The association between cannabis and codeine use: a nationally representative cross-sectional study in Canada

Background

Due to the growing use of cannabis for the purposes of pain relief, evidence is needed on the impact of cannabis use on concurrent analgesic use. Therefore, our objective was to evaluate the association between the use of cannabis and codeine.

Methods

We conducted a cross-sectional study using data from the nationally representative Canadian Tobacco, Alcohol and Drugs Survey (2017). The primary explanatory variable was self-reported use of cannabis within the past year. The outcome was the use of codeine-containing product(s) within the past year. We used multivariable binomial logistic regression models.

Results

Our study sample comprised 15,459 respondents including 3338 individuals who reported cannabis use within the past year of whom 955 (36.2%) used it for medical purposes. Among individuals who reported cannabis use, the majority were male (N = 1833, 62.2%). Self-reported use of cannabis was associated with codeine use (adjusted odds ratio [aOR] 1.89, 95% CI 1.36 to 2.62). Additionally, when limited to cannabis users only, we found people who used cannabis for medical purposes to be three times more likely to also report codeine use (adjusted odds ratio [aOR] 2.96, 95% CI 1.72 to 5.09).

Discussion

The use of cannabis was associated with increased odds of codeine use, especially among individuals who used it for medical purposes. Our findings suggest a potential role for healthcare providers to be aware of or monitor patients’ use of cannabis, as the long-term adverse events associated with concurrent cannabis and opioid use remain unknown.

The respiratory depressant effects of mitragynine are limited by its conversion to 7-OH mitragynine

Background and Purpose

Mitragynine, the major alkaloid in Mitragyna speciosa (kratom), is a partial agonist at the μ opioid receptor. CYP3A‐dependent oxidation of mitragynine yields the metabolite 7‐OH mitragynine, a more efficacious μ receptor agonist. While both mitragynine and 7‐OH mitragynine can induce anti‐nociception in mice, recent evidence suggests that 7‐OH mitragynine formed as a metabolite is sufficient to explain the anti‐nociceptive effects of mitragynine. However, the ability of 7‐OH mitragynine to induce μ receptor‐dependent respiratory depression has not yet been studied.

Experimental Approach

Respiration was measured in awake, freely moving, male CD‐1 mice, using whole body plethysmography. Anti‐nociception was measured using the hot plate assay. Morphine, mitragynine, 7‐OH mitragynine and the CYP3A inhibitor ketoconazole were administered orally.

Key Results

The respiratory depressant effects of mitragynine showed a ceiling effect, whereby doses higher than 10 mg·kg⁻¹ produced the same level of effect. In contrast, 7‐OH mitragynine induced a dose‐dependent effect on mouse respiration. At equi‐depressant doses, both mitragynine and 7‐OH mitragynine induced prolonged anti‐nociception. Inhibition of CYP3A reduced mitragynine‐induced respiratory depression and anti‐nociception without affecting the effects of 7‐OH mitragynine.

Conclusions and Implications

Both the anti‐nociceptive effects and the respiratory depressant effects of mitragynine are partly due to its metabolic conversion to 7‐OH mitragynine. The limiting rate of conversion of mitragynine into its active metabolite results in a built‐in ceiling effect of the mitragynine‐induced respiratory depression. These data suggest that such ‘metabolic saturation’ at high doses may underlie the improved safety profile of mitragynine as an opioid analgesic.

The association between the availability of over the counter codeine and the prevalence of non-medical use

PURPOSE

To investigate the prevalence of non-medical use (NMU) of codeine in Germany, Italy, Spain and the UK and whether availability of OTC codeine has any association with NMU of the drug.

METHODS

Data collected in the online Survey of Non-Medical Use of Prescription Drugs, in surveys launched in the second half of 2018 from (Germany (n = 14,969), Italy, (n = 9974), Spain (n = 9912) and the UK (n = 9819) were analysed. For each survey, the estimated prevalence and 95% confidence interval (CI) of respondents reporting NMU of prescription and/or OTC codeine within the last 12 months were calculated and compared.

