatment. Optimisation of induction therapy is essential to provide longer term disease control and the current standard of care for most patients incorporates an immunomodulatory agent and proteasome inhibitor, most commonly lenalidomide and bortezomib in combination with dexamethasone (RVD), with maintenance until progression. Historically there has been limited access to RVD as an induction strategy outside of the United States; fortunately, there is now increasing access worldwide. This review discusses the rationale for use of RVD as induction therapy and aims to provide guidance in prescribing this regimen in order to optimise efficacy while minimising the toxicities of treatment. We also highlight the increasing evidence for the utility of addition of a monoclonal antibody to the RVD backbone to deepen responses and potentially provide longer disease control.

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.

Potency and Therapeutic THC and CBD Ratios: U.S. Cannabis Markets Overshoot

Background and aims: The effects exuded by cannabis are a result of the cannabinoids trans-Δ⁹-tetrahydrocannabinol (THC) and cannabidiol (CBD), and is dependent upon their pharmacological interaction and linked to the two cannabinoids’ concentrations and ratios. Based on current literature and trends of increasing cannabis potency, we postulate that most medical cannabis products with THC and CBD have ratios capable of producing significant acute intoxication and are similar to recreational products. We will test this by organizing products into clinically distinct categories according to TCH:CBD ratios, evaluating the data in terms of therapeutic potential, and comparing the data obtained from medical and recreational programs and from states with differing market policies.

Methods: We utilized data encompassing online herbal dispensary product offerings from nine U.S. states. The products were analyzed after being divided into four clinically significant THC:CBD ratio categories identified based on the literature: CBD can enhance THC effects (THC:CBD ratios ≥1:1), CBD has no significant effect on THC effects (ratios ∼ 1:2), CBD can either have no effect or can mitigate THC effects (ratios 1:>2 < 6), or CBD is protective against THC effects (ratios ≤1:6).

Results: A significant number of products (58.5%) did not contain any information on CBD content. Across all states sampled, the majority (72–100%) of both medical and recreational products with CBD (>0%) fall into the most intoxicating ratio category (≥1:1 THC:CBD), with CBD likely enhancing THC’s acute effects. The least intoxicating categories (1:>2 < 6 and ≤1:6 THC:CBD) provided the smallest number of products. Similarly, the majority of products without CBD (0%) contained highly potent amounts of THC (>15%). These results were consistent, regardless of differing market policies in place.

Conclusions: Despite the distinct goals of medical and recreational cannabis users, medical and recreational program product offerings are nearly identical. Patients seeking therapeutic benefits from herbal cannabis products are therefore at a substantial risk of unwanted side effects, regardless of whether they obtain products from medical or recreational programs. Efforts are needed to better inform patients of the risks associated with high potency cannabis and the interaction between THC and CBD, and to help shape policies that promote more therapeutic options.

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.

Therapeutic Cannabis Use in Kidney Disease: A Survey of Canadian Nephrologists

Rationale & Objective

Cannabis use may be helpful for symptom management in patients with chronic kidney disease (CKD). Knowledge, attitudes, and comfort with use of medical cannabis among kidney care providers may be limiting more widespread evaluation and use. We surveyed Canadian nephrologists regarding current prescribing habits, attitudes, and overall comfort level with cannabis products.

Study Design

We carried out a nationwide, mail-in survey focused on capturing general and practice demographics, current cannabis prescribing status, and knowledge and attitudes regarding therapeutic cannabis use in patients with CKD.

Setting & Population

This survey was distributed to every registered nephrologist in Canada.

Analytical Approach

The results of this survey are reported descriptively.

Results

Responses were received from 208 of 723 (29%) nephrologists. Only 21 (10.1%) respondents currently prescribe cannabis, with chronic pain syndromes being the most frequent reason for cannabis prescription (95.2%). Overall, 116 (55.5%) participants reported that changes in legality of cannabis did not influence their decision to prescribe cannabis. The majority of respondents (n = 123; 59%) indicated that they were uncomfortable with their knowledge of the medical cannabis literature. Most respondents (n=188; 91%) indicated that further studies exploring the efficacy and safety of cannabis would likely influence their prescribing habits.

