Cannabis and cannabinoids for the treatment of people with chronic noncancer pain conditions: a systematic review and meta-analysis of controlled and observational studies

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.

Cannabis, cannabinoids and health: a review of evidence on risks and medical benefits

The legalization of cannabis for medical and recreational purposes has progressed internationally. Cannabis and cannabinoids are advocated for a plethora of medical indications. An increasing number of medical and nonmedical users regularly consume large doses of delta-9-Tetrahydrocannabinol (THC), the main active component of cannabis. Aim: to summarize the evidence on (1) risks of recreational cannabis use and (2) effectiveness and safety of medicinal cannabis. Findings on recreational use: Cannabis is mostly used to experience its acute rewarding effects. Regular use of high THC products can produce addiction (cannabis use disorder or CUD). Acute consumption of high THC doses (including unintentionally) can cause time-limited mental, gastrointestinal, and cardiovascular problems and motor vehicle accidents. Chronic patterns of cannabis use have been associated with multiple adverse outcomes that are of particular concern among adolescents and young adults, such as, disrupted learning, impaired cognitive performance, reduced educational attainment and an increased risk of CUD, psychosis/schizophrenia, mood and anxiety disorders and suicidal behaviors. There is debate about the extent to which cannabis use is a cause of these adverse outcomes. Physical health risks (e.g., respiratory and cardiovascular, prematurity and restricted fetal growth, hyperemesis syndrome among others) have also been linked with repeated consumption of cannabis with a high THC content. Findings on medical cannabis use: Herbal cannabis, medicines from extracted or synthetized cannabinoids-often used as adjuvants to standard medicines-may produce small to modest benefits. This is primarily the case in treating chronic pain, muscle spasticity, chemotherapy-induced nausea and vomiting, and refractory epilepsy (in the case of cannabidiol, CBD). The evidence is inconclusive on their value in treating mental disorders and other medical conditions. Safety: Cannabis-based medicine is generally well tolerated. There is a risk of mild to moderate adverse effects and CUD.

Comparative Safety Analysis of Nabilone Versus Opioids: A Population-Based Cohort Study

BACKGROUND

Some have advocated that nabilone be used rather than opioids to manage chronic, noncancer pain, since the former drug may have a better safety profile.

OBJECTIVE

We compared the safety of incident nabilone use relative to incident opioid use with respect to multiple clinically important outcomes.

DESIGN

A population-based, retrospective cohort study.

SETTING

Province of Ontario, Canada.

PARTICIPANTS

Persons aged 12 years and older, diagnosed with a musculoskeletal condition within the past 3 years prior to the index date.

EXPOSURES

Incident nabilone use, with incident opioid use serving as the reference group.

MEASUREMENTS

Within 3 months following the index date, we separately evaluated for pneumonia, motor vehicle accidents, falls or fractures, mental and behavioral disorder due to psychoactive substance use, and all-cause mortality.

RESULTS

A total of 18,863 incident nabilone users were propensity score matched to an equal number of opioid users. In the overall matched analysis, incident nabilone users vs. incident opioid users had significantly lower rates of pneumonia (hazard ratio [HR] 0.78, 95% CI 0.63-0.96), falls or fractures (HR 0.56, 95% CI 0.50-0.64), and all-cause mortality (HR 0.79, 95% CI 0.65-0.95), but significantly higher rate of mental or behavioral disorder (HR 2.23, 95% CI 1.45-3.43). There was no significant difference between groups with respect to rate of motor vehicle accidents.

LIMITATIONS

Unmeasured confounding may have influenced results.

CONCLUSIONS

While usage of nabilone relative to opioids was associated with reduced rates of pneumonia, falls or fractures, and all-cause mortality, it was simultaneously associated with an increased rate of adverse mental health outcomes. This picture of mixed safety results raises concerns with the policy approach of broadly substituting use of opioids with nabilone.

FUNDING SOURCE

Ontario Ministry of Health.

Characterization of a Fatty Acid Amide Hydrolase (FAAH) in Hirudo Verbana

The endocannabinoid system plays a critical role in modulating both peripheral and central nervous system function. Despite being present throughout the animal kingdom, there has been relatively little investigation of the endocannabinoid system beyond traditional animal models. In this study, we report on the identification and characterization of a putative fatty acid amide hydrolase (FAAH) in the medicinal leech, Hirudo verbana. FAAH is the primary enzyme responsible for metabolizing the endocannabinoid signaling molecule arachidonoyl ethanolamide (anandamide or AEA) and therefore plays a critical role in regulating AEA levels in the nervous system. mRNA encoding Hirudo FAAH (HirFAAH) is expressed in the leech central nervous system (CNS) and sequence analysis suggests that this is an orthologue of FAAH-2 observed in vertebrates. Functionally, HirFAAH has serine hydrolase activity based on activity-based protein profiling (ABPP) studies using the fluorophosphonate probe TAMRA-FP. HirFAAH also hydrolyzes arachidonyl 7-amino, 4-methyl coumarin amide (AAMCA), a substrate specific to FAAH. Hydrolase activity during both the ABPP and AAMCA assays was eliminated by a mutation at a conserved catalytic serine. Activity was also blocked by the known FAAH inhibitor, URB597. Treatment of Hirudo ganglia with URB597 potentiated synapses made by the pressure-sensitive mechanosensory neuron (P cell), mimicking the effects of exogenously applied AEA. The Hirudo CNS has been a useful system in which to study properties of endocannabinoid modulation of nociception relevant to vertebrates. Therefore, this characterization of HirFAAH is an important contribution to comparative studies of the endocannabinoid system.

Pain-suppressed consumption of highly palatable liquid in rats

This study determined whether consumption of a highly palatable liquid is a reliable measure of inflammatory pain and antinociception in male and female rats. After a 10-day acquisition period, the impact of intraplantar oil vs. complete Freund adjuvant (CFA) on consumption of vanilla-flavored Ensure was assessed, with a sipper tube height 12 or 19 cm above the floor. CFA significantly decreased Ensure consumption, which completely recovered within 4-7 days to levels in oil-treated controls; neither sex nor sipper tube height significantly influenced Ensure consumption. CFA also significantly suppressed Ensure consumption in rats not exposed to the 10-day acquisition period, but only in males. To test the predictive validity of Ensure consumption as a measure of pain, separate rats were pretreated with a vehicle, an opioid, a nonsteroidal anti-inflammatory drug, or a cannabinoid the day after CFA treatment. Morphine and ibuprofen significantly attenuated CFA-suppressed drinking in at least one sex, and tetrahydrocannabinol did not. Neither ibuprofen nor tetrahydrocannabinol significantly altered drinking in oil-injected, 'pain-free' controls, but morphine increased drinking. These results demonstrate that CFA decreases consumption of a highly palatable liquid regardless of previous exposure (training) to the consumption procedure, but only in males. Although standard analgesics attenuate CFA-suppressed drinking, nonspecific hyperphagic effects can confound the interpretation of results. Thus, consumption of a highly palatable liquid is not an optimal measure for candidate analgesic screening.

The Effects of Stigma: Older Persons and Medicinal Cannabis

Cannabis has long been stigmatized as an illicit drug. Since legalization in Canada for both medical and recreational purposes, older adults' cannabis consumption has increased more than any other age group. Yet, it is unclear how the normalization of cannabis has impacted perceptions of stigma for older adults consuming cannabis medicinally. Qualitative description was used to elucidate the experiences of older Canadians aged 60+ related to stigma and their consumption of cannabis for medicinal purposes. Data collection involved semi-structured interviews. Data analysis examined how participants managed stigma related to cannabis use. Perceived stigma was evident in many participants' descriptions of their perceptions of cannabis in the past and present, and influenced how they accessed and consumed cannabis and their comfort in discussing its use with their healthcare providers. Participants employed several distinct strategies for managing stigma-concealing, re-framing, re-focusing, and proselytizing. Findings suggest that while medical cannabis consumption is becoming increasingly normalized among older adults, stigma related to cannabis persists and continues to shape older adults' experiences. A culture shift needs to occur among healthcare providers so that they are educated about cannabis and willing to discuss the possibilities of medicinal cannabis consumption with older adults. Otherwise, older adults may seek advice from recreational or other non-medical sources. Healthcare providers require education about the use of medical cannabis, so they can better advise older adults regarding its consumption for medicinal purposes.

