Reversal of Opioid-Induced Ventilatory Depression Using Low-Dose Naloxone (0.04 mg): a Case Series

Effectiveness of intramuscular naloxone 1,600 μg in addition to titrated intravenous naloxone 100 μg for opioid poisoning: a randomised controlled trial

INTRODUCTION

Naloxone is an effective antidote, but its short half-life means repeated doses, and infusions are often required. We investigated the effectiveness of adding intramuscular naloxone to titrated intravenous naloxone in opioid overdose in preventing recurrence of respiratory depression.

METHODS

This double-blinded randomised placebo-controlled trial was conducted in patients with suspected opioid poisoning and respiratory depression (respiratory rate <10 breaths/min or oxygen saturation <93%). Patients were randomised to receive either intramuscular naloxone 1,600 µg or saline placebo. All patients received titrated intravenous naloxone 100 µg and were managed on an opioid poisoning care pathway. The primary outcome was recurrence of respiratory depression within 4 h. Secondary outcomes were the proportion receiving naloxone infusions, number of naloxone boluses administered, reversal of respiratory depression at 10 min, and precipitation of opioid withdrawal (any symptom).

RESULTS

Recurrence of respiratory depression within 4 h was less common in 28/69 (41%) patients receiving intramuscular naloxone versus 48/67 (72%) patients receiving placebo (difference 31%, 95% CI: 13-46%; P < 0.001). Fewer naloxone infusions (5/69; 7% versus 25/67; 37%, difference 30%, 95% CI: 15 to 55%; P < 0.001) and fewer naloxone doses were administered (median 2, IQR: 1 to 5, versus median 5, IQR: 2 to 8; P = 0.001) in the intramuscular group. Reversal of respiratory depression at 10 min was similar between groups (51/69; 74% intramuscular naloxone versus 47/67; 70% placebo; P = 0.703). Opioid withdrawal occurred in 35/69 (51%) given intramuscular naloxone compared to 28/67 (42%) in the placebo group (difference 9%; 95% CI: -8 to 27%; P = 0.308).

DISCUSSION

The favourable pharmacokinetics of intramuscular naloxone, particularly its longer duration of activity, likely explains the improved effectiveness with lower recurrence of respiratory depression.

CONCLUSION

The addition of intramuscular naloxone 1,600 µg to titrated intravenous naloxone prolonged effective reversal of respiratory depression, with fewer naloxone doses and infusions given, and no significant difference in patients developing withdrawal.

Human IPSC-Derived PreBötC-Like Neurons and Development of an Opiate Overdose and Recovery Model

Opioid overdose is the leading cause of drug overdose lethality, posing an urgent need for investigation. The key brain region for inspiratory rhythm regulation and opioid-induced respiratory depression (OIRD) is the preBötzinger Complex (preBötC) and current knowledge has mainly been obtained from animal systems. This study aims to establish a protocol to generate human preBötC neurons from induced pluripotent cells (iPSCs) and develop an opioid overdose and recovery model utilizing these iPSC-preBötC neurons. A de novo protocol to differentiate preBötC-like neurons from human iPSCs is established. These neurons express essential preBötC markers analyzed by immunocytochemistry and demonstrate expected electrophysiological responses to preBötC modulators analyzed by patch clamp electrophysiology. The correlation of the specific biomarkers and function analysis strongly suggests a preBötC-like phenotype. Moreover, the dose-dependent inhibition of these neurons' activity is demonstrated for four different opioids with identified IC50's comparable to the literature. Inhibition is rescued by naloxone in a concentration-dependent manner. This iPSC-preBötC mimic is crucial for investigating OIRD and combating the overdose crisis and a first step for the integration of a functional overdose model into microphysiological systems.

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-potency benzodiazepine misuse in opioid-dependent patients: use naloxone with care

The misuse of highly potent benzodiazepines is increasing in the UK, particularly among the opioid-using population in Scotland. Differentiating opioid from benzodiazepine toxicity is not always straightforward in patients with reduced level of consciousness following drug overdose. Patients on long-term opioid substitution who present with acute benzodiazepine intoxication and are given naloxone may develop severe opioid withdrawal while still obtunded from benzodiazepines. This situation can be difficult to manage, and these patients may be at increased risk of vomiting while still unable to protect their airway. Fortunately, the short half-life of naloxone means that the situation is generally short-lived. Naloxone should never be withheld from patients with life-threatening respiratory depression where opioids may be contributing, particularly in community and prehospital settings; however, where appropriate clinical experience exists, naloxone should ideally be administered in small incremental intravenous doses with close monitoring of respiratory function. Increased awareness of the potential risks of naloxone in opioid-dependent patients acutely intoxicated with benzodiazepines may reduce the risk of iatrogenic harm in an already very vulnerable population.

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.