Limitations

Limitations of this study include possible nonresponse bias and a lack of specific data on practice considerations for specific subpopulations, such as transplant patients.

Conclusions

Only a small minority of Canadian nephrologists currently prescribe cannabis, with relatively little practice change after legalization. There is broad support amongst Canadian nephrologists for encouraging their patients to enroll in efficacy/safety studies of cannabis in the CKD population. Ultimately, given limited therapeutic options available for symptom control in CKD, this survey demonstrates the potential for nationwide practice change if cannabis efficacy and safety can be demonstrated in this population.

Beliefs about marijuana use during pregnancy and breastfeeding held by residents of a Latino-majority, rural region of California

Marijuana use among pregnant and breastfeeding women is on the rise and carries risks for infant health and well-being. Decisions to use marijuana while pregnant and breastfeeding are motivated by beliefs that use poses minimal risk to infants and offers benefits to maternal users. Misperceptions and usage trend higher among disadvantaged populations. This study surveyed 401 community residents on beliefs about risks and benefits of marijuana use by pregnant and breastfeeding women. The study utilized techniques to enhance recruitment of Latino and disadvantaged residents of rural communities in California, a state where recreational marijuana use is legal. Analyses revealed substantial endorsement of beliefs about benefits and low risks of marijuana use while pregnant and breastfeeding, many of which run counter to current evidence. Misperceptions were particularly prevalent for cannabis users and male respondents. Trends in valid beliefs, while modest, were higher for Latinos and parents.

Cannabinoids: Therapeutic Use in Clinical Practice

Medical case reports suggest that cannabinoids extracted from Cannabis sativa have therapeutic effects; however, the therapeutic employment is limited due to the psychotropic effect of its major component, Δ9-tetrahydrocannabinol (THC). The new scientific discoveries related to the endocannabinoid system, including new receptors, ligands, and mediators, allowed the development of new therapeutic targets for the treatment of several pathological disorders minimizing the undesirable psychotropic effects of some constituents of this plant. Today, FDA-approved drugs, such as nabiximols (a mixture of THC and non-psychoactive cannabidiol (CBD)), are employed in alleviating pain and spasticity in multiple sclerosis. Dronabinol and nabilone are used for the treatment of chemotherapy-induced nausea and vomiting in cancer patients. Dronabinol was approved for the treatment of anorexia in patients with AIDS (acquired immune deficiency syndrome). In this review, we highlighted the potential therapeutic efficacy of natural and synthetic cannabinoids and their clinical relevance in cancer, neurodegenerative and dermatological diseases, and viral infections.

A mixed methods analysis of cannabis use routines for chronic pain management

BACKGROUND

The wide heterogeneity of available cannabis products makes it difficult for physicians to appropriately guide patients. In the current study, our objective was to characterize naturalistic cannabis use routines and explore associations between routines and reported benefits from consuming cannabis.

METHODS

We performed a mixed methods analysis of n=1087 cross-sectional survey responses from adults with self-reported chronic pain using cannabis for symptom management in the USA and Canada. First, we qualitatively analyzed responses to an open-ended question that assessed typical cannabis use routines, including administration routes, cannabinoid content, and timing. We then sub-grouped responses into categories based on inhalation (smoking, vaporizing) vs. non-inhalation (e.g., edibles). Finally, we investigated subgroups perceptions of how cannabis affected pain, overall health, and use of medications (e.g., substituting for opioids, benzodiazepines). Substitutions were treated as a count of medication classes, while responses for both pain and health were analyzed continuously, with - 2 indicating health declining a lot or pain increasing a lot and 2 indicating that health improved a lot or pain decreased a lot.

