Adverse events after naloxone treatment of episodes of suspected acute opioid overdose

Naloxone increases conditioned fear responses during social buffering in male rats

Social buffering is the phenomenon in which the presence of an affiliative conspecific mitigates stress responses. We previously demonstrated that social buffering completely ameliorates conditioned fear responses in rats. However, the neuromodulators involved in social buffering are poorly understood. Given that opioids, dopamine, oxytocin and vasopressin play an important role in affiliative behaviour, here, we assessed the effects of the most well-known antagonists, naloxone (opioid receptor antagonist), haloperidol (dopamine D2 receptor antagonist), atosiban (oxytocin receptor antagonist) and SR49059 (vasopressin V1a receptor antagonist), on social buffering. In Experiment 1, fear-conditioned male subjects were intraperitoneally administered one of the four antagonists 25 min prior to exposure to a conditioned stimulus with an unfamiliar non-conditioned rat. Naloxone, but not the other three antagonists, increased freezing and decreased walking and investigation as compared with saline administration. In Experiment 2, identical naloxone administration did not affect locomotor activity, anxiety-like behaviour or freezing in an open-field test. In Experiment 3, after confirming that the same naloxone administration again increased conditioned fear responses, as done in Experiment 1, we measured Fos expression in 16 brain regions. Compared with saline, naloxone increased Fos expression in the paraventricular nucleus of the hypothalamus and decreased Fos expression in the nucleus accumbens shell, anterior cingulate cortex and insular cortex and tended to decrease Fos expression in the nucleus accumbens core. Based on these results, we suggest that naloxone blocks social buffering of conditioned fear responses in male rats.

Prediction of naloxone dose in opioids toxicity based on machine learning techniques (artificial intelligence)

BACKGROUND

Treatment management for opioid poisoning is critical and, at the same time, requires specialized knowledge and skills. This study was designed to develop and evaluate machine learning algorithms for predicting the maintenance dose and duration of hospital stay in opioid poisoning, in order to facilitate appropriate clinical decision-making.

METHOD AND RESULTS

This study used artificial intelligence technology to predict the maintenance dose and duration of administration by selecting clinical and paraclinical features that were selected by Pearson correlation (filter method) (Stage 1) and then the (wrapper method) Recursive Feature Elimination Cross-Validated (RFECV) (Stage2). The duration of administration was divided into two categories: A (which includes a duration of less than or equal to 24 h of infusion) and B (more than 24 h of naloxone infusion). XGBoost algorithm model with an accuracy rate of 91.04%, a prediction rate of 91.34%, and a sensitivity rate of 91.04% and area under the Curve (AUC) 0.97 was best model for classification patients. Also, the best maintenance dose of naloxone was obtained with XGBoost algorithm with R2 = 0.678. Based on the selected algorithm, the most important features for classifying patients for the duration of treatment were bicarbonate, respiration rate, physical sign, The partial pressure of carbon dioxide (PCO2), diastolic blood pressure, pulse rate, naloxone bolus dose, Blood Creatinine(Cr), Body temperature (T). The most important characteristics for determining the maintenance dose of naloxone were physical signs, bolus dose of 4.5 mg/kg, Glasgow Coma Scale (GCS), Creatine Phosphokinase (CPK) and intensive care unit (ICU) add.

CONCLUSION

A predictive model can significantly enhance the decision-making and clinical care provided by emergency physicians in hospitals and medical settings. XGBoost was found to be the superior model.

High-dose naloxone formulations are not as essential as we thought

Naloxone is an effective FDA-approved opioid antagonist for reversing opioid overdoses. Naloxone is available to the public and can be administered through intramuscular (IM), intravenous (IV), and intranasal spray (IN) routes. Our literature review investigates the adequacy of two doses of standard IM or IN naloxone in reversing fentanyl overdoses compared to newer high-dose naloxone formulations. Moreover, our initiative incorporates the experiences of people who use drugs, enabling a more practical and contextually-grounded analysis. The evidence indicates that the vast majority of fentanyl overdoses can be successfully reversed using two standard IM or IN dosages. Exceptions include cases of carfentanil overdose, which necessitates ≥ 3 doses for reversal. Multiple studies documented the risk of precipitated withdrawal using ≥ 2 doses of naloxone, notably including the possibility of recurring overdose symptoms after resuscitation, contingent upon the half-life of the specific opioid involved. We recommend distributing multiple doses of standard IM or IN naloxone to bystanders and educating individuals on the adequacy of two doses in reversing fentanyl overdoses. Individuals should continue administration until the recipient is revived, ensuring appropriate intervals between each dose along with rescue breaths, and calling emergency medical services if the individual is unresponsive after two doses. We do not recommend high-dose naloxone formulations as a substitute for four doses of IM or IN naloxone due to the higher cost, risk of precipitated withdrawal, and limited evidence compared to standard doses. Future research must take into consideration lived and living experience, scientific evidence, conflicts of interest, and the bodily autonomy of people who use drugs.

Is a randomised controlled trial of take home naloxone distributed in emergency settings likely to be feasible and acceptable? Findings from a UK qualitative study exploring perspectives of people who use opioids and emergency services staff

OBJECTIVE

Distribution of take-home naloxone (THN) by emergency services may increase access to THN and reduce deaths and morbidity from opioid overdose. As part of a feasibility study for a randomised controlled trial (RCT) of distribution of THN kits and education within ambulance services and Emergency Departments (EDs), we used qualitative methods to explore key stakeholders' perceptions of feasibility and acceptability of delivering the trial.

METHODS

We undertook semi-structured interviews and focus groups with 26 people who use opioids and with 20 paramedics and ED staff from two intervention sites between 2019 and 2021. Interviews and focus groups were recorded, transcribed verbatim and analysed using Framework Analysis.

RESULTS

People using opioids reported high awareness of overdose management, including personal experience of THN use. Staff perceived emergency service provision of THN as a low-cost, low-risk intervention with potential to reduce mortality, morbidity and health service use. Staff understood the trial aims and considered it compatible with their work. All participants supported widening access to THN but reported limited trial recruitment opportunities partly due to difficulties in consenting patients during overdose. Procedural problems, restrictive recruitment protocols, limited staff buy-in and patients already owning THN limited trial recruitment. Determining trial effectiveness was challenging due to high levels of alternative community provision of THN.

CONCLUSIONS

Distribution of THN in emergency settings was considered feasible and acceptable for stakeholders but an RCT to establish the effectiveness of THN delivery is unlikely to generate further useful evidence due to difficulties in recruiting patients and assessing benefits.

Clinical Pharmacokinetics and Pharmacodynamics of Naloxone

Naloxone is a World Health Organization (WHO)-listed essential medicine and is the first choice for treating the respiratory depression of opioids, also by lay-people witnessing an opioid overdose. Naloxone acts by competitive displacement of opioid agonists at the μ-opioid receptor (MOR). Its effect depends on pharmacological characteristics of the opioid agonist, such as dissociation rate from the MOR receptor and constitution of the victim. Aim of treatment is a balancing act between restoration of respiration (not consciousness) and avoidance of withdrawal, achieved by titration to response after initial doses of 0.4-2 mg. Naloxone is rapidly eliminated [half-life (t1/2) 60-120 min] due to high clearance. Metabolites are inactive. Major routes for administration are intravenous, intramuscular, and intranasal, the latter primarily for take-home naloxone. Nasal bioavailability is about 50%. Nasal uptake [mean time to maximum concentration (Tmax) 15-30 min] is likely slower than intramuscular, as reversal of respiration lag behind intramuscular naloxone in overdose victims. The intraindividual, interindividual and between-study variability in pharmacokinetics in volunteers are large. Variability in the target population is unknown. The duration of action of 1 mg intravenous (IV) is 2 h, possibly longer by intramuscular and intranasal administration. Initial parenteral doses of 0.4-0.8 mg are usually sufficient to restore breathing after heroin overdose. Fentanyl overdoses likely require higher doses of naloxone. Controlled clinical trials are feasible in opioid overdose but are absent in cohorts with synthetic opioids. Modeling studies provide valuable insight in pharmacotherapy but cannot replace clinical trials. Laypeople should always have access to at least two dose kits for their interim intervention.

Adverse Effects After Prehospital Administration of Naloxone by Bystanders: A Preliminary Study

OBJECTIVE

Opioid use disorder is a cause of significant morbidity and mortality. In order to reverse opioid overdose as quickly as possible, many institutions and municipalities have encouraged people with no professional medical training to carry and administer naloxone. This study sought to provide preliminary data for research into the rates of adverse effects of naloxone when administered by bystanders compared to Emergency Medical Services (EMS) personnel, since this question has not been studied previously.

METHODS

This was a retrospective cohort study performed at an urban, tertiary, academic medical center that operates its own EMS service. A consecutive sample of patients presenting to EMS with opioid overdose requiring naloxone was separated into two groups based on whether naloxone was administered by bystanders or by EMS personnel. Each group was analyzed to determine the incidence of four pre-specified adverse events.

RESULTS

There was no significant difference in the rate of adverse events between the bystander (19%) and EMS (16%) groups (OR = 1.23; 95% CI, 0.63 - 2.32; P = .499) in this small sample. Based on these initial results, a study would need a sample size of 6,188 in order to reach this conclusion with 80% power. Similarly, there were no significant differences in the rates of any of the individual adverse events. Secondary analysis of patients' demographics showed differences between the two groups which generate hypotheses for further investigation of disparities in naloxone administration.