Cannabinoids for Acute Pain Management: Approaches and Rationale

PURPOSE OF THE REVIEW

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

RECENT FINDINGS

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

Disrupted stress-induced analgesia in a neuropathic pain state is rescued by the endocannabinoid degradation inhibitor JZL195

Acute stress normally engages descending brain pathways to produce an antinociceptive response, known as stress-induced analgesia. Paradoxically, these descending pain modulatory pathways are also involved in the maintenance of the abnormal pain associated with chronic neuropathic pain. It remains unclear how stress-induced analgesia is affected by neuropathic pain states. We therefore examined the impact of a chronic constriction nerve-injury (CCI) model of neuropathic pain on restraint stress-induced analgesia in C57BL/6 mice. Thirty minutes of restraint stress produced analgesia in the hotplate thermal nociceptive assay that was less in CCI compared to control mice who underwent a sham-surgery. In sham but not CCI mice, stress-induced analgesia was reduced by the opioid receptor antagonist naltrexone. The cannabinoid CB1 receptor antagonist AM281 did not affect stress-induced analgesia in either sham or CCI mice. Low-dose pre-treatment with the dual fatty acid amide hydrolase and monoacylglycerol lipase inhibitor JZL195 increased stress-induced analgesia in CCI but not sham mice. The JZL195 enhancement of stress-induced analgesia in CCI mice was abolished by AM281 but was unaffected by naltrexone. These findings indicate that the acute opioid-mediated analgesic response to a psychological stressor is disrupted in a nerve-injury model of neuropathic pain. Importantly, this impairment of stress-induced analgesia was rescued by blockade of endocannabinoid breakdown via a cannabinoid CB1 receptor dependent mechanism. These findings suggest that subthreshold treatment with endocannabinoid degradation blockers could be used to alleviate the disruption of endogenous pain control systems in a neuropathic pain state.

Pathology of pain and its implications for therapeutic interventions

Pain is estimated to affect more than 20% of the global population, imposing incalculable health and economic burdens. Effective pain management is crucial for individuals suffering from pain. However, the current methods for pain assessment and treatment fall short of clinical needs. Benefiting from advances in neuroscience and biotechnology, the neuronal circuits and molecular mechanisms critically involved in pain modulation have been elucidated. These research achievements have incited progress in identifying new diagnostic and therapeutic targets. In this review, we first introduce fundamental knowledge about pain, setting the stage for the subsequent contents. The review next delves into the molecular mechanisms underlying pain disorders, including gene mutation, epigenetic modification, posttranslational modification, inflammasome, signaling pathways and microbiota. To better present a comprehensive view of pain research, two prominent issues, sexual dimorphism and pain comorbidities, are discussed in detail based on current findings. The status quo of pain evaluation and manipulation is summarized. A series of improved and innovative pain management strategies, such as gene therapy, monoclonal antibody, brain-computer interface and microbial intervention, are making strides towards clinical application. We highlight existing limitations and future directions for enhancing the quality of preclinical and clinical research. Efforts to decipher the complexities of pain pathology will be instrumental in translating scientific discoveries into clinical practice, thereby improving pain management from bench to bedside.

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.

Prescribed Medical Cannabis Use Among Older Individuals: Patient Characteristics and Improvements in Well-Being: Findings from T21

BACKGROUND

Previous research has suggested that the use of cannabis-based medicinal products is increasing most rapidly among older aged individuals (65+ years). Despite this, little is known about the characteristics of older people using cannabis-based medicinal products and their effectiveness.

OBJECTIVES

We aimed to document the characteristics, outcomes and prescribing patterns of individuals aged 65+ years receiving prescribed cannabis compared to younger individuals receiving prescribed cannabis.

METHODS

Data from T21, an observational study of patients seeking treatment with medicinal cannabinoids, including self-report ratings of quality of life (assessed via the EQ-5D-5L), general health (assessed via the visual analogue scale of the EQ-5D-5L), mood (assessed via the Patient Health Questionnaire-9) and sleep (assessed using four items derived from the Pittsburgh Sleep Quality Index) were available at treatment entry [n = 4228; 198 (4.7%) 65+ years] and at a 3-month follow-up [n = 2455; 98 (4.2%) = 65+ years].

RESULTS

Relative to younger individuals, those aged over 64 years were more likely to be female (52.5% vs 47.0%; p < 0.001), more likely to report pain as their primary condition (76.3% vs 45.6%; p < 0.001) and less likely to report current daily use (20.2% vs 60.3%, p < 0.001). They received fewer cannabis-based medicinal products (mean = 1.4 vs 2.1; F(1,2199) = 32.3, p < 0.001) and were more likely to receive a prescription for a cannabidiol dominant oil (17.5% vs 5.7%; p < 0.001) and less likely to receive a prescription for delta-9-tetrahydrocannabinol dominant flower (32.5% vs 75.2%; p < 0.001). There were significant improvements across all measures of well-being (p < 0.001), but the extent of improvements in sleep were more marked in younger individuals (p < 0.001).

CONCLUSIONS

There are important differences between individuals aged 65+ years and younger individuals receiving cannabis-based medicinal products. Older aged individuals experience considerable improvement in health and well-being when prescribed cannabis-based medicinal products.

How Biodegradable Polymers Can be Effective Drug Delivery Systems for Cannabinoids? Prospectives and Challenges

Cannabinoids are compounds found in and derived from the Cannabis plants that have become increasingly recognised as significant modulating factors of physiological mechanisms and inflammatory reactions of the organism, thus inevitably affecting maintenance of homeostasis. Medical Cannabis popularity has surged since its legal regulation growing around the world. Numerous promising discoveries bring more data on cannabinoids' pharmacological characteristics and therapeutic applications. Given the current surge in interest in the medical use of cannabinoids, there is an urgent need for an effective method of their administration. Surpassing low bioavailability, low water solubility, and instability became an important milestone in the advancement of cannabinoids in pharmaceutical applications. The numerous uses of cannabinoids in clinical practice remain restricted by limited administration alternatives, but there is hope when biodegradable polymers are taken into account. The primary objective of this review is to highlight the wide range of indications for which cannabinoids may be used, as well as the polymeric carriers that enhance their effectiveness. The current review described a wide range of therapeutic applications of cannabinoids, including pain management, neurological and sleep disorders, anxiety, and cancer treatment. The use of these compounds was further examined in the area of dermatology and cosmetology. Finally, with the use of biodegradable polymer-based drug delivery systems (DDSs), it was demonstrated that cannabinoids can be delivered specifically to the intended site while also improving the drug's physicochemical properties, emphasizing their utility. Nevertheless, additional clinical trials on novel cannabinoids' formulations are required, as their full spectrum therapeutical potential is yet to be unravelled.

Recreational cannabis policy reform-What mental health nurses need to know about minimising harm and contributing to the reform debate

The recently rapidly evolving legal status of recreational cannabis in various countries has triggered international debate, particularly around measures required to minimise resulting harms. The present article argues that mental health nurses should have a key role in promoting safe and appropriate use of recreational cannabis, and minimising harm based on the extant evidence. The article summarises the factors driving legalisation, outlines the evident medicinal benefits of cannabis, and appraises the evidence on the negative mental health impacts associated with use. We go on to discuss research findings on the potentially deleterious mental health effects resulting from legalising recreational cannabis and strategies to minimise these harms, including directions for future research and evaluation. Further, we consider the importance of the implementation of harm minimisation measures that are context-specific, using Thailand as an example. Finally, we present the key health promotion messages that mental health nurses should aim to convey to people who use or consider using recreational cannabis. Ultimately, we aim to provide a summary of the existing evidence that mental health nurses can draw upon to promote mental health and engage with the policy reform debate.

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.

Medicinal cannabis for treating post-traumatic stress disorder and comorbid depression: real-world evidence

BACKGROUND

Cannabis-based medicinal products (CBMPs) are increasingly being used to treat post-traumatic stress disorder (PTSD), despite limited evidence of their efficacy. PTSD is often comorbid with major depression, and little is known about whether comorbid depression alters the effectiveness of CBMPs.

AIMS

To document the prevalence of depression among individuals seeking CBMPs to treat PTSD and to examine whether the effectiveness of CBMPs varies by depression status.

METHOD

Data were available for 238 people with PTSD seeking CBMP treatment (5.9% of the treatment-seeking sample) and 3-month follow-up data were available for 116 of these. Self-reported PTSD symptoms were assessed at treatment entry and at 3-month follow-up using the PTSD Checklist - Civilian Version (PCL-C). The probable presence of comorbid depression at treatment entry was assessed using the nine-item Patient Health Questionnaire (PHQ-9). Additional data included sociodemographic characteristics and self-reported quality of life.

