Methadone toxicity fatalities: a review of medical examiner cases in a large metropolitan area

Possible Delay in Symptomatology of a Methadone Overdose in a Patient Ingesting an Energy Drink and Dextroamphetamine/Amphetamine

Introduction: Methadone is a mu-opioid agonist with a delayed time to peak concentration that requires an extended period of monitoring following an overdose. Available data suggests that the combination of psychostimulants with methadone may augment antinociception and tolerance to opioids. Case Report: A 26-year-old male (83.9 kg) presented to the ED approximately 1 hour after unintentionally ingesting 200-250 mg of liquid methadone and an energy drink, along with 20 mg of dextroamphetamine/amphetamine prior to the event. Vital signs were: blood pressure (BP), 143/91 mmHg; heart rate (HR), 74; respirations (RR), 16; oxygen saturation 95% on room air. His urine drug screen was positive for amphetamines and methadone. Patient was monitored for 4 hours with no change in status and was discharged home. Approximately 26 hours later patient was found cyanotic and apneic. Patient was given 2 mg of naloxone and awoke with normal mental status. On presentation the patient's vital signs were: BP, 114/70 mmHg; HR, 114; RR 16; oxygen saturation 94% on 3 liters nasal cannula. During his ED stay, he required 2 doses of naloxone secondary to oxygen desaturation and was admitted to the hospital. His repeat urine drug screen was positive for amphetamines and methadone. The patient was discharged the following day. Discussion: This case illustrates an unintentional methadone overdose combined with the intentional ingestion of an energy drink and dextroamphetamine/amphetamine that possibly masked the toxicity for over 24 hrs. Monitoring parameters for methadone overdoses may need re-evaluation in the setting of the co-ingestion of a stimulant.

Chronic exposure to methadone induces activated microglia and astrocyte and cell death in the cerebellum of adult male rats

Methadone is a centrally-acting synthetic opioid analgesic widely used in the methadone maintenance therapy (MMT) programs throughout the world. Considering its neurotoxic effects particularly on the cerebellum, this study aims to address the behavioral and histological alterations in the cerebellar cortex associated with methadone administration. Twenty-four adult male albino rats were randomized into two groups of control and methadone treatment. Methadone was subcutaneously administered (2.5-10 mg/kg) once a day for two consecutive weeks. The functional and structural changes in the cerebellum were compared to the control group. Our data revealed that treating rats with methadone not only induced cerebellar atrophy, but also prompted the actuation of microgliosis, astrogliosis, and apoptotic biomarkers. We further demonstrated that treating rats with methadone increased complexity of astrocyte processes and decreased complexity of microglia processes. Our result showed that methadone impaired motor coordination and locomotor performance and neuromuscular activity. Additionally, relative gene expression of TNF-α, caspase-3 and RIPK3 increased significantly due to methadone. Our findings suggest that methadone administration has a neurodegenerative effect on the cerebellar cortex via dysregulation of microgliosis, astrogliosis, apoptosis, and neuro-inflammation.

Beyond the 'purple drank': Study of promethazine abuse according to the European Medicines Agency adverse drug reaction reports

BACKGROUND

Promethazine is a medicinal product, available on its own or in combination with other ingredients including dextromethorphan, paracetamol and/or expectorants. Anecdotal reports have however indicated that promethazine may have a misuse potential, especially in adolescents.

OBJECTIVE

We here aimed at studying how this phenomenon has been reported to the European Monitoring Agency Adverse Drug Reactions database.

METHODS

After a formal request to the European Monitoring Agency, the promethazine-specific dataset has been studied, performing a descriptive analysis of misuse/abuse/dependence-related adverse drug reaction reports. The study was approved by the University of Hertfordshire (LMS/PGR/UH/03234).

RESULTS

The analysis of promethazine data showed increasing levels of misuse/abuse/ dependence issues over time (2003-2019). Out of a total number of 1543 cases of adverse drug reactions, the abuse/misuse/dependence-related cases reported were 557, with 'drug abuse' (300/557: 53.8%) and 'intentional product misuse' (117/557: 21.0%). being the most represented adverse drug reactions. A high number of fatalities were described (310/557: 55.6%), mostly recorded as 'drug toxicity/drug abuse' cases, with opiates/opioids having been the most commonly reported concomitant drugs used.

