The need for multiple naloxone administrations for opioid overdose reversals: A review of the literature

Comparison of intranasal naloxone and intranasal nalmefene in a translational model assessing the impact of synthetic opioid overdose on respiratory depression and cardiac arrest

Introduction

Using a validated translational model that quantitatively predicts opioid-induced respiratory depression and cardiac arrest, we compared cardiac arrest events caused by synthetic opioids (fentanyl, carfentanil) following rescue by intranasal (IN) administration of the μ-opioid receptor antagonists naloxone and nalmefene.

Methods

This translational model was originally developed by Mann et al. (Clin Pharmacol Ther 2022) to evaluate the effectiveness of intramuscular (IM) naloxone. We initially implemented this model using published codes, reproducing the effects reported by Mann et al. on the incidence of cardiac arrest events following intravenous doses of fentanyl and carfentanil as well as the reduction in cardiac arrest events following a standard 2 mg IM dose of naloxone. We then expanded the model in terms of pharmacokinetic and µ-opioid receptor binding parameters to simulate effects of 4 mg naloxone hydrochloride IN and 3 mg nalmefene hydrochloride IN, both FDA-approved for the treatment of opioid overdose. Model simulations were conducted to quantify the percentage of cardiac arrest in 2000 virtual patients in both the presence and absence of IN antagonist treatment.

Results

Following simulated overdoses with both fentanyl and carfentanil in chronic opioid users, IN nalmefene produced a substantially greater reduction in the incidence of cardiac arrest compared to IN naloxone. For example, following a dose of fentanyl (1.63 mg) producing cardiac arrest in 52.1% (95% confidence interval, 47.3-56.8) of simulated patients, IN nalmefene reduced this rate to 2.2% (1.0-3.8) compared to 19.2% (15.5-23.3) for IN naloxone. Nalmefene also produced large and clinically meaningful reductions in the incidence of cardiac arrests in opioid naïve subjects. Across dosing scenarios, simultaneous administration of four doses of IN naloxone were needed to reduce the percentage of cardiac arrest events to levels that approached those produced by a single dose of IN nalmefene.

Conclusion

Simulations using this validated translational model of opioid overdose demonstrate that a single dose of IN nalmefene produces clinically meaningful reductions in the incidence of cardiac arrest compared to IN naloxone following a synthetic opioid overdose. These findings are especially impactful in an era when >90% of all opioid overdose deaths are linked to synthetic opioids such as fentanyl.

Intranasal Naloxone Repeat Dosing Strategies and Fentanyl Overdose: A Simulation-Based Randomized Clinical Trial

Importance

Questions have emerged as to whether standard intranasal naloxone dosing recommendations (ie, 1 dose with readministration every 2-3 minutes if needed) are adequate in the era of illicitly manufactured fentanyl and its derivatives (hereinafter, fentanyl).

Objective

To compare naloxone plasma concentrations between different intranasal naloxone repeat dosing strategies and to estimate their effect on fentanyl overdose.

Design, Setting, and Participants

This unblinded crossover randomized clinical trial was conducted with healthy participants in a clinical pharmacology unit (Spaulding Clinical Research, West Bend, Wisconsin) in March 2021. Inclusion criteria included age 18 to 55 years, nonsmoking status, and negative test results for the presence of alcohol or drugs of abuse. Data analysis was performed from October 2021 to May 2023.

Intervention

Naloxone administered as 1 dose (4 mg/0.1 mL) at 0, 2.5, 5, and 7.5 minutes (test), 2 doses at 0 and 2.5 minutes (test), and 1 dose at 0 and 2.5 minutes (reference).

Main Outcomes and Measures

The primary outcome was the first prespecified time with higher naloxone plasma concentration. The secondary outcome was estimated brain hypoxia time following simulated fentanyl overdoses using a physiologic pharmacokinetic-pharmacodynamic model. Naloxone concentrations were compared using paired tests at 3 prespecified times across the 3 groups, and simulation results were summarized using descriptive statistics.

