Category Archives: Neuropathic Pain

The Use of Cannabinoids in the Treatment of Peripheral Neuropathy and Neuropathic Pain: A Systematic Review

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“Purpose: Peripheral neuropathies are commonly occurring conditions that are chronic and debilitating for patients. Established nonsurgical treatments have yielded mixed and patient-dependent results. Although cannabinoids have demonstrated efficacy as a treatment for central neuropathic pain, the therapeutic potential of cannabis-based medications for the management of peripheral neuropathic pain caused by nerve injury, trauma, and other noncompressive etiologies has yet to be definitively established. This study aims to determine whether cannabinoids are a potentially effective treatment for pain and symptoms associated with peripheral neuropathy.

Methods: A systematic search was conducted by two independent reviewers across PubMed, Cochrane, Ovid Medline, and CINAHL to identify studies in accordance with the predetermined inclusion/exclusion criteria. Information regarding study design, medication, dosage, effect on neuropathic pain, and other related outcomes was extracted. Meta-analysis of pain scores was performed for seven studies, and descriptive statistics were used to summarize other study findings as appropriate.

Results: Of the 927 studies identified, 14 randomized controlled trials were included. Thirteen of 14 studies (79%) observed a statistically significant decrease in neuropathic pain score following treatment with a cannabinoid. Meta-analysis yielded a mean difference of -0.67 [-0.89, -0.45]) on a 0-10 scale compared with placebo. Improvements in secondary outcomes such as sleep, sensory symptoms, and quality of life were observed.

Conclusions: Our analysis of the literature shows that cannabis-based medicines may be effective in treating the pain and symptoms of peripheral neuropathy. These findings suggest the applicability of cannabis-based medicines for peripheral neuropathy.”

https://pubmed.ncbi.nlm.nih.gov/39570218/

https://www.jhandsurg.org/article/S0363-5023(24)00474-X/abstract

Efficiency of cannabis and cannabidiol in managing chronic pain syndromes: A comprehensive narrative review

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“Chronic pain affects up to 40% of adults, contributing to high medical expenses, the loss of productivity, reduced quality of life (QoL), and disability. Chronic pain requires detailed diagnostic assessment, treatment and rehabilitation, yet approx. 80% of patients report inadequate pain management.

As new treatment options are needed, we aimed to explore the effectiveness of medical cannabis-based products in managing chronic pain, with a particular focus on treatment patterns.

We searched the PubMed, Scopus and Web of Science databases using keywords related to cannabinoids and chronic pain syndromes. In total, 3,954 articles were identified, and 74 studies involving 12,562 patients were included. The effectiveness of cannabis-based products varied across studies.

Cannabinoids were most effective in treating chronic secondary headache and orofacial pain, chronic secondary musculoskeletal pain, chronic secondary visceral pain, and chronic neuropathic pain. Properly qualifying patients is the first crucial step in managing chronic pain, considering pain characteristics, comorbidities and other treatment options.

Treatment should start with low doses of cannabinoids, which are then increased to achieve the desired therapeutic effect while minimizing adverse effects.This narrative review revealed significant gaps in the evidence regarding precise treatment patterns, particularly for the long-term maintenance treatment needed by patients with chronic pain.

Medical cannabis can be considered an option for carefully selected patients with chronic pain syndromes when other treatment options fail to achieve an adequate response, and when the potential benefits outweigh the risks. However, there is still a need for well-designed clinical research to establish the long-term efficacy and safety of cannabinoids.”

https://pubmed.ncbi.nlm.nih.gov/39499191/

“Medical cannabis can be considered an option in carefully selected patients with chronic pain syndrome for the management of chronic pain when other treatment options fail to achieve an adequate response, and when potential benefits outweigh the risks. Patients with chronic secondary headache and orofacial pain, chronic secondary visceral pain, chronic secondary musculoskeletal pain, and chronic neuropathic pain can benefit more than other groups of patients experiencing chronic pain.”

https://dmp.umw.edu.pl/en/article/2024/61/5/765/

Identification of the TRPA1 Cannabinoid-Binding Site

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“Chronic pain accounts for nearly two-thirds of conditions eligible for medical cannabis licenses, yet the mechanisms underlying cannabis-induced analgesia remain poorly understood.

The principal phytocannabinoids, the psychoactive Δ9-tetrahydrocannabinol (THC) and non-psychoactive cannabidiol (CBD), exhibit comparable efficacy in pain management. Notably, THC functions as an agonist of cannabinoid receptor 1 (CB1), whereas CBD shows minimal activity on CB1 and CB2 receptors.

Elucidating the molecular targets through which phytocannabinoids modulate the pain system is required for advancing our understanding of the pain pathway and optimizing medical cannabis therapies.