RESULTS

In total, 77% met screening criteria for depression, which was associated with higher levels of PTSD symptomatology (mean 67.8 v. 48.4, F(1,236) = 118.5, P < 0.001) and poorer general health, quality of life and sleep. PTSD symptomatology reduced substantially 3 months after commencing treatment (mean 58.0 v. 47.0, F(1,112) = 14.5, P < 0.001), with a significant interaction (F(1,112) = 6.2, P < 0.05) indicating greater improvement in those with depression (mean difference 15.3) than in those without (mean difference 7).

CONCLUSIONS

Depression is common among individuals seeking CBMPs to treat PTSD and is associated with greater symptom severity and poorer quality of life. Effectiveness of CBMPs for treating PTSD does not appear to be impaired in people with comorbid depression.

Differences in prescribed medicinal cannabis use by cannabinoid product composition: Findings from the cannabis as medicine survey 2020 (CAMS-20) Australia-wide study

INTRODUCTION

Prescribed medicinal cannabis (MC) is an increasingly common prescription in Australia for treating pain, anxiety, and sleep disorders. Prescribed MC products generally contain tetrahydrocannabinol (THC) and/or cannabidiol (CBD) in a variety of dose levels and forms. It is unclear whether THC and CBD products are used by patients with different characteristics and for different conditions.

OBJECTIVES

To examine consumer experiences of using THC- and CBD-containing prescribed MC products to better understand how they are being used within the Australian context.

METHODS

We utilised data collected from an online anonymous cross-sectional survey of individuals (CAMS-20 survey), consisting of Australian residents using cannabis for therapeutic reasons. We focused on a subgroup of participants (N = 546) receiving prescribed MC products. We utilised linear, logistic, and multinomial regression modelling to analyse responses to survey questions based on the cannabinoid profile of the prescribed product.

RESULTS

Participants prescribed THC-dominant MC products were statistically more likely to be younger, male, and to prefer inhaled routes of administration than participants using CBD-dominant products who were older, female, and preferred oral routes of administration. Pain and mental health were the most common reasons for all types of prescribed MC, but were more likely to be treated with THC than CBD despite the significantly higher risk of mild to severe drowsiness, dry mouth and eye irritation. Consumer reported effectiveness of prescribed MC was very positive, particularly for THC-containing products. Consumers on opioids and antipsychotics were statistically more likely to be prescribed THC-containing products than products containing CBD only, despite the greater risk of impairment.

CONCLUSIONS

This Australia-wide study found clear differences in consumer-reported experiences of prescribed THC- and CBD-containing products. Current prescriptions of these products do not always align with relevant clinical guidance. Educating prescribers around cannabinoid products is essential to ensure optimal prescribing practices and to prevent avoidable drug side effects and interactions.

The Use of Cannabinoids in Pediatric Palliative Care-A Retrospective Single-Center Analysis

This data analysis aimed to systematically analyze a pediatric patient population with a life-limiting disease who were administered cannabinoids. It was a retrospective single-center analysis of patients under supervision of the specialized outpatient pediatric palliative care (SOPPC) team at the Department of Pediatrics and Adolescent Medicine of the Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU). Thirty-one patients with a primary diagnosis of neuropediatric, oncologic, metabolic, and cardiologic categories were included. The indications we identified were spasticity, pain, restlessness, anxiety, loss of appetite, epilepsy, and paresis. Certain aspects of quality of life were improved for 20 of 31 patients (64.5%). For nine patients (29%), no improvement was detected. No conclusions could be drawn for two patients (6.5%). Adverse events were reported for six of the thirty-one patients (19.4%). These were graded as mild, including symptoms such as restlessness, nausea, and behavioral issues. We detected no clinically relevant interactions with other medications. We collected fundamental data on the use of cannabinoids by pediatric palliative patients. Cannabinoids are now frequently administered in pediatric palliative care. They seem to be safe to use and should be considered an add-on therapy for other drug regimens.

Effects of Nature-Based Multisensory Stimulation on Pain Mechanisms in Women with Fibromyalgia Syndrome: A Randomized Double-Blind Placebo-Controlled Trial

BACKGROUND

The term "nature-based sensory stimuli" refers to the sensory information produced by biotic and abiotic agents from natural environments. The literature has reported the beneficial effects of these agents on various pain dimensions in non-clinical populations.

AIMS

To evaluate the potential analgesic effects of nature-based multisensory stimulation in women with fibromyalgia syndrome.

METHODS

A randomized, double-blind, placebo-controlled, parallel-group trial with a 1:1 allocation ratio was conducted. Forty-two women with fibromyalgia syndrome interacted with either different plant species with flowers, stones, and soil organic matter or their synthetic imitations for 30 minutes. Outcome measurements were performed before and after the intervention, including clinical pain intensity using the Numeric Rating Scale, cold pain thresholds using the Cold Pressor Test, mechanical hyperalgesia and wind-up using a monofilament, and pressure pain thresholds using a pressure algometer.

RESULTS

Analyses revealed group × time interactions for clinical pain intensity (F = 7.915, p = .008), cold-water immersion time (F = 7.271, p = .010), mechanical hyperalgesia (F = 4.701, p = .036), and pressure pain threshold (p ≤ .017). Between-group differences were found in clinical pain intensity (p = .012), cold pain thresholds (p = .002), and pressure pain thresholds (p < .05). The experimental group exhibited reduced clinical pain intensity (p = .001) and increased pressure pain thresholds (p ≤ .034).

CONCLUSIONS

Women with fibromyalgia syndrome may benefit from multisensory stimulation using biotic and abiotic agents from natural environments for 30 minutes. Interacting with flowering plants and soil components appears to induce analgesic effects.

An observational study of pain severity, cannabis use, and benefit expenditures in work disability

OBJECTIVE

This study pools two cohorts of workers in Ontario interviewed 18 months following a disabling work-related injury to estimate the association between pain severity, cannabis use, and disability benefit expenditures.

METHODS

Among 1650 workers, disability benefit expenditures obtained from administrative records were combined with self-reported measures of pain symptoms and cannabis use. Disability benefit expenditures comprised wage replacement benefits and expenditures on healthcare services.

RESULTS

Past-year cannabis use was reported by 31% of participants, with approximately one third of cannabis use attributed to the treatment of conditions arising from the work-related injury. Condition-related cannabis use was elevated among the 34% of participants reporting severe pain symptoms. In regression models adjusted for age, sex, nature of injury, opioid prescription, and pre-injury chronic conditions, participants reporting condition-related cannabis use had equivalent wage replacement benefit expenditures (β = 0.254, ns) and higher healthcare benefit expenditures (β = 0.433, p = 0.012) compared to participants who did not use cannabis. Participants reporting cannabis use unrelated to conditions arising from their work-related injury had lower wage replacement benefit expenditures (β =  - 0.309, p = 0.002) and equivalent healthcare benefit expenditures (β =  - 0.251, ns) compared to participants not using cannabis.

CONCLUSION

This novel study of workers' compensation claimants interviewed at 18 months post-injury did not observe a substantial relationship between cannabis use and disability benefit expenditures, suggesting that neither harm nor significant benefit is associated with cannabis use. These findings contribute to understanding the potential benefits and risks associated with cannabis use in settings that have legalized cannabis use.

Perceptions in orthopedic surgery on the use of cannabis in treating pain: a survey of patients with spine pain (POSIT Spine)

BACKGROUND

Back pain is the leading cause of disability worldwide. Despite guidelines discouraging opioids as first-line treatment, opioids remain the most prescribed drugs for back pain. There is renewed interest in exploring the potential medical applications of cannabis, and with the recent changes in national legislation there is a unique opportunity to investigate the analgesic properties of cannabis.

METHODS

This was a multi-center survey-based study examining patient perceptions regarding cannabis for spine pain. We included patients presenting with back or neck pain to one of three Orthopedic clinics in Ontario. Our primary outcome was perceived effect of cannabis on back pain, while secondary outcomes were perceptions regarding potential applications and barriers to cannabis use.