CONCLUSION

Anecdotal promethazine misuse/abuse reports have been confirmed by European Monitoring Agency data. Promethazine misuse/abuse appears to be an alarming issue, being associated with drug-related fatalities. Thus, healthcare professionals should be warned about a possible misuse of promethazine and be vigilant, as in some countries medicinal products containing promethazine can be purchased over the counter. Since promethazine is often available in association with opioids, its abuse may be considered a public health issue, with huge implications for clinical practice.

The Role of Risk or Contributory Death Factors in Methadone-Related Fatalities: A Review and Pooled Analysis

Methadone-related deaths are characterized by a wide range of post-mortem blood concentrations, due to the high pharmacokinetic/dynamic inter-individual variability, the potential subjective tolerance state and to other risk factors or comorbidities, which might enhance methadone acute toxicity. In the present study, the association among pre-existing and external conditions and diseases and the resultant methadone death capacity have been investigated. Beside a systematic literature review, a retrospective case-control study was done, dividing cases in which methadone was the only cause of death (controls), and those with associated clinical-circumstantial (naive/non-tolerant state), pathological (pulmonary or cardiovascular diseases) or toxicological (other drugs detected) conditions. Methadone concentrations were compared between the two groups and the association with conditions/diseases was assessed by multiple linear and binomial logistic regressions. Literature cases were 139, in house 35, consisting of 22 controls and 152 cases with associated conditions/diseases. Mean methadone concentrations were 2122 ng/mL and 715 ng/mL in controls and cases respectively, with a statistically significant difference (p < 0.05). Lower methadone concentrations (by 24, 19 and 33% respectively) were detected in association with naive/non-tolerant state, pulmonary diseases and presence of other drugs, and low levels of methadone (<600 ng/mL) might lead to death in the presence of the above conditions/diseases.

Quantification of methadone and its metabolites: EDDP and EMDP determined in autopsy cases using LC-MS/MS

The paper presents a method for the determination of methadone, EDDP, and EMDP in postmortem biological materials using liquid-liquid extraction with ethyl acetate (pH9) and UHPLC-MS/MS technique. Methadone-d₉ and EDDP-d₃ were used as the internal standards. The method validation results for blood and urine were as follows: linearity: 0.5-1000 ng/ml; R²  > 0.9993 for methadone, EDDP and R²  > 0.9944 for EMDP. Intra- and inter-day precision: 0.1%-7.5% and 0.3%-8.6%, respectively; intra- and inter-day accuracy: -11.8% to 13.9% and -9.3 to 14.8%, respectively; recovery: 91.5%-123.0%; matrix effect: 83.5%-123.9%. This study also describes 18 postmortem cases, where methadone concentrations ranged 2.3-1180 ng/ml in blood (n = 17), from 11.0 to >10,000 ng/ml in urine (n = 13) and 135.2-409.0 in vitreous humor (VH, n = 3). EDDP concentrations ranged from not detectable to 180 ng/mL in blood, from 42.4 to >10,000 ng/ml in urine and 18.3-36.5 in VH. EMDP concentrations were found in four cases in blood from below LLOQ to 1.8 ng/ml and in seven cases in urine, ranged 2.1-243.0 ng/ml. EMDP was not detected in VH samples. The EDDP/methadone ratios and blood/urine ratios for methadone and EDDP in EMDP-positive and negative cases were performed. The paper presents mass spectra of other methadone metabolites, than EDDP and EMDP (ring hydroxylated methadone, ring hydroxylated EDDP, ring hydroxylated EMDP, methadol, and DDP). Simultaneous determination of methadone and its metabolites in order to unequivocally interpret the results of toxicological tests seems to be useful in cases related to prescription/illicit use of methadone.

Overdose mortality rates in Croatia and factors associated with self-reported drug overdose among persons who inject drugs in three Croatian cities

BACKGROUND

Drug overdose is the major cause of morbidity and mortality among persons who inject drugs (PWID). We assessed factors associated with the non-fatal drug overdose among PWID in three Croatian cities and national trends of overdose-related mortality (OM), and rates of uptake of opioid agonist drug treatment (OAT).

METHODS

We used a respondent-driven sampling method to recruit 830 PWID in Zagreb, Split and Rijeka in 2014/2015. Participants completed behavioural questionnaires that included questions about overdose history, and we used Poisson regression to assess factors associated with self-reported overdose. We used joinpoint regression to calculate national trends of OM from 2001 to 2015 and rates of uptake of drug treatment from 2005 to 2015.