CONCLUSIONS

This preliminary study provides foundational data for further investigation of naloxone administration by bystanders. Adverse events after the prehospital administration of naloxone are rare, and future studies will require large sample sizes. These preliminary data did not demonstrate a statistically significant difference in adverse event rates when comparing naloxone administration by bystanders and EMS clinicians. This study provides data that will be useful for conducting further research on multiple facets of this topic.

Organize and mobilize for implementation effectiveness to improve overdose education and naloxone distribution from syringe services programs: a randomized controlled trial

BACKGROUND

The United States (US) continues to face decades-long increases in opioid overdose fatalities. As an opioid overdose reversal medication, naloxone can dramatically reduce opioid overdose mortality rates when distributed to people likely to experience or witness an opioid overdose and packaged with education on its use, known as overdose education and naloxone distribution (OEND). Syringe services programs (SSPs) are ideal venues for OEND with staff who are culturally competent in providing services for people who are at risk of experiencing or observing an opioid overdose. We carried out a randomized controlled trial of SSPs to understand the effectiveness of the organize and mobilize for implementation effectiveness (OMIE) approach at improving OEND implementation effectiveness within SSPs.

METHODS

Using simple randomization, 105 SSPs were enrolled into the trial and assigned to one of two study arms - (1) dissemination of OEND best practice recommendations (Control SSPs) or the OMIE approach along with dissemination of the OEND best practice recommendations (i.e., OMIE SSPs). OMIE SSPs could participate in 60-min OMIE sessions once a month for up to 12 months. At 12-month post-baseline, 102 of 105 SSPs (97%) responded to the follow-up survey.

RESULTS

The median number of sessions completed by OMIE SSPs was 10. Comparing OMIE SSPs to control SSPs, we observed significant increases in the number of participants receiving naloxone (incidence rate ratio: 2.15; 95% CI: 1.42, 3.25; p < 0.01) and the rate of naloxone doses distributed per SSP participant (adjusted incidence rate ratio: 1.97; 95% CI: 1.18, 3.30; p = 0.01). We observed no statistically significant difference in the number of adopted best practices between conditions (difference in means 0.2, 95% CI: - 0.7, 1.0; p = 0.68). We also observed a threshold effect where SSPs receiving a higher OMIE dose had greater effect sizes with regard to the number of people given naloxone and the number of naloxone doses distributed.

CONCLUSIONS

In conclusion, the multifaceted OMIE approach was effective at increasing naloxone distribution from SSPs, despite substantial external shocks during the trial. These findings have major implications for addressing the overdose crisis, which has continued unabated for decades.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03924505 . Registered 19 April 2019.

2023 American Heart Association Focused Update on the Management of Patients With Cardiac Arrest or Life-Threatening Toxicity Due to Poisoning: An Update to the American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care

In this focused update, the American Heart Association provides updated guidance for resuscitation of patients with cardiac arrest, respiratory arrest, and refractory shock due to poisoning. Based on structured evidence reviews, guidelines are provided for the treatment of critical poisoning from benzodiazepines, β-adrenergic receptor antagonists (also known as β-blockers), L-type calcium channel antagonists (commonly called calcium channel blockers), cocaine, cyanide, digoxin and related cardiac glycosides, local anesthetics, methemoglobinemia, opioids, organophosphates and carbamates, sodium channel antagonists (also called sodium channel blockers), and sympathomimetics. Recommendations are also provided for the use of venoarterial extracorporeal membrane oxygenation. These guidelines discuss the role of atropine, benzodiazepines, calcium, digoxin-specific immune antibody fragments, electrical pacing, flumazenil, glucagon, hemodialysis, hydroxocobalamin, hyperbaric oxygen, insulin, intravenous lipid emulsion, lidocaine, methylene blue, naloxone, pralidoxime, sodium bicarbonate, sodium nitrite, sodium thiosulfate, vasodilators, and vasopressors for the management of specific critical poisonings.

Systematic Review of Naloxone Dosing and Adverse Events in the Emergency Department

BACKGROUND

Experts recommend using the lowest effective dose of naloxone to balance the reversal of opioid-induced respiratory depression and avoid precipitated opioid withdrawal, however, there is no established dosing standards within the emergency department (ED).

OBJECTIVES

The aim of this review was to determine current naloxone dosing practice in the ED and their association with adverse events.

METHODS

We conducted a systematic review by searching PubMed, Cochrane, Embase, and EBSCO from 2000-2021. Articles containing patient-level data for initial ED dose and patient outcome had data abstracted by two independent reviewers. Patients were divided into subgroups depending on the initial dose of i.v. naloxone: low dose ([LD], < 0.4 mg), standard dose ([SD], 0.4-2 mg), or high dose ([HD], > 2 mg). Our outcomes were the dose range administered and adverse events per dose. We compared groups using chi-squared difference of proportions or Fisher's exact test.

RESULTS

The review included 13 articles with 209 patients in the results analysis: 111 patients in LD (0.04-0.1 mg), 95 in SD (0.4-2 mg), and 3 in HD (4-12 mg). At least one adverse event was reported in 37 SD patients (38.9%), compared with 14 in LD (12.6%, p < 0.0001) and 2 in HD (100.0%, p = 0.16). At least one additional dose was administered to 53 SD patients (55.8%), compared with 55 in LD (49.5%, p < 0.0001), and 3 in HD (100.0%, p = 0.48).

CONCLUSIONS

Lower doses of naloxone in the ED may help reduce related adverse events without increasing the need for additional doses. Future studies should evaluate the effectiveness of lower doses of naloxone to reverse opioid-induced respiratory depression without causing precipitated opioid withdrawal.

High-Dose Naloxone Formulations Are Not as Essential as We Thought

Naloxone is a U.S. Food and Drug Administration (FDA) approved opioid antagonist for reversing opioid overdoses. Naloxone is available to the public, and can be administered through intramuscular (IM), intravenous (IV), and intranasal spray (IN) routes. Our literature review aimed to improve understanding regarding the adequacy of the regularly distributed two doses of low-dose IM or IN naloxone in effectively reversing fentanyl overdoses and whether high-dose naloxone formulations (HDNF) formulations are an optimal solution to this problem. Moreover, our initiative incorporated the perspectives and experiences of people who use drugs (PWUD), enabling a more practical and contextually-grounded analysis. We began by discussing the knowledge and perspectives of Tennessee Harm Reduction, a small peer-led harm reduction organization. A comprehensive literature review was then conducted to gather relevant scholarly works on the subject matter. The evidence indicates that, although higher doses of naloxone have been administered in both clinical and community settings, the vast majority of fentanyl overdoses can be successfully reversed using standard IM dosages with the exception of carfentanil overdoses and other more potent fentanyl analogs, which necessitate three or more doses for effective reversal. Multiple studies documented the risk of precipitated withdrawal using high doses of naloxone. Notably, the possibility of recurring overdose symptoms after resuscitation exists, contingent upon the half-life of the specific opioid. Considering these findings and the current community practice of distributing multiple doses, we recommend providing at least four standard doses of IN or IM naloxone to each potential bystander, and training them to continue administration until the recipient achieves stability, ensuring appropriate intervals between each dose. Based on the evidence, we do not recommend HDNF in the place of providing four doses of standard naloxone due to the higher cost, risk of precipitated withdrawal and limited evidence compared to standard IN and IM. All results must be taken into consideration with the inclusion of the lived experiences, individual requirements, and consent of PWUD as crucial factors. It is imperative to refrain from formulating decisions concerning PWUD in their absence, as their participation and voices should be integral to the decision-making process.

"Another tool in the toolkit"-Perceptions, suggestions, and concerns of emergency service providers about the implementation of a supervised consumption site

BACKGROUND

As Supervised Consumption Sites (SCS) are implemented in the United States, it is important to consider the needs and perceptions of impacted stakeholders. Emergency service providers (ESP) have a central role in responding to the overdose epidemic. This study intended to assess the how ESP perceive the potential implementation of an SCS in their community, as well as solicit program design and implementation-related concerns and suggestions.

METHODS

In-depth interviews were conducted by videoconference with 22 ESP, including firefighters, paramedics, police, and social workers in King County, Washington, USA. Data were analyzed using a thematic analysis approach.

RESULTS

Participants expressed the importance of feeling safe while responding to calls where drug use is involved and highlighted how this perception would be linked to ESP response times to calls from an SCS. Suggestions for improving the perceived safety of an SCS included training program staff in de-escalation as well as planning the layout of the SCS to accommodate ESP. The inadequacy of the emergency department as a point of care for PWUD was also identified as a theme, and some participants expressed enthusiasm regarding the prospect of the SCS as an alternative destination for transport. Finally, support for the SCS model was conditional on the appropriate utilization of emergency services and a reduction in call volume. Participants listed clarifying roles and pursuing opportunities for collaboration as ways to ensure appropriate utilization and maintain positive working relationships.

CONCLUSION

This study builds on literature regarding stakeholder perceptions of SCS by focusing on the perceptions of a critically important stakeholder group. Results enhance understanding of what motivates ESP to support SCS implementation in their community. Other novel insights pertain to ESP thoughts about alternative care delivery models and strategies for emergency department visit diversion.