RESULTS

The prevalence of last 12-month NMU in Spain was 12.6% (95% CI 11.7-13.6) for prescription codeine, 6.3% (5.6-7.0) for OTC codeine and 16.1% (15.1-17.3) for any codeine (prescription and/or OTC). The prevalence of last 12-month NMU in the UK was 5.4% (4.9-5.8) for prescription codeine, 4.5% (4.1-5.0) for OTC codeine and 8.3% (7.8-8.9) for any codeine (prescription and/or OTC). The prevalence of last 12-month NMU for prescription codeine was 2.1% (1.9-2.4) in Germany and 1.9% (1.7-2.2) in Italy.

CONCLUSION

The prevalence of last 12-month NMU of any codeine product is approximately eight times greater in Spain and four times greater in the UK compared to Germany and Italy where the drug is only available by prescription. While other factors may contribute, these findings suggest that availability of codeine OTC is associated with greater NMU.

A prospective cohort study evaluating the impact of upscheduling codeine in Australia among frequent users of codeine

AIM

To evaluate and document the impacts of re-scheduling codeine to a prescription-only medication in Australia in February 2018.

DESIGN

Prospective cohort study. Participants completed an on-line survey with a range of outcome measures at four time-points, once before codeine was re-scheduled (November 2017) and three times after the event: 1 month after (February 2018), 4 months after (June 2018) and 12 months after (February 2019).

SETTING

Australia.

PARTICIPANTS

Participants were 260 Australians aged 18 years and above who reported regular over-the-counter (OTC) codeine use and, at the time of the study, were not engaged in treatment for codeine dependence.

MEASUREMENTS

Survey measures included estimates of daily average codeine use (mg) and overall daily average opioid use [calculated using an oral morphine equivalent daily dose (OMEDD, mg)], opioid use disorder with regard to codeine use (using a modified Alcohol Use Disorder and Associated Disabilities Interview Schedule-IV), pain and pain self-efficacy, anxiety and depression and health service use.

FINDINGS

A reduction in total daily codeine use (mg) from 64.3 mg [95% confidence interval (CI) = 46.7-81.9] in November 2017 (baseline) to 27.6 mg (95% CI = 19.2-36.0) in February 2019 (final time-point) was observed. A decline in the proportion of participants who met criteria for an opioid use disorder was also evident, with 51.2% (n = 133) at baseline relative to 33.3% (n = 58) at the 12-month follow-up. This study had an overall participant retention rate of 67% at the final time-point.

CONCLUSION

Re-scheduling codeine in Australia has been accompanied by significant reductions in codeine use and prevalence rates of opioid use disorder in a cohort of individuals who regularly use the medication, without apparent adverse impacts on pain or measures of anxiety and depression.

Functional connectome-based biomarkers predict chronic codeine-containing cough syrup dependent

PURPOSE

Codeine-containing cough syrup (CCS) is considered among the most popular drugs of abuse in adolescents worldwide. Accurate prediction and identification of CCS dependent (CCSD) users are crucial. This study aimed to identify a brain-connectome-based predictor of CCSD using a machine learning model based on a ten-fold cross-validation logistic regression (LR) classifier.

METHODS

40 CCSD users and 40 healthy control (HC) subjects underwent functional magnetic resonance imaging to construct weight functional networks. Partial correlation analysis was used to analyze relations between abnormal network metrics and clinical characteristics (BIS total scores, CCS abuse duration, and mean CCS dose) in CCSD. A ten-fold cross-validation LR classifier was used to classify CCSD users and HC subjects.

RESULTS

The CCSD group showed significantly abnormal nodes and connections in the right posterior cingulate, right middle insula, bilateral prefrontal cortex, parietal lobe, temporal lobe, occipital lobe, and cerebellum. Furthermore, higher characteristic path length and lower clustering coefficient (Cp), global efficiency, and local efficiency (Eloc) were observed in the global topologies in CCSD. The abnormal global properties (Cp and Eloc) and node properties of the prefrontal cortex were significantly correlated with clinical characteristics (BIS-11 scores, CCS abuse duration) in CCSD. The LR classifier models demonstrated accuracy, sensitivity, specificity, precision, and AUC of 82.5%, 82.5%, 82.5%, 76.8%, and 82.5%.

CONCLUSIONS

These data demonstrate that abnormal functional connectome may be closely linked to clinical characteristics in CCSD. Functional connectome-based biomarkers can be a powerful tool for personalized diagnosis of CCSD in the future.

Pharmacological Aspects of Over-the-Counter Opioid Drugs Misuse

Several over-the-counter (OTC) drugs are known to be misused. Among them are opioids such as codeine, dihydrocodeine, and loperamide. This work elucidates their pharmacology, interactions, safety profiles, and how pharmacology is being manipulated to misuse these common medications, with the aim to expand on the subject outlined by the authors focusing on abuse prevention and prevalence rates. The reviewed literature was identified in several online databases through searches conducted with phrases created by combining the international non-proprietary names of the drugs with terms related to drug misuse. The results show that OTC opioids are misused as an alternative for illicit narcotics, or prescription-only opioids. The potency of codeine and loperamide is strongly dependent on the individual enzymatic activity of CYP2D6 and CYP3A4, as well as P-glycoprotein function. Codeine can also be utilized as a substrate for clandestine syntheses of more potent drugs of abuse, namely desomorphine (“Krokodil”), and morphine. The dangerous methods used to prepare these substances can result in poisoning from toxic chemicals and impurities originating from the synthesis procedure. OTC opioids are generally safe when consumed in accordance with medical guidelines. However, the intake of supratherapeutic amounts of these substances may reveal surprising traits of common medications.

Exploring Australian pharmacists' perceptions and attitudes toward codeine up-scheduling from over-the-counter to prescription only

Objective:

Explore the perceptions, attitudes and experiences of pharmacists relating to the up-scheduling of low dose codeine containing analgesics and the impact on pharmacy practice.

Methods:

A mixed design method was used consisting of an anonymous online questionnaire survey to quantitatively capture broad pre-scheduling change perceptions paired with a series of in-depth post-scheduling semi-structured interviews to provide a qualitative picture of the impact of codeine up-scheduling on pharmacy practice in Australia.

Results:

A total of 191 pharmacists completed the quantitative survey and 10 participated in the in-depth interview. The majority of respondents supported the decision to up-schedule over-the-counter combination products containing codeine to some degree. Three main themes emerged from the data: pharmacists’ perceptions of the codeine up-scheduling decision, preparing for the up-schedule and impact of the up-schedule on pharmacy practice. Pharmacists were concerned about the impact of up-scheduling on the pharmacy business, patient access to pain relief and the diminishment of their professional role.

Conclusions:

There were diverse perceptions, preparedness and impact on practice regarding the up-scheduling of low dose codeine products. Further research should be conducted to gauge if and how these perceptions have changed over time and to identify whether pain is being managed more effectively post codeine up-scheduling.

Resolving Issues About Efficacy and Safety of Low-Dose Codeine in Combination Analgesic Drugs: A Systematic Review

INTRODUCTION

The objective of this systematic review is to reflect on assumptions in relation to codeine use in combination with other analgesics.

METHODS

MEDLINE was searched according to the predetermined keywords and criteria. Only English language studies were taken into consideration and the outcome data of the final studies were extracted by two reviewers independently from each other and were checked by the third reviewer. Additionally, the available codeine-related Individual Case Safety Reports (ICSRs) retrieved from EudraVigilance were reviewed.

RESULTS

Sixteen placebo-controlled studies that involved 3378 subjects suffering from acute pain were analyzed for the efficacy of low-dose codeine (≤ 30 mg) combination products. Twelve of them found low-dose codeine combinations more efficient in relieving pain than the assigned comparator. According to 20 randomized clinical trials which included at least one dose of codeine (from 30 to 240 mg daily), the vast majority of reported side-effects were mild or moderate in severity. A total of 20 ICSRs for dependence were identified in the EudraVigilance database with codeine as a suspect drug for the 10-year time period for the European region.

CONCLUSIONS

Low-dose codeine combinations are effective after a single application in treating acute pain. Codeine in doses ≤ 30 mg and higher was considered safe since only mild to moderate side-effects were observed. There is no indication in the available sources which clearly links low doses of codeine to substance use disorder in non-dependent subjects.

Experiences of over-the-counter codeine misusers and accounts of recovery: A qualitative study in Tasmania, Australia

INTRODUCTION AND AIMS

There is international concern about misuse of over-the-counter (OTC) codeine, yet few studies have reported the perspectives of misusers themselves. This study explored the experience of OTC codeine misuse and recovery in Tasmania, Australia.

DESIGN AND METHODS

Semi-structured telephone interviews were conducted with 15 self-identified long-term users of OTC codeine. The interview guide prompted responses about reasons for codeine use, positive and negative impacts, recovery, identity and codeine accessibility. Transcripts were analysed abductively using qualitative content analysis. Categories that emerged from misuser accounts were aligned to three broad temporal phases: (i) transition to misuse; (ii) growing awareness; and (iii) towards recovery.

RESULTS

Salient features of the misuse experience included: initial use for the self-treatment of physical pain; ongoing use to self-medicate physical pain, stress or mental health conditions; a perception of safety of OTC codeine; an insidious transition from use to misuse; growing awareness of a problem over time; support provided by family, friends and the internet; recovery through self-change; and recognition that recovery is an ongoing process.

DISCUSSION AND CONCLUSIONS

Knowledge and understanding of the experience of OTC codeine misuse and recovery is critical to inform and tailor approaches to prevention and intervention. The findings suggest that strategies to improve the management of pain, stress and mental health, raise self-awareness of problematic use and potential for self-change, and increase social and web-based supports, should be considered when designing health policy initiatives that aim to reduce misuse.

Comparisons of In Vivo and In Vitro Opioid Effects of Newly Synthesized 14-Methoxycodeine-6-O-sulfate and Codeine-6-O-sulfate

The present work represents the in vitro (potency, affinity, efficacy) and in vivo (antinociception, constipation) opioid pharmacology of the novel compound 14-methoxycodeine-6-O-sulfate (14-OMeC6SU), compared to the reference compounds codeine-6-O-sulfate (C6SU), codeine and morphine. Based on in vitro tests (mouse and rat vas deferens, receptor binding and [³⁵S]GTPγS activation assays), 14-OMeC6SU has µ-opioid receptor-mediated activity, displaying higher affinity, potency and efficacy than the parent compounds. In rats, 14-OMeC6SU showed stronger antinociceptive effect in the tail-flick assay than codeine and was equipotent to morphine, whereas C6SU was less efficacious after subcutaneous (s.c.) administration. Following intracerebroventricular injection, 14-OMeC6SU was more potent than morphine. In the Complete Freund’s Adjuvant-induced inflammatory hyperalgesia, 14-OMeC6SU and C6SU in s.c. doses up to 6.1 and 13.2 µmol/kg, respectively, showed peripheral antihyperalgesic effect, because co-administered naloxone methiodide, a peripherally acting opioid receptor antagonist antagonized the measured antihyperalgesia. In addition, s.c. C6SU showed less pronounced inhibitory effect on the gastrointestinal transit than 14-OMeC6SU, codeine and morphine. This study provides first evidence that 14-OMeC6SU is more effective than codeine or C6SU in vitro and in vivo. Furthermore, despite C6SU peripheral antihyperalgesic effects with less gastrointestinal side effects the superiority of 14-OMeC6SU was obvious throughout the present study.

Codeine use and harms in Australia: evaluating the effects of re-scheduling

BACKGROUND AND AIMS

Globally, codeine is the most-used opioid. In December 2016, Australia announced that low-strength codeine (≤ 15 mg) would be re-scheduled and no longer available for purchase over-the-counter; this was implemented in February 2018. We aimed to evaluate the effect of this scheduling change on codeine misuse and use and misuse of other opioids.

DESIGN AND SETTING

Interrupted time-series analysis of monthly opioid exposure calls to New South Wales Poisons Information Centre (NSWPIC, captures 50% of Australia's poisoning calls), January 2015- January 2019 and monthly national codeine sales, March 2015-March 2019. We incorporated a washout period (January 2017 - January 2018) between the announcement and implementation, when prescriber/consumer behaviour may have been influenced.

PARTICIPANTS

Intentional opioid overdoses resulting in a call to NSWPIC.

MEASUREMENTS

We used linear segmented regression to identify abrupt changes in level and slope of fitted lines. Codeine poisonings and sales were stratified into high strength (> 15 mg per dose unit) and low strength (≤ 15 mg). Only low-strength formulations were re-scheduled.

FINDINGS

We observed an abrupt -50.8 percentage [95% confidence interval (CI) = -79.0 to -22.6%] level change in monthly codeine-related poisonings and no change in slope in the 12 months after February 2018. There was no increase in calls to the NSWPIC for high-strength products, level change: -37.2% (95% CI = -82.3 to 8%) or non-codeine opioids, level change: -4.4% (95% CI = -33.3 to 24.4%). Overall, the re-scheduling resulted in a level change in opioid calls of -35.8% calls/month (95% CI = -51.2 to -20.4%). Low-strength codeine sales decreased by 87.3% (95% CI = -88.5 to -85.9%), with no increase in high-strength codeine sales in the 14 months following re-scheduling, -4.0% (95% CI = -19.6 to 14.6%).

CONCLUSIONS

Codeine re-scheduling in Australia appears to have reduced codeine misuse and sales.

Genetic and environmental risk factors in the non-medical use of over-the-counter or prescribed analgesics, and their relationship to major classes of licit and illicit substance use and misuse in a population-based sample of young adult twins

BACKGROUND AND AIMS

The non-medical use of over-the-counter or prescribed analgesics (NMUA) is a significant public health problem. Little is known about the genetic and environmental etiology of NMUA and how these risks relate to other classes of substance use and misuse. Our aims were to estimate the heritability NMUA and sources of genetic and environmental covariance with cannabis and nicotine use, cannabis and alcohol use disorders and nicotine dependence in Australian twins.

DESIGN

Biometrical genetic analyses or twin methods using structural equation univariate and multivariate modeling.

SETTING

Australia.

PARTICIPANTS

A total of 2007 young adult twins [66% female; μage  = 25.9, standard deviation (SD) = 3.6, range = 18-38] from the Brisbane Longitudinal Twin Study retrospectively assessed between 2009 and 2016.

MEASUREMENTS

Self-reported NMUA (non-opioid or opioid-based), life-time nicotine, cannabis and opioid use, DSM-V cannabis and alcohol use disorders and the Fagerström Test for Nicotine Dependence.

FINDINGS

Life-time NMUA was reported by 19.4% of the sample. Univariate heritability explained 46% [95% confidence interval (CI) = 0.29-0.57] of the risks in NMUA. Multivariate analyses revealed that NMUA is moderately associated genetically with cannabis (rg  = 0.41) and nicotine (rg  = 0.45) use and nicotine dependence (rg  = 0.34). In contrast, the genetic correlations with cannabis (rg  = 0.15) and alcohol (rg  = 0.07) use disorders are weak.

CONCLUSIONS

In young male and female adults in Australia, the non-medical use of over-the-counter or prescribed analgesics appears to have moderate heritability. NMUA is moderately associated with cannabis and nicotine use and nicotine dependence. Its genetic etiology is largely distinct from that of cannabis and alcohol use disorders.

'For pain, no shame' and 'My secret solace': Accounts of over-the-counter codeine dependence using Q methodology

BACKGROUND

Dependence on over-the-counter (OTC) codeine is recognised internationally as a rising public health issue. The effectiveness of health intervention strategies may be influenced by the beliefs held by those who are dependent. Applying Q methodology, this study aimed to identify shared accounts of OTC codeine dependence.

METHODS

Twenty-six participants from Tasmania, Australia, met eligibility criteria for the study as long-term OTC codeine users with a Severity of Dependence Score of five or higher. Forty-six opinion statements about OTC codeine dependence were sourced from the literature and online discussion forums. These were rank-ordered by participants from least to most agree and explanatory comments for the most strongly positioned statements were provided. By-person factor analysis was used to group participants who had sorted the statements similarly.

RESULTS

Two distinct accounts of OTC codeine dependence were identified. Participants representing Factor One, 'For pain, no shame', were not ashamed of their OTC codeine use, believed access should not be restricted and regarded it as necessary for the relief of physical pain. In contrast, Factor Two, 'My secret solace', was characterized by feelings of guilt and shame. Participants in this group intentionally used codeine for its effects on mood; to help them relax and to relieve stress, rather than solely for pain relief. They did not consider regular use of codeine to be socially acceptable and hid their use from others.

CONCLUSION

The way in which OTC codeine use is viewed by those who are dependent is not uniform. Two distinct accounts were identified in this sample. Participants from each group varied in their beliefs about access, causality, reasons for use and feelings of legitimacy and shame. An understanding of these differences can be used to better target interventions and guide policy for the prevention and management of OTC codeine dependence.

Implementation of a clinical tool to assess and address pain management requests in the pharmacy

BACKGROUND

Morbidity and mortality associated with inappropriate use of over-the-counter combination analgesics containing codeine (OTC CACC) in Australia resulted in it being upscheduled in 2010 from "Pharmacy Only" (Schedule 2) to "Pharmacist Only" (Schedule 3), and further to "Prescription Only" (Schedule 4) in February 2018. There have been a number of concerns and challenges identified by community pharmacists in the provision of OTC CACC. In practice, sub-optimal management of patients accessing these medications has been demonstrated. To assist the management of patients using OTC CACC, the development of a management and referral pathway would be advantageous.

OBJECTIVES

To evaluate the use of an online interactive clinical tool and/or clinical information via an online PDF-based platform for managing OTC CACC requests and codeine dependence.

METHOD

Two interactive online clinical tools to aid management of patients who presented requesting OTC CACC were developed. Evaluation of these tools was undertaken using responses to multiple choice questions and feedback from pharmacist surveys.

RESULTS

Of the 904 pharmacists who responded to the evaluation survey, 66.7% had not used the tool in the preceding 12 months. The most common reason why pharmacists did not access either the online interactive, or online PDF clinical tools was that they had no knowledge of them. Older age of the pharmacist (50 years or older compared to younger than 30) predicted tool access (adjusted proportional odds ratio = 3.16, 95% CI 1.72-5.80, p < 0.001). The access of the tool was positively associated with it being perceived as useful (adjusted odds ratio = 14.7, 95% CI 6.7-32.5, p < 0.001).

CONCLUSION

A number of pharmacists participating in the evaluation had never accessed either the online interactive or online PDF clinical tool, as they were not aware of them. Further research needs to be conducted into how to best promote and increase awareness of online clinical tools to pharmacists, especially younger pharmacists, and determine the best way to integrate online clinical tools effectively and efficiently into current practice.