RESULTS

Lifetime prevalence of self-reported drug overdose in our RDS sample was 45.2%, while 4.1% of PWID reported overdose in the past 12 months; PWID who injected more than one type of drug in the past 12 months (adjusted prevalence ratio [aPR] = 4.56, 95% confidence intervals [CI] = 1.35-15.38) compared to injecting only heroin, and those enrolled in OAT (aPR = 1.94, 95% CI = 1.01-3.74) were more likely to report overdose in the past 12 months. We observed an increase in annual percent change (APC) of the national OM rates from 2001 to 2007 (APC = 22.5%, 95% CI = 16.3-29.0) and a decline from 2007 to 2015 (APC = -8.0%, 95% CI = -5.3- -10.5). The national rates of drug treatment enrollment increased from 2005 to 2010 (APC = 12.0%, 95% CI = 10.3-13.8), mostly due to increase in provision of buprenorphine from 2005 to 2008 (APC = 130.4%, 95% CI = 102.1-162.7).

CONCLUSION

Injecting more than one type of drugs and enrollment in OAT while still injecting drugs was positively associated with non-fatal overdose in our sample. To further reduce OM in Croatia we suggest improvements in coverage and delivery of OAT and establishment of provision of naloxone for PWID.

Methadone Maintenance Treatment: A 15-year Retrospective Study in Split-Dalmatia County, Croatia

BACKGROUND

The aim of this retrospective study is to use existing epidemiological data on patients in methadone maintenance treatment in Split-Dalmatia County from 2001 to 2015 to evaluate the substitution treatment system and policy of opiate addicts treatment, the epidemiological trend, and risk of overdose mortality. In addition, we would like to highlight the problem of poor control of methadone therapy and thus the possibility of selling methadone. The result is a greater number of deaths caused by methadone in people who were not in methadone therapy.

METHODS

The research included data collected from 3189 patients who had been in the drug abuse treatment program in Split-Dalmatia County during 2001-2015 and data gathered from autopsy examinations of patients in Split-Dalmatia County with emphasis on data for 186 overdosed patients during research period.

RESULTS

The total number of patients in the methadone treatment program in Split-Dalmatia County during the research period, except in 2005 and 2006, has been stable, while the number of new opiate patients, being in first-time treatment, decreased by 62.5%. The number of addicts who were in a long-term maintenance program has increased by 198%, whereas the number of addicts who were in a short-term detoxification treatment has decreased by 96.4%. According to results obtained from performed autopsies, 186 death cases were determined as overdoses. Methadone was found in 56 of those cases and was declared as the cause of death in 39 cases (70%). Of the total number of autopsied patients with diagnosed methadone overdose, only 23 (59%) had been recorded to receive methadone therapy in Public Health Institute of Split-Dalmatia County database.

CONCLUSIONS

The results of this study show the favorable epidemiological trend because of the decreasing number of new opiate patients in treatment. The retention of opiate patients in substitution therapy indicates the effectiveness of methadone maintenance programs. Our research did not determine any influence of methadone substitution therapy on an increasing risk of specific (overdose) mortality.

Delay-Dependent Impairments in Memory and Motor Functions After Acute Methadone Overdose in Rats

Methadone is used as a substitution drug for the treatment of opioid dependence and chronic pain. Despite its widespread use and availability, there is a serious concern with respect to the relative safety of methadone. The purpose of this study was to characterize how acute methadone overdose affects the cognitive and motor performance of naïve healthy rats. The methadone overdose was induced by administering an acute toxic dose of methadone (15 mg/kg; ip; the equivalent dose of 80% of LD50) to adolescent rats. Resuscitation using a ventilator pump along with a single dose of naloxone (2 mg/kg; ip) was administered following the occurrence of apnea. The animals which were successfully resuscitated divided randomly into three apnea groups that evaluated either on day 1, 5, or 10 post-resuscitation (M/N-Day 1, M/N-Day 5, and M/N-Day 10 groups) in the Y-maze and novel object memory recognition tasks as well as pole and rotarod tests. The data revealed that a single toxic dose of methadone had an adverse effect on spontaneous behavior. In addition, Recognition memory impairment was observed in the M/N-Day 1, 5, and 10 groups after methadone-induced apnea. Further, descending time in the M/N-Day 5 group increased significantly in comparison with its respective Saline control group. The overall results indicate that acute methadone-overdose-induced apnea produced delay-dependent cognitive and motor impairment. We suggest that methadone poisoning should be considered as a possible cause of delayed neurological disorders, which might be transient, in some types of memory or motor performance in naïve healthy rats.

