Review of Case Narratives from Fatal Overdoses Associated with Injectable Naltrexone for Opioid Dependence

Using structural topic modelling to reveal patterns in reports on opioid drugs in a pharmacovigilance database

BACKGROUND

Adverse drug reaction (ADR) reports in pharmacovigilance databases often contain coded information and large amounts of unstructured or semi-structured information in plain text format. The unstructured format and sheer volume of these data often render them neglected. Structural topic modelling (STM) represents a potentially insightful way of harnessing these valuable data and to detect grouping or themes in spontaneous reports to aid signal detection.

PURPOSE

This was an explorative study of the potential for structural topic modelling to identify useful patterns in ADR reports involving opioid drugs in a pharmacovigilance database.

METHODS

A dataset of ADR reports on opioid drugs reported to the Netherlands Pharmacovigilance Centre Lareb from 1991 to December 2020 was used, comprising a total of 3069 unique reports. Qualitative text analysis was combined with structural topic modelling (STM), an automated text analysis method, to examine these data.

RESULTS

In reports submitted directly by patients and healthcare professionals, 11 meaningful topics were identified, whereby patient experience reports, particularly in relation to pain (relief), and the timing of intake and ADRs of tramadol and paracetamol, were the most common. Of the 12 topics identified in reports received via Marketing Authorization Holders, patch and skin-related side effects, addiction and constipation were the most prevalent.

CONCLUSIONS

The STM-based analysis identified information that cannot always be captured by coding with the Medical Dictionary for Regulatory Activities (MedDRA®). The identified topics reflect findings in the literature on opioids. This article is protected by copyright. All rights reserved.

Goofballing of Opioid and Methamphetamine: The Science Behind the Deadly Cocktail

Globally, millions of people suffer from various substance use disorders (SUD), including mono-and polydrug use of opioids and methamphetamine. Brain regions such as the cingulate cortex, infralimbic cortex, dorsal striatum, nucleus accumbens, basolateral and central amygdala have been shown to play important roles in addiction-related behavioral changes. Clinical and pre-clinical studies have characterized these brain regions and their corresponding neurochemical changes in numerous phases of drug dependence such as acute drug use, intoxication, craving, withdrawal, and relapse. At present, many studies have reported the individual effects of opioids and methamphetamine. However, little is known about their combined effects. Co-use of these drugs produces effects greater than either drug alone, where one decreases the side effects of the other, and the combination produces a prolonged intoxication period or a more desirable intoxication effect. An increasing number of studies have associated polydrug abuse with poorer treatment outcomes, drug-related deaths, and more severe psychopathologies. To date, the pharmacological treatment efficacy for polydrug abuse is vague, and still at the experimental stage. This present review discusses the human and animal behavioral, neuroanatomical, and neurochemical changes underlying both morphine and methamphetamine dependence separately, as well as its combination. This narrative review also delineates the recent advances in the pharmacotherapy of mono- and poly drug-use of opioids and methamphetamine at clinical and preclinical stages.

Slow-sustained delivery of naloxone reduces typical naloxone-induced precipitated opioid withdrawal effects in male morphine-dependent mice

Thousands of individuals die each year from opioid-related overdoses. While naloxone (Narcan®) is currently the most widely employed treatment to reverse opioid toxicity, high or repeated doses of this antidote often lead to precipitated opioid withdrawal (POW). We hypothesized that a slow linear release of naloxone from a nanoparticle would induce fewer POW symptoms compared to high-dose free naloxone. First, we measured the acute impact of covalent naloxone nanoparticles (Nal-cNPs) on morphine-induced antinociception in the hotplate test. We found that Nal-cNP treatment blocked the antinociceptive effect of morphine within 15 min of administration. Next, we tested the impact of Nal-cNPs on POW symptoms in male morphine-dependent mice. To induce morphine dependence, mice were treated with 5 mg/kg morphine (or saline) twice-daily for six consecutive days. On day 7 mice received 5 mg/kg morphine (or saline) injections 2 hr prior to receiving treatment of either unmodified free naloxone, a high or low dose of Nal-cNP, empty nanoparticle (cNP-empty), or saline. Behavior was analyzed for 0-6 hr followed by 24 and 48 hr time points after treatment. As expected, free naloxone induced a significant increase in POW behavior in morphine-dependent mice compared to saline-treated mice upon free naloxone administration. In comparison, reduced POW behavior was observed with both doses of Nal-cNP. Side effects of Nal-cNP on locomotion and fecal boli production were measured and no significant side-effects were observed. Overall, our data show that sustained release of naloxone from a covalent nanoparticle does not induce severe POW symptoms in morphine-dependent mice.