RESULTS

Routines varied widely in terms of administration routes, cannabinoid content, and use timing. Overall, 18.8%, 36.2%, and 45% used non-inhalation, inhalation, and non-inhalation + inhalation routes, respectively. Those who used inhalation routes were younger (mean age 46.5 [inhalation] and 49.2 [non-inhalation + inhalation] vs. 56.3 [inhalation], F=36.1, p<0.001), while a higher proportion of those who used non-inhalation routes were female (72.5% non-inhalation vs. 48.3% inhalation and 65.3% non-inhalation + inhalation, X2=59.6, p<0.001). THC-rich products were typically used at night, while CBD-rich products were more often used during the day. While all participants reported similarly decreased pain, participants using non-inhalation + inhalation administration routes reported larger improvements in health than the non-inhalation (mean difference = 0.32, 95% CI: 0.07-0.37, p<0.001) and inhalation subgroups (mean difference = 0.22, 95% CI: 0.07-0.37, p=0.001). Similarly, the non-inhalation + inhalation group had significantly more medication substitutions than those using non-inhalation (mean difference = 0.62, 95% CI: 0.33-0.90, p<0.001) and inhalation administration routes (mean difference = 0.45, 95% CI: 0.22-0.69, p<0.001), respectively.

CONCLUSIONS

Subgrouping medical cannabis patients based on administration route profile may provide useful categories for future studies examining the risks and benefits of medical cannabis.

Cannabinoids in Chronic Pain: Therapeutic Potential Through Microglia Modulation

Chronic pain is a complex sensory, cognitive, and emotional experience that imposes a great personal, psychological, and socioeconomic burden on patients. An estimated 1.5 billion people worldwide are afflicted with chronic pain, which is often difficult to treat and may be resistant to the potent pain-relieving effects of opioid analgesics. Attention has therefore focused on advancing new pain therapies directed at the cannabinoid system because of its key role in pain modulation. Endocannabinoids and exogenous cannabinoids exert their actions primarily through Gi/o-protein coupled cannabinoid CB1 and CB2 receptors expressed throughout the nervous system. CB1 receptors are found at key nodes along the pain pathway and their activity gates both the sensory and affective components of pain. CB2 receptors are typically expressed at low levels on microglia, astrocytes, and peripheral immune cells. In chronic pain states, there is a marked increase in CB2 expression which modulates the activity of these central and peripheral immune cells with important consequences for the surrounding pain circuitry. Growing evidence indicate that interventions targeting CB1 or CB2 receptors improve pain outcomes in a variety of preclinical pain models. In this mini-review, we will highlight recent advances in understanding how cannabinoids modulate microglia function and its implications for cannabinoid-mediated analgesia, focusing on microglia-neuron interactions within the spinal nociceptive circuitry.

Cannabinoids for Symptom Management in Patients with Kidney Failure

People with kidney failure can experience a range of symptoms that lead to suffering and poor quality of life. Available therapies are limited, and evidence for new treatment options is sparse, often resulting in incomplete relief of symptoms. There is growing interest in the potential for cannabinoids, including cannabidiol and tetrahydrocannabinol, to treat symptoms across a wide range of chronic diseases. As legal prohibitions are withdrawn or minimized in many jurisdictions, patients are increasingly able to access these agents. Cannabinoid receptors, CB1 and CB2, are widely expressed in the body, including within the nervous and immune systems, and exogenous cannabinoids can have anxiolytic, anti-emetic, analgesic and anti-inflammatory effects. Considering their known physiological actions and successful studies in other patient populations, cannabinoids may be viewed as potential therapies for a variety of common symptoms affecting those with kidney failure, including pruritus, nausea, insomnia, chronic neuropathic pain, anorexia, and restless legs syndrome. In this review, we summarize the pharmacology and pharmacokinetics of cannabinoids, along with what is known about the use of cannabinoids for symptom relief in those with kidney disease, and the evidence available concerning their role in management of common symptoms. Presently, while these agents show varying efficacy with a reasonable safety profile in other patient populations, evidence-based prescribing of cannabinoids for people with symptomatic kidney failure is not possible. Given the symptom burden experienced by individuals with kidney failure, there is an urgent need to understand the tolerability and safety of these agents in this population, which must ultimately be followed by robust, randomized controlled trials to determine if they are effective for symptom relief.