Transient receptor potential ankyrin 1 (TRPA1), a pivotal chemosensor in the pain pathway, has been identified as a phytocannabinoid target. Unlike most TRPA1 activators, phytocannabinoid activation is not mediated through the electrophilic binding site, suggesting an alternative mechanism. Here, we identified the human TRPA1 channel cannabinoid-binding site (CBS) and demonstrated that mutations at residue Y840 abolished responses to both THC and CBD at saturating concentrations, indicating a shared primary binding site. Molecular modeling revealed distinct interactions of THC and CBD with the Y840 residue within the CBS. Additionally, CBD binds to the adjacent general anesthetic binding site at oversaturating concentrations.

Our findings define the CBS of TRPA1 as overlapping with and adjacent to binding sites for other allosteric activators, suggesting that TRPA1 possesses a highly adaptable domain for binding non-electrophilic activators. This underscores its unique role as a chemosensor in the pain pathway. Furthermore, our results provide new insights into the molecular mechanisms of cannabinoid-induced analgesia and identify novel targets for pain management therapies.”

https://pubmed.ncbi.nlm.nih.gov/39368566/

https://www.sciencedirect.com/science/article/pii/S104366182400389X?via%3Dihub

Cannabis sativa L. Extract Alleviates Neuropathic Pain and Modulates CB1 and CB2 Receptor Expression in Rat

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“Introduction: Cannabis sativa L. (CSL) extract has pain-relieving potential due to its cannabinoid content, so the effects of two CSL extracts on alleviating neuropathic pain were investigated in vivo. Methods and groups: Male Wistar rats (n = 130) were divided into groups and received vincristine (0.1 mg/kg) and gabapentin (60 mg/kg) to induce and relieve neuropathic pain or CSL extracts (D and B). The mRNA and protein expression of the cannabinoid receptors type 1 and 2 (CB1R, CB2R) were evaluated in the cerebral cortex, hippocampus, and lymphocytes. Behavioural tests (Tail-Flick and von Frey) were performed on all animals.

Results: VK-induced neuropathic pain was accompanied by decreased CB1R protein level and CB2R mRNA expression in the cortex. Gabapentin relieved pain and increased CB1R protein levels in the hippocampus compared to the vincristine group. Hippocampus CB1R protein expression increased with the administration of extract D (10 mg/kg, 40 mg/kg) and extract B (7.5 mg/kg, 10 mg/kg) compared to VK group. In the cerebral cortex CSL decreased CB1R protein expression (10 mg/kg, 20 mg/kg, 40 mg/kg of extract B) and mRNA level (5 mg/kg, 7.5 mg/kg of extract B; 20 mg/kg of extract D) compared to the VK-group.CB2R protein expression increased in the hippocampus after treatment with extract B (7.5 mg/kg) compared to the VK-group. In the cerebral cortex extract B (10 mg/kg, 20 mg/kg) increased CB2R protein expression compared to VK-group.

Conclusion: Alterations in cannabinoid receptor expression do not fully account for the observed behavioural changes in rats. Therefore, additional signalling pathways may contribute to the initiation and transmission of neuropathic pain. The Cannabis extracts tested demonstrated antinociceptive effects comparable to gabapentin, highlighting the antinociceptive properties of Cannabis extracts for human use.”

https://pubmed.ncbi.nlm.nih.gov/39334832/

“Furthermore, both tested Cannabis sativa L. extracts demonstrated antinociceptive effects comparable to gabapentin, highlighting the potential medical value of Cannabis extracts for human use.”

https://www.mdpi.com/2218-273X/14/9/1065

Cannabinoids as a Natural Alternative for the Management of Neuropathic Pain: A Systematic Review of Randomized Placebo-Controlled Trials

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“Dysfunction or damage to the nervous system may develop into and result in a chronic pain condition known as neuropathic pain. Neuropathic pain is defined as the structural and functional alteration of the somatosensory component of the nervous system. The treatment of neuropathic pain is a complex endeavor, which often requires specialist care and intensive drug therapy. Recently, cannabinoids have emerged as an alternative and natural option for the treatment of chronic pain, with tetrahydrocannabinol (THC) and cannabidiol (CBD) being the most extensively studied neuroactive components. The therapeutic potential of cannabis remains largely underexplored, primarily due to its social stigma and the restrictions that are in place on its cultivation. The primary aim of this systematic review was to explore the therapeutic value of cannabinoids in the management of chronic pain and thus achieve an improved quality of life for those patients.