Evaluation of Opioid Overdose Reports in Patients Treated with Extended-Release Naltrexone: Postmarketing Data from 2006 to 2018

INTRODUCTION

After treatment with naltrexone extended-release injectable suspension (XR-NTX), a µ-opioid receptor antagonist, opioid tolerance is reduced from pretreatment baseline. Patients may be vulnerable to opioid overdose if they attempt to override the blockade during treatment, at the end of a dosing interval, after missing a dose, or after discontinuing treatment.

OBJECTIVE

We analyzed postmarketing data to characterize reporting rates of opioid overdose during treatment with and after discontinuation of XR-NTX.

METHODS

Postmarketing adverse event reports within the XR-NTX safety database, received 2006-2018, for patients treated with XR-NTX for any indication were reviewed for opioid overdose cases. Assessable cases were categorized by timing of the event from the last dose of XR-NTX (latency): ≤28 days (on treatment), 29-56 days, and >56 days from last dose of XR-NTX. Within each latency group, cases were further classified as serious and, of those, cases that had a fatal outcome.

RESULTS

During the 12-year period, an estimated 495,602 patients received XR-NTX. Opioid overdose was reported in 161 cases; of these, 66 contained sufficient information to determine latency. Reporting rates of opioid overdose per 10,000 patients treated were similar among latency groups: 0.54 for ≤28 days (0.24 fatal), 0.34 for 29-56 days (0.16 fatal), and 0.44 for >56 days (0.40 fatal) from the last dose of XR-NTX.

CONCLUSIONS

Over the 12-year period, the reporting rates of opioid overdose were similar during treatment with or after discontinuation of XR-NTX and <10/10,000 patients exposed. Our findings are limited by the nature of spontaneously reported safety data.

Optimizing the impact of medications for opioid use disorder at release from prison and jail settings: A microsimulation modeling study

BACKGROUND

We examined the impact of expanded access to medications for opioid use disorder (MOUD) in a unified prison and jail system on post-release, opioid-related overdose mortality.

METHODS

We developed a microsimulation model to simulate a population of 55,000 persons at risk of opioid-related overdose mortality in Rhode Island. The effect of an extended-release (XR) naltrexone only intervention and the effect of providing access to all three MOUD (i.e., methadone, buprenorphine, and XR-naltrexone) at release from incarceration on cumulative overdose death over eight years (2017-2024) were compared to the standard of care (i.e., limited access to MOUD).

RESULTS

In the standard of care scenario, the model predicted 2385 opioid-related overdose deaths between 2017 and 2024. An XR-naltrexone intervention averted 103 deaths (4.3% reduction), and access to all three MOUD averted 139 deaths (5.8% reduction). Among those with prior year incarceration, an XR-naltrexone only intervention and access to all three MOUD reduced overdose deaths by 22.8% and 31.6%, respectively.

CONCLUSIONS

Expanded access to MOUD in prison and jail settings can reduce overdose mortality in a general, at-risk population. However, the real-world impact of this approach will vary by levels of incarceration, treatment enrollment, and post-release retention.

Impact of Pharmacological Treatments for Opioid Use Disorder on Mortality

The use of pharmacological treatments for opioid use disorders, including methadone, buprenorphine and naltrexone has been associated with a reduction in mortality compared with illicit opioid use. However, these treatments can also contribute significantly to the risk of death. The opioid agonists methadone and buprenorphine achieve clinical efficacy in patients with an opioid use disorder through suppressing craving and diminishing the effectiveness of illicit opioid doses, while the antagonist naltrexone blocks the action of opioids. Pharmacological differences between opioid pharmacotherapies then create different temporal patterns of protection and mortality risk, different risks of relapse to illicit opioid use, and variations in direct and indirect toxicity, which are revealed in clinical and epidemiological studies. Induction onto methadone and the cessation of oral naltrexone treatment are associated with an elevated risk of opioid poisoning, which is not apparent in patients treated with buprenorphine or sustained-release naltrexone. Beyond drug-related mortality, these pharmacotherapies can impact a participant's risk of death. Buprenorphine may also have some advantages over methadone in patients with depressive disorders or cardiovascular abnormalities. Naltrexone, which is also commonly prescribed to manage problem alcohol use, may reduce deaths in chronic co-alcohol users. Understanding these pharmacologically driven patterns then guides the judicious choice of drug and dosing schedule and the proactive risk management that is crucial to minimising the risk of death in treatment.

America's opioid crisis: the need for an integrated public health approach

Continued increases in overdose deaths and recent declines in life expectancy call for need to adopt comprehensive public health approaches to the United States opioid crisis and to establish an infrastructure to avert future crises. Successfully addressing the challenges posed by the crisis requires a translational, integrated approach that combines the contribution of neuroscience, pharmacology, epidemiology, treatment services and prevention. It also is critical to integrate interventions across settings, including healthcare, justice, education and social service systems. This review highlights four interconnected themes: (1) social determinants of health and disease; (2) person-centered approaches for prevention and treatment; (3) bridging the gap between implementation science and practice; and (4) using data to build learning systems of care, relevant to public health approaches to address the opioid crisis. We discuss how across these four themes taking into account the influence of developmental factors on brain function and sensitivity to environmental stimuli including drugs, addressing the complex interactions between biological and social factors, and promoting an ongoing dialogue across disciplines and settings will help accelerate public health advances that are evidenced based and sustainable to address the current opioid crisis and avert future ones.