RESULTS

259 patients participated in this study, 35.3% (90/255) stating they used cannabis medically. Average pain severity was 6.5/10 ± 0.3 (95% CI 6.2-6.8). Nearly three-quarters were prescribed opioids (73.6%, 148/201), with oxycodone/oxycontin (45.9% 68/148) being the most common, and almost half of (49.3%, 73/148) had used an opioid in the last week. Patients estimated cannabis could treat 54.3% ± 4.0 (95% CI 50.3-58.3%) of their spine pain and replace 46.2% ± 6. 6 (95% CI 39.6-52.8%) of their current analgesics. Age (β = - 0.3, CI - 0.6-0.0), higher pain severity (β = 0.4, CI 0.1-0.6) and previous cannabis use (β = 14.7, CI 5.1-24.4) were associated with a higher perceived effect of cannabis. Patients thought cannabis would be beneficial to treat pain (129/146, 88.4%), and reduce (116/146, 79.5%) or eliminate opioids (102/146, 69.9%). Not considering using cannabis for medical purposes (65/150, 43.3%) was the number one reported barrier.

CONCLUSIONS

Patients estimated medical cannabis could treat more than half of their spine pain, with one in three patients already using medical cannabis. 79% of patients also believe cannabis could reduce opioid usage. This data will help support more research into cannabis for musculoskeletal pain.

Serum levels of endocannabinoids and related lipids in painful vs painless diabetic neuropathy: results from the Pain in Neuropathy Study

ABSTRACT

N-arachidonoylethanolamine (also known as anandamide) and 2-arachidonoylglycerol are activators of the cannabinoid receptors. The endocannabinoid system also includes structurally and functionally related lipid mediators that do not target cannabinoid receptors, such as oleoylethanolamide, palmitoylethanolamide, and stearoylethanolamide. These bioactive lipids are involved in various physiological processes, including regulation of pain. The primary aim of the study was to analyze associations between serum levels of these lipids and pain in participants in the Pain in Neuropathy Study, an observational, cross-sectional, multicentre, research project in which diabetic patients with painless or painful neuropathy underwent deep phenotyping. Our hypothesis was that painful neuropathy would be associated with higher levels of the 5 lipids compared with painless neuropathy. Secondary aims were to analyze other patient-reported outcome measures and clinical data in relationship to lipid levels. The lipid mediators were analyzed in serum samples using liquid chromatography tandem mass spectrometry (LC-MS/MS). Serum levels of anandamide were significantly higher in the painful group, but the effect size was small (Cohen d = 0.31). Using cluster analysis of lipid data, patients were dichotomized into a "high-level" endocannabinoid group and a "low-level" group. In the high-level group, 61% of patients had painful neuropathy, compared with 45% in the low-level group ( P = 0.039). This work is of a correlative nature only, and the relevance of these findings to the search for analgesics targeting the endocannabinoid system needs to be determined in future studies.

An Overview of Cannabidiol

Cannabidiol (CBD) is one of the most interesting constituents of cannabis, garnering significant attention in the medical community in recent years due to its proven benefit for reducing refractory seizures in pediatric patients. Recent legislative changes in the United States have made CBD readily available to the general public, with up to 14% of adults in the United States having tried it in 2019. CBD is used to manage a myriad of symptoms, including anxiety, pain, and sleep disturbances, although rigorous evidence for these indications is lacking. A significant advantage of CBD over the other more well-known cannabinoid delta-9-tetrahydroncannabinol (THC) is that CBD does not produce a "high." As patients increasingly self-report its use to manage their medical conditions, and as the opioid epidemic continues to drive the quest for alternative pain management approaches, the aims of this narrative review are to provide a broad overview of the discovery, pharmacology, and molecular targets of CBD, its purported and approved neurologic indications, evidence for its analgesic potential, regulatory implications for patients and providers, and future research needs.

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.

Attitudes of Swiss psychiatrists towards cannabis regulation and medical use in psychiatry: a cross-sectional study

BACKGROUND

Changes in regulation for cannabis for nonmedical use (CNMU) are underway worldwide. Switzerland amended the law in 2021 allowing pilot trials evaluating regulative models for cannabis production and distribution. Simultaneously, cannabis for medical use (CMU) in psychiatry is a growing issue, asked for by patients and being discussed by medical professionals.

METHODS

From December 2021 to February 2022, we conducted an online survey of psychiatrists in Switzerland. The survey comprised questions on attitudes towards regulative models for CNMU and towards prescribing CMU for mental disorders.

RESULTS

We contacted 2010 psychiatrists in Switzerland. A total of 274 (14%) participated in the survey. Sixty-four percent agreed to a regulated legalization of CNMU, and 89% would welcome pilot trials in Switzerland assessing models for regulating CNMU with those from a French-speaking region being more skeptical. Forty-nine percent of psychiatrists agree that CMU might have a therapeutic effect in mental disorders, but 50% agree that there is not enough scientific evidence yet. Participants working in an inpatient setting or in a French-speaking region as well as those with a longer duration of practice were more skeptical on CMU for mental health.

CONCLUSIONS

Most surveyed Swiss psychiatrists favor the regulation of CNMU and the conduct of pilot trials. Despite little evidence and potential negative consequences, many participating Swiss psychiatrists agreed that cannabis could be efficacious in the treatment of some mental disorders advocating for more research in this topic.

Multi-ancestry genome-wide association study of cannabis use disorder yields insight into disease biology and public health implications

As recreational use of cannabis is being decriminalized in many places and medical use widely sanctioned, there are growing concerns about increases in cannabis use disorder (CanUD), which is associated with numerous medical comorbidities. Here we performed a genome-wide association study of CanUD in the Million Veteran Program (MVP), followed by meta-analysis in 1,054,365 individuals (ncases = 64,314) from four broad ancestries designated by the reference panel used for assignment (European n = 886,025, African n = 123,208, admixed American n = 38,289 and East Asian n = 6,843). Population-specific methods were applied to calculate single nucleotide polymorphism-based heritability within each ancestry. Statistically significant single nucleotide polymorphism-based heritability for CanUD was observed in all but the smallest population (East Asian). We discovered genome-wide significant loci unique to each ancestry: 22 in European, 2 each in African and East Asian, and 1 in admixed American ancestries. A genetically informed causal relationship analysis indicated a possible effect of genetic liability for CanUD on lung cancer risk, suggesting potential unanticipated future medical and psychiatric public health consequences that require further study to disentangle from other known risk factors such as cigarette smoking.

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

Purpose of Review

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

Recent Findings

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

Summary

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

Prescription Practices of Cannabinoids in Children with Cerebral Palsy Worldwide-A Survey of the Swiss Cerebral Palsy Registry

Cannabinoids are prescribed to children with cerebral palsy despite limited evidence. We aimed to assess cannabinoid prescribing practices in children with cerebral palsy, focusing on indications, types of preparations used, and tolerability. Furthermore, we investigated how physicians acquire knowledge about cannabinoid medication. We asked physicians with expertise in the care of children with cerebral palsy about their prescribing practices for cannabinoids. Data were collected through an online survey, which was distributed by email. In addition to the demographic information of participants, we also inquired about the indications for the prescription of cannabinoids, experiences regarding efficacy, and observed side effects of the therapy. Seventy physicians from Europe, North America, and Australia completed the survey. Forty-seven participants were experienced in treating of children with cerebral palsy with cannabinoids. The most common indication was epilepsy (69%), followed by spasticity (64%) and pain (63%). The preparations and doses prescribed varied considerably. Half of the participants evaluated the effect of the cannabinoids as moderate. Twenty-nine physicians reported side effects, most frequently, drowsiness (26%), somnolence (19%), fatigue (13%), and diarrhea (13%). Despite the lack of evidence to date, cannabinoids are used to treat children with cerebral palsy in a wide variety of indications. Randomized controlled trials in this vulnerable patient group are therefore of utmost importance.

Daily cannabis use may cause cannabis-induced hyperalgesia

BACKGROUND AND OBJECTIVES

Public opinion about cannabis as a medical treatment is generally favorable. As many as 35% of primary care patients report medical use of cannabis, most commonly for pain treatment. We designed a way to test whether cannabis helps chronic pain.

METHODS

A retrospective cohort study was conducted to explore whether daily long-term cannabis use was associated with increased pain sensitivity using the cold pressor test (CPT) to measure pain tolerance. Patients who used cannabis every day were compared to patients who inhaled tobacco and control patients who never used tobacco or cannabis. The effect of cannabis use on CPT was assessed using a generalized linear model.

RESULTS

Patients using cannabis daily had a median CPT of 46 s, similar to those who did not use cannabis but who inhaled tobacco (median CPT 45 s). Patients who used both cannabis and tobacco had the lowest CPT (median 26 s). The control group had a median CPT of 105 s. Cannabis use was associated with a significantly decreased pain tolerance (χ²(1)  = 8.0, p = .004). The effect of tobacco on CPT was only marginally significant (χ²(1)  = 3.8, p = .052).