Cannabis, Cannabinoids and Cannabis-Based Medicines in Cancer Care

As medical cannabis becomes legal in more states, cancer patients are increasingly interested in the potential utility of the ancient botanical in their treatment regimen. Although eager to discuss cannabis use with their oncologist, patients often find that their provider reports that they do not have adequate information to be helpful. Oncologists, so dependent on evidence-based data to guide their treatment plans, are dismayed by the lack of published literature on the benefits of medical cannabis. This results largely from the significant barriers that have existed to effectively thwart the ability to conduct trials investigating the potential therapeutic efficacy of the plant. This is a narrative review aimed at clinicians, summarizing cannabis phytochemistry, trials in the areas of nausea and vomiting, appetite, pain and anticancer activity, including assessment of case reports of antitumor use, with reflective assessments of the quality and quantity of evidence. Despite preclinical evidence and social media claims, the utility of cannabis, cannabinoids or cannabis-based medicines in the treatment of cancer remains to be convincingly demonstrated. With an acceptable safety profile, cannabis and its congeners may be useful in managing symptoms related to cancer or its treatment. Further clinical trials should be conducted to evaluate whether the preclinical antitumor effects translate into benefit for cancer patients. Oncologists should familiarize themselves with the available database to be able to better advise their patients on the potential uses of this complementary botanical therapy.

The value of real world evidence: The case of medical cannabis

Randomised controlled trials (RCTs) have long been considered the gold standard of medical evidence. In relation to cannabis based medicinal products (CBMPs), this focus on RCTs has led to very restrictive guidelines in the UK, which are limiting patient access. There is general agreement that RCT evidence in relation to CBPMs is insufficient at present. As well as commercial reasons, a major problem is that RCTs do not lend themselves well to the study of whole plant medicines. One solution to this challenge is the use of real world evidence (RWE) with patient reported outcomes (PROs) to widen the evidence base. Such data increasingly highlights the positive impact medical cannabis can have on patients' lives. This paper outlines the value of this approach which involves the study of interventions and patients longitudinally under medical care. In relation to CBMPs, RWE has a broad range of advantages. These include the study of larger groups of patients, the use of a broader range and ratio of components of CBMPs, and the inclusion of more and rarer medical conditions. Importantly, and in contrast to RCTs, patients with significant comorbidities-and from a wider demographic profile-can also be studied, so providing higher ecological validity and increasing patient numbers, whilst offering significant cost savings. We conclude by outlining 12 key recommendations of the value of RWE in relation to medical cannabis. We hope that this paper will help policymakers and prescribers understand the importance of RWE in relation to medical cannabis and help them develop approaches to overcome the current situation which is detrimental to patients.

Cannabis-Based Medicines and Medical Cannabis for Chronic Neuropathic Pain

Neuropathic pain represents a broad category of pain syndromes that include a wide variety of peripheral and central disorders. The overall prevalence of neuropathic pain in the general population is reported to be between 7 and 10%. Management of neuropathic pain presents an unmet clinical need, with less than 50% of patients achieving substantial pain relief with medications currently recommended such as pregabalin, gabapentin, duloxetine and various tricyclic antidepressants. It has been suggested that cannabis-based medicines (CbMs) and medical cannabis (MC) may be a treatment option for those with chronic neuropathic pain. CbMs/MC are available in different forms: licensed medications or medical products (plant-derived and/or synthetic products such as tetrahydrocannabinol or cannabidiol); magistral preparations of cannabis plant derivatives with defined molecular content such as dronabinol (tetrahydrocannabinol); and herbal cannabis with a defined content of tetrahydrocannabinol and/or cannabidiol, together with other active ingredients (phytocannabinoids other than cannabidiol/tetrahydrocannabinol, terpenes and flavonoids). The availability of different types of CbMs/MC varies between countries worldwide. Systematic reviews of available randomised controlled trials have stated low-quality evidence for CbMs and MC for chronic neuropathic pain. Depending on the studies included in the various quantitative syntheses, authors have reached divergent conclusions on the efficacy of CbMs/MC for chronic neuropathic pain (from not effective to a clinically meaningful benefit). Clinically relevant side effects of CbMs/MC, especially for central nervous system and psychiatric disorders, have been reported by some systematic reviews. Recommendations for the use of CbMs/MC for chronic neuropathic pain by various medical associations also differ, from negative recommendations, no recommendation possible, recommended as third-line therapy, or recommended as an alternative in selected cases failing standard therapies within a multimodal concept. After reading this paper, readers are invited to formulate their own conclusions regarding the potential benefits and harms of CbMs/MC for the treatment of chronic neuropathic pain.