Results

This study included 21 participants, and 18 (86%) completed the trial. The median participant age was 34 years (IQR, 27-50 years), and slightly more than half of participants were men (11 [52%]). Compared with 1 naloxone dose at 0 and 2.5 minutes, 1 dose at 0, 2.5, 5, and 7.5 minutes significantly increased naloxone plasma concentration at 10 minutes (7.95 vs 4.42 ng/mL; geometric mean ratio, 1.95 [1-sided 97.8% CI, 1.28-∞]), whereas 2 doses at 0 and 2.5 minutes significantly increased the plasma concentration at 4.5 minutes (2.24 vs 1.23 ng/mL; geometric mean ratio, 1.98 [1-sided 97.8% CI, 1.03-∞]). No drug-related serious adverse events were reported. The median brain hypoxia time after a simulated fentanyl 2.97-mg intravenous bolus was 4.5 minutes (IQR, 2.1-∞ minutes) with 1 naloxone dose at 0 and 2.5 minutes, 4.5 minutes (IQR, 2.1-∞ minutes) with 1 naloxone dose at 0, 2.5, 5, and 7.5 minutes, and 3.7 minutes (IQR, 1.5-∞ minutes) with 2 naloxone doses at 0 and 2.5 minutes.

Conclusions and Relevance

In this clinical trial with healthy participants, compared with 1 intranasal naloxone dose administered at 0 and 2.5 minutes, 1 dose at 0, 2.5, 5, and 7.5 minutes significantly increased naloxone plasma concentration at 10 minutes, whereas 2 doses at 0 and 2.5 minutes significantly increased naloxone plasma concentration at 4.5 minutes. Additional research is needed to determine optimal naloxone dosing in the community setting.

Trial Registration

ClinicalTrials.gov Identifier: NCT04764630.

Remaking the 'angry Narcanned subject': Affording new subject positions through take-home naloxone training

Naloxone is a medication used to reverse opioid overdose. Alongside its lifesaving effects, it also has a reputation for producing distress, aggression and occasionally violence upon administration. This article analyses how take-home naloxone (THN) training initiatives address naloxone's reputation for producing aggression and conflict, and how new subject positions emerge in the context of this training. While the role of naloxone in producing aggression has been discussed in a range of research, this work emphasises that such conflict is neither inevitable nor even likely because it is contingent on several other issues such as administration practices. Building on this scholarship, we work with Bruno Latour's theorisation of technological 'affordances' to analyse THN as a socially co-produced technology that, rather than either determining or neutrally communicating actions and effects, 'affords' possibilities, capacities and subjects. Analysing data drawn from observations of THN training in Victoria, Australia, and in-depth interviews with training participants, we argue that the issue of conflict upon revival affords a subject position we term the 'angry Narcanned subject'. This subject, we note, has come to hold a powerful position in understandings of naloxone, not least because it tends to accord with stereotypes of antisocial drug users. From here, we argue that a much of THN training is focused on challenging and reframing naloxone's reputation for conflict and questioning related subject positions, especially that of the angry Narcanned subject. We argue that this process of challenging and reframing affords two new subject positions for consumers: the 'capable administrator' and the 'calmer revivee'. We conclude that while THN training affords multiple, potentially positive, subject positions, unless these initiatives are accompanied by broader interventions such as decriminalisation campaigns, they may inadvertently responsibilise people who consume opioids for addressing overdose and erase the role of prohibition, criminalisation and stigmatisation in producing overdose events.

Pharmacokinetic Properties of an FDA-approved Intranasal Nalmefene Formulation for the Treatment of Opioid Overdose