Medication Treatment of Opioid Use Disorder

Opioid use disorder (OUD) is a chronic, relapsing condition, often associated with legal, interpersonal, and employment problems. Medications demonstrated to be effective for OUD are methadone (a full opioid agonist), buprenorphine (a partial agonist), and naltrexone (an opioid antagonist). Methadone and buprenorphine act by suppressing opioid withdrawal symptoms and attenuating the effects of other opioids. Naltrexone blocks the effects of opioid agonists. Oral methadone has the strongest evidence for effectiveness. Longer duration of treatment allows restoration of social connections and is associated with better outcomes. Treatments for OUD may be limited by poor adherence to treatment recommendations and by high rates of relapse and increased risk of overdose after leaving treatment. Treatment with methadone and buprenorphine has the additional risk of diversion and misuse of medication. New depot and implant formulations of buprenorphine and naltrexone have been developed to address issues of safety and problems of poor treatment adherence. For people with OUD who do not respond to these treatments, there is accumulating evidence for supervised injectable opioid treatment (prescribing pharmaceutical heroin). Another medication mode of minimizing risk of overdose is take-home naloxone. Naloxone is an opioid antagonist used to reverse opioid overdose, and take-home naloxone programs aim to prevent fatal overdose. All medication-assisted treatment is limited by lack of access and by stigma. In seeking to stem the rising toll from OUD, expanding access to approved treatment such as methadone, for which there remains the best evidence of efficacy, may be the most useful approach.

A Brief Overview of Identification and Management of Opiate Use Disorder in the Primary Care Setting

This article offers a brief review geared toward primary care providers of the most critical aspects of the management of opiate use disorder, including screening, brief intervention, and referral to treatment as well as medication-assisted treatment and the alarming trends and dangers of illicitly produced fentanyl.

Circumstances of death of opioid users being treated with naltrexone

BACKGROUND AND AIMS

Naltrexone is an opioid antagonist used as a maintenance drug for the treatment of opioid dependence and in opioid withdrawal regimens. The current study aimed to: (1) determine the clinical characteristics and circumstances of death of people undergoing naltrexone treatment for opioid dependence; and (2) determine the blood toxicology of cases including naltrexone concentrations, the presence of other drugs and a comparison of morphine concentrations in the presence and absence of naltrexone.

DESIGN

Retrospective study of all deaths among people undergoing naltrexone treatment for opioid dependence retrieved from the National Coronial Information System, 2000-17.

SETTING

Australia-wide.

CASES

Seventy-four cases, with a mean age of 32.5 years; 81.1% male.

MEASUREMENTS

Information was collected on demographics, manner of death, naltrexone treatment history, toxicology and major organ pathology.

FINDINGS

Death was attributed to opioid toxicity in 86.5% of cases: accidental (79.7%), deliberate (6.8%). In 55.4% of all cases the decedent was maintained on oral naltrexone and 32.4% had a recent naltrexone implant. In five cases the decedent was undergoing opioid detoxification. Among those screened for naltrexone, naltrexone was present in the blood or urine of 52.5% (15.8% of oral maintenance cases, 85.7% of implant cases). Fourteen cases were known to have died from opioid toxicity with naltrexone present in their blood or urine. The median blood naltrexone concentrations were within the reported therapeutic range.

CONCLUSIONS

The primary cause of death among people undergoing naltrexone treatment for opioid dependence in Australia from 2000 to 2017 was opioid toxicity, the majority of cases having been maintained on oral naltrexone. Cases in which naltrexone was not detected indicate the importance of treatment compliance. Deaths due to opioid toxicity where naltrexone was present indicates the possibility of overdose while naltrexone medication is maintained.

Global patterns of opioid use and dependence: harms to populations, interventions, and future action