Efficacy of cannabis-based medications compared to placebo for the treatment of chronic neuropathic pain: a systematic review with meta-analysis

Background

Chronic neuropathic pain (NP) presents therapeutic challenges. Interest in the use of cannabis-based medications has outpaced the knowledge of its efficacy and safety in treating NP. The objective of this review was to evaluate the effectiveness of cannabis-based medications in individuals with chronic NP.

Methods

Randomized placebo-controlled trials using tetrahydrocannabinol (THC), cannabidiol (CBD), cannabidivarin (CBDV), or synthetic cannabinoids for NP treatment were included. The MEDLINE, Cochrane Library, EMBASE, and Web of Science databases were examined. The primary outcome was the NP intensity. The risk of bias analysis was based on the Cochrane handbook.

Results

The search of databases up to 2/1/2021 yielded 379 records with 17 RCTs included (861 patients with NP). Meta-analysis showed that there was a significant reduction in pain intensity for THC/CBD by -6.624 units (P < .001), THC by -8.681 units (P < .001), and dronabinol by -6.0 units (P = .008) compared to placebo on a 0-100 scale. CBD, CBDV, and CT-3 showed no significant differences. Patients taking THC/CBD were 1.756 times more likely to achieve a 30% reduction in pain (P = .008) and 1.422 times more likely to achieve a 50% reduction (P = .37) than placebo. Patients receiving THC had a 21% higher improvement in pain intensity (P = .005) and were 1.855 times more likely to achieve a 30% reduction in pain than placebo (P < .001).

Conclusion

Although THC and THC/CBD interventions provided a significant improvement in pain intensity and were more likely to provide a 30% reduction in pain, the evidence was of moderate-to-low quality. Further research is needed for CBD, dronabinol, CT-3, and CBDV.

Complex Regional Pain Syndrome: A Comprehensive Review

Complex regional pain syndrome (CRPS) is a chronic pain condition often involving hyperalgesia and allodynia of the extremities. CRPS is divided into CRPS-I and CRPS-II. Type I occurs when there is no confirmed nerve injury. Type II is when there is known associated nerve injury. Female gender is a risk factor for developing CRPS. Other risk factors include fibromyalgia and rheumatoid arthritis. Unfortunately, the pathogenesis of CRPS is not yet clarified. Some studies have demonstrated different potential pathways. Neuropathic inflammation, specifically activation of peripheral nociceptors of C-fibers, has been shown to play a critical role in developing CRPS. The autonomic nervous system (ANS) is involved. Depending on whether it is acute or chronic CRPS, norepinephrine levels are either decreased or increased, respectively. Some studies have suggested the importance of genetics in developing CRPS. More consideration is being given to the role of psychological factors. Some association between a history of depression and/or post-traumatic stress disorder (PTSD) and the diagnosis of CRPS has been demonstrated. Treatment modalities available range from physical therapy, pharmacotherapy, and interventional techniques. Physical and occupational therapies include mirror therapy and graded motor imagery. Medical management with non-steroidal anti-inflammatory drugs (NSAIDs) has not shown significant improvement. There have been supporting findings in the use of short-course steroids, bisphosphonates, gabapentin, and ketamine. Antioxidant treatment has also shown some promise. Other pharmacotherapies include low-dose naltrexone and Botulinum toxin A (BTX-A). Sympathetic blocks are routinely used, even if their short- and long-term effects are not clear. Finally, spinal cord stimulation (SCS) has been used for decades. In conclusion, CRPS is a multifactorial condition that still requires further studying to better understand its pathogenesis, epidemiology, genetic involvement, psychological implications, and treatment options. Future studies are warranted to better understand this syndrome. This will provide an opportunity for better prevention, diagnosis, and treatment of CRPS.