Fatal opiate overdose following regimen changes in naltrexone treatment

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.

Rapid opiate detoxification and antagonist induction under general anaesthesia or intravenous sedation is humane, sometimes essential and should always be an option. Three illustrative case reports involving diabetes and epilepsy and a review of the literature

When abstinence is an appropriate goal, controlled studies and systematic reviews confirm that rapid, antagonist-precipitated opiate withdrawal procedures are the most effective and cost effective methods of initiating abstinence, and naltrexone (NTX) maintenance. While 'rapid' withdrawal, better conceptualised as Rapid Antagonist Induction (RAI), can often be humanely achieved with modest sedation levels, we present three case histories to support our argument that for some patients, general anaesthesia (GA), or techniques of intravenous sedation (IVS) that approach GA, are essential for safety and success. This includes patients with intercurrent disease (e.g. epilepsy or insulin-dependent diabetes) but also those with severe withdrawal phobia after previous distressing experiences. We discuss the history of the procedure. The dangers of RAI under GA or IVS in experienced hands have been exaggerated and the appropriate expertise should be more easily available. Patients and clinicians readily accept risks of major surgery for the excessive intake of food that causes most obesity. Similar risk-acceptance exists in cosmetic surgery and obstetrics. The increasing use and effectiveness of long-acting implants or depot-injections of NTX for relapse-prevention have largely solved compliance problems that undermined the potential of oral NTX. Their ability to prevent opiate overdose in abstinent, non-tolerant patients also strengthens arguments both for offering RAI as a therapeutic option and for reducing psychological, professional and practical barriers to using it.

Naltrexone depot formulations for opioid and alcohol dependence: a systematic review

Naltrexone is an opioid receptor antagonist that blocks the reinforcing effects of opioids and reduces alcohol consumption and craving. It has no abuse potential, mild and transient side effects, and thus appears an ideal pharmacotherapy for opioid dependence. Its effectiveness in alcohol dependence is less evident, but compliance with naltrexone combined with psychosocial support has been repeatedly shown to improve drinking outcomes. Limited compliance with oral naltrexone treatment is a known drawback. Several naltrexone implant and injectable depot formulations are being investigated and provide naltrexone release for at least 1 month. Studies among opioid-dependent patients indicate significant reductions in heroin use, but sample sizes are usually small. In alcohol dependence, two large multicenter trials report alcohol and craving reductions for naltrexone and placebo groups, indicating a significant but moderate effect. The pharmacokinetic profile of the injectable formulation indicates reliable naltrexone release over 1 month at therapeutic levels. Implant formulations releasing naltrexone up to 7 months are reported. Findings on safety and tolerability confirm the generally mild adverse effects described for naltrexone tablets. However, further research on therapeutic levels (i.e., opioid blocking) is warranted. The majority of naltrexone implants lacks approval for regular clinical use and larger longitudinal studies are needed. The available naltrexone depot formulations have the potential to significantly improve medication compliance in opioid and alcohol dependence. In certain circumstances, they may constitute a promising new treatment option.

Pharmacological enhancement of naltrexone treatment for opioid dependence: a review

PURPOSE: Opioid dependence (OD) is a serious and growing clinical condition with increasing social costs that requires expanding treatment beyond opioid agonist substitution. The opioid antagonist naltrexone has displayed a remarkable association of theoretical effectiveness and poor clinical utility in treating OD due to noncompliant behavior and low acceptability among patients, only partly modified by psychosocial interventions. We reviewed pharmacological studies, including naltrexone depot formulations and combination treatments. METHOD: We searched PubMed for clinical studies on the use of naltrexone implants and slow-release injections in OD, and investigations using adjunct medications to improve naltrexone maintenance therapy of OD. We discussed the results in view of their application to the clinical practice. RESULTS: Significant reduction in opioid use and improved retention in treatment have been found in several studies using depot naltrexone formulations, some of which are controlled clinical trials. Pilot investigations have gathered initial positive results on the use of naltrexone in combination with serotonin reuptake inhibitors, α-2 adrenergic, opioid, and γ-aminobutyric acid agonist medications. CONCLUSION: Current evidence suggests that more research on effectiveness and safety is needed in support of depot naltrexone treatment for OD. Further research comparing slow-release with oral naltrexone and opioid agonist medications will help characterize the role of opioid antagonist-mediated treatment of OD. Preliminary investigations on naltrexone combination treatments suggest the opportunity to continue study of new mixed receptor activities for the treatment of OD and other drug addictions.

Sustained-release naltrexone for opioid dependence

BACKGROUND

Naltrexone is an opioid antagonist which effectively blocks heroin effects. Since opioid dependence treatment with naltrexone tablets suffers from high dropout rates, several depot injections and implants are under investigation. Sustained-release formulations are claimed to be effective, but a systematic review of the literature is lacking.

OBJECTIVES

To evaluate the effectiveness of sustained-release naltrexone for opioid dependence and its adverse effects in different study populations.

SEARCH STRATEGY

The following databases were searched from their inception to November 2007: Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, CINAHL, LILACS, PsycINFO, ISI Web of Science, trial database at http://clinicaltrials.gov, available NIDA monographs, CPDD and AAAP conference proceedings. The reference lists of identified studies, published reviews and relevant web sides were searched manually. Study authors and drug companies were contacted to obtain any unpublished material or missing data.

SELECTION CRITERIA

To evaluate effectiveness only RCTs were included. To evaluate safety, any clinical trial reporting adverse effects was assessed. Treatment condition was extended to include alcohol dependent subjects and healthy volunteers.

DATA COLLECTION AND ANALYSIS

Reviewers independently evaluated the reports, rated methodological quality and extracted data. Analyses were performed separately for opioid dependent, alcohol dependent and healthy participants.

MAIN RESULTS

Foe effectiveness, one report met inclusion criteria. Two dosages of naltrexone depot injections (192 and 384 mg) were compared to placebo. High-dose significantly increased days in treatment compared to placebo (WMD 21.00, 95% CI 10.68 to 31.32, p<0.0001). High-dose compared to low-dose significantly increased days in treatment (WMD 12.00, 95% CI 1.69 to 22.31, p=0.02). Number of patients retained in treatment did not show significant differences between groups. For adverse effects, seventeen reports met inclusion criteria analyses, six were RCTs. Side effects were significantly more frequent in naltrexone depot groups compared to placebo. In alcohol dependent samples only, adverse effects appeared to be significantly more frequent in the low-dose naltrexone depot groups compared to placebo (RR 1.18, 95% CI 1.02 to 1.36, p=0.02). In the opioid dependent sample, group differences were not statistically significant. Reports on systematic assessment of side effects and adverse events were scarce.

AUTHORS' CONCLUSIONS

There is insufficient evidence to evaluate the effectiveness of sustained-release naltrexone for treatment of opioid dependence. For naltrexone injections, administration site-related adverse effects appear to be frequent, but of moderate intensity and time limited. For a harm-benefit evaluation of naltrexone implants, more data on side effects and adverse events are needed.

Mortality related to pharmacotherapies for opioid dependence: a comparative analysis of coronial records

INTRODUCTION AND AIMS

The aim of this study was to compare the mortality associated with oral naltrexone, methadone and buprenorphine in opioid dependence treatment, employing a retrospective data analysis using coronial and prescription data.

DESIGN AND METHODS

The number of deaths were identified through national coronial data and number of treatment recipients were estimated from 2000 to 2003 prescriptions and restricted medications data. Mortality rates were expressed as deaths per number of treatment episodes and per person-years at high and low risk of fatal opioid overdose.

RESULTS

Thirty-two oral naltrexone, one buprenorphine and 282 methadone-related deaths were identified. Mortality rates in the highest risk period in deaths per 100 person-years were 22.1 (14.6 - 32.2) for oral naltrexone following treatment cessation and 3.0 (2.3 - 3.9) for methadone during treatment induction. Rates in the lowest risk period in deaths per 100 person-years were 1.0 (0.3 - 2.2) during oral naltrexone treatment and 0.34 (0.3 - 0.4) during post-induction methadone treatment. The relative risk of death for oral naltrexone subjects was 7.4 times (high-risk period, p < 0.0001) or 2.8 times (low-risk period, p = 0.055) that of methadone subjects.

DISCUSSION AND CONCLUSIONS

This is the first comparison of mortality associated with these three pharmacotherapies for opioid dependence. The risk of death related to oral naltrexone appears higher than that related to methadone treatment.

Mortality in heroin users 3 years after naltrexone implant or methadone maintenance treatment

Concerns that treatment for heroin dependence using naltrexone may increase suicide rates during treatment and fatal overdoses posttreatment have been expressed. There is also disquiet about mortality during induction onto methadone. We assessed mortality during specific periods following treatment with naltrexone implants or methadone. Data were assembled using the Western Australian Data Linkage System. The methadone cohort comprised all those who started methadone in Western Australia during 2001-2002: The naltrexone cohort comprised all Western Australian heroin-dependent persons who received their first implant in 2001-2002. There were 15 (2.7%) deaths in the methadone cohort (n = 553) and 6 (1.8%) deaths in the naltrexone cohort (n = 341). Mortality rates for the "initial 14-day period," "stable treatment," and "overall" were 94.47, 0.0, and 5.83 deaths/1,000 person-years for the methadone group. In the naltrexone group, the rates "during first treatment (0-6 months)," "post first treatment," and overall were 0.0, 4.21, and 3.76 deaths/1,000 person-years. The age-standardized mortality rate ratio for naltrexone compared to methadone was 0.645 (95% confidence interval = 0.123-1.17). Increased mortality during induction onto methadone was confirmed. Evidence relating naltrexone to either increased suicide or overdose was not found. Overall mortality rates for naltrexone implant were similar to those for methadone, but increased mortality during methadone induction was avoided.

Prescription naloxone: a novel approach to heroin overdose prevention

The mortality and morbidity from heroin overdose have increased in the United States and internationally in the last decade. The lipid solubility allows the rapid deposition of heroin and its metabolites into the central nervous system and accounts for the "rush" experienced by users and for the toxicity. Risk factors for fatal and nonfatal heroin overdoses such as recent abstinence, decreased opiate tolerance, and polydrug use have been identified. Opiate substitution treatment such as methadone or buprenorphine is the only proven method of heroin overdose prevention. Death from a heroin overdose most commonly occurs 1 to 3 hours after injection at home in the company of other people. Numerous communities have taken advantage of this opportunity for treatment by implementing overdose prevention education to active heroin users, as well as prescribing naloxone for home use. Naloxone is a specific opiate antagonist without agonist properties or potential for abuse. It is inexpensive and nonscheduled and readily reverses the respiratory depression and sedation caused by heroin, as well as causing transient withdrawal symptoms. Program implementation considerations, legal ramifications, and research needs for prescription naloxone are discussed.

Sustained-release naltrexone formulations for the treatment of alcohol and opioid dependence

Naltrexone, an opioid receptor antagonist, is effective in the treatment of alcohol and opioid dependence. An important limitation of the use of oral naltrexone is the lack of efficacy among patients who do not consistently take the medication. The advent of a sustained-release naltrexone addresses the problem of noncompliance. Naltrexone can be compounded into microcapsules that can be injected or implanted, producing a clinical response lasting from 30 days to several months. Several randomized, placebo-controlled clinical trials demonstrate that sustained-release naltrexone is safe and effective for the treatment of both alcohol and opioid dependence. Sustained-release formulations of naltrexone may offer several advantages over its oral formulation with respect to medication compliance, pharmacokinetics, side effect profile and ease of use. Recently, one formulation of sustained-release naltrexone received approval from the US FDA and offers a new option for addiction treatment.