Outcomes following Naloxone Administration by Bystanders and First Responders

Background: Naloxone is widely available to bystanders and first responders to treat patients with suspected opioid overdose. In these patients, the prognostic factors and potential benefits associated with additional naloxone administered by emergency medical services (EMS) are uncertain. Objectives: We sought to identify prognostic factors for admission to the hospital following prehospital administration of naloxone for suspected opioid overdose by bystanders and first responders. We secondarily examined whether administration of additional naloxone by paramedics after initial treatment by non-EMS personnel was associated with improvement in level of consciousness prior to hospital arrival. Methods: This is a retrospective cross-sectional study of patients treated within a single urban EMS system from 2013 to 2016. Inclusion criteria were administration of naloxone by bystanders or first responders and transport to one of three academic medical centers. For the secondary analysis, only patients with a Glasgow Coma Scale (GCS) score ≤12 on paramedic arrival were included. We performed univariate and multivariable analyses examining a primary outcome of hospital admission and secondary outcome of improvement in consciousness as defined by GCS >12 in patients with initial GCS ≤12. Results: Of 359 patients identified for the primary analysis, 60 were admitted to the hospital. Factors associated with increased rate of admission included higher total naloxone dosage (OR 1.36, 95% CI 1.09-1.70) and presence of alternate/additional non-opioid central nervous system (CNS) depressants (OR 2.51, 95% CI 1.13-5.56). Among 178 patients who had poor neurologic status (GCS ≤12) on paramedic arrival following naloxone administered by bystander or first responder, administration of additional naloxone was not associated with a better rate of neurologic improvement prior to hospital arrival (77% improved with additional naloxone, 81% improved without additional naloxone; OR 0.82, 95% CI 0.39-1.76). Conclusions: Among patients with suspected opioid overdose treated with naloxone by bystanders and first responders, a higher total dose of naloxone and polysubstance intoxication with additional CNS depressants were predictors of admission. Administration of additional naloxone by paramedics was not associated with a higher rate of neurologic improvement prior to hospital arrival, suggesting a ceiling effect on naloxone efficacy in opioid overdose.

Endogenous opiates and behavior: 2017

This paper is the fortieth consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2017 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).

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.

Comparison of lower-dose versus higher-dose intravenous naloxone on time to recurrence of opioid toxicity in the emergency department

INTRODUCTION

The initial dose of naloxone administered to patients who present to the emergency department (ED) with opioid overdose is highly variable. The objective of this study was to determine if the initial dose of intravenous (IV) naloxone given to these patients was associated with the time to recurrence of opioid toxicity.

METHODS

This was a multicenter retrospective cohort study, conducted at two academic EDs in the United States. Consecutive adults who had a positive response to naloxone for opioid overdose in the ED were included. Patients were categorized into two groups based on initial IV naloxone dose administered: 0.4 mg (lower-dose) or 1-2 mg (higher-dose). The main outcome measure was the time to recurrence of opioid toxicity requiring a second dose of naloxone. Secondary outcomes included the need for naloxone continuous infusion and adverse events.

RESULTS

The study included 84 patients with 42 patients receiving lower-dose and 42 patients receiving higher-dose naloxone. Median time to re-dose of naloxone was similar between the lower-dose (72 [IQR 46-139] minutes) and higher-dose (70 [IQR 44-126] minutes) groups (p=.810). There were 12 patients (29%) in the lower-dose group and 17 patients (41%) in the higher-dose group who subsequently required continuous infusions (p=.359). The proportion of patients with adverse events was similar between lower-dose and higher-dose groups (31% versus 41%, p=.495). There was no difference in the incidence of specific withdrawal related adverse effects.

CONCLUSIONS

The initial dose of naloxone given to patients in the ED does not influence the time to recurrence of opioid toxicity.

The Evolution of Recommended Naloxone Dosing for Opioid Overdose by Medical Specialty

INTRODUCTION

Opioid abuse and opioid overdose deaths have increased significantly over the past decade. Naloxone is a potentially life-saving medication that can reverse opioid-induced respiratory depression, though precipitated opioid withdrawal can pose acute risks to the patient and medical personnel. The optimal naloxone dose is unclear and few studies address this question.

METHODS

A convenience sample of commonly available references were queried for the recommended IV naloxone dose. When dosing recommendations were different for opioid-tolerant patients these were also recorded.

RESULTS

Twenty-five references were located. 48% recommended a starting dose ≤ 0.05 mg while 36% recommend a dose ten-fold higher. More than half of medical toxicology and general medical sources recommended a low-dose strategy with a starting dose lower than 0.05 mg IV.

CONCLUSION

There are variations in the recommended doses for naloxone with ranges spanning an order of magnitude. Further exploration is needed to determine the dose that balances reversal of respiratory depression with mitigation of withdrawal.