A systematic review of the literature published over the last two decades was performed using the following databases: PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), Turning research into practice (Trip), and Google Scholar. Studies that were completed and published between January 01, 2000 and August 31, 2024, in English language, were extracted and appraised. A combination of keywords and Boolean operators Cannabis OR Chronic Pain OR End of life OR Pain Management AND Drug therapy was employed for data extraction. The Cochrane risk-of-bias tool for randomized trials (RoB 2) was used for risk-of-bias assessment. The initial search resulted in 125282 articles; 86,781 of the articles were identified as duplicates and were removed from the primary analysis, and 38,501 abstracts were thus screened. Abstracts, case studies, reports, editorials, viewpoints, cross-sectional studies, cohort studies, case-control studies, case series, and letters to the editor/correspondence manuscripts (n =38,492) were furthermore excluded. Nine full-text articles were critically assessed and tested against the inclusion and exclusion criteria, and a further four articles were excluded with a total of five placebo-controlled randomized control studies being ultimately included in the final systematic review.

Compared to placebo, cannabinoids provided significant relief from chronic pain (33% vs 15%) as measured by the visual analog scale. The transdermal application of CBD led to a more pronounced reduction in sharp pain, according to the neuropathic pain scale. Minimal to no side effects were recorded, further highlighting the potential benefits of cannabinoids. 

The potential benefit of cannabinoids is that they are naturally derived drugs that have already been shown to have the potential to effectively decrease chronic pain with minimal side effects as compared to the standard drugs being used. The ability of cannabinoids to provide pain relief with minimal side effects and concurrently be a naturally derived product may potentially be a life-changing alternative that the pharmaceutical market is in dire need of.”

https://www.cureus.com/articles/297124-cannabinoids-as-a-natural-alternative-for-the-management-of-neuropathic-pain-a-systematic-review-of-randomized-placebo-controlled-trials#!/

The endocannabinoid system as a therapeutic target in neuropathic pain: a review

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“Introduction: This review highlights the critical role of the endocannabinoid system (ECS) in regulating neuropathic pain and explores the therapeutic potential of cannabinoids. Understanding the mechanisms of the ECS, including its receptors, endogenous ligands, and enzymatic routes, can lead to innovative treatments for chronic pain, offering more effective therapies for neuropathic conditions. This review bridges the gap between preclinical studies and clinical applications by emphasizing ECS modulation for better pain management outcomes.

Areas covered: A review mapped the existing literature on neuropathic pain and the effects of modulating the ECS using natural and synthetic cannabinoids. This analysis examined ECS components and their alterations in neuropathic pain, highlighting the peripheral, spinal, and supraspinal mechanisms. This review aimed to provide a thorough understanding of the therapeutic potential of cannabinoids in the management of neuropathic pain.

Expert opinion: Advances in cannabinoid research have shown significant potential for the management of chronic neuropathic pain. The study emphasizes the need for high-quality clinical trials and collaborative efforts among researchers, clinicians, and regulatory bodies to ensure safe and effective integration of cannabinoids into pain management protocols. Understanding the mechanisms and optimizing cannabinoid formulations and delivery methods are crucial for enhancing therapeutic outcomes.”

https://pubmed.ncbi.nlm.nih.gov/39317147/

“Research on the modulation of the endocannabinoid system in nervous tissue related to neuropathic pain reveals complex mechanisms of pain modulation. Dysregulation of the endocannabinoid system, microglial activation, and interactions between various signaling pathways contribute to the onset and persistence of neuropathic pain. Understanding these molecular and cellular processes is crucial for developing targeted therapies that leverage the endocannabinoid system to alleviate neuropathic pain.”

https://www.tandfonline.com/doi/full/10.1080/14728222.2024.2407824

“Smoked Cannabis Proven Effective In Treating Neuropathic Pain”

https://www.sciencedaily.com/releases/2007/10/071024141745.htm

Neuromolecular and behavioral effects of Cannabidiol on depressive-associated behaviors and neuropathic pain conditions in mice

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“Background and aims: Neuropathic pain (NP) has a high incidence in the general population, is closely related to anxiety disorders, and has a negative impact on the quality of life. Cannabidiol (CBD), as a natural product, has been extensively studied for its potential therapeutic effects on symptoms such as pain and depression (DP). However, the mechanism of CBD in improving NP with depression is not fully understood.

Methods: First, we used bioinformatics tools to deeply mine the intersection genes associated with NP, DP, and CBD. Secondly, the core targets were screened by Protein-protein interaction network, Gene Ontology, Kyoto Encyclopedia of Genes and Genomes analysis, molecular docking and molecular dynamics simulation. Next, the effects of CBD intervention on pain and depressive behaviors in the spinal nerve ligation (SNL) mouse model were evaluated using behavioral tests, and dose-response curves were plotted. After the optimal intervention dose was determined, the core targets were verified by Western blot (WB) and Quantitative Polymerase Chain Reaction (qPCR). Finally, we investigated the potential mechanism of CBD by Nissl staining, Immunofluorescence (IF) and Transmission Electron Microscopy (TEM).