CONCLUSION AND SCIENTIFIC SIGNIFICANCE

This suggests a phenomenon similar to opioid-induced hyperalgesia; a drug that reduces pain short term, induces pain long term-opponent process. Daily cannabis use may make chronic pain worse over time by reducing pain tolerance. In terms of risk/benefit, daily cannabis users risk addiction without any long-term benefit for chronic pain.

Cannabis for Healing in a Native Community Clinic: Development and Results from an Informatics Research Tool

This paper describes how the Puyallup Tribe created a clinic specializing in cannabis-based treatments and partnered with a university research team to assess the impacts of cannabis on patient outcomes. Clinic leaders and research team co-developed an informatics research tool that included survey questions about patient demographics, cannabis use, and measures of pain, depression, anxiety, other substance use, and trauma. Over the first 2.5 years of operations, 69 patients completed a survey. Participants were an average age of 50 years old (SD = 16.7), female (77.6%) and American Indian/Alaska Native (61.5%) with more than 12 years of education (66.7%). Over 77% of the participants used either cannabidiol-dominant (CBD) alone or both CBD and Tetrahydrocannabinol-dominant (THC) products, nearly 23% used neither CBD nor THC products. Most came to the clinic for a pain relief appointment (70.3%). Compared to the general population, participants experienced more pain-related comorbidities, such as anxiety, fatigue, sleep, and pain, and fewer physical functioning capabilities. Over half reported symptoms consistent with depressive or post-traumatic stress disorder. The informatics research tool was successfully integrated into a unique Tribally owned medical clinic.

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.

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

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

Cannabinoids in Medicine: A Multifaceted Exploration of Types, Therapeutic Applications, and Emerging Opportunities in Neurodegenerative Diseases and Cancer Therapy

In this review article, we embark on a thorough exploration of cannabinoids, compounds that have garnered considerable attention for their potential therapeutic applications. Initially, this article delves into the fundamental background of cannabinoids, emphasizing the role of endogenous cannabinoids in the human body and outlining their significance in studying neurodegenerative diseases and cancer. Building on this foundation, this article categorizes cannabinoids into three main types: phytocannabinoids (plant-derived cannabinoids), endocannabinoids (naturally occurring in the body), and synthetic cannabinoids (laboratory-produced cannabinoids). The intricate mechanisms through which these compounds interact with cannabinoid receptors and signaling pathways are elucidated. A comprehensive overview of cannabinoid pharmacology follows, highlighting their absorption, distribution, metabolism, and excretion, as well as their pharmacokinetic and pharmacodynamic properties. Special emphasis is placed on the role of cannabinoids in neurodegenerative diseases, showcasing their potential benefits in conditions such as Alzheimer's disease, Parkinson's disease, Huntington's disease, and multiple sclerosis. The potential antitumor properties of cannabinoids are also investigated, exploring their potential therapeutic applications in cancer treatment and the mechanisms underlying their anticancer effects. Clinical aspects are thoroughly discussed, from the viability of cannabinoids as therapeutic agents to current clinical trials, safety considerations, and the adverse effects observed. This review culminates in a discussion of promising future research avenues and the broader implications for cannabinoid-based therapies, concluding with a reflection on the immense potential of cannabinoids in modern medicine.

Vaporized cannabis extract-induced antinociception in male vs female rats with persistent inflammatory pain

ABSTRACT

Although preclinical studies generally report robust antinociceptive effects of cannabinoids in rodent persistent pain models, randomized controlled trials in chronic pain patients report limited pain relief from cannabis/cannabinoids. Differences between animal and human studies that may contribute to these discrepant findings include route of cannabis/cannabinoid administration, type of cannabis/cannabinoid, and how pain is measured. To address these factors, rats with complete Freund adjuvant (CFA)-induced hind paw inflammation were exposed acutely or repeatedly to vaporized cannabis extract that was either tetrahydrocannabinol (THC) or cannabidiol (CBD)dominant. One measure of evoked pain (mechanical threshold), 2 functional measures of pain (hind paw weight-bearing, and locomotor activity), and hind paw edema were assessed for up to 2 hours after vapor exposure. Acute exposure to vaporized THC-dominant extract (200 or 400 mg/mL) decreased mechanical allodynia and hind paw edema and increased hind paw weight-bearing and locomotor activity, with no sex differences. After repeated exposure to vaporized THC-dominant extract (twice daily for 3 days), only the antiallodynic effect was significant. Acute exposure to vaporized CBD-dominant cannabis extract (200 mg/mL) did not produce any effects in either sex; repeated exposure to this extract (100, 200, or 400 mg/mL) decreased mechanical allodynia in male rats only. Sex differences (or lack thereof) in the effects of vaporized cannabis extracts were not explained by sex differences in plasma levels of THC, CBD, or their major metabolites. These results suggest that although vaporized THC-dominant extract is likely to be modestly effective against inflammatory pain in both male and female rats, tolerance may develop, and the CBD-dominant extract may be effective only in male rats.

Looking Back, Moving Forward in Pain Medicine

Pain is an ancient medical complaint and a clinical riddle that has never been entirely solved. Looking back into history was the springboard to a look into the future of pain medicine. This article was based on a series of presentations given in a recent congress (May 2023) and represents the research, views, and opinions of the authors. Opium has been used for millennia to treat pain, but when it gained broad use in the United States in the 1980s and 1990s, it was so vastly overprescribed and mis-prescribed that it led to a public health crisis. This, in turn, led to the reaction where opioids at times were under-prescribed, leaving out many patients who may have benefited from opioids while leaving many legacy pain patients to manage withdrawal on their own and with few analgesic options. Cannabinoids (CB) were likewise widely used for various conditions, including pain, but were outlawed in the 20th century, only to be brought back as a potential analgesic agent. Interventional pain medicine is a developing discipline and has reinforced the concept of the interdisciplinary pain clinic. It plays an increasingly important part in modern medicine overall, especially with the support of ultrasound, for both diagnosis and therapy. Today, the views about pain have changed. Anyone has accepted that pain is not purely a physical phenomenon but a biopsychosocial phenomenon that occurs within a cultural context. Pain management remains a small but vitally important medical subspecialty that is critical from a functional enablement and population health perspective, which is helping to navigate new therapeutic targets, new drugs and routes of administration, greater understanding of pain psychology, and new technologies. Pain control today means early intervention, functional enablement through pain alleviation, educating patients about pain management, and minimizing the transition from acute to chronic pain.

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.

Cannabis use frequency and pain interference among people with HIV

Cannabis is often used by people with HIV (PWH) for pain, yet study results are inconsistent regarding whether and how it affects pain. This study examines whether greater cannabis use frequency is associated with lower pain interference and whether cannabis use modifies the association of pain severity and pain interference among 134 PWH with substance dependence or a lifetime history of injection drug use. Multi-variable linear regression models examined the association between past 30-day cannabis use frequency and pain interference. Additional models evaluated whether cannabis use modified the association between pain severity and pain interference. Cannabis use frequency was not significantly associated with pain interference. However, in a model with interaction between cannabis use frequency and pain severity, greater cannabis use frequency attenuated the strength of the association between pain severity and pain interference (p = 0.049). The adjusted mean difference (AMD) in pain interference was +1.13, + 0.81, and +0.05 points for each 1-point increase in pain severity for those with no cannabis use, 15 days of use, and daily use, respectively. These findings suggest that attenuating the impact of pain severity on pain-related functional impairment is a potential mechanism for a beneficial role of cannabis for PWH.

Cannabis use among workers with work-related injuries and illnesses: results from a cross-sectional study of workers' compensation claimants in Ontario, Canada

OBJECTIVES

Little is known about how workers use cannabis following a work-related injury/illness, including whether they receive clinical guidance. The objective was to compare characteristics of workers using and not using cannabis after a work-related injury/illness and describe use patterns.

DESIGN

Cross-sectional study.

SETTING AND PARTICIPANTS

Workers who experienced a work-related physical injury/illness resulting in one or more days of lost time compensated by the workers' compensation authority in Ontario, Canada (n=1196).

METHODS

Participants were interviewed 18 or 36 months after their injury/illness. Participants were asked about their past-year cannabis use, including whether use was for the treatment of their work-related condition. Sociodemographic, work and health characteristics were compared across cannabis groups: no past-year use; use for the work-related condition; use unrelated to the work-related condition. Cannabis use reasons, patterns, perceived impact and healthcare provider engagement were described.

RESULTS

In total, 27.4% of the sample reported using cannabis (14.1% for their work-related condition). Workers using cannabis for their condition were less likely to be working (58.0%) and more likely to have quite a bit/extreme pain interference (48.5%), psychological distress (26.0%) and sleep problems most/all the time (62.1%) compared with those not using cannabis (74.3%, 26.3%, 12.0% and 38.0%, respectively) and those using cannabis for other reasons (74.2%, 19.5%, 12.0% and 37.1%, respectively) (all p<0.0001). No significant differences were observed in medical authorisations for use among those using cannabis for their condition (20.4%) or unrelated to their condition (15.7%) (p=0.3021). Healthcare provider guidance was more common among those using cannabis for their condition (32.7%) compared with those using for other reasons (17.1%) (p=0.0024); however, two-thirds of this group did not receive guidance.

CONCLUSIONS

Cannabis may be used to manage the consequences of work-related injuries/illnesses, yet most do not receive clinical guidance. It is important that healthcare providers speak with injured workers about their cannabis use.

Chronic Pain, Cannabis Legalization and Cannabis Use Disorder in Veterans Health Administration Patients, 2005 to 2019

Background

The risk for cannabis use disorder (CUD) is elevated among U.S. adults with chronic pain, and CUD rates are disproportionately increasing in this group. Little is known about the role of medical cannabis laws (MCL) and recreational cannabis laws (RCL) in these increases. Among U.S. Veterans Health Administration (VHA) patients, we examined whether MCL and RCL effects on CUD prevalence differed between patients with and without chronic pain.

Methods

Patients with ≥1 primary care, emergency, or mental health visit to the VHA and no hospice/palliative care within a given calendar year, 2005-2019 (yearly n=3,234,382 to 4,579,994) were analyzed using VHA electronic health record (EHR) data. To estimate the role of MCL and RCL enactment in the increases in prevalence of diagnosed CUD and whether this differed between patients with and without chronic pain, staggered-adoption difference-in-difference analyses were used, fitting a linear binomial regression model with fixed effects for state, categorical year, time-varying cannabis law status, state-level sociodemographic covariates, a chronic pain indicator, and patient covariates (age group [18-34, 35-64; 65-75], sex, and race and ethnicity). Pain was categorized using an American Pain Society taxonomy of painful medical conditions.

Outcomes

In patients with chronic pain, enacting MCL led to a 0·14% (95% CI=0·12%-0·15%) absolute increase in CUD prevalence, with 8·4% of the total increase in CUD prevalence in MCL-enacting states attributable to MCL. Enacting RCL led to a 0·19% (95%CI: 0·16%, 0·22%) absolute increase in CUD prevalence, with 11·5% of the total increase in CUD prevalence in RCL-enacting states attributable to RCL. In patients without chronic pain, enacting MCL and RCL led to smaller absolute increases in CUD prevalence (MCL: 0·037% [95%CI: 0·03, 0·05]; RCL: 0·042% [95%CI: 0·02, 0·06]), with 5·7% and 6·0% of the increases in CUD prevalence attributable to MCL and RCL. Overall, MCL and RCL effects were significantly greater in patients with than without chronic pain. By age, MCL and RCL effects were negligible in patients age 18-34 with and without pain. In patients age 35-64 with and without pain, MCL and RCL effects were significant (p<0.001) but small. In patients age 65-75 with pain, absolute increases were 0·10% in MCL-only states and 0·22% in MCL/RCL states, with 9·3% of the increase in CUD prevalence in MCL-only states attributable to MCL, and 19.4% of the increase in RCL states attributable to RCL. In patients age 35-64 and 65-75, MCL and RCL effects were significantly greater in patients with pain.

Interpretation

In patients age 35-75, the role of MCL and RCL in the increasing prevalence of CUD was greater in patients with chronic pain than in those without chronic pain, with particularly pronounced effects in patients with chronic pain age 65-75. Although the VHA offers extensive behavioral and non-opioid pharmaceutical treatments for pain, cannabis may seem a more appealing option given media enthusiasm about cannabis, cannabis commercialization activities, and widespread public beliefs about cannabis efficacy. Cannabis does not have the risk/mortality profile of opioids, but CUD is a clinical condition with considerable impairment and comorbidity. Because cannabis legalization in the U.S. is likely to further increase, increasing CUD prevalence among patients with chronic pain following state legalization is a public health concern. The risk of chronic pain increases as individuals age, and the average age of VHA patients and the U.S. general population is increasing. Therefore, clinical monitoring of cannabis use and discussion of the risk of CUD among patients with chronic pain is warranted, especially among older patients.

Research in Context

Evidence before this study: Only three studies have examined the role of state medical cannabis laws (MCL) and/or recreational cannabis laws (RCL) in the increasing prevalence of cannabis use disorder (CUD) in U.S. adults, finding significant MCL and RCL effects but with modest effect sizes. Effects of MCL and RCL may vary across important subgroups of the population, including individuals with chronic pain. PubMed was searched by DH for publications on U.S. time trends in cannabis legalization, cannabis use disorders (CUD) and pain from database inception until March 15, 2023, without language restrictions. The following search terms were used: (medical cannabis laws) AND (pain) AND (cannabis use disorder); (recreational cannabis laws) AND (pain) AND (cannabis use disorder); (cannabis laws) AND (pain) AND (cannabis use disorder). Only one study was found that had CUD as an outcome, and this study used cross-sectional data from a single year, which cannot be used to determine trends over time. Therefore, evidence has been lacking on whether the role of state medical and recreational cannabis legalization in the increasing US adult prevalence of CUD differed by chronic pain status.Added value of this study: To our knowledge, this is the first study to examine whether the effects of state MCL and RCL on the nationally increasing U.S. rates of adult cannabis use disorder differ by whether individuals experience chronic pain or not. Using electronic medical record data from patients in the Veterans Health Administration (VHA) that included extensive information on medical conditions associated with chronic pain, the study showed that the effects of MCL and RCL on the prevalence of CUD were stronger among individuals with chronic pain age 35-64 and 65-75, an effect that was particularly pronounced in older patients ages 65-75.Implications of all the available evidence: MCL and RCL are likely to influence the prevalence of CUD through commercialization that increases availability and portrays cannabis use as 'normal' and safe, thereby decreasing perception of cannabis risk. In patients with pain, the overall U.S. decline in prescribed opioids may also have contributed to MCL and RCL effects, leading to substitution of cannabis use that expanded the pool of individuals vulnerable to CUD. The VHA offers extensive non-opioid pain programs. However, positive media reports on cannabis, positive online "information" that can sometimes be misleading, and increasing popular beliefs that cannabis is a useful prevention and treatment agent may make cannabis seem preferable to the evidence-based treatments that the VHA offers, and also as an easily accessible option among those not connected to a healthcare system, who may face more barriers than VHA patients in accessing non-opioid pain management. When developing cannabis legislation, unintended consequences should be considered, including increased risk of CUD in large vulnerable subgroups of the population.

Cannabis-based medicines and medical cannabis for adults with cancer pain

BACKGROUND

Pain is a common symptom in people with cancer; 30% to 50% of people with cancer will experience moderate-to-severe pain. This can have a major negative impact on their quality of life. Opioid (morphine-like) medications are commonly used to treat moderate or severe cancer pain, and are recommended for this purpose in the World Health Organization (WHO) pain treatment ladder. Pain is not sufficiently relieved by opioid medications in 10% to 15% of people with cancer. In people with insufficient relief of cancer pain, new analgesics are needed to effectively and safely supplement or replace opioids.

OBJECTIVES

To evaluate the benefits and harms of cannabis-based medicines, including medical cannabis, for treating pain and other symptoms in adults with cancer compared to placebo or any other established analgesic for cancer pain.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was 26 January 2023.

SELECTION CRITERIA

We selected double-blind randomised, controlled trials (RCT) of medical cannabis, plant-derived and synthetic cannabis-based medicines against placebo or any other active treatment for cancer pain in adults, with any treatment duration and at least 10 participants per treatment arm.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. The primary outcomes were 1. proportions of participants reporting no worse than mild pain; 2. Patient Global Impression of Change (PGIC) of much improved or very much improved and 3. withdrawals due to adverse events. Secondary outcomes were 4. number of participants who reported pain relief of 30% or greater and overall opioid use reduced or stable; 5. number of participants who reported pain relief of 30% or greater, or 50% or greater; 6. pain intensity; 7. sleep problems; 8. depression and anxiety; 9. daily maintenance and breakthrough opioid dosage; 10. dropouts due to lack of efficacy; 11. all central nervous system adverse events. We used GRADE to assess certainty of evidence for each outcome.

MAIN RESULTS

We identified 14 studies involving 1823 participants. No study assessed the proportions of participants reporting no worse than mild pain on treatment by 14 days after start of treatment. We found five RCTs assessing oromucosal nabiximols (tetrahydrocannabinol (THC) and cannabidiol (CBD)) or THC alone involving 1539 participants with moderate or severe pain despite opioid therapy. The double-blind periods of the RCTs ranged between two and five weeks. Four studies with a parallel design and 1333 participants were available for meta-analysis. There was moderate-certainty evidence that there was no clinically relevant benefit for proportions of PGIC much or very much improved (risk difference (RD) 0.06, 95% confidence interval (CI) 0.01 to 0.12; number needed to treat for an additional beneficial outcome (NNTB) 16, 95% CI 8 to 100). There was moderate-certainty evidence for no clinically relevant difference in the proportion of withdrawals due to adverse events (RD 0.04, 95% CI 0 to 0.08; number needed to treat for an additional harmful outcome (NNTH) 25, 95% CI 16 to endless). There was moderate-certainty evidence for no difference between nabiximols or THC and placebo in the frequency of serious adverse events (RD 0.02, 95% CI -0.03 to 0.07). There was moderate-certainty evidence that nabiximols and THC used as add-on treatment for opioid-refractory cancer pain did not differ from placebo in reducing mean pain intensity (standardised mean difference (SMD) -0.19, 95% CI -0.40 to 0.02). There was low-certainty evidence that a synthetic THC analogue (nabilone) delivered over eight weeks was not superior to placebo in reducing pain associated with chemotherapy or radiochemotherapy in people with head and neck cancer and non-small cell lung cancer (2 studies, 89 participants, qualitative analysis). Analyses of tolerability and safety were not possible for these studies. There was low-certainty evidence that synthetic THC analogues were superior to placebo (SMD -0.98, 95% CI -1.36 to -0.60), but not superior to low-dose codeine (SMD 0.03, 95% CI -0.25 to 0.32; 5 single-dose trials; 126 participants) in reducing moderate-to-severe cancer pain after cessation of previous analgesic treatment for three to four and a half hours (2 single-dose trials; 66 participants). Analyses of tolerability and safety were not possible for these studies. There was low-certainty evidence that CBD oil did not add value to specialist palliative care alone in the reduction of pain intensity in people with advanced cancer. There was no difference in the number of dropouts due to adverse events and serious adverse events (1 study, 144 participants, qualitative analysis). We found no studies using herbal cannabis.

AUTHORS' CONCLUSIONS

There is moderate-certainty evidence that oromucosal nabiximols and THC are ineffective in relieving moderate-to-severe opioid-refractory cancer pain. There is low-certainty evidence that nabilone is ineffective in reducing pain associated with (radio-) chemotherapy in people with head and neck cancer and non-small cell lung cancer. There is low-certainty evidence that a single dose of synthetic THC analogues is not superior to a single low-dose morphine equivalent in reducing moderate-to-severe cancer pain. There is low-certainty evidence that CBD does not add value to specialist palliative care alone in the reduction of pain in people with advanced cancer.

The Information-Seeking Behavior and Unmet Knowledge Needs of Older Medicinal Cannabis Consumers in Canada: A Qualitative Descriptive Study

INTRODUCTION

Older Canadians (age 60+) are increasingly using cannabis to treat their health problems, but little is known regarding how they learn about medicinal cannabis. This study explored the perspectives of older cannabis consumers, prospective consumers, healthcare professionals, and cannabis retailers on older adults' information-seeking behavior and unmet knowledge needs.

METHODS

A qualitative descriptive design was used. Semi-structured telephone interviews were conducted with a purposeful sample of 36 older cannabis consumers and prospective consumers, as well as 4 healthcare professionals and 5 cannabis retailers from across Canada, for a total sample of 45 participants. Data were thematically analyzed.

RESULTS

Three main themes characterizing older cannabis consumers' information-seeking were identified: (1) knowledge sources, (2) types of information sought, and (3) unmet knowledge needs. Participants accessed a variety of knowledge sources to inform themselves about medicinal cannabis. Cannabis retailers were identified as providing medical information to many older adults, despite regulations to the contrary. Cannabis-specialized healthcare professionals were also viewed as key knowledge sources, while primary care providers were perceived as both knowledge sources and gatekeepers limiting access to information. The types of information participants sought included the effects and potential benefits of medicinal cannabis, the side effects and risks involved, and guidance regarding suitable cannabis products. Participants' most salient unmet knowledge needs focused on dosing and use of cannabis to treat specific health conditions.

DISCUSSION

Findings suggest that barriers to learning about medical cannabis among older consumers identified in prior research remain pervasive and cut across jurisdictions. To address these barriers, there is a need for better knowledge products tailored to older cannabis consumers and their information needs, and further education for primary healthcare providers on medicinal cannabis and its therapeutic applications with older patients.

Mediators of Placebo Response to Cannabinoid Treatment in Children with Autism Spectrum Disorder

The placebo response has a substantial impact on treatment outcome. However, data regarding mediators of the placebo response in children with autism spectrum disorder (ASD) are sparse. This retrospective study investigated possible mediators of the placebo response among participants of a placebo-controlled trial of cannabinoid treatment for behavioral problems in children with ASD (CBA trial, age 5-21 years). We used a specifically designed questionnaire to explore possible mediators of the placebo response in 88 participants of the CBA trial who received a placebo and had valid outcome scores. The parents of 67 participants completed the questionnaire. The placebo response was positively associated with the child's comprehension of the treatment purpose (p = 0.037). There was also a trend for participants who had a relative aggravation of symptoms before treatment onset to improve following placebo treatment (p = 0.053). No other domains, including parental expectations, previous positive experience with similar treatments (behavioral conditioning), parental locus of control, quality of the patient-physician relationships, and adherence to study medications were associated with placebo-response. This finding suggests that efforts to explain the treatment purpose to children with disabilities may enhance treatment efficacy in clinical practice and decrease differences in the placebo response between study arms. Contrary to our hypothesis, parental expectations regarding cannabinoid treatment were not associated with the placebo response.

Heterosynaptic long-term potentiation of non-nociceptive synapses requires endocannabinoids, NMDARs, CamKII, and PKCζ

Noxious stimuli or injury can trigger long-lasting sensitization to non-nociceptive stimuli (referred to as allodynia in mammals). Long-term potentiation (LTP) of nociceptive synapses has been shown to contribute to nociceptive sensitization (hyperalgesia) and there is even evidence of heterosynaptic spread of LTP contributing to this type of sensitization. This study will focus on how activation of nociceptors elicits heterosynaptic LTP (hetLTP) in non-nociceptive synapses. Previous studies in the medicinal leech (Hirudo verbana) have demonstrated that high-frequency stimulation (HFS) of nociceptors produces both homosynaptic LTP as well as hetLTP in non-nociceptive afferent synapses. This hetLTP involves endocannabinoid-mediated disinhibition of non-nociceptive synapses at the presynaptic level, but it is not clear if there are additional processes contributing to this synaptic potentiation. In this study, we found evidence for the involvement of postsynaptic level change and observed that postsynaptic N-methyl-d-aspartate (NMDA) receptors (NMDARs) were required for this potentiation. Next, Hirudo orthologs for known LTP signaling proteins, CamKII and PKCζ, were identified based on sequences from humans, mice, and the marine mollusk Aplysia. In electrophysiological experiments, inhibitors of CamKII (AIP) and PKCζ (ZIP) were found to interfere with hetLTP. Interestingly, CamKII was found to be necessary for both induction and maintenance of hetLTP, whereas PKCζ was only necessary for maintenance. These findings show that activation of nociceptors can elicit a potentiation of non-nociceptive synapses through a process that involves both endocannabinoid-mediated disinhibition and NMDAR-initiated signaling pathways.NEW & NOTEWORTHY Pain-related sensitization involves increases in signaling by non-nociceptive sensory neurons. This can allow non-nociceptive afferents to have access to nociceptive circuitry. In this study, we examine a form of synaptic potentiation in which nociceptor activity elicits increases in non-nociceptive synapses. This process involves endocannabinoids, "gating" the activation of NMDA receptors, which in turn activate CamKII and PKCζ. This study provides an important link in how nociceptive stimuli can enhance non-nociceptive signaling related to pain.

Medical cannabis and stigma: A qualitative study with patients living with chronic pain

AIMS AND OBJECTIVES

To explore the ways in which stigma is experienced, and what strategies are used to manage stigma among patients using medical cannabis to ease suffering from chronic pain.

BACKGROUND

Various jurisdictions have legalised medical cannabis in recent decades. Despite increasing prevalence and more liberal attitudes towards medical cannabis, it is possible that patients who use medical cannabis experience stigma.

DESIGN

A phenomenological qualitative study.

METHODS

Fifteen patients living with chronic pain and licensed by the Israeli Ministry of Health to use medical cannabis to treat pain symptoms for at least 1 year participated in semi-structured interviews. Transcribed data were analysed using thematic analysis to identify themes related to stigma. The manuscript is in correspondence to SRQR EQUATOR checklist.

RESULTS

Expressions of stigma were more related to 'felt' than 'enacted' stigma. Stigma related to decisions to delay onset of medical cannabis treatment and the ways in which participants managed medical cannabis use during their everyday lives. Participants dissociated themselves from recreational cannabis users, by presenting themselves as responsible normative individuals and engaging in a form of normalisation known as 'normification', emphasising their own discrete and controlled medical cannabis use and cannabis' benefits.

CONCLUSIONS

Patients experienced 'felt' stigma which had consequences for their self-presentations and medical cannabis use. This suggests that medical cannabis is not normalised in Israel and interventions may be needed to handle stigma related to medical cannabis.

RELEVANCE TO CLINICAL PRACTICE

The findings emphasise the effects of 'felt' stigma on patients. Aiming to increase the effectiveness of medical cannabis treatment and reducing harms, we suggest that particular focus should be placed on managing stigma at the intrapersonal level. In addition, there may be a need to address stigma at the societal level including social interactions with friends, family and medical personnel.

Alternative pain management via endocannabinoids in the time of the opioid epidemic: Peripheral neuromodulation and pharmacological interventions

The use of opioids in pain management is hampered by the emergence of analgesic tolerance, which leads to increased dosing and side effects, both of which have contributed to the opioid epidemic. One promising potential approach to limit opioid analgesic tolerance is activating the endocannabinoid system in the CNS, via activation of CB1 receptors in the descending pain inhibitory pathway. In this review, we first discuss preclinical and clinical evidence revealing the potential of pharmacological activation of CB1 receptors in modulating opioid tolerance, including activation by phytocannabinoids, synthetic CB1 receptor agonists, endocannabinoid degradation enzyme inhibitors, and recently discovered positive allosteric modulators of CB1 receptors. On the other hand, as non-pharmacological pain relief is advocated by the US-NIH to combat the opioid epidemic, we also discuss contributions of peripheral neuromodulation, involving the electrostimulation of peripheral nerves, in addressing chronic pain and opioid tolerance. The involvement of supraspinal endocannabinoid systems in peripheral neuromodulation-induced analgesia is also discussed. LINKED ARTICLES: This article is part of a themed issue on Advances in Opioid Pharmacology at the Time of the Opioid Epidemic. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v180.7/issuetoc.

Do We Have Structure, Process and Outcomes to Support Cannabis as Supportive Therapy in Cancer?

Cannabis is becoming more popular and more available in the United States. It has been approved for use by multiple states for various conditions and several states now allow recreational cannabis. We explore the structure of cannabis distribution, the process of acquisition, outcomes, and the safety of cannabis in the United States.

Burrowing as an index of inflammatory pain in male vs. female rats

The study objective was to determine whether burrowing behavior is useful as a functional index of pain in both male and female rats, and whether a 'no-training' protocol can be used to increase testing efficiency. Adult Sprague-Dawley rats were injected in one or both hindpaws with oil vehicle or complete Freund's adjuvant (CFA); starting the next day, the amount of gravel each rat burrowed out of a tube in 1 h was measured daily for ≤7 days. Without preliminary training on the burrowing procedure, CFA reliably suppressed burrowing for 2-3 days compared to controls, in both sexes. However, whereas unilateral CFA completely suppressed burrowing 1-day post-CFA in nearly all males, bilateral CFA was required to do so in females. When administered 30 min before testing, once daily for 5 days post-CFA, the nonsteroidal anti-inflammatory drug ketoprofen (0.01-3.2 mg/kg) and the opioid morphine (0.1-3.2 mg/kg) significantly increased CFA-suppressed burrowing, whereas the purported cannabinoid analgesic Δ 9 -tetrahydrocannabinol (0.01-2.0 mg/kg) did not. The benzodiazepine chlordiazepoxide (1.25-10 mg/kg), included as a 'true negative' control, also did not restore CFA-suppressed burrowing in either sex. However, in CFA-treated males only, chlordiazepoxide decreased burrowing, suggesting that anxiety may contribute to burrowing in males but not females that are in pain. Overall these results suggest that burrowing is a valid, functional index of inflammatory pain in both sexes, and training on the burrowing procedure is not necessary. However, females are more avid burrowers than males, which should be considered when both sexes are used in inflammatory pain testing.

Mental disorders are no predictors to determine the duration of cannabis-based treatment for chronic pain

Background

Chronic pain (CP), a complex biopsychosocial disorder with a global prevalence of up to 33%, can be treated by following multidisciplinary approaches that may include cannabis-based medicine (CBM). However, because CBM continues to be a new treatment, questions remain regarding the ideal duration for CBM and its psychosocial determinants, including mental comorbidities.

Methods

In a retrospective cross-sectional study involving 46 patients with CP (ICD-10 code F45.4-), three validated instruments-the German Pain Questionnaire, the Depression Anxiety Stress Scale (DASS), and the Marburg Questionnaire of Habitual WellBeing-were used to identify pain-specific psychosocial determinants and mental disorders. Descriptive analyses, a group differences analysis, and a logistic regression analysis were performed using SPSS.

Results

The patients most frequently reported low back pain as the primary location of their CP, and in attributing the condition to tissue damage, most had largely adopted a somatic orientation in conceptualizing their illness. Most had experienced CP for more than 5 years (M = 5.13 years, SD = 1.41) and, as a consequence, faced significant restrictions in their everyday life and exhibited low subjective wellbeing (MFHW median = 4.00, N = 43, Q1: 2.00, Q3: 9.00, range: 0-20). Comorbidities among the patients included depression, (DASS-Depression, median: 11.50, Q1: 7.00, Q3: 16.25), anxiety (DASS-Anxiety, median: 4.50, Q1: 2.75, Q3: 8.00), and stress (DASS-Stress, median: 11.00, Q1: 7.00, Q3: 15.00). Between the two cannabis-based treatments with a course lasting either less or more than a year, the duration of treatment showed no between-group differences in terms of sociodemographic factors, pain-specific factors, conceptualizations of the illness, or mental disorders. Psychosocial determinants such as subjective wellbeing and mental comorbidities were not significant predictors of the duration of cannabis-based treatment.

Conclusion

We found no evidence indicating that the benefits of short-term vs. long-term cannabis-based treatment can be predicted by mental comorbidities or psychosocial factors. However, because CBM may be included in approaches to treat CP, questions about the ideal duration of such treatment remain to be answered.

Tetrahydrocannabinol in Pediatrics: Room for Improvement?

Introduction

The use of medical cannabis in pediatrics is not common in clinical practice, and there is a lack of prospective studies, especially in pediatric subpopulations. This study aimed to provide data on the off-label administration of tetrahydrocannabinol (∆9-THC) in a pediatric tertiary center in Austria.

Methods

A retrospective data analysis was performed to assess the use of ∆9-THC at the Department of Pediatrics and Adolescent Medicine at the Comprehensive Center of Pediatrics (Medical University Vienna) from 2016 to 2018. The use of ∆9-THC in the Pediatric Department at the Medical University Vienna between 2016 and 2018 was analyzed using a retrospective design.

Results

The most common diagnoses of patients receiving ∆9-THC were brain cancer and genetic diseases, including inborn metabolic disorders. The 32 patients who had received ∆9-THC had an arithmetic mean of 9.42 diagnoses and were treated with an arithmetic mean of 13.52 other drugs. Eleven of the 32 patients died by the end of the study period, indicating palliative use.

Conclusion

The data shows that only severely ill patients were treated with ∆9-THC. A lack of information on the drug's indications, duration, and dosage was noticed in the files, which could represent problems for patient safety.