Transverse Myelitis in Naloxone Reversible Acute Respiratory Failure-A Case Report

Transverse myelitis (TM) is a rare inflammatory myelopathy presenting as bilateral neurologic deficit localized to the spinal cord. A critical management step in the emergency department (ED) is evaluating for and treating acute reversible causes such as mass lesion or reversible ischemia when present. Described in this case report is TM presenting after a respiratory arrest in suspected opioid overdose. Magnetic resonance imaging (MRI), ideally with contrast, and lumbar puncture are essential diagnostic studies to confirm inflammation. Finally, further diagnostic efforts are aimed at evaluation and treatment for other concurrent illnesses.

Topics

Transverse myelitis, transverse myelopathy, hypoxia, opioid overdose, hypoxic spinal cord injury.

Importance of Analyzing Intervals to Emergency Medical Service Treatments

BACKGROUND

Although most US emergency medical services (EMS) systems collect time-to-treatment data in their electronic prehospital patient care reports (PCRs), analysis of these data seldom appears in publications. We believe EMS agencies should routinely analyze the initial time-to-treatment data for various potentially life-threatening conditions. This not only assures that protocol-required treatments have been provided but can discover avoidable delays and drive protocol/treatment priority change. Our study purpose was to analyze the interval from 9-1-1 call receipt until the first administration of naloxone to adult opioid overdose victims to demonstrate the quality assurance importance of analyzing time-to-treatment data.

METHODS

Retrospective analysis of intervals from 9-1-1 call receipt to initial naloxone treatment in adult opioid overdose victims. We excluded victims <18 years of age and cases where a bystander, police, or a health care worker gave naloxone before EMS arrival. We compared data collected before and during the COVID-19 pandemic to determine its effect on the analysis.

RESULTS

The mean patient age of 582 opioid overdose victims was 40.7 years [95% CI 39.6, 41.8] with 405 males (69.6%). EMS units' scene arrival was 6.7 minutes from the 9-1-1 call receipt. It took 1.8 minutes to reach the victim, and 8.6 additional minutes to administer the first naloxone regardless of administration route (70.4% intravenous, 26.1% intranasal, 2.7% intraosseous, 0.7% intramuscular). EMS personnel administered the first naloxone 17.1 minutes after the 9-1-1 call receipt, with 50.3% of the delay occurring after patient contact. There was no statistically significant difference in the times-to-treatment before vs. during the pandemic.

CONCLUSION

The prepandemic interval from 9-1-1 call receipt until initial EMS administration of naloxone was substantial and did not change significantly during COVID-19. Our findings exemplify why EMS agencies should analyze initial time-to-treatment data, especially for life-threatening conditions, beyond assuring that protocol-required treatments have been provided. Based on our analysis, fire department crews now carry intranasal naloxone, and intranasal naloxone is given to "impaired" opioid overdose victims the first-arriving fire department or EMS personnel. We continue to collect data on intervals-to-treatment prospectively and monitor our critical process/treatment intervals using the plan-do-study-act model to improve our process/carry out change, and publish our results in a future publication.

"It wasn't here, and now it is. It's everywhere": fentanyl's rising presence in Oregon's drug supply

Background

Illicit fentanyl has contributed to a drastic increase in overdose drug deaths. While fentanyl has subsumed the drug supply in the Northeastern and Midwestern USA, it has more recently reached the Western USA. For this study, we explored perspectives of people who use drugs (PWUD) on the changing drug supply in Oregon, experiences of and response to fentanyl-involved overdose, and recommendations from PWUD to reduce overdose risk within the context of illicit fentanyl’s dramatic increase in the recreational drug supply over the past decade.

Methods

We conducted in-depth interviews by phone with 34 PWUD in Oregon from May to June of 2021. We used thematic analysis to analyze transcripts and construct themes.

Results

PWUD knew about fentanyl, expressed concern about fentanyl pills, and were aware of other illicit drugs containing fentanyl. Participants were aware of the increased risk of an overdose but remained reluctant to engage with professional first responders due to fear of arrest. Participants had recommendations for reducing fentanyl overdose risk, including increasing access to information, harm reduction supplies (e.g., naloxone, fentanyl test strips), and medications for opioid use disorder; establishing drug checking services and overdose prevention sites; legalizing and regulating the drug supply; and reducing stigma enacted by healthcare providers.

Conclusion

PWUD in Oregon are aware of the rise of fentanyl and fentanyl pills and desire access to tools to reduce harm from fentanyl. As states in the Western USA face an inflection point of fentanyl in the drug supply, public health staff, behavioral health providers, and first responders can take action identified by the needs of PWUD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12954-022-00659-9.

Pharmacokinetic considerations for community-based dosing of nasal naloxone in opioid overdose in adults

INTRODUCTION

The administration of the opioid antagonist naloxone in the community is a measure to prevent death from opioid overdose. Approved nasal naloxone sprays deliver initial doses of 0.9 to 8 mg. The level of the initial community dose is controversial, as the scientific base is weak.In this review knowledge of the pharmacokinetics of nasal, both approved and improvised nasal sprays, and intramuscular naloxone will be utilized to evaluate dose-effect relationships in previous studies of opioid overdose outcomes.

AREAS COVERED

The aim was to present scientifically based considerations on the initial nasal naloxone doses currently available, which reasonably balances the effect and adverse outcomes, given that at least two doses are at hand. Also included in these considerations is the challenge by illicitly manufactured fentanyl and analogs.This paper is based on both peer-reviewed and grey literature identified by several searches, of such as naloxone pharmacokinetics/formulations/outcomes/emergency medical services, in PubMed and Embase.

EXPERT OPINION

There is little scientific evidence that supports the use of initial systemic dosing that exceeds 0.8 mg in the community. Higher doses increase the risk of withdrawal symptoms feared in people who use opioids. Many obstacles may reduce the potential of community-administered naloxone.

A Study on the Efficacy of a Naloxone Training Program

Introduction: The use of naloxone to reverse a potentially fatal opioid overdose is a harm reduction strategy that reduces mortality and increases the potential for referral to substance use treatment for affected individuals. In the setting of outreach performed by a street medicine team, we aimed to determine the effectiveness of an educational intervention involving distribution of naloxone accompanied by a brief instructive session about opioids, opioid overdose, and medication administration.

Methods: Our street medicine outreach team distributed 200 naloxone kits to clinicians and volunteers involved in caring for patients on ‘street rounds,’ as well as in shelters, soup kitchens, and street medicine clinic settings. Those receiving a naloxone kit engaged in a peer-reviewed presentation on how to safely use the medication to reverse a potentially fatal opioid overdose. The study team developed and administered a pre- and post-survey of 10 multiple choice questions on material covered in the educational training. The pre- and post-survey scores were compared to assess the effectiveness of implementing this training. Results were stratified by participant gender and age group.

Results: Out of the 200 participants, six were excluded from the analysis due to completely missing data from one or both surveys. The mean age of participants was 40.2±12.5 years; 120 (65.6%) were female, 62 (33.9%) were male, and 1 (0.6%) identified as nonbinary. Every survey question had an increase in correct responses from pre-survey to post-survey (identified by an increase in the percentage of correct responses). The mean survey total score increased from 5.5±1.6 to 7.5±1.3. Within the sample of 194, the mean difference in scores from pre-survey to post-survey was 2.02 points (95% CI [1.77, 2.26]), p<0.0001. Males had a mean increase in the total score from 5.6±1.8 to 7.4±1.1. Females had a mean increase in the total score from 5.5±1.5 to 7.5±1.3. The difference in total scores in males was 1.89 points (95% CI [1.42, 2.35]), p<0.0001, and in females was 2.02 points (95% CI [1.71, 2.32]), p<0.0001. Post-test scores improved in all age groups.

Conclusion: The educational training on opioids, opioid overdose, and the use of naloxone was an effective adjunct to naloxone kit distribution to volunteers and clinicians caring for people experiencing homelessness.

Naloxone dosing in the era of ultra-potent opioid overdoses: a systematic review

OBJECTIVES

Evaluate the relationship between naloxone dose (initial and cumulative) and opioid toxicity reversal and adverse events in undifferentiated and presumed fentanyl/ultra-potent opioid overdoses.

METHODS

We searched Embase, MEDLINE, Cochrane Central Register of Controlled Trials, DARE, CINAHL, Science Citation Index, reference lists, toxicology websites, and conference proceedings (1972 to 2018). We included interventional, observational, and case studies/series reporting on naloxone dose and opioid toxicity reversal or adverse events in people >12 years old.

RESULTS

A total of 174 studies (110 case reports/series, 57 observational, 7 interventional) with 26,660 subjects (median age 35 years; 74% male). Heterogeneity precluded meta-analysis. Where reported, we abstracted naloxone dose and proportion of patients with toxicity reversal. Among patients with presumed exposure to fentanyl/ultra-potent opioids, 56.9% (617/1,085) responded to an initial naloxone dose ≤0.4 mg compared with 80.2% (170/212) of heroin users, and 30.4% (7/23) responded to an initial naloxone dose >0.4 mg compared with 59.1% (1,434/2,428) of heroin users. Among patients who responded, median cumulative naloxone doses were higher for presumed fentanyl/ultra-potent opioids than heroin overdoses in North America, both before 2015 (fentanyl/ultra-potent opioids: 1.8 mg [interquartile interval {IQI}, 1.0, 4.0]; heroin: 0.8 mg [IQI, 0.4, 0.8]) and after 2015 (fentanyl/ultra-potent opioids: 3.4 mg [IQI, 3.0, 4.1]); heroin: 2 mg [IQI, 1.4, 2.0]). Where adverse events were reported, 11% (490/4,414) of subjects experienced withdrawal. Variable reporting, heterogeneity and poor-quality studies limit conclusions.