Results: A total of five core genes of CBD most associated with NP and DP were screened by bioinformatics analysis, including PTGS2, GPR55, SOD1, CYP1A2 and NQO1. Behavioral test results showed that CBD by intraperitoneal administration 5mg/kg can significantly improve the pain behavior and depressive state of SNL mice. WB, qPCR, IF, and TEM experiments further confirmed the regulatory effects of CBD on key molecules.

Conclusion: In this study, we found five targets of CBD in the treatment of NP with DP. These findings provide further theoretical and experimental basis for CBD as a potential therapeutic agent.”

https://pubmed.ncbi.nlm.nih.gov/39245142/

“We identified five core genes associated with comorbid NP and DP targeted by CBD. CBD intervention can improve NP and depressive-associated behavior in mice.”

https://www.sciencedirect.com/science/article/abs/pii/S0028390824003228?via%3Dihub


THC vapor inhalation attenuates hyperalgesia in rats using a chronic inflammatory pain model

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“Humans use cannabinoid drugs to alleviate pain.

As cannabis and cannabinoids are legalized in the U.S. for medicinal and recreational use, it has become critical to determine the potential utilities and harms of cannabinoid drugs in individuals living with chronic pain.

Here, we tested the effects of repeated THC vapor inhalation on thermal nociception and mechanical sensitivity, in adult male and female Wistar rats using a chronic inflammatory pain model (i.e., treated with Complete Freund’s Adjuvant [CFA]).

We report that repeated THC vapor inhalation rescues thermal hyperalgesia in males and females treated with CFA, and also reduces mechanical hypersensitivity in CFA males but not females. Many of the anti-hyperalgesic effects of chronic THC vapor were still observable 24 hours after cessation of the last THC exposure.

We also report plasma levels of THC and its major metabolites, some of which are cannabinoid type-1 receptor (CB1) agonists, after the first and tenth days of THC vapor inhalation. Finally, we report that systemic administration of the CB1 inverse agonist AM251 (1mg/kg; i.p.) blocks the anti-hyperalgesic effects of THC vapor in males and females.

These data provide a foundation for future work that will explore the cells and circuits underlying the anti-hyperalgesic effects of THC vapor inhalation in individuals with chronic inflammatory pain.

PERSPECTIVE: Cannabinoids are thought to have potential utility in the treatment of chronic pain, but few animal studies have tested the effects of chronic THC or cannabis in animal models of chronic pain. We tested the effects of repeated THC vapor inhalation on chronic pain-related outcomes in male and female animals.”

https://pubmed.ncbi.nlm.nih.gov/39121915/

https://www.jpain.org/article/S1526-5900(24)00599-6/abstract

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

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“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.”

https://pubmed.ncbi.nlm.nih.gov/39096481/

https://link.springer.com/article/10.1007/s40122-024-00643-0

Analgesic properties of next generation modulators of endocannabinoid signaling: leveraging modern tools for the development of novel therapeutics

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“Targeting the endocannabinoid (eCB) signaling system for pain relief is an important treatment option that is only now beginning to be mechanistically explored.

In this review, we focus on two recently appreciated cannabinoid-based targeting strategies, treatments with cannabidiol (CBD) and a/b-hydrolase domain containing 6 (ABHD6) inhibitors, which have the exciting potential to produce pain relief through distinct mechanisms of action (MOA) and without intoxication.

We review evidence on plant-derived cannabinoids for pain, with an emphasis on CBD and its multiple molecular targets expressed in pain pathways. We also discuss the function of eCB signaling in regulating pain responses and the therapeutic promises of inhibitors targeting ABHD6, a 2-arachidonoylglycerol (2-AG) hydrolyzing enzyme. Finally, we discuss how the novel cannabinoid biosensor, GRABeCB2.0, may be leveraged to enable the discovery of targets modulated by cannabinoids at a circuit-specific level. 

Significance Statement Cannabis has been used by humans as an effective medicine for millennia, including for pain management. Recent evidence emphasizes the therapeutic potential of compounds that modulate endocannabinoid signaling. Specifically, cannabidiol and inhibitors of the enzyme ABHD6 represent promising strategies to achieve pain relief by modulating endocannabinoid signaling in pain pathways via distinct, non-intoxicating, mechanisms of action.”

https://pubmed.ncbi.nlm.nih.gov/39060165/

https://jpet.aspetjournals.org/content/early/2024/07/26/jpet.124.002119