Abuse and Intentional Misuse of Promethazine Reported to US Poison Centers: 2002 to 2012

OBJECTIVE

Promethazine abuse has been reported. The objective was to investigate promethazine abuse/misuse in the United States.

METHODS

An 11-year retrospective review was conducted of promethazine abuse and intentional misuse cases without co-ingestants in persons 10 years and older reported to the National Poison Data System. Data were stratified by product (promethazine-alone [PA] or co-formulation [PC]) and evaluated for demographics, toxicity, management sites, and outcomes.

RESULTS

There were 354 single product abuse or misuse exposures-95 PA and 259 PC. Over the 11-year timeframe, the annual exposure rate per 100,000 population doubled. Exposures were most prevalent among 10 to 19 years old and young adults (20s), accounting for 69.5% of PA and 57.5% of PC cases. Clinical effects due to PA included drowsiness (43.2%), tachycardia (7.4%), agitation (13.7%), confusion (13.7%), slurred speech (12.6%), hallucinations (7.4%), dizziness (7.4%), and hypertension (5.3%). Drowsiness (53.4%) and tachycardia (20.8%) were more frequent with PC. There were significant differences between PA and PC in management site (P = 0.0078). Management sites for PA and PC, respectively, were emergency department (37.9%, 55.6%), non-health care facility (33.7%, 14.7%), critical care unit (8.4%, 11.2%), non-critical care unit (7.4%, 7.3%), psychiatry (2.1%, 4.2%), and other/unknown (10.5%, 7.0%). Outcomes for PA and PC, respectively, were no effect (21.0%, 12.4%), minor (58.9%, 53.7%), moderate (17.9%, 32.0%), and major effects (2.1%, 1.9%).

CONCLUSIONS

Promethazine-alone abuse/misuse most frequently resulted in minor outcomes, and less than 20% required medical admission. Abuse/misuse of PC resulted in a higher frequency of health care facility treatment and a trend toward more moderate outcomes. These differences are most likely attributed to the co-formulate.

Characteristics of methadone maintenance treatment patients prescribed opioid analgesics

BACKGROUND

Opioid analgesic use and disorders have dramatically increased among the general American population and those receiving methadone maintenance treatment (MMT). Most research among MMT patients focuses on opioid analgesics misuse or disorders; few studies focus on MMT patients prescribed opioid analgesics. We describe demographic, clinical, and substance use characteristics of MMT patients prescribed opioid analgesics and compare them with MMT patients not prescribed opioid analgesics.

METHODS

We conducted a cross-sectional secondary data analysis using screening interviews from a parent study. From 2012 to 2015, we recruited adults from 3 MMT Bronx clinics. Questionnaire data included patterns of opioid analgesic use, substance use, comorbid illnesses, and demographic characteristics. Our main dependent variable was patients' report of currently taking prescribed opioid analgesics. To compare characteristics between MMT patients prescribed and not prescribed opioid analgesics, we conducted chi-square tests, t tests, and Mann-Whitney U tests.

RESULTS

Of 611 MMT patients, most reported chronic pain (62.0%), hepatitis C virus (HCV) infection (52.1%), and current use of illicit substances (64.2%). Of the 29.8% who reported currently taking prescribed opioid analgesics, most misused their opioid analgesics (57.5%). Patients prescribed (versus not prescribed) opioid analgesics were more likely to report human immunodeficiency virus (HIV) infection (adjusted odds ratio [aOR] = 1.6, 95% confidence interval [CI]: 1.1-2.3) and chronic pain (aOR = 7.6, 95% CI: 4.6-12.6).

CONCLUSION

Among MMT patients primarily in 3 Bronx clinics, nearly one third reported taking prescribed opioid analgesics. Compared with patients not prescribed opioid analgesics, those prescribed opioid analgesics were more likely to report chronic pain and HIV infection. However, between these patients, there was no difference in illicit substance use. These findings highlight the complexity of addressing chronic pain in MMT patients.