We summarise the evidence for medicinal uses of opioids, harms related to the extramedical use of, and dependence on, these drugs, and a wide range of interventions used to address these harms. The Global Burden of Diseases, Injuries, and Risk Factors Study estimated that in 2017, 40·5 million people were dependent on opioids (95% uncertainty interval 34·3-47·9 million) and 109 500 people (105 800-113 600) died from opioid overdose. Opioid agonist treatment (OAT) can be highly effective in reducing illicit opioid use and improving multiple health and social outcomes-eg, by reducing overall mortality and key causes of death, including overdose, suicide, HIV, hepatitis C virus, and other injuries. Mathematical modelling suggests that scaling up the use of OAT and retaining people in treatment, including in prison, could avert a median of 7·7% of deaths in Kentucky, 10·7% in Kiev, and 25·9% in Tehran over 20 years (compared with no OAT), with the greater effects in Tehran and Kiev being due to reductions in HIV mortality, given the higher prevalence of HIV among people who inject drugs in those settings. Other interventions have varied evidence for effectiveness and patient acceptability, and typically affect a narrower set of outcomes than OAT does. Other effective interventions focus on preventing harm related to opioids. Despite strong evidence for the effectiveness of a range of interventions to improve the health and wellbeing of people who are dependent on opioids, coverage is low, even in high-income countries. Treatment quality might be less than desirable, and considerable harm might be caused to individuals, society, and the economy by the criminalisation of extramedical opioid use and dependence. Alternative policy frameworks are recommended that adopt an approach based on human rights and public health, do not make drug use a criminal behaviour, and seek to reduce drug-related harm at the population level.

Medications for management of opioid use disorder

Purpose

The use of buprenorphine, methadone, and long-acting naltrexone for treatment of opioid use disorder (OUD) is discussed, including a review of current literature detailing treatment approaches and action steps to optimize treatment in acute care and office-based settings.

Summary

The U.S. epidemic of opioid-related deaths has been driven by misuse of prescription opioids and, increasingly, illicit drugs such as heroin, fentanyl, and fentanyl analogs, necessitating a refocusing of treatment efforts on expanding access to life-saving, evidence-based OUD pharmacotherapy. Inpatient treatment of opioid withdrawal includes acute symptom control through a combination of nonopioid medications and long-term pharmacotherapy to lessen opioid craving and facilitate stabilization and recovery. Methadone and buprenorphine reduce opioid craving, increase treatment retention, reduce illicit opioid use, and increase overall survival. Buprenorphine has logistical advantages over methadone, such as greater flexibility of treatment setting and less risk of adverse effects. Studies have shown the efficacy of long-acting injectable naltrexone to be comparable to that of buprenorphine if patients are detoxified prior to initiation of therapy; however, patients with active OUD are often not able to complete the week-long period of opioid abstinence needed prior to initiation of naltrexone injections. Although buprenorphine is preferred by many patients and can be prescribed in office-based settings, there remains a paucity of physicians certified to prescribe it.

Conclusion

Buprenorphine has become the medication of choice for many patients with OUD, but its use is limited by the low number of physicians certified to prescribe the agent. Other agents studied for treatment of OUD include methadone and naltrexone.

Overdose following initiation of naltrexone and buprenorphine medication treatment for opioid use disorder in a United States commercially insured cohort

BACKGROUND AND AIMS

Despite the growing opioid overdose crisis, medication treatment for opioid use disorder remains uncommon. The comparative effectiveness of buprenorphine and naltrexone treatment in reducing overdose and the comparative risks of discontinuing treatment in the real world, remain uncertain. Our aim was to examine the effectiveness of medications for opioid use disorder in preventing opioid-related overdose.

DESIGN

Retrospective cohort study SETTING: United States.

PATIENTS

46,846 commercially insured individuals diagnosed with opioid use disorder and initiating medication treatment between 2010 and 2016.

MEASUREMENTS

Opioid-related overdose identified by International Classification of Diseases, Ninth and Tenth Revisions.

FINDINGS

In our sample, 1386 individuals were prescribed extended-release injectable naltrexone (median filled prescriptions = 9 months), 7782 were prescribed oral naltrexone (5 months), and 40,441 were prescribed buprenorphine (19 months) at least once during follow-up. Individuals receiving buprenorphine therapy were at significantly reduced risk of opioid-related overdose compared to no treatment (adjusted hazard ratio (HR) = 0.40, 95% CI 0.35-0.46), while a significant association was not observed in extended-release injectable (HR = 0.74, 95% CI 0.42-1.31) or oral (HR = 0.93, 95% CI 0.71-1.22) naltrexone. We found no association with opioid overdose within four weeks of discontinuation of any medication.

CONCLUSION

Among commercially-insured patients who initiate medications for opioid use disorder, buprenorphine, but not naltrexone, was associated with lower risk of overdose during active treatment compared to post-discontinuation. More research is needed to understand the benefits and risks unique to each treatment option to better tailor therapies to patients with opioid use disorder.

The United States opioid epidemic

The United States opioid epidemic is a nationwide public health crisis. Initially driven by increased consumption and availability of pharmaceutical opioids, an increasing number of opioid overdoses are now related to heroin and illicitly manufactured fentanyl and fentanyl analogs. Addressing this epidemic requires addressing the stigma associated with opioid use disorders and its treatment, improving access to efficacious treatment options, specifically methadone and buprenorphine, and reducing opioid overdose fatalities with distribution of the opioid antagonist and overdose reversal agent naloxone.