CONCLUSIONS

Practitioners have used higher initial doses, and in some cases higher cumulative naloxone doses to reverse toxicity due to presumed fentanyl/ultra-potent opioid exposure compared with other opioids. High-quality comparative naloxone dosing studies assessing effectiveness and safety are needed.

The Effect of Overdose Education and Naloxone Distribution: An Umbrella Review of Systematic Reviews

Background. Opioids contribute to more than 60 000 deaths annually in North America. While the expansion of overdose education and naloxone distribution (OEND) programs has been recommended in response to the opioid crisis, their effectiveness remains unclear. Objectives. To conduct an umbrella review of systematic reviews to provide a broad-based conceptual scheme of the effect and feasibility of OEND and to identify areas for possible optimization. Search Methods. We conducted the umbrella review of systematic reviews by searching PubMed, Embase, PsycINFO, Epistemonikos, the Cochrane Database of Systematic Reviews, and the reference lists of relevant articles. Briefly, an academic librarian used a 2-concept search, which included opioid subject headings and relevant keywords with a modified PubMed systematic review filter. Selection Criteria. Eligible systematic reviews described comprehensive search strategies and inclusion and exclusion criteria, evaluated the quality or risk of bias of included studies, were published in English or French, and reported data relevant to either the safety or effectiveness of OEND programs, or optimal strategies for the management of opioid overdose with naloxone in out-of-hospital settings. Data Collection and Analysis. Two reviewers independently extracted study characteristics and the quality of included reviews was assessed in duplicate with AMSTAR-2, a critical appraisal tool for systematic reviews. Review quality was rated critically low, low, moderate, or high based on 7 domains: protocol registration, literature search adequacy, exclusion criteria, risk of bias assessment, meta-analytical methods, result interpretation, and presence of publication bias. Summary tables were constructed, and confidence ratings were provided for each outcome by using a previously modified version of the Royal College of General Practitioners' clinical guidelines. Main Results. Six systematic reviews containing 87 unique studies were included. We found that OEND programs produce long-term knowledge improvement regarding opioid overdose, improve participants' attitudes toward naloxone, provide sufficient training for participants to safely and effectively manage overdoses, and effectively reduce opioid-related mortality. High-concentration intranasal naloxone (> 2 mg/mL) was as effective as intramuscular naloxone at the same dose, whereas lower-concentration intranasal naloxone was less effective. Evidence was limited for other naloxone formulations, as well as the need for hospital transport after overdose reversal. The preponderance of evidence pertained persons who use heroin. Author's Conclusions. Evidence suggests that OEND programs are effective for reducing opioid-related mortality; however, additional high-quality research is required to optimize program delivery. Public Health Implications. Community-based OEND programs should be implemented widely in high-risk populations.

Are opioid receptor antagonists adequate for "Opioid" overdose in a changing reality?

WHAT IS KNOWN AND OBJECTIVE

Deaths due to opioid-induced respiratory depression (OIRD) continue to rise despite intense regulatory and professional actions. COVID-19 has only worsened this situation.¹ An opioid receptor antagonist (ORA) such as naloxone is the most common intervention for OIRD. However, with increasing overdose from highly potent illicit opioids and polysubstance abuse, appraisal of the adequacy of ORA seems warranted and timely.

COMMENT

OIRD results from the binding of an excess number of agonist molecules to opioid receptors. Mechanistically, it makes sense to reverse this by displacing agonist molecules by administering an ORA. But realistically, the trend to higher-potency agonists and polysubstance abuse diminishes the effectiveness of this approach. We are left facing a crisis without a solution.

WHAT IS NEW AND CONCLUSION

For the increasingly common OIRD from highly potent illicit agonists and polysubstance overdose, ORAs are correspondingly less effective. Alternatives are needed-soon.

Restoration of breathing after opioid overdose and spinal cord injury using temporal interference stimulation

Respiratory insufficiency is a leading cause of death due to drug overdose or neuromuscular disease. We hypothesized that a stimulation paradigm using temporal interference (TI) could restore breathing in such conditions. Following opioid overdose in rats, two high frequency (5000 Hz and 5001 Hz), low amplitude waveforms delivered via intramuscular wires in the neck immediately activated the diaphragm and restored ventilation in phase with waveform offset (1 Hz or 60 breaths/min). Following cervical spinal cord injury (SCI), TI stimulation via dorsally placed epidural electrodes uni- or bilaterally activated the diaphragm depending on current and electrode position. In silico modeling indicated that an interferential signal in the ventral spinal cord predicted the evoked response (left versus right diaphragm) and current-ratio-based steering. We conclude that TI stimulation can activate spinal motor neurons after SCI and prevent fatal apnea during drug overdose by restoring ventilation with minimally invasive electrodes.

Prehospital Naloxone and Emergency Department Adverse Events: A Dose-Dependent Relationship

BACKGROUND

The purpose of this study was to evaluate prehospital and emergency department (ED) interventions and outcomes of patients who received prehospital naloxone for a suspected opioid overdose.

OBJECTIVES

The primary objective was to evaluate if the individual dose, individual route, total dose, number of prehospital naloxone administrations, or occurrence of a prehospital adverse event (AE) were associated with the occurrence of AEs in the ED. Secondary objectives included a subset analysis of patients who received additional naloxone while in the ED, or were admitted to an intensive care or step-down unit (ICU).

METHODS

This was a retrospective, observational chart review of adult patients who received prehospital naloxone and were transported by ambulance to a suburban academic tertiary care center between 2014 and 2017. Descriptive, univariate, and multivariate statistics were used, with p < 0.05 indicating significance.

RESULTS

There were 513 patients included in the analysis, with a median age of 29 years, and median total prehospital naloxone dose of 2 mg. An increasing number of prehospital naloxone doses, an occurrence of a prehospital AE, and a route of administration other than intranasally for the first dose of prehospital naloxone were significantly associated with an increased likelihood of an ED AE. Patients who received < 2 mg of prehospital naloxone had the least likelihood of being admitted to an ICU, whereas patients who received at least 6 mg had a dramatically increased likelihood of ICU admission.

CONCLUSIONS

Our results suggest that an increasing number of prehospital naloxone doses was significantly associated with an increased likelihood of an ED adverse event.

Prehospital naloxone administration - what influences choice of dose and route of administration?

Background

Amidst the ongoing opioid crisis there are debates regarding the optimal route of administration and dosages of naloxone. This applies both for lay people administration and emergency medical services, and in the development of new naloxone products.

We examined the characteristics of naloxone administration, including predictors of dosages and multiple doses during patient treatment by emergency medical service staff in order to enlighten this debate.

Methods

This was a prospective observational study of patients administered naloxone by the Oslo City Center emergency medical service, Norway (2014–2018). Cases were linked to The National Cause of Death Registry. We investigated the route of administration and dosage of naloxone, clinical and demographic variables relating to initial naloxone dose and use of multiple naloxone doses and one-week mortality.

Results

Overall, 2215 cases were included, and the majority (91.9%) were administered intramuscular naloxone. Initial doses were 0.4 or 0.8 mg, and 15% of patients received multiple dosages. Unconscious patients or those in respiratory arrest were more likely to be treated with 0.8 mg naloxone and to receive multiple doses. The one-week mortality from drug-related deaths was 4.1 per 1000 episodes, with no deaths due to rebound opioid toxicity.

Conclusions

Intramuscular naloxone doses of 0.4 and 0.8 mg were effective and safe in the treatment of opioid overdose in the prehospital setting. Emergency medical staff appear to titrate naloxone based on clinical presentation.

Factors associated with withdrawal symptoms and anger among people resuscitated from an opioid overdose by take-home naloxone: Exploratory mixed methods analysis

INTRODUCTION

Take-home naloxone (THN) is a clinically effective and cost-effective means of reducing opioid overdose fatality. Nonetheless, naloxone administration that successfully saves a person's life can still produce undesirable and harmful effects.

AIM

To better understand factors associated with two widely reported adverse outcomes following naloxone administration; namely the person resuscitated displays: i. withdrawal symptoms and ii. anger.

METHODS

A mixed methods study combining a randomized controlled trial of overdose education and naloxone prescribing to people with opioid use disorder and semi-structured qualitative interviews with trial participants who had responded to an overdose whilst in the trial. All data were collected in New York City (2014-2019). A dataset (comprising demographic, pharmacological, situational, interpersonal, and overdose training related variables) was generated by transforming qualitative interview data from 47 overdose events into dichotomous variables and then combining these with quantitative demographic and overdose training related data from the main trial. Associations between variables within the dataset and reports of: i. withdrawal symptoms and ii. anger were explored using chi-squared tests, t-tests, and logistic regressions.

RESULTS

A multivariate logistic regression found that people who had overdosed were significantly more likely to display anger if the person resuscitating them criticized, berated or chastised them during resuscitation (adjusted OR = 27 [95% CI = 4.0-295]). In contrast, they were significantly less likely to display anger if the person resuscitating them communicated positively with them (OR = 0.10 [95% CI = 0.01-0.78]). Both positive and negative communication styles were independently associated with anger, and communication was associated with 59% of the variance in anger. There was no evidence that people who displayed withdrawal symptoms were more likely to display anger than those not displaying withdrawal symptoms, and neither displaying withdrawal symptoms nor displaying anger were associated with using more drugs after resuscitation.

CONCLUSIONS

Contrary to common assumptions, withdrawal symptoms and anger following naloxone administration may be unrelated phenomena. Findings are consistent with previous research that has suggested that a lay responder's positive or reassuring communication style may lessen anger post overdose. Implications for improving THN programmes and naloxone administration are discussed.

Protocol for Take-home naloxone In Multicentre Emergency (TIME) settings: feasibility study

Background

Opioids, such as heroin, kill more people worldwide by overdose than any other type of drug, and death rates associated with opioid poisoning in the UK are at record levels (World Drug Report 2018 [Internet]. [cited 2019 Nov 19]. Available from: http://www.unodc.org/wdr2018/; Deaths related to drug poisoning in England and Wales - Office for National Statistics [Internet]. [cited 2019 Nov 19]. Available from: https://www.ons.gov.uk/peoplepopulationandcommunity/birthsdeathsandmarriages/deaths/bulletins/deathsrelatedtodrugpoisoninginenglandandwales/2018registrations). Naloxone is an opioid antagonist which can be distributed in ‘kits’ for administration by witnesses in an overdose emergency. This intervention is known as take-home naloxone (THN). We know that THN can save lives on an individual level, but there is currently limited evidence about the effectiveness of THN distribution on an aggregate level, in specialist drug service settings or in emergency service settings. Notably, we do not know whether THN kits reduce deaths from opioid overdose in at-risk populations, if there are unforeseen harms associated with THN distribution or if THN is cost-effective. In order to address this research gap, we aim to determine the feasibility of a fully powered cluster randomised controlled trial (RCT) of THN distribution in emergency settings.

Methods

We will carry out a feasibility study for a RCT of THN distributed in emergency settings at four sites, clustered by Emergency Department (ED) and catchment area within its associated ambulance service. THN is a peer-administered intervention. At two intervention sites, emergency ambulance paramedics and ED clinical staff will distribute THN to adult patients who are at risk of opioid overdose. At two control sites, practice will carry on as usual. We will develop a method of identifying a population to include in an evaluation, comprising people at risk of fatal opioid overdose, who may potentially receive naloxone included in a THN kit.

We will gather anonymised outcomes up to 1 year following a 12-month ‘live’ trial period for patients at risk of death from opioid poisoning. We expect approximately 100 patients at risk of opioid overdose to be in contact with each service during the 1-year recruitment period. Our outcomes will include deaths, emergency admissions, intensive care admissions, and ED attendances. We will collect numbers of eligible patients attended by participating in emergency ambulance paramedics and attending ED, THN kits issued, and NHS resource usage. We will determine whether to progress to a fully powered trial based on pre-specified progression criteria: sign-up of sites (n = 4), staff trained (≥ 50%), eligible participants identified (≥ 50%), THN provided to eligible participants (≥ 50%), people at risk of death from opioid overdose identified for inclusion in follow-up (≥ 75% of overdose deaths), outcomes retrieved for high-risk individuals (≥ 75%), and adverse event rate (< 10% difference between study arms).

Discussion

This feasibility study is the first randomised, methodologically robust investigation of THN distribution in emergency settings. The study addresses an evidence gap related to the effectiveness of THN distribution in emergency settings. As this study is being carried out in emergency settings, obtaining informed consent on behalf of participants is not feasible. We therefore employ novel methods for identifying participants and capturing follow-up data, with effectiveness dependent on the quality of the available routine data.

Trial registration

ISRCTN13232859 (Registered 16/02/2018)

Comparison of rates of opioid withdrawal symptoms and reversal of opioid toxicity in patients treated with two naloxone dosing regimens: a retrospective cohort study

INTRODUCTION

When managing opioid overdose (OD) patients, the optimal naloxone regimen should rapidly reverse respiratory depression while avoiding opioid withdrawal. Published naloxone administration guidelines have not been empirically validated and most were developed before fentanyl OD was common. In this study, rates of opioid withdrawal symptoms (OW) and reversal of opioid toxicity in patients treated with two naloxone dosing regimens were evaluated.

METHODS

In this retrospective matched cohort study, health records of patients who experienced an opioid OD treated in two urban emergency departments (ED) during an ongoing fentanyl OD epidemic were reviewed. Definitions for OW and opioid reversal were developed a priori. Low dose naloxone (LDN; ≤0.15 mg) and high dose naloxone (HDN; >0.15 mg) patients were matched in a 1:4 ratio based upon initial respiratory rate (RR). The proportion of patients who developed OW and who met reversal criteria were compared between those treated initially with LDN or HDN. Odds ratios (OR) for OW and opioid reversal were obtained via logistic regression stratified by matched sets and adjusted for age, sex, pre-naloxone GCS, and presence of non-opioid drugs or alcohol.

RESULTS

Eighty LDN patients were matched with 299 HDN patients. After adjustment, HDN patients were more likely than LDN patients to have OW after initial dose (OR = 8.43; 95%CI: 1.96, 36.3; p = 0.004) and after any dose (OR = 2.56; 95%CI: 1.17, 5.60; p = 0.019). HDN patients were more likely to meet reversal criteria after initial dose (OR = 2.73; 95%CI: 1.19, 6.26; p = 0.018) and after any dose (OR = 6.07; 95%CI: 1.81, 20.3; p = 0.003).

CONCLUSIONS

HDN patients were more likely to have OW but also more likely to meet reversal criteria versus LDN patients.

Opioid overdose reversals using naloxone in New York City by people who use opioids: Implications for public health and overdose harm reduction approaches from a qualitative study

BACKGROUND

Adverse reactions to naloxone, such as withdrawal symptoms and aggression, are widely recognised in the literature by pharmaceutical manufacturers and clinical practitioners as standard reactions of individuals who are physically dependent upon opioid drugs following the reversal of potentially fatal opioid overdose. This paper seeks to provide a differentiated view on reactions to naloxone that may have important implications for public health and harm reduction approaches.

METHODS

Analyses from a qualitative investigation embedded within a 5-year Randomised Controlled Trial (RCT) examined the risks and benefits of Overdose Education and Naloxone Distribution (OEND) training models (brief or extended training) in various populations of people who use opioids in New York City. The qualitative experiences (obtained through semi-structured interviews) of 46 people who use opioids and who were each involved in the delivery of naloxone, during 56 separate overdose events that occurred throughout 2016-2018, were studied. Situational analysis and inductive content analysis of interview data focused upon overdose reversals in an attempt to provide understandings of the various adverse effects associated with naloxone from their perspective. These analyses were supplemented by data sessions within the research team during which the findings obtained from situational analysis and inductive content analysis were reviewed and complemented by deductive (clinical) appraisals of the various physical and psychological effects associated with the overdose reversals.

RESULTS

People who use opioids recognise three distinct and interconnected outcomes that may follow a successful opioid overdose reversal after intramuscular or intranasal administration of naloxone. These outcomes are here termed, (i) 'rage' (describing a wide range of angry, hostile and/or aggressive outbursts), (ii) 'withdrawal symptoms,' and (iii) 'not rage, not withdrawal' (i.e., a wide range of short-lived, 'harmless' conditions (such as temporary amnesia, mild emotional outbursts, or physical discomfort) that do not include rage or withdrawal symptoms).

CONCLUSION

Physical and psychological reactions to naloxone should not be understood exclusively as a consequence of acute, opioid-related, withdrawal symptoms. The three distinct and interconnected reversal outcomes identified in this study are considered from a harm reduction policy perspective and are further framed by concepts associated with 'mediated toxicity' (i.e., harm triggered by medicine). The overall conclusion is that harm reduction training programmes that are aligned to the policy and practice of take home naloxone may be strengthened by including awareness and training in how to best respond to 'rage' associated with overdose reversal following naloxone administration by people who use opioids and other laypersons.

A descriptive study of racial and ethnic differences of drug overdoses and naloxone administration in Pennsylvania

INTRODUCTION

Drug overdose is a significant public health problem, yet little is known about racial/ethnic differences in drug overdose rates and/or in responses to a drug overdose following naloxone administration. This paper examines differences in rates of survivorship, response, revival and administration of naloxone by race and ethnicity among those who experienced a drug overdose in Pennsylvania between January 1, 2018 and December 31, 2019. Spatio-temporal variations in drug overdose locations were examined to facilitate understanding of service development, planning, and delivery of effective treatment need.

METHODS

Ten thousand two hundred and ninety drug overdose incidents were analyzed from the Pennsylvania Overdose Information Network (ODIN). The ODIN is a centralized repository that contains information on drug overdoses victims including age, gender and race/ethnicity, naloxone administrations and survivorship, drug(s) suspected of causing the overdose, victim outcomes (e.g. hospitalizations and arrests) and average naloxone dosage per victim. Between group differences were tested using χ2 -tests of independence. Multivariate logistic regression was used to estimate the predicted probability of survivorship according to victim characteristics. All statistical analyses and mapping were performed using the R statistical programming environment.

RESULTS

About eighty-seven percent of drug overdose response victims were white, and seventy-one percent were between the ages of 20-39. White females were more likely to receive an overdose response compared to black or Hispanic females. A non-opioid was indicated more frequently in overdoses involving black victims compared to either whites or Latinos. Latinos and blacks were more likely to survive a drug overdose. However, following naloxone administration, no racial or ethnic differences in survivorship were noted. Differences in responsiveness to naloxone and transitions to care following the drug overdose event were also found. Finally, overdoses among Blacks and Latinos demonstrated a stronger spatial patterning across counties compared to whites.

CONCLUSIONS

This study found a significant, disparate impact of race/ethnicity on fatal drug overdoses when naloxone is not administered. Further, individuals who were administered naloxone and subsequently received medical care in a hospital experienced lower drug-related mortality, suggesting that first responders are critical intervention points for individuals in need of medical treatment following a drug overdose. However, while naloxone administration is a necessary first step in the recovery process, longitudinal pathways towards treatment are critical to stem the drug overdose crisis.

Protocol for a multi-site study of the effects of overdose prevention education with naloxone distribution program in Skåne County, Sweden

BACKGROUND

Continuously high rates of overdose deaths in Sweden led to the decision by the Skåne County to initiate the first regional take-home naloxone program in Sweden. The project aims to study the effect of overdose prevention education and naloxone distribution on overdose mortality in Skåne County. Secondary outcome measures include non-fatal overdoses and overdose-related harm in the general population, as well as cohort-specific effects in study participants regarding overdoses, mortality and retention in naloxone program.

METHODS

Implementation of a multi-site train-the-trainer cascade model was launched in June 2018. Twenty four facilities, including opioid substitution treatment units, needle exchange programs and in-patient addiction units were included for the first line of start-up, aspiring to reach a majority of individuals at-risk within the first 6 months. Serving as self-sufficient naloxone hubs, these units provide training, naloxone distribution and study recruitment. During 3 years, questionnaires are obtained from initial training, follow up, every sixth month, and upon refill. Estimated sample size is 2000 subjects. Naloxone distribution rates are reported, by each unit, every 6 months. Medical diagnoses, toxicological raw data and data on mortality and cause of death will be collected from national and regional registers, both for included naloxone recipients and for the general population. Data on vital status and treatment needs will be collected from registers of emergency and prehospital care.

DISCUSSION

Despite a growing body of literature on naloxone distribution, studies on population effect on mortality are scarce. Most previous studies and reports have been uncontrolled, thus not being able to link naloxone distribution to survival, in relation to a comparison period. As Swedish registers present the opportunity to monitor individuals and entire populations over time, conditions for conducting systematic follow-ups in the Swedish population are good, serving the opportunity to study the impact of large scale overdose prevention education and naloxone distribution and thus fill the knowledge gap.

TRIAL REGISTRATION

Naloxone Treatment in Skåne County - Effect on Drug-related Mortality and Overdose-related Complications, NCT03570099, registered on 26 June 2018.

Take-Home Naloxone for the Emergency Interim Management of Opioid Overdose: The Public Health Application of an Emergency Medicine

Naloxone is a well-established essential medicine for the treatment of life-threatening heroin/opioid overdose in emergency medicine. Over two decades, the concept of 'take-home naloxone' has evolved, comprising pre-provision of an emergency supply to laypersons likely to witness an opioid overdose (e.g. peers and family members of people who use opioids as well as non-medical personnel), with the recommendation to administer the naloxone to the overdose victim as interim care while awaiting an ambulance. There is an urgent need for more widespread naloxone access considering the growing problem of opioid overdose deaths, accounting for more than 100,000 deaths worldwide annually. Rises in mortality are particularly sharp in North America, where the ongoing prescription opioid problem is now overlaid with a rapid growth in overdose deaths from heroin and illicit fentanyl. Using opioids alone is dangerous, and the mortality risk is clustered at certain times and contexts, including on prison release and discharge from hospital and residential care. The provision of take-home naloxone has required the introduction of new legislation and new naloxone products. These include pre-filled syringes and auto-injectors and, crucially, new concentrated nasal sprays (four formulations recently approved in different countries) with speed of onset comparable to intramuscular naloxone and relative bioavailability of approximately 40-50%. Choosing the right naloxone dose in the fentanyl era is a matter of ongoing debate, but the safety margin of the approved nasal sprays is superior to improvised nasal kits. New legislation in different countries permits over-the-counter sales or other prescription-free methods of provision. However, access remains uneven with take-home naloxone still not provided in many countries and communities, and with ongoing barriers contributing to implementation inertia. Take-home naloxone is an important component of the response to the global overdose problem, but greater commitment to implementation will be essential, alongside improved affordable products, if a greater impact is to be achieved.

More than just availability: Who has access and who administers take-home naloxone in Baltimore, MD

Background

Fatal opioid overdose is a pressing public health concern in the United States. Addressing barriers and augmenting facilitators to take-home naloxone (THN) access and administration could expand program reach in preventing fatal overdoses.

Methods

THN access (i.e., being prescribed or receiving THN) was assessed in a Baltimore, Maryland-based sample of 577 people who use opioids (PWUO) and had a history of injecting drugs. A sub-analysis examined correlates of THN administration among those with THN access and who witnessed an overdose (N = 345). Logistic generalized estimating equations with robust standard errors were used to identify facilitators and barriers to accessing and using THN.

Results

The majority of PWUO (66%) reported THN access. In the multivariable model, decreased THN access was associated with the fear that a person may become aggressive after being revived with THN (aOR: 0.55, 95% CI: 0.35–0.85), police threaten people at an overdose event (aOR: 0.68, 95% CI: 0.36–1.00), and insufficient overdose training (aOR: 0.43, 95% CI: 0.28–0.68). Enrollment in medication-assisted treatment, personally experiencing an overdose, and graduating from high school were associated with higher access. About half (49%) of PWUO with THN access and who had witnessed an overdose reported having administered THN. THN use was positively associated with “often” or “always” carrying THN (aOR: 3.47, 95% CI: 1.99–6.06), witnessing more overdoses (aOR:5.18, 95% CI: 2.22–12.07), experiencing recent homelessness, and injecting in the past year. THN use was reduced among participants who did not feel that they had sufficient overdose training (aOR: 0.56, 95% CI: 0.32–0.96).

Conclusion

THN programs must bolster confidence in administering THN and address barriers to use, such as fear of a THN recipient becoming aggressive. Normative change around carrying THN is an important component in an overdose prevention strategy.

Progress in agonist therapy for substance use disorders: Lessons learned from methadone and buprenorphine

Substance use disorders (SUD) are serious public health problems worldwide. Although significant progress has been made in understanding the neurobiology of drug reward and the transition to addiction, effective pharmacotherapies for SUD remain limited and a majority of drug users relapse even after a period of treatment. The United States Food and Drug Administration (FDA) has approved several medications for opioid, nicotine, and alcohol use disorders, whereas none are approved for the treatment of cocaine or other psychostimulant use disorders. The medications approved by the FDA for the treatment of SUD can be divided into two major classes - agonist replacement therapies, such as methadone and buprenorphine for opioid use disorders (OUD), nicotine replacement therapy (NRT) and varenicline for nicotine use disorders (NUD), and antagonist therapies, such as naloxone for opioid overdose and naltrexone for promoting abstinence. In the present review, we primarily focus on the pharmacological rationale of agonist replacement strategies in treatment of opioid dependence, and the potential translation of this rationale to new therapies for cocaine use disorders. We begin by describing the neural mechanisms underlying opioid reward, followed by preclinical and clinical findings supporting the utility of agonist therapies in the treatment of OUD. We then discuss recent progress of agonist therapies for cocaine use disorders based on lessons learned from methadone and buprenorphine. We contend that future studies should identify agonist pharmacotherapies that can facilitate abstinence in patients who are motivated to quit their illicit drug use. Focusing on those that are able to achieve abstinence from cocaine will provide a platform to broaden the effectiveness of medication and psychosocial treatment strategies for this underserved population. This article is part of the Special Issue entitled 'New Vistas in Opioid Pharmacology'.

One single large intramuscular dose of naloxone is effective and safe in suspected heroin poisoning

OBJECTIVE

Naloxone is an established antidote for the treatment of heroin poisoning; however, dosing regimens vary widely, with a current trend towards small titrated intravenous dosing. This study aims to characterise naloxone use in the treatment of patients presenting with suspected heroin poisoning.

METHODS

This was a retrospective review of poisoned patients presenting to a clinical toxicology unit in Brisbane from January 2015 to December 2017. Patient demographics, clinical effects, naloxone dosing, observation periods and complications were extracted from the patient's medical records.

RESULTS

There were 117 presentations accounted for by 108 patients. Prehospital naloxone was provided to 57 (49%) patients, 46 of which received a standardised 1.6 mg i.m. dose. The remaining 60 (51%) patients received their first naloxone in hospital, with 58 (97%) receiving this by titrated i.v. doses. A subsequent naloxone infusion was required significantly more often in those treated with i.v. titrated naloxone compared to i.m. dose (27/69 [39%] vs 5/48 [10%], P = 0.0006). The need for parenteral sedation to manage acute behavioural disturbance following naloxone provision was rare (3/117 [3%]).

CONCLUSIONS

In this retrospective observational study, a single large i.m. dose of naloxone reversed the toxicity of suspected heroin overdose in the majority of patients. In addition, patients were less likely to require repeated intermittent doses or naloxone infusion than those treated solely with i.v. naloxone. Further comparison in a prospective study is warranted to validate these observations in confirmed heroin overdose. Requirement for sedation secondary to acute behavioural disturbance was rare regardless of the route.

Naloxone interventions in opioid overdoses: a systematic review protocol

BACKGROUND

North America is in the midst of an unabated opioid overdose epidemic due to the increasing non-medical use of fentanyl and ultra-potent opioids. Naloxone is an effective antidote to opioid toxicity, yet its optimal dosing in the context of fentanyl and ultra-potent opioid overdoses remains unknown. This review aims to determine the relationship between the first empiric dose of naloxone and reversal of toxicity, adverse events, and the total cumulative dose required among patients with undifferentiated opioid overdoses and those with suspected toxicity from ultra-potent opioids. Secondary objectives include evaluating the relationship between the cumulative naloxone dose and toxicity reversal and adverse events, among patients with undifferentiated opioid overdoses and those with suspected toxicity from ultra-potent opioids.

METHODS

To identify studies, we will search MEDLINE, Embase, CENTRAL, DARE, CDAG, CINAHL, Science Citation Index, multiple trial registries, and the gray literature. Included studies will evaluate patients with suspected or confirmed opioid toxicity from undifferentiated opioids and ultra-potent opioids, who received an empiric and possibly additional doses of naloxone. The main outcomes of interest are the relationship between naloxone dose and toxicity reversal and adverse events. We will include controlled and non-controlled interventional studies, observational studies, case reports/series, and reports from poison control centers. We will extract data and assess study quality in duplicate with discrepancies resolved by consensus or a third party. We will use the Downs and Black and Cochrane risk of bias tools for observational and randomized controlled studies. If we find sufficient variation in dose, we will fit a random effects one-stage model to estimate a dose-response relationship. We will conduct multiple subgroup analyses, including by type of opioid used and by suspected high and low prevalence of ultra-potent opioid use based on geographic location and time of the original studies.

DISCUSSION

Our review will include the most up-to-date available data including ultra-potent opioids to inform the current response to the opioid epidemic, addressing the limitations of recent reviews. We anticipate limitations relating to study heterogeneity. We will disseminate study results widely to update overdose treatment guidelines and naloxone dosing in Take Home Naloxone programs.

Pharmacokinetics of a novel, approved, 1.4-mg intranasal naloxone formulation for reversal of opioid overdose-a randomized controlled trial

BACKGROUND AND AIMS

Intranasal (i.n.) naloxone is an established treatment for opioid overdose. Anyone likely to witness an overdose should have access to the antidote. We aimed to determine whether an i.n. formulation delivering 1.4 mg naloxone hydrochloride would achieve systemic exposure comparable to that of 0.8 mg intramuscular (i.m.) naloxone.

DESIGN

Open, randomized four-way cross-over trial.

SETTING

Clinical Trials Units in St Olav's Hospital, Trondheim and Rikshospitalet, Oslo, Norway.

PARTICIPANTS

Twenty-two healthy human volunteers, 10 women, median age = 25.8 years.

INTERVENTION AND COMPARATOR

One and two doses of i.n. 1.4 mg naloxone compared with i.m. 0.8 mg and intravenous (i.v.) 0.4 mg naloxone.

MEASUREMENTS

Quantification of plasma naloxone was performed by liquid chromatography tandem mass spectrometry. Pharmacokinetic non-compartment analyses were used for the main analyses. A non-parametric pharmacokinetic population model was developed for Monte Carlo simulations of different dosing scenarios.

FINDINGS

Area under the curve from administration to last measured concentration (AUC_0-last ) for i.n. 1.4 mg and i.m. 0.8 mg were 2.62 ± 0.94 and 3.09 ± 0.64 h × ng/ml, respectively (P = 0.33). Maximum concentration (C_max ) was 2.36 ± 0.68 ng/ml for i.n. 1.4 mg and 3.73 ± 3.34 for i.m. 0.8 mg (P = 0.72). Two i.n. doses showed dose linearity and achieved a C_max of 4.18 ± 1.53 ng/ml. T_max was reached after 20.2 ± 9.4 minutes for i.n. 1.4 mg and 13.6 ± 15.4 minutes for i.m. 0.8 mg (P = 0.098). The absolute bioavailability for i.n. 1.4 mg was 0.49 (±0.24), while the relative i.n./i.m. bioavailability was 0.52 (±0.25).

CONCLUSION

Intranasal 1.4 mg naloxone provides adequate systemic concentrations to treat opioid overdose compared with intramuscular 0.8 mg, without statistical difference on maximum plasma concentration, time to maximum plasma concentration or area under the curve. Simulations support its appropriateness both as peer administered antidote and for titration of treatment by professionals.

Analysis of the citation of articles published in the European Journal of Emergency Medicine since its foundation

OBJECTIVES

The aim of this study was to evaluate the evolution of the citation of articles from the European Journal of Emergency Medicine (EJEM) from 1994 (EJEM foundation) to 2015 and identify highly cited articles and their principal characteristics and determine a possible correlation between the citations counted in different databases.

MATERIALS AND METHODS

We obtained the articles published in EJEM from 1994 to 2015 in ISI-WoS (main source) and Scopus, Google Scholar, and Medline databases (accessory sources). The citations were quantified and their annual evolution and the bibliometric indices derived (impact factor and SCImago Journal Rank) were evaluated. We identified and analyzed the highly cited EJEM articles and evaluated the possible correlation between the citations counted for these articles in the databases.

RESULTS

Overall, 1705 EJEM articles were cited 9422 times in 8122 different articles. The evolution of the global citation, impact factor, and SCImago Journal Rank from 1994 to 2015 increased significantly. The h-index of EJEM was 30, and 31 articles were considered highly cited (≥30 citations), 16.1% of them being clinical trials. By subjects, 22.5% corresponded to cardiology, 19.3% to emergency department management, and 12.9% to pediatrics; by countries, 81% were from Europe, with Belgian authors publishing four (12.9%) highly cited articles, and French, Spanish, British, and Swedish authors having three (9.7%) each. Two studies in the EJEM achieved the definition of 'citation classics' (more than 100 citations). The number of citations in all the databases, except Medline, showed statistically significant correlations.

CONCLUSION

Citation of EJEM articles has progressively increased and EJEM bibliometric indicators have improved; most highly cited articles are mainly by European authors.

Incidence of mortality due to rebound toxicity after ‘treat and release’ practices in prehospital opioid overdose care: a systematic review

Introduction

Death due to opioid overdose was declared a public health crisis in Canada in 2015. Traditionally, patients who have overdosed on opioids that are managed by emergency medical services (EMS) are treated with the opioid antagonist naloxone, provided ventilatory support and subsequently transported to hospital. However, certain EMS agencies have permitted patients who have been reversed from opioid overdose to refuse transport, if the patient exhibits capacity to do so. Evidence on the safety of this practice is limited. Therefore, our intent was to examine the available literature to determine mortality and serious adverse events within 48 hours of EMS treat and release due to suspected rebound opioid toxicity after naloxone administration.

Methods

A systematic search was performed on 11 May 2017 in PubMed, Cochrane Central, Embase and CINHAL. Studies that reported on the outcome of patients treated with prehospital naloxone and released at the scene were included. Analyses for incidence of mortality and adverse events at the scene were conducted. Risk of bias and assessment of publication bias was also done.

Results

1401 records were screened after duplicate removal. Eighteen full-text studies were reviewed with seven selected for inclusion. None were found to be high risk of bias. In most studies, heroin was the source of the overdose. Mortality within 48 hours was infrequent with only four deaths among 4912 patients ﴾0.081%﴿ in the seven studies. Only one study reported on adverse events and found no incidence of adverse events from their sample of 71 released patients.

Conclusion

Mortality or serious adverse events due to suspected rebound toxicity in patients released on scene post-EMS treatment with naloxone were rare. However, studies involving longer-acting opioids were rare and no study involved fentanyl.

Altered Mental Status: Current Evidence-based Recommendations for Prehospital Care

Introduction

In the United States emergency medical services (EMS) protocols vary widely across jurisdictions. We sought to develop evidence-based recommendations for the prehospital evaluation and treatment of a patient with an acute change in mental status and to compare these recommendations against the current protocols used by the 33 EMS agencies in the State of California.

Methods

We performed a literature review of the current evidence in the prehospital treatment of a patient with altered mental status (AMS) and augmented this review with guidelines from various national and international societies to create our evidence-based recommendations. We then compared the AMS protocols of each of the 33 EMS agencies for consistency with these recommendations. The specific protocol components that we analyzed were patient assessment, point-of-care tests, supplemental oxygen, use of standardized scoring, evaluating for causes of AMS, blood glucose evaluation, toxicological treatment, and pediatric evaluation and management.

Results

Protocols across 33 EMS agencies in California varied widely. All protocols call for a blood glucose check, 21 (64%) suggest treating adults at <60mg/dL, and half allow for the use of dextrose 10%. All the protocols recommend naloxone for signs of opioid overdose, but only 13 (39%) give specific parameters. Half the agencies (52%) recommend considering other toxicological causes of AMS, often by using the mnemonic AEIOU TIPS. Eight (24%) recommend a 12-lead electrocardiogram; others simply suggest cardiac monitoring. Fourteen (42%) advise supplemental oxygen as needed; only seven (21%) give specific parameters. In terms of considering various etiologies of AMS, 25 (76%) give instructions to consider trauma, 20 (61%) to consider stroke, and 18 (55%) to consider seizure. Twenty-three (70%) of the agencies have separate pediatric AMS protocols; others include pediatric considerations within the adult protocol.

Conclusion

Protocols for patients with AMS vary widely across the State of California. The evidence-based recommendations that we present for the prehospital diagnosis and treatment of this condition may be useful for EMS medical directors tasked with creating and revising these protocols.

Pharmacokinetics of concentrated naloxone nasal spray for opioid overdose reversal: Phase I healthy volunteer study

BACKGROUND AND AIMS

Take-home naloxone can prevent death from heroin/opioid overdose, but pre-provision is difficult because naloxone is usually given by injection. Non-injectable alternatives, including naloxone nasal sprays, are currently being developed. To be effective, the intranasal (i.n.) spray dose must be adequate but not excessive, and early absorption must be comparable to intramuscular (i.m.) injection. We report on the pharmacokinetics (PK) of a specially produced concentrated novel nasal spray. The specific aims were to: (1) estimate PK profiles of i.n. naloxone, (2) compare early systemic exposure with i.n. versus i.m. naloxone and (3) estimate i.n. bioavailability.

DESIGN

Open-label, randomized, five-way cross-over PK study.

SETTING

Clinical trials facility (Croydon, UK).

PARTICIPANTS

Thirty-eight healthy volunteers (age 20-54 years; 11 female).

INTERVENTION AND COMPARATOR

Three doses of i.n. (1 mg/0.1 ml, 2 mg/0.1 ml, 4 mg/0.2 ml) versus 0.4 mg i.m. (reference) and 0.4 mg intravenous (i.v.) naloxone.

MEASUREMENTS

Regular blood samples were taken, with high-frequency sampling during the first 15 minutes to capture early systemic exposure. PK parameters were determined from plasma naloxone concentrations. Exploratory analyses involved simulation of repeat administration.

FINDINGS

Mean peak concentration (C_max ) values for 1 mg (1.51 ng/ml), 2 mg (2.87 ng/ml) and 4 mg (6.02 ng/ml) i.n. exceeded 0.4 mg i.m. (1.27 ng/ml) naloxone. All three i.n. doses rapidly achieved plasma levels > 50% of peak concentrations (T50%) by 10 minutes, peaking at 15-30 minutes (T_max ). For comparison, the i.m. reference reached T_max at 10 minutes. Mean bioavailability was 47-51% for i.n. relative to i.m. naloxone. Simulation of repeat dosing (2 × 2 mg i.n. versus 5 × 0.4 mg i.m. doses) at 3-minute intervals showed that comparable plasma naloxone concentrations would be anticipated.

CONCLUSIONS

Concentrated 2 mg intranasal naloxone is well-absorbed and provides early exposure comparable to 0.4 mg intramuscular naloxone, following the 0.4 mg intramuscular curve closely in the first 10 minutes post-dosing and maintaining blood levels above twice the intramuscular reference for the next 2 hours.

Naloxone dosage for opioid reversal: current evidence and clinical implications

Opioid-related mortality is a growing problem in the United States, and in 2015 there were over 33,000 opioid-related deaths. To combat this mortality trend, naloxone is increasingly being utilized in a pre-hospital setting by emergency personnel and prescribed to laypersons for out-of-hospital administration. With increased utilization of naloxone there has been a subsequent reduction in mortality following an opioid overdose. Reversal of opioid toxicity may precipitate an opioid-withdrawal syndrome. At the same time, there is a risk of inadequate response or re-narcotization after the administration of a single dose of naloxone in patients who have taken large doses or long-acting opioid formulations, as the duration of effect of naloxone is shorter than that of many opioid agonists. As out-of-hospital use of this medication is growing, so too is concern about effective but safe dosing.

Is naloxone the best antidote to reverse tramadol-induced neuro-respiratory toxicity in overdose? An experimental investigation in the rat

CONTEXT

Since the banning of dextropropoxyphene from the market, overdoses, and fatalities attributed to tramadol, a WHO step-2 opioid analgesic, have increased markedly. Tramadol overdose results not only in central nervous system (CNS) depression attributed to its opioid properties but also in seizures, possibly related to non-opioidergic pathways, thus questioning the efficiency of naloxone to reverse tramadol-induced CNS toxicity.

OBJECTIVE

To investigate the most efficient antidote to reverse tramadol-induced seizures and respiratory depression in overdose.

MATERIALS AND METHODS

Sprague-Dawley rats overdosed with 75 mg/kg intraperitoneal (IP) tramadol were randomized into four groups to receive solvent (control group), diazepam (1.77 mg/kg IP), naloxone (2 mg/kg intravenous bolus followed by 4 mg/kg/h infusion), and diazepam/naloxone combination. Sedation depth, temperature, number of seizures, and intensity, whole-body plethysmography parameters and electroencephalography activity were measured.

RESULTS

Naloxone reversed tramadol-induced respiratory depression (p < .05) but significantly increased seizures (p < .01) and prolonged their occurrence time. Diazepam abolished seizures but significantly deepened rat sedation (p < .05) without improving ventilation. Diazepam/naloxone combination completely abolished seizures, significantly improved rat ventilation by reducing inspiratory time (p < .05) but did not worsen sedation. None of these treatments significantly modified rat temperature.

CONCLUSIONS

Diazepam/naloxone combination is the most efficient antidote to reverse tramadol-induced CNS toxicity in the rat.

Toxicologic Emergencies in Patients with Mental Illness: When Medications Are No Longer Your Friends

Patients with psychiatric disorders are at risk for toxicologic emergencies. Psychotropic medications have numerous effects on the neurologic, cardiac, and other organ systems and interact with other medications, potentially leading to further side effects. It is important to become familiar with accepted psychiatric practice guidelines, common toxidromes, medical sequelae associated with prescribed medications, and the specific workup and treatment of overdoses of frequently prescribed psychotropics.

International patent applications for non-injectable naloxone for opioid overdose reversal: Exploratory search and retrieve analysis of the PatentScope database

ISSUES

Non-injectable naloxone formulations are being developed for opioid overdose reversal, but only limited data have been published in the peer-reviewed domain. Through examination of a hitherto-unsearched database, we expand public knowledge of non-injectable formulations, tracing their development and novelty, with the aim to describe and compare their pharmacokinetic properties.

APPROACH

(i) The PatentScope database of the World Intellectual Property Organization was searched for relevant English-language patent applications; (ii) Pharmacokinetic data were extracted, collated and analysed; (iii) PubMed was searched using Boolean search query '(nasal OR intranasal OR nose OR buccal OR sublingual) AND naloxone AND pharmacokinetics'.

KEY FINDINGS

Five hundred and twenty-two PatentScope and 56 PubMed records were identified: three published international patent applications and five peer-reviewed papers were eligible. Pharmacokinetic data were available for intranasal, sublingual, and reference routes. Highly concentrated formulations (10-40 mg mL^-1 ) had been developed and tested. Sublingual bioavailability was very low (1%; relative to intravenous). Non-concentrated intranasal spray (1 mg mL^-1 ; 1 mL per nostril) had low bioavailability (11%). Concentrated intranasal formulations (≥10 mg mL^-1 ) had bioavailability of 21-42% (relative to intravenous) and 26-57% (relative to intramuscular), with peak concentrations (dose-adjusted C_max  = 0.8-1.7 ng mL^-1 ) reached in 19-30 min (t_max ).

IMPLICATIONS

Exploratory analysis identified intranasal bioavailability as associated positively with dose and negatively with volume.

CONCLUSION

We find consistent direction of development of intranasal sprays to high-concentration, low-volume formulations with bioavailability in the 20-60% range. These have potential to deliver a therapeutic dose in 0.1 mL volume. [McDonald R, Danielsson Glende Ø, Dale O, Strang J. International patent applications for non-injectable naloxone for opioid overdose reversal: Exploratory search and retrieve analysis of the PatentScope database. Drug Alcohol Rev 2017;00:000-000].

Circumstances surrounding non-fatal opioid overdoses attended by ambulance services

INTRODUCTION AND AIMS

Opioid overdose fatalities are a significant concern globally. Non-fatal overdoses have been described as a strong predictor for future overdoses, and are often attended by the ambulance services. This paper explores characteristics associated with non-fatal overdoses and aims to identify possible trends among these events in an urban area in Norway.

DESIGN AND METHODS

This is a retrospective analysis of non-fatal overdoses from Bergen ambulance services from 2012 to 2013. Demographic, temporal and geographic data were explored.

RESULTS

During the two years, 463 non-fatal opioid overdoses were attended by ambulance services. Ambulance call-outs occurred primarily during the late afternoon and evening hours of weekdays. Summer months had more overdoses than other seasons, with a peak in August. Overdoses were nearly twice as likely to occur in a public location in August (risk ratio 1.92, P = 0.042). Ambulance response times were more likely to be longer to private locations, and these victims were more likely to be treated and left at the scene. There was no difference in arrival time for drug-related and non-drug related dispatch.

DISCUSSION AND CONCLUSIONS

The temporal patterns suggest that non-fatal overdoses occur during non-recreational time periods. The longer ambulance response time and disposition for private addresses indicate potential opportunities for peer interventions. Our analysis describes circumstances surrounding non-fatal overdoses and can be useful in guiding relevant, targeted prevention interventions. [Madah-Amiri D, Clausen T, Myrmel L, Brattebø G, Lobmaier P. Circumstances surrounding non-fatal opioid overdoses attended by ambulance services. Drug Alcohol Rev 2017;36:288-294].