Characteristics of methadone-related fatalities in Norway

There are currently over 7000 patients enrolled in opioid maintenance treatment (OMT) programs in Norway. A rise in methadone-related deaths proportional to increasing methadone sales over the period 2000-2006 has been observed, but the causative factors for these fatalities have been elusive. In the present study, individual characteristics, methadone concentrations and additional toxicological findings were analyzed. Methadone intoxication deaths (n = 264) were divided into 3 groups according to toxicological findings in whole blood: group 1 - methadone detected alone, or together with one additional drug at low or therapeutic levels, or a low concentration of ethanol (<1 g/L) (n = 21); group 2 - multiple additional drugs/substances detected below lethal levels (n = 175); group 3 - one or more additional drugs/substances detected at lethal levels, or ethanol >3 g/L (n = 55). Methadone blood concentrations in decedents who had been enrolled in OMT were higher than for decedents not in treatment, in all groups. Blood methadone concentrations around 1 mg/L were present in fatal multi-drug intoxications in OMT patients. Results suggest that some patients may be at risk of dying when combining therapeutic concentrations of methadone with other psychoactive substances. Somatic disease was a common finding among deceased OMT patients. Concentrations in methadone users not enrolled in OMT were predominantly between 0.3 and 0.4 mg/L and were not related to the presence of other drugs. However, methadone concentrations below 0.1 mg/L may be associated with intoxication following methadone use, both alone and in combination with other drugs. Younger male users (mean age 34 years) seemed to have a higher susceptibility to methadone intoxication.

Parent and Metabolite Opioid Drug Concentrations in Unintentional Deaths Involving Opioid and Benzodiazepine Combinations

Effects of benzodiazepines on postmortem opioid parent and parent/metabolite blood concentration ratios were determined for fentanyl-, hydrocodone-, methadone-, or oxycodone-related accidental deaths. These opioids are partially metabolized by the CYP3A4 enzyme system, which is also affected by diazepam and alprazolam. Opioid/metabolite combinations examined were as follows: fentanyl/norfentanyl, hydrocodone/dihydrocodeine, methadone/EDDP, and oxycodone/oxymorphone. Parent opioid concentrations were analyzed for 877 deaths. Parent/metabolite concentration ratios were analyzed for 349 deaths, excluding cases with co-intoxicants present known to interfere with opioid elimination. Alprazolam in combination with diazepam significantly decreased median hydrocodone concentrations by 48% (p = 0.01) compared to hydrocodone alone. The methadone parent/metabolite concentration ratio was reduced by 35% in the presence of diazepam compared to methadone alone (p = 0.03). Benzodiazepines did not statistically significantly affect fentanyl or oxycodone concentrations. Possible factors affecting opioid concentrations and possible toxicity development, including any differential effects on specific opioids, should continue to be explored.

A systematic review of the cardiotoxicity of methadone

Methadone is one of the most popular synthetic opioids in the world with some favorable properties making it useful both in the treatment of moderate to severe pain and for opioid addiction. Increased use of methadone has resulted in an increased prevalence of its toxicity, one aspect of which is cardiotoxicity. In this paper, we review the effects of methadone on the heart as well as cardiac concerns in some special situations such as pregnancy and childhood.

METHODS

We searched for the terms methadone, toxicity, poisoning, cardiotoxicity, heart, dysrhythmia, arrhythmia, QT interval prolongation, torsade de pointes, and Electrocardiogram (ECG) in bibliographical databases including TUMS digital library, PubMed, Scopus, and Google Scholar. This review includes relevant articles published between 2000 and 2013. The main cardiac effects of methadone include prolongation of QT interval and torsade de pointes. Other effects include changes in QT dispersion, pathological U waves, Taku-Tsubo syndrome (stress cardiomyopathy), Brugada-like syndrome, and coronary artery diseases. The aim of this paper is to inform physicians and health care staff about these adverse effects. Effectiveness of methadone in the treatment of pain and addiction should be weighed against these adverse effects and physicians should consider the ways to lessen such undesirable effects. This article presents some recommendations to prevent heart toxicity in methadone users.

Promethazine use among chronic pain patients

BACKGROUND

Concomitant use of opioids and promethazine has been reported in various subpopulations, including methadone maintenance patients, injection drug users, and at-risk teenagers. Promethazine is thought to potentiate the "high" from opioids. However, to date, the prevalence of promethazine use has not been determined among patients prescribed opioids for chronic pain.