Nalmefene is a high-affinity, long-duration opioid antagonist that was approved in 1995 as an injection for the treatment of opiate overdose, but subsequently withdrawn (2008) for reasons other than safety or effectiveness. The dramatic rise in opioid overdose deaths over the past 7-8 years catalyzed the development of an intranasal (IN) formulation of nalmefene for the emergency treatment of opioid overdose. The studies described here compare the pharmacokinetic properties and safety profiles of an IN formulation containing nalmefene (2.7 mg in 0.1 mL) to an approved 1 mg intramuscular (IM) dose. IN nalmefene produced maximum plasma concentrations that were significantly higher than observed following the IM dose (12.2 and 1.77 ng/mL, respectively). The time to reach maximum plasma concentrations was also faster following IN administration (0.25 and 0.33 hours, respectively) with significant differences in plasma concentrations manifested as early as 2.5 minutes after administration (NCT04759768). The plasma half-life of nalmefene was similar following IM and IN administration (10.6-11.4 hours). Furthermore, dose-normalized nalmefene exposure was similar for both 1 spray in each nostril and 2 sprays in the same nostril compared to a single spray in each nostril (NCT05219669). There were no sex differences in the pharmacokinetic properties of either IN or IM nalmefene. In an era when almost 90% of opioid overdose deaths have been linked to high-potency synthetic opioids, the ability to rapidly deliver high concentrations of nalmefene could represent an important tool for reducing both morbidity and mortality.

Investigation of monoclonal antibody CSX-1004 for fentanyl overdose

The opioid crisis in the United States is primarily driven by the highly potent synthetic opioid fentanyl leading to >70,000 overdose deaths annually; thus, new therapies for fentanyl overdose are urgently needed. Here, we present the first clinic-ready, fully human monoclonal antibody CSX-1004 with picomolar affinity for fentanyl and related analogs. In mice CSX-1004 reverses fentanyl antinociception and the intractable respiratory depression caused by the ultrapotent opioid carfentanil. Moreover, toxicokinetic evaluation in a repeat-dose rat study and human tissue cross-reactivity study reveals a favorable pharmacokinetic profile of CSX-1004 with no safety-related issues. Using a highly translational non-human primate (NHP) model of respiratory depression, we demonstrate CSX-1004-mediated protection from repeated fentanyl challenges for 3-4 weeks. Furthermore, treatment with CSX-1004 produces up to a 15-fold potency reduction of fentanyl in NHP respiration, antinociception and operant responding assays without affecting non-fentanyl opioids like oxycodone. Taken together, our data establish the feasibility of CSX-1004 as a promising candidate medication for preventing and reversing fentanyl-induced overdose.

"I'm not going to lay back and watch somebody die": a qualitative study of how people who use drugs' naloxone experiences are shaped by rural risk environment and overdose education/naloxone distribution intervention

BACKGROUND

Overdoses have surged in rural areas in the U.S. and globally for years, but harm reduction interventions have lagged. Overdose education and naloxone distribution (OEND) programs reduce overdose mortality, but little is known about people who use drugs' (PWUD) experience with these interventions in rural areas. Here, we analyze qualitative data with rural PWUD to learn about participants' experiences with an OEND intervention, and about how participants' perceptions of their rural risk environments influenced the interventions' effects.

METHODS

Twenty-nine one-on-one, semi-structured qualitative interviews were conducted with rural PWUD engaged in the CARE2HOPE OEND intervention in Appalachian Kentucky. Interviews were conducted via Zoom, audio-recorded, and transcribed verbatim. Thematic analysis was conducted, guided by the Rural Risk Environment Framework.

RESULTS

Participants' naloxone experiences were shaped by all domains of their rural risk environments. The OEND intervention transformed participants' roles locally, so they became an essential component of the local rural healthcare environment. The intervention provided access to naloxone and information, thereby increasing PWUDs' confidence in naloxone administration. Through the intervention, over half of participants gained knowledge on naloxone (access points, administration technique) and on the criminal-legal environment as it pertained to naloxone. Most participants opted to accept and carry naloxone, citing factors related to the social environment (responsibility to their community) and physical/healthcare environments (overdose prevalence, suboptimal emergency response systems). Over half of participants described recent experiences administering intervention-provided naloxone. These experiences were shaped by features of the local rural social environment (anticipated negative reaction from recipients, prior naloxone conversations).

