Cannabis use moderates the relationship between pain and negative affect in adults with opioid use disorder

Cannabinoid-Induced Inhibition of Morphine Glucuronidation and the Potential for In Vivo Drug-Drug Interactions

Opioids are commonly prescribed for the treatment of chronic pain. Approximately 50% of adults who are prescribed opioids for pain co-use cannabis with their opioid treatment. Morphine is primarily metabolized by UDP-glucuronosyltransferase (UGT) 2B7 to an inactive metabolite, morphine-3-glucuronide (M3G), and an active metabolite, morphine-6-glucuronide (M6G). Previous studies have shown that major cannabis constituents including Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) inhibit major UGT enzymes. To examine whether cannabinoids or their major metabolites inhibit morphine glucuronidation by UGT2B7, in vitro assays and mechanistic static modeling were performed with these cannabinoids and their major metabolites including 11-hydroxy-Δ9-tetrahydrocannabinol (11-OH-THC), 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (11-COOH-THC), 7-hydroxy-cannabidiol (7-OH-CBD), and 7-carboxy-cannabidiol (7-COOH-CBD). In vitro assays with rUGT-overexpressing microsomes and human liver microsomes showed that THC and CBD and their metabolites inhibited UGT2B7-mediated morphine metabolism, with CBD and THC exhibiting the most potent Ki,u values (0.16 µM and 0.37 µM, respectively). Only 7-COOH-CBD exhibited no inhibitory activity against UGT2B7-mediated morphine metabolism. Static mechanistic modeling predicted an in vivo drug-drug interaction between morphine and THC after inhaled cannabis, and between THC, CBD, and 7-OH-CBD after oral consumption of cannabis. These data suggest that the co-use of these agents may lead to adverse drug events in humans.

An answered call for aid? Cannabinoid clinical framework for the opioid epidemic

BACKGROUND

The opioid crisis continues in full force, as physicians and caregivers are desperate for resources to help patients with opioid use and chronic pain disorders find safer and more accessible non-opioid tools.

MAIN BODY

The purpose of this article is to review the current state of the opioid epidemic; the shifting picture of cannabinoids; and the research, policy, and current events that make opioid risk reduction an urgent public health challenge. The provided table contains an evidence-based clinical framework for the utilization of cannabinoids to treat patients with chronic pain who are dependent on opioids, seeking alternatives to opioids, and tapering opioids.

CONCLUSION

Based on a comprehensive review of the literature and epidemiological evidence to date, cannabinoids stand to be one of the most interesting, safe, and accessible tools available to attenuate the devastation resulting from the misuse and abuse of opioid narcotics. Considering the urgency of the opioid epidemic and broadening of cannabinoid accessibility amidst absent prescribing guidelines, the authors recommend use of this clinical framework in the contexts of both clinical research continuity and patient care.

Co-use of cannabis and prescription opioids in adults in the USA: a population-based, cross-sectional analysis of the NHANES from 2009 to 2018

INTRODUCTION

Cannabis and cannabinoids continue to gain popularity as adjuncts or alternatives to opioids in pain management, with evolving evidence of effectiveness. The relationship between cannabis and opioid use has previously been investigated in smaller cohorts or ecological samples, but not yet in a nationally representative sample.

METHODS

A cross-sectional analysis of adults in the USA was undertaken using National Health and Nutrition Examination Survey (NHANES) data from 2009 to 2018. The primary exposure was self-reported use of at least one opioid-containing prescription medication in the 30 days prior to survey administration. The outcome of interest was self-reported cannabis use in the same period. Multivariable logistic regression was used to adjust for sociodemographic and health-related covariates, and NHANES survey sample weights were included in modeling. Prescription opioid users were then subclassified as short-term users (<90 days) or chronic users (≥90 days) in secondary analysis.

RESULTS

A total 10,928 survey respondents were included in analyses, representing 110 million adults in the USA aged 18-59. In this weighted cohort, 5.6%±0.4% reported a recent opioid prescription. Among prescription opioid users, 18.4%±3.1% reported recent cannabis use, not significantly different from 17.7%±0.7% among non-users (OR 1.05, 95% CI 0.81 to 1.36, p=0.714). After adjustment for covariates, opioid users were significantly less likely to have recently used cannabis (adjusted OR, aOR 0.70, 95% CI 0.51 to 0.97, p=0.032). When opioid users were subclassified by duration of prescription, there was no detectable difference in recent cannabis use between chronic opioid users and short-term opioid users (aOR 1.11, 95% CI 0.70 to 1.78, p=0.649).

CONCLUSION

Recent prescription opioid use was associated with decreased odds of cannabis use in this cross-sectional analysis of a nationally representative cohort. These findings suggest that use of cannabis or prescription opioids may not independently promote use of the other.

Longitudinal associations between pain and substance use disorder treatment outcomes

INTRODUCTION

Pain is commonly reported among those in treatment for substance use disorders (SUD) and is associated with poorer SUD treatment outcomes. The current study examined the trajectory of pain over the course of SUD treatment and associations with substance use outcomes.

METHODS

This observational study included adults seeking treatment for alcohol, cannabis, or opioid use disorders (N = 811). Participants completed a battery of assessments at treatment admission, 30 days post admission, and at discharge, including measures of demographics, pain, quality of life, abstinence self-efficacy, and craving.

RESULTS

Analyses indicated linear reductions in pain intensity and interference over time. Significant interactive effects were observed for opioid use disorder (OUD) and time, such that participants with OUD had greater reductions in pain intensity and interference over time compared to those without OUD. Elevated pain intensity was associated with negative treatment outcomes, including reduced quality of life and abstinence self-efficacy, and greater craving and negative affect.

CONCLUSIONS

Reductions in pain occur over the course of SUD treatment, particularly for those with OUD. Greater pain was also associated with adverse SUD treatment outcomes. Results suggest that treatment and associated abstinence may be beneficial for those with co-occurring pain and SUD, highlighting an additional benefit of improving access to SUD treatment for patients and health care systems. Future research should replicate these findings among diverse samples and further characterize the trajectory of pain during and after SUD treatment.

"It's Like Your Whole Body Hates You": Experiences of Withdrawal, Distress, and Barriers to Relief Among Adults Receiving Methadone for Opioid Use Disorder

ABSTRACT

A qualitative descriptive study was conducted concurrent with a larger study investigating the effects of hyperbaric oxygen treatment on withdrawal symptoms for adults receiving daily methadone for opioid use disorder. The aims of this study were to (a) evaluate the perceptions of withdrawal symptoms and sleep characteristics of study participants and (b) explore the experiences of participation in the parent trial of hyperbaric oxygen treatment.Adults with opioid use disorder can experience distressing symptoms related to withdrawal as well as co-occurring symptoms; sleep impairment is frequently reported. Few studies have examined how adults who receive medication for opioid use disorder experience sleep. A preliminary study of adults receiving daily methadone found that withdrawal symptoms were improved after hyperbaric oxygen treatment. This study explores the narrative of opioid users who report their overall experiences with withdrawal and sleep as well as their experiences of hyperbaric therapy.A convenience sample of six participants was recruited, who represented a small subgroup of participants who completed the larger hyperbaric treatment study. Data were collected via semistructured interviews. Data were analyzed using the qualitative content analysis guidelines proposed by Schreier (2012). All participants described poor overall sleep hygiene and disturbed sleep. More than half of the respondents reported improved or eliminated withdrawal symptoms, and all reported improvement in sleep quality after participation in the sleep study.This companion study confirms that subjective sleep disturbance may be prevalent for adults with opioid use disorder. Participants felt the experience of hyperbaric oxygen treatment produced a positive effect on sleep.

Assessing the impact of a cannabis course on pharmacy students' understanding, beliefs and preparedness regarding medical and recreational cannabis

Background

With the legalization of cannabis in Canada in 2018, pharmacists are increasingly likely to encounter patients using this substance. The primary objective of this pre-post questionnaire study was to evaluate the impact of an accredited cannabis course on the understanding, beliefs, perceptions and knowledge of undergraduate PharmD students.

Methods

A 38-question, web-based survey generated in REDCap was administered to third-year PharmD students at the University of Waterloo, prior to and right after taking an accredited cannabis course. The pre- and postsurvey data were analyzed using SPSS version 25. Pearson chi-square tests were performed on questions in which answers consisted of qualitative categorical data. Two-sided t tests were performed to test the significance of mean differences of questions measuring continuous variables.

Results

In a class of 120 students, 110 completed the presurvey and 79 students completed the postsurvey. After the course, students were more likely to report being knowledgeable and prepared for patient encounters dealing with medical and recreational cannabis, understanding that medical cannabis should be prescribed for select (vs all) medical conditions, rating the quality of evidence as poor to moderate for medical use of cannabis, understanding that medical documents should be more prescriptive and understanding that cannabis should not be sold in pharmacies (p < 0.05).

Interpretation

With cannabis education a part of their curriculum, pharmacy students felt more prepared to engage patients using cannabis both medically and recreationally. Furthermore, students were more cautious regarding the potential use of cannabis therapeutically and indicated that more oversight should be in place. Can Pharm J (Ott) 2021;154:xx-xx.

Concomitant Cannabis Misuse and Associations with Depression, Pain and Substance Misuse among Patients Prescribed Opioids

BACKGROUND

Cannabis use is common among individuals with pain who are prescribed opioids, occurring in approximately 10% of this population. This study aims to explore the relationship between non-medical cannabis use and other health risks among individuals filling opioids at community pharmacies.

METHODS

This study was an exploratory secondary data analysis of a National Drug Abuse Treatment Clinical Trials Network (CTN)-sponsored study, Validation of a Community Pharmacy-Based Prescription Drug Monitoring Program Risk Screening, examining the relationship between risky cannabis use and depressive symptoms, pain, overdose, and other substance misuse among individuals filling opioid prescriptions in community pharmacies (N = 1440).

RESULTS

Participants reporting moderate- to high-risk compared to low-risk cannabis use were more likely to report depressive symptoms (adjusted OR = 1.67, 95% CI = 1.11-2.56), history of overdose (adjusted OR = 2.15, 95% CI = 1.34-3.44), and moderate- to high-risk use of alcohol (adjusted OR = 2.10, 95% CI = 1.28-3.45), opioids (adjusted OR = 2.50, 95% CI = 1.67-3.76), sedatives (adjusted OR = 2.58, 95% CI = 1.72-3.86), stimulants (adjusted OR = 4.79, 95% CI = 2.83-8.01), and tobacco (adjusted OR = 3.60, 95% CI = 2.47-5.24).

CONCLUSIONS

Community pharmacies may be valuable sites for identifying, studying, and intervening with substance use problems.

Green Hope: Perspectives on Cannabis from People who Use Opioids

While states are implementing policies to legalize cannabis for medical or recreational purposes, it remains a Schedule 1 controlled substance with no medical uses according to US federal law. The perception of cannabis depends on social and cultural norms that impact political institutions involved in implementing policy. Because of negative social constructions, such as the "gateway hypothesis," legalization of cannabis has been slow and contentious. Recent studies suggest that cannabis can help combat the opioid epidemic. This paper fills a gap in our understanding of how cannabis is viewed by people who are actively misusing opioids and not in treatment. Using ethnographic methods to recruit participants living in a state that legalized cannabis and a state where cannabis was illegal, survey and interview data were analyzed informed by a social constructionist lens. Findings from their "insider perspective" suggest that for some people struggling with problematic opioid use, cannabis can be beneficial.

Neuroimmune Mechanisms as Novel Treatment Targets for Substance Use Disorders and Associated Comorbidities

Recent studies examining the neurobiology of substance abuse have revealed a significant role of neuroimmune signaling as a mechanism through which drugs of abuse induce aberrant changes in synaptic plasticity and contribute to substance abuse-related behaviors. Immune signaling within the brain and the periphery critically regulates homeostasis of the nervous system. Perturbations in immune signaling can induce neuroinflammation or immunosuppression, which dysregulate nervous system function including neural processes associated with substance use disorders (SUDs). In this review, we discuss the literature that demonstrates a role of neuroimmune signaling in regulating learning, memory, and synaptic plasticity, emphasizing specific cytokine signaling within the central nervous system. We then highlight recent preclinical studies, within the last 5 years when possible, that have identified immune mechanisms within the brain and the periphery associated with addiction-related behaviors. Findings thus far underscore the need for future investigations into the clinical potential of immunopharmacology as a novel approach toward treating SUDs. Considering the high prevalence rate of comorbidities among those with SUDs, we also discuss neuroimmune mechanisms of common comorbidities associated with SUDs and highlight potentially novel treatment targets for these comorbid conditions. We argue that immunopharmacology represents a novel frontier in the development of new pharmacotherapies that promote long-term abstinence from drug use and minimize the detrimental impact of SUD comorbidities on patient health and treatment outcomes.

Use of Medical Cannabis to Treat Traumatic Brain Injury

There is not a single pharmacological agent with demonstrated therapeutic efficacy for traumatic brain injury (TBI). With recent legalization efforts and the growing popularity of medical cannabis, patients with TBI will inevitably consider medical cannabis as a treatment option. Pre-clinical TBI research suggests that cannabinoids have neuroprotective and psychotherapeutic properties. In contrast, recreational cannabis use has consistently shown to have detrimental effects. Our review identified a paucity of high-quality studies examining the beneficial and adverse effects of medical cannabis on TBI, with only a single phase III randomized control trial. However, observational studies demonstrate that TBI patients are using medical and recreational cannabis to treat their symptoms, highlighting inconsistencies between public policy, perception of potential efficacy, and the dearth of empirical evidence. We conclude that randomized controlled trials and prospective studies with appropriate control groups are necessary to fully understand the efficacy and potential adverse effects of medical cannabis for TBI.

Factors of Negative Affect in Elderly Patients With Substance Use Disorders During COVID-19 Pandemic

Background: The outbreak of the novel coronavirus disease 2019 (COVID-19) has become the greatest public health emergency and has attracted global attention. During the COVID-19 pandemic, the negative affect (NA) of elderly patients with substance use disorders (SUDs) has also become a more serious public concern. The current study aims to clarify the NA and its influencing factors in elderly patients with SUDs during the pandemic. Methods: Two psychiatrists conducted semi-structured interviews with 77 SUD patients aged above 50 years to collect their demographical information and certain drug use characteristics. Barratt Impulse Scale and the Positive and Negative Affect Scale were used to obtain information about patients' self-reported impulsivity and NA. Results: Univariate linear regression analysis showed that NA was positively correlated with the frequency of drug use, type of SUDs, cravings during COVID-19, and impulsivity. Multiple linear regression analysis showed that being female, higher frequency of drug use, stronger cravings, and greater impulsiveness jointly accounted for the variation of NA in elderly patients with SUDs. Conclusions: This study confirmed that, during the COVID-19 pandemic, gender, frequency of drug use, cravings, and impulsivity were associated with NA in elderly patients with SUDs. This study provided a theoretical basis for clinicians to reduce the patients' NA.

Emerging Clinical Technology: Application of Machine Learning to Chronic Pain Assessments Based on Emotional Body Maps

Depression and anxiety co-occur with chronic pain, and all three are thought to be caused by dysregulation of shared brain systems related to emotional processing associated with body sensations. Understanding the connection between emotional states, pain, and bodily sensations may help understand chronic pain conditions. We developed a mobile platform for measuring pain, emotions, and associated bodily feelings in chronic pain patients in their daily life conditions. Sixty-five chronic back pain patients reported the intensity of their pain, 11 emotional states, and the corresponding body locations. These variables were used to predict pain 2 weeks later. Applying machine learning, we developed two predictive models of future pain, emphasizing interpretability. One model excluded pain-related features as predictors of future pain, and the other included pain-related predictors. The best predictors of future pain were interactive effects of (a) body maps of fatigue with negative affect and (b) positive affect with past pain. Our findings emphasize the contribution of emotions, especially emotional experience felt in the body, to understanding chronic pain above and beyond the mere tracking of pain levels. The results may contribute to the generation of a novel artificial intelligence framework to help in the development of better diagnostic and therapeutic approaches to chronic pain.

Knowledge, Practices, and Attitudes of Washington State Health Care Professionals Regarding Medical Cannabis

Introduction: Health care providers in Washington State practice in a unique environment where both medical and recreational cannabis use are legal. Five types of health care providers can authorize medical cannabis. State-certified medical cannabis consultants may advise patients in a cannabis retail store regarding use and consumption. Washington State's health care professionals' perspectives about medical cannabis can inform policy-makers nationwide who are navigating challenges posed by legalization of medical and recreational cannabis. Materials and Methods: A cross-sectional mixed-mode survey using a 26-item questionnaire was administered to a random sample of actively licensed health care professionals legally permitted to provide medical cannabis authorizations in Washington State. We describe participant demographics and summarize responses to survey questions. We report comparisons across provider types using Fisher's exact tests with a level of significance of p<0.01. Results: Among the 1440 health care professionals invited to participate in the study, 310 respondents met eligibility criteria (response rate 24%). Only 57 respondents (18.4%) indicated having ever issued a medical cannabis authorization. Among them, 6, all naturopaths, had provided more than 500. Over half (58%) reported that they did not feel they had the knowledge and skills necessary to provide authorizations. Depending on the condition, 29-93% of respondents correctly identified conditions that qualified a patient to receive a medical cannabis authorization. Very few knew that employers are not required to provide accommodations for medical cannabis. Health care professionals (64.8%) served as the most frequent source of information regarding cannabis risks and benefits. Over half (62%) strongly or somewhat agreed that the Drug Enforcement Agency should reschedule cannabis to make it legal at the federal level. Conclusion: A wide range of knowledge was exhibited within our sample of health care professionals regarding qualifying conditions for medical cannabis. As more states adopt comprehensive medical cannabis laws, health care professionals must be prepared to provide information to patients regarding the effects, risks, and benefits of cannabis. Standardized education could ensure that health care professionals are prepared to responsibly promote the use of cannabis when indicated for medically appropriate symptoms and conditions. A rational approach to medical cannabis is needed to assure that unforeseen consequences are mitigated.

Mobile Peer-Support for Opioid Use Disorders: Refinement of an Innovative Machine Learning Tool

Background:

The majority of individuals with Opioid Use Disorder (OUD) do not receive any formal substance use treatment. Due to limited engagement and access to traditional treatment, there is increasing evidence that patients with OUDs turn to online social platforms to access peer support and obtain health-related information about addiction and recovery. Interacting with peers before and during recovery is a key component of many evidence-based addiction recovery programs, and may improve self-efficacy and treatment engagement as well as reduce relapse. Commonly-used online social platforms are limited in utility and scalability as an adjunct to addiction treatment; lack effective content moderation (e.g., misinformed advice, maliciousness or “trolling”); and lack common security and ethical safeguards inherent to clinical care.

Methods:

This present study will develop a novel, artificial-intelligence (AI) enabled, mobile treatment delivery method that fulfills the need for a robust, secure, technology-based peer support platform to support patients with OUD. Forty adults receiving outpatient buprenorphine treatment for OUD will be asked to pilot a smartphone-based mobile peer support application, the “Marigold App”, for a duration of six weeks. The program will use (1) a prospective cohort study to obtain text message content and feasibility metrics, and (2) qualitative interviews to evaluate usability and acceptability of the mobile platform.

Anticipated findings and future directions:

The Marigold mobile platform will allow patients to access a tailored chat support group 24/7 as a complement to different forms of clinical OUD treatment. Marigold can keep groups safe and constructive by augmenting chats with AI tools capable of understanding the emotional sentiment in messages, automatically “flagging” critical or clinically relevant content. This project will demonstrate the robustness of these AI tools by adapting them to catch OUD-specific “flags” in peer messages while also examining the adoptability of the platform itself within OUD patients.

Effects of the synthetic cannabinoid receptor agonist JWH-018 on abuse-related effects of opioids in rhesus monkeys

Opioid abuse remains a public health crisis despite a tremendous outpouring of resources to address the problem. One factor that might complicate this issue is polydrug abuse. While cannabis is increasingly available due to legalization by states, phytocannabinoids do not appear to alter the abuse-related effects of opioids. Synthetic cannabinoids, which are not pharmacologically identical to phytocannabinoids, are also increasingly available, and differences among cannabinoids might affect their interactions with opioids. This study assessed the impact of one synthetic cannabinoid, JWH-018, on the effects of two μ opioid receptor agonists using two procedures that address different aspects of abuse. First, four monkeys could choose to self-administer the opioid remifentanil alone (0.32 μg/kg/infusion) or a mixture containing 0.32 μg/kg/infusion remifentanil and JWH-018 (1-10 μg/kg/infusion). On separate occasions, monkeys could choose between remifentanil available alone or combined with 100 μg/kg/infusion cocaine. While monkeys chose the remifentanil/cocaine mixture over remifentanil alone, they responded equally for remifentanil alone and the remifentanil/JWH-018 mixture. The ability of JWH-018 to reinstate extinguished responding previously maintained by heroin was examined in four other monkeys. When presented with drug-associated stimuli, heroin, but not JWH-018, reinstated responding, and when combined, JWH-018 did not increase the potency of heroin. While opioids and synthetic cannabinoids, including JWH-018, are abused, these results indicate that JWH-018 does not modify the behavioral effects of opioids in monkeys in a manner that would predict greater abuse liability of cannabinoid/opioid mixtures, a result that is consistent with a growing literature on mixtures of opioids and phytocannabinoids.

Cannabis Use and Cognition in Adults Prescribed Opioids for Persistent Pain

BACKGROUND

Adults with persistent pain frequently report cannabis use to help manage their symptoms. The impact of cannabis use on cognition in the presence of concurrent symptoms of depression and anxiety is poorly understood.

AIMS

Our study explored how cannabis use affects relationships among symptoms of depression, anxiety, and cognition.

DESIGN

A cross-sectional survey study was conducted.

SETTINGS

Surveys were distributed at outpatient clinics treating adults for pain in the Pacific Northwestern United States.

PARTICIPANTS

A total of 150 adults prescribed an opioid medicine for persistent pain were recruited.

METHODS

A pencil and paper survey was used to collect several self-reported ratings of cognition, symptoms of depression and anxiety, and the average potency of cannabis consumed as measured by the percentage of delta-9-tetrahydrocannibinol (THC) and cannabidiol (CBD), as well as frequency of cannabis use.

RESULTS

Depression, anxiety and cognition significantly worsened as the reported percentage of CBD, THC and overall frequency of cannabis use in the past 30 days increased. Depression and anxiety both significantly predicted worsening cognition in the sample. The relationship between depressive symptoms and cognition was strengthened as reported percentages of CBD use increased. The relationship was the same for anxiety and cognition, although not as strong.

CONCLUSIONS

More cannabis use, particularly high CBD products, may be linked with increased symptom burdens and may strengthen relationships between negative affect and cognition. Further cannabis research within persistent pain populations is warranted to add evidence that can assist patients in managing mood and mental processes. Nurses should evaluate how negative affective health symptoms may impact cognition among adults with persistent pain using prescription opioid medications, especially in the context of concurrent cannabis use.

Cannabis Use Motivations among Adults Prescribed Opioids for Pain versus Opioid Addiction

BACKGROUND

Cannabis has been linked to reduced opioid use, although reasons for cannabis use among adults prescribed opioids are unclear.

AIMS

The purpose of this study was to determine whether motivations for cannabis use differ between adults prescribed opioids for persistent pain versus those receiving opioids as medication-assisted treatment for opioid use disorder.

DESIGN

A cross-sectional survey design was used.

PARTICIPANTS

Adults prescribed opioids for persistent pain (n = 104) or opioid use disorder (n = 139) were recruited from outpatient settings.

METHODS

Data were collected on surveys asking about cannabis use and compared the two populations. A series of regression models examined population characteristics and cannabis use motivations using validated measures of the Marijuana Motives Measure scale.

RESULTS

More than half the sample (n = 122) reported current, daily cannabis use and 63% reported pain as a motivation for use. Adults with persistent pain were more likely to be older, female, and have higher levels of education (p < .05). Adults with opioid use disorder were more likely to report "enhancement" (p < .01) and relief of drug withdrawal symptoms (p < .001) as motivations for cannabis use. The most common reasons for cannabis use in both populations were social and recreational use and pain relief.

CONCLUSIONS

Both studied populations have unmet health needs motivating them to use cannabis and commonly use cannabis for pain. Persistent pain participants were less likely to use cannabis for euphoric effects or withdrawal purposes. Nurses should assess for cannabis use, provide education on known risks and benefits, and offer options for holistic symptom management.

Effect of cannabis use in people with chronic non-cancer pain prescribed opioids: findings from a 4-year prospective cohort study

BACKGROUND

Interest in the use of cannabis and cannabinoids to treat chronic non-cancer pain is increasing, because of their potential to reduce opioid dose requirements. We aimed to investigate cannabis use in people living with chronic non-cancer pain who had been prescribed opioids, including their reasons for use and perceived effectiveness of cannabis; associations between amount of cannabis use and pain, mental health, and opioid use; the effect of cannabis use on pain severity and interference over time; and potential opioid-sparing effects of cannabis.

METHODS

The Pain and Opioids IN Treatment study is a prospective, national, observational cohort of people with chronic non-cancer pain prescribed opioids. Participants were recruited through community pharmacies across Australia, completed baseline interviews, and were followed up with phone interviews or self-complete questionnaires yearly for 4 years. Recruitment took place from August 13, 2012, to April 8, 2014. Participants were asked about lifetime and past year chronic pain conditions, duration of chronic non-cancer pain, pain self-efficacy, whether pain was neuropathic, lifetime and past 12-month cannabis use, number of days cannabis was used in the past month, and current depression and generalised anxiety disorder. We also estimated daily oral morphine equivalent doses of opioids. We used logistic regression to investigate cross-sectional associations with frequency of cannabis use, and lagged mixed-effects models to examine temporal associations between cannabis use and outcomes.

FINDINGS

1514 participants completed the baseline interview and were included in the study from Aug 20, 2012, to April 14, 2014. Cannabis use was common, and by 4-year follow-up, 295 (24%) participants had used cannabis for pain. Interest in using cannabis for pain increased from 364 (33%) participants (at baseline) to 723 (60%) participants (at 4 years). At 4-year follow-up, compared with people with no cannabis use, we found that participants who used cannabis had a greater pain severity score (risk ratio 1·14, 95% CI 1·01-1·29, for less frequent cannabis use; and 1·17, 1·03-1·32, for daily or near-daily cannabis use), greater pain interference score (1·21, 1·09-1·35; and 1·14, 1·03-1·26), lower pain self-efficacy scores (0·97, 0·96-1·00; and 0·98, 0·96-1·00), and greater generalised anxiety disorder severity scores (1·07, 1·03-1·12; and 1·10, 1·06-1·15). We found no evidence of a temporal relationship between cannabis use and pain severity or pain interference, and no evidence that cannabis use reduced prescribed opioid use or increased rates of opioid discontinuation.

INTERPRETATION

Cannabis use was common in people with chronic non-cancer pain who had been prescribed opioids, but we found no evidence that cannabis use improved patient outcomes. People who used cannabis had greater pain and lower self-efficacy in managing pain, and there was no evidence that cannabis use reduced pain severity or interference or exerted an opioid-sparing effect. As cannabis use for medicinal purposes increases globally, it is important that large well designed clinical trials, which include people with complex comorbidities, are conducted to determine the efficacy of cannabis for chronic non-cancer pain.

FUNDING

National Health and Medical Research Council and the Australian Government.

Role of endocannabinoid system in dopamine signalling within the reward circuits affected by chronic pain

The association between chronic pain, depression and anxiety has gained particular attention due to high rates of comorbidity. Recent data demonstrated that the mesolimbic reward circuitry is involved in the pathology of chronic pain. Interestingly, the mesolimbic reward circuit participates both in pain perception and in pain relief. The endocannabinoid system (ECS) has emerged as a highly relevant player involved in both pain perception and reward processing. Targeting ECS could become a novel treatment strategy for chronic pain patients. However, little is known about the underlying mechanisms of action of cannabinoids at the intersection of neurochemical changes in reward circuits and chronic pain. Because understanding the benefits and risks of cannabinoids is paramount, the aim of this review is to evaluate the state-of-art knowledge about the involvement of the ECS in dopamine signalling within the reward circuits affected by chronic pain.

Benefits and adverse effects of cannabis use among adults with persistent pain

BACKGROUND

Increasingly, states are legalizing cannabis for recreational use. Improved accessibility may allow adults with pain to use cannabis more liberally. Greater understanding is needed about how adults with pain perceive the effects of cannabis, particularly those who also use opioid analgesics.

PURPOSE

To examine the perceived effects of cannabis among adults who have been prescribed opioids for persistent pain.

METHODS

A survey-based study was conducted on 150 adults with persistent pain. Data from two open-ended questions were analyzed using a qualitative descriptive approach and content analysis.

FINDINGS

Data analysis led to identification of two main categories and five subcategories: (a) cannabis benefits with two subcategories of "physiological" and "mental health"; (b) adverse effects with three subcategories of "physiological," "mental health," and "social and economic concerns."

DISCUSSION

Both positive and negative effects of cannabis were described. Nursing practice, including open communication with patients, can be guided by patient perspectives surrounding benefits and adverse effects of cannabis use.

What does the ecological and epidemiological evidence indicate about the potential for cannabinoids to reduce opioid use and harms? A comprehensive review

Pre-clinical research supports that cannabinoids reduce opioid dose requirements, but few studies have tested this in humans. This review evaluates ecological and epidemiological studies that have been cited as evidence that medical cannabis use may reduce opioid use and opioid-related harms. Medline and Embase were searched for relevant articles. Data were extracted on study setting, analyses approach, covariates, and outcomes. Eleven ecological and 14 epidemiological studies were found. In ecological studies, states that allow medical cannabis laws have reported a slower rate of increase in opioid overdose deaths compared with states without such laws. These differences have increased over time and persisted after controlling for state sociodemographic characteristics and use of prescription monitoring programmes. Few studies have controlled for other potential confounders such as opioid dependence treatment and imprisonment rates. Some epidemiological studies provide evidence that cannabis availability may reduce opioid use, but are limited by selection bias, cross-sectional designs, and self-reported assessments of the opioid-sparing effects of cannabis. Some epidemiological and ecological studies suggest that cannabis may reduce opioid use and harms, although important methodological weaknesses were identified. Well-designed clinical studies may provide more conclusive evidence on whether cannabinoids can reduce opioid use and related harm.