METHODS

Urine samples from 921 patients prescribed opioids for chronic pain were analyzed for promethazine. Demographic data, toxicology results, and opioid prescription information were obtained through medical record abstraction. We assessed the prevalence and factors associated with promethazine use with bivariable and multivariable statistics.

RESULTS

The prevalence of promethazine-positive urine samples among chronic pain patients was 9%. Only 50% of promethazine-positive patients had an active prescription for promethazine. Having benzodiazepine-positive urine with no prescription for a benzodiazepine was statistically associated with promethazine use. Also, having a prescription for methadone for pain or being in methadone maintenance for the treatment of opioid dependence were both statistically associated with promethazine use. Chronic pain patients prescribed only a long-acting opioid were more likely to have promethazine-positive urines than patients prescribed a short-acting opioid.

CONCLUSIONS

The study provides compelling evidence of significant promethazine use in chronic pain patients. Promethazine should be considered as a potential drug of abuse that could cause increased morbidity in opioid-using populations.

Prognostic factors in acute methadone toxicity: a 5-year study

Background. Delayed or recurrent profound respiratory depression, ventricular dysrhythmias, acute lung injury, and death are the major complications of MTD overdose. We aimed to clarify the prognostic factors in MTD toxicity. Materials and Methods. Retrospectively, medical files of all patients poisoned by MTD and older than 12 years of age who had presented to Loghman Hakim Poison Center between 2007 and 2012 were evaluated. The data was compared between survivors and nonsurvivors. Results. Twenty-eight out of 322 patients died (mortality rate = 8.7%). MTD-related death was higher in patients with acute on chronic toxicity who were on daily dose of MTD and had ingested higher doses (in comparison to those with acute toxicity due to first-time exposure; 13% versus 6%). Renal failure was the most common medical complication related to deaths due to MTD toxicity. Conclusions. Based on previous researches, the most common cause of MTD overdose-related deaths is respiratory impairment; however, in our study, acute renal failure with or without rhabdomyolysis was the main delayed cause of deaths in MTD-poisoned patients. Antidotal therapy, early recognition, and treatment of hemodynamic compromise and rhabdomyolysis can be life-saving in these patients.

Assessment and Management of Chemical Coping in Patients With Cancer

Chemical coping is a working definition that describes patients' intake of opioids on a scale that spans the range between normal nonaddictive opioid use for pain all the way to opioid addiction. Most patients will fall somewhere between the two extremes in using opioid analgesics to cope with their psychological or spiritual distress. The degree to which patients use their medications in a maladaptive manner will determine their susceptibility to drug toxicity and harm. When there are no obvious cancer-related causes for increased pain intensity, chemical coping and other patient-related factors such as delirium, somatization, and depression should be considered. As part of the initial evaluation of patients with cancer-related pain, a brief screening tool such as the CAGE questionnaire should be used to identify patients who may be at risk for chemical coping. Identifying patients at risk will allow clinicians to avoid unnecessary opioid toxicity, control pain, and improve quality of life. A structured approach for managing opioid use should be adopted, including standardized documentation, opioid treatment agreements, urine drug screens, frequent visits, and restricted quantities of breakthrough opioids. All patients at risk should receive brief motivational interviewing with an objective, nonjudgmental, and empathic style that includes personalized feedback, particularly about markers of risk or harm. For chemical copers approaching the addiction end of the spectrum, with evidence of compulsive use and destructive behavior, referral should be made to substance abuse specialists.

Safe methadone induction and stabilization: report of an expert panel

OBJECTIVES

Methadone is a well-studied, safe, and effective medication when dispensed and consumed properly. However, a number of studies have identified elevated rates of overdose and death in patients being treated with methadone for either addiction or chronic pain. Among patients being treated with methadone in federally certified opioid treatment programs, deaths most often occur during the induction and stabilization phases of treatment. To address this issue, the federal Substance Abuse and Mental Health Services Administration invited the American Society of Addiction Medicine to convene an expert panel to develop a consensus statement on methadone induction and stabilization, with recommendations to reduce the risk of patient overdose or death related to methadone maintenance treatment of addiction.

METHODS

A comprehensive literature search of English-language publications (1979-2011) was conducted via MEDLINE and EMBASE. Methadone Action Group members evaluated the resulting information and collaborated in formulating the consensus statement presented here, which subsequently was reviewed by more than 100 experts in the field.