CONCLUSIONS

By providing naloxone paired with non-stigmatizing health and policy information, the OEND intervention offered support that allowed participants to become a part of the healthcare environment. Findings highlight need for more OEND interventions; outreach to rural PWUD on local policy that impacts them; tailored strategies to help rural PWUD engage in productive dialogue with peers about naloxone and navigate interpersonal conflict associated with overdose reversal; and opportunities for rural PWUD to formally participate in emergency response systems as peer overdose responders. Trial registration The ClinicalTrials.gov ID for the CARE2HOPE intervention is NCT04134767. The registration date was October 19th, 2019.

Factors Associated with Gaps in Naloxone Knowledge: Evidence from a 2022 Great Plains Survey

Background

The rising prevalence of fast-acting opioids in the United States suggests the increased need for non-first responder administration of naloxone. Effective administration of naloxone during an overdose requires that bystanders are familiar with, have access to, and know how to use naloxone.

Methods

Drawing on the 2022 Nebraska Annual Social Indicators survey, we analyzed naloxone familiarity, access, and competency to administer among a statewide, address-based sample of Nebraskan adults.

Results

There were significant gaps in naloxone knowledge in Nebraska. Although 75.6% of respondents were familiar with naloxone, only 18.6% knew how to access naloxone and 17.6% knew how to use naloxone. We find that more frequent religious service attendance is associated with lower odds of naloxone familiarity. Among those familiar with naloxone, a higher perception of community stigma towards opioids generally is associated with lower odds of naloxone access and competency. Higher perception of community stigma towards heroin, methamphetamines, and cocaine, however, is associated with higher odds of naloxone access. Finally, past overdose experience, lifetime illicit opioid use, being close to a person who uses opioids, and having access to illicit opioids was not significantly associated with naloxone familiarity, access, or competency among respondents in Nebraska's two largest cities, Omaha and Lincoln. Outside of these cities, past overdose experience and access to illicit opioids was associated with higher odds of naloxone access and competency, but lifetime opioid use and being close to a person who uses opioids had no effect.

Conclusions

Our findings highlight the continued need for education on naloxone with a specific focus on access and competency to further reduce opioid-related overdose deaths. Education campaigns targeted at places of worship or individuals close to people who use opioids may further serve those with a lower likelihood of naloxone familiarity and promote knowledge of naloxone among those with higher odds of encountering an overdose. Further work is needed to understand differences in the relationship between substance-specific perceived stigma and its association with naloxone access.

Prehospital Naloxone Administration Patterns during the Era of Synthetic Opioids

Background: The opioid epidemic is an ongoing public health emergency, exacerbated in recent years by the introduction and rising prevalence of synthetic opioids. The National EMS Scope of Practice Model was changed in 2017 to recommend allowing basic life support (BLS) clinicians to administer intranasal (IN) naloxone. This study examines local IN naloxone administration rates for 4 years after the new recommendation, and Glasgow Coma Scale (GCS) scores and respiratory rates before and after naloxone administration.Methods: This retrospective cohort study evaluated naloxone administrations between April 1st 2017 and March 31st 2021 in a mixed urban-suburban EMS system. Naloxone dosages, routes of administration, and frequency of administrations were captured along with demographic information. Analysis of change in the ratio of IN to intravenous (IV) naloxone administrations per patient was performed, with the intention of capturing administration patterns in the area. Analyses were performed for change over time of IN naloxone rates of administration, change in respiratory rates, and change in GCS scores after antidote administration. ALS and BLS clinician certification levels were also identified. Bootstrapping procedures were used to estimate 95% confidence intervals for correlation coefficients.Results: Two thousand and ninety patients were analyzed. There was no statistically significant change in the IN/parenteral ratio over time (p = 0.79). Repeat dosing increased over time from 1.2 ± 0.4 administrations per patient to 1.3 ± 0.5 administrations per patient (r = 0.078, 95% CI: 0.036 - 0.120; p = 0.036). Mean respiratory rates before (mean = 12.6 - 12.6, r = -0.04, 95% CI: -0.09 - 0.01; p = 0.1) and after (mean = 15.2 - 14.9, r = -0.03, 95% CI: -0.08 - 0.01; p = 0.172) naloxone administration have not changed. While initial GCS scores have become significantly lower, GCS scores after administration of naloxone have not changed (initial median GCS 10 - 6, p < 0.001; final median GCS 15 - 15, p = 0.23).Conclusions: Current dosing protocols of naloxone appear effective in the era of synthetic opioids in our region, although patients may be marginally more likely to require repeat naloxone doses.

Patient perceptions of higher-dose naloxone nasal spray for opioid overdose

BACKGROUND

Higher-dose formulations of naloxone were recently approved by the FDA for the treatment of opioid overdose. These products were developed based on projected saturation of high-potency fentanyl analogues in the illicit marketplace although the evidence base for their necessity is still under scrutiny. Concern has been raised that unintended reductions in patient acceptance of naloxone may occur due to increased precipitated withdrawal risk associated with higher naloxone doses. A well-founded and time-sensitive call for representation of people who use drugs in this decision-making process has been made. This study provides the first data on patient perceptions of higher-dose formulations to inform this scientific debate and distribution efforts.

METHODS

Patients (N=1152) entering treatment for opioid use disorder at one of 49 addiction treatment facilities located across the United States completed a preference assessment of naloxone nasal spray formulations. Patients selected a formulation preference across three scenarios (administration for self, administration to others, community responder administration).

RESULTS

A majority of respondents that had been administered naloxone previously reported that their most recent overdose reversal included two or more naloxone administrations (59.9%). Most respondents either had no preference (48.4%) or preferred a higher-dose formulation (35.9%) if personally experiencing an overdose. Similar preference distributions were observed for administration to others and by community responders. Relative to standard-dose preference, respondents preferring higher-dose formulations had a greater odds of recent suspected fentanyl exposure.

CONCLUSIONS

These data inform patients, advocates, and policy-makers considering distribution and utilization of naloxone formulations by reporting perspectives of patients with opioid use and overdose experience. Limited evidence for widespread avoidance of higher-dose formulations was found. As real-world evidence of acceptability and effectiveness emerges, either supporting or refuting the widespread need for higher-dose naloxone formulations, it is the responsibility of the scientific and public health community to be responsive to those data.

Real-world study of multiple naloxone administration for opioid overdose reversal among bystanders

Background

The increasing prevalence of highly potent, illicitly manufactured fentanyl and its analogues (IMF) in the USA is exacerbating the opioid epidemic which has worsened during the COVID-19 pandemic. Narcan® (naloxone HCl) Nasal Spray has been approved by the US Food and Drug Administration as a treatment for opioid-related overdoses. Due to the high potency of IMF, multiple naloxone administrations (MNA) may be needed per overdose event. It is essential to determine the patterns of naloxone use, including MNA, and preferences among bystanders who have used naloxone for opioid overdose reversal.

Methods

A cross-sectional web-based survey was administered to 125 adult US residents who administered 4 mg Narcan® Nasal Spray during an opioid overdose in the past year. The survey asked about the most recent overdose event, the use of Narcan® during the event and the associated withdrawal symptoms, and participant preferences regarding dosages of naloxone nasal spray. An open-ended voice survey was completed by 35 participants.

Results

Participants were mostly female (70%) and white (78%), while reported overdose events most frequently occurred in people who were males (54%) and white (86%). Most events (95%) were successfully reversed, with 78% using ≥ 2 doses and 30% using ≥ 3 doses of Narcan® Nasal Spray. Over 90% were worried that 1 Narcan® box may not be enough for a successful future reversal. Reported withdrawal symptoms were similar in overdose events where 1 versus ≥ 2 sprays were given. Eighty-six percent of participants reported more confidence in an 8 mg versus a 4 mg naloxone nasal spray and 77% reported a stronger preference for 8 mg over 4 mg.

Conclusions

MNA occurred in most overdose events, often involving more sprays than are provided in one Narcan® nasal spray box, and participants predominantly expressed having a stronger preference for and confidence in an 8 mg compared to a 4 mg nasal spray. This suggests the need and desire for a higher dose naloxone nasal spray formulation option. Given that bystanders may be the first to administer naloxone to someone experiencing an opioid overdose, ensuring access to an adequate naloxone supply is critical in addressing the opioid overdose epidemic.