RESULTS

Published data indicate that deaths during methadone induction occur because the initial dose is too high, the dose is increased too rapidly, or the prescribed methadone interacts with another drug. Therefore, the Methadone Action Group has developed recommendations to help methadone providers avoid or minimize these risks.

CONCLUSIONS

Careful management of methadone induction and stabilization, coupled with patient education and increased clinical vigilance, can save lives in this vulnerable patient population.

Opioid-related mortality and filled prescriptions for buprenorphine and methadone

INTRODUCTION AND AIMS

To assess opioid-related mortality and correlation with filled prescriptions for buprenorphine and methadone.

DESIGN AND METHODS

A register study, including data from the Swedish Forensic Pathology and Forensic Toxicology databases 2003-2010, the Prescribed Drug Register and the National Patient Register.

RESULTS

A total of 1301 deaths, assessed as related to buprenorphine, methadone or heroin, or a combination of them, were studied. The largest number of fatalities was related to intake of heroin (n = 776), followed by methadone (n = 342) and buprenorphine (n = 168). The total annual number of fatal cases related to the studied drugs more than doubled (116 to 255) during the study period. There were increases in mortality related to both buprenorphine and methadone: from 1 to 49 cases for buprenorphine, and from 19 to 81 cases for methadone. Only one-fifth of the fatal cases had a filled prescription for the maintenance drug assessed as the cause of death.

DISCUSSION AND CONCLUSION

This study showed that most fatalities were not related to filled prescriptions of maintenance drugs, and a substantial illicit use of buprenorphine and methadone resulting in deaths was revealed. To prevent opioid toxicity deaths it is important to make efforts not only to reduce drug diversion from maintenance programs, but also to improve the control of drug trafficking and other illegal sources.

Use of hair testing to determine methadone exposure in pediatric deaths

A case of death attributed to methadone acute poisoning in an infant aged 11 months is reported. A sudden infant death syndrome (SIDS) was suspected, whereas a traumatic cause of death was excluded regarding autopsy findings. Specimens were submitted to a large toxicological analysis, which included ethanol measurement by HS-GC-FID, a targeted screening for drugs of abuse and various prescription drug classes followed by quantification using UPLC-MS/MS methods. Methadone and its metabolite (EDDP) were detected in all the tested fluids, as well as in hair, with a blood concentration of methadone considered as lethal for children (73 ng/mL). The cause of death was determined to be acute "methadone poisoning", and the manner of death was "accidental". A discussion of the case circumstances, the difficulties with the interpretation of toxicological findings in children (blood concentration and hair testing), and the origin of exposure are discussed.

Methadone-related deaths - epidemiological, pathohistological, and toxicological traits in 10-year retrospective study in Vojvodina, Serbia

The number of methadone-related deaths (MRDs) during a 10-year period (2002-2011) in the region of Vojvodina, Serbia, was increased. The cases were evaluated according to epidemiological parameters, pathohistological findings, and toxicological screening. The majority of victims were men, aged from 20 to 38. Pathohistologically, the signs of acute focal myocardial damage were present in the heart of victims with drug abuse history shorter than 2 years, while both signs of recent and chronic focal myocardial damage were developed among victims with longer drug abuse history (2-5 years). In postmortem blood samples of 54.84% of victims, methadone was detected in combination with diazepam, both in therapeutic range. Alcohol was absent in most cases. Other detected drugs were antipsychotics and antidepressants in therapeutic concentrations. These findings raise the attention to the concomitant use of methadone and benzodiazepines with the need for further studies to clarify the mechanism of death in such cases.

Respiratory effects of diazepam/methadone combination in rats: a study based on concentration/effect relationships

BACKGROUND

Methadone may cause respiratory depression and fatalities. Concomitant use of benzodiazepines in methadone-treated patients for chronic pain or as maintenance therapy for opiate abuse is common. However, the exact contribution of benzodiazepines to methadone-induced respiratory toxicity remains debatable.

METHODS

We investigated the respiratory effects of the combination diazepam (20mg/kg)/methadone (5mg/kg) in the rat, focusing on methadone concentration/effect relationships. Respiratory effects were studied using arterial blood gases and whole-body plethysmography. Plasma concentrations of both R- and S-methadone enantiomers were measured using high-performance liquid chiral chromatography coupled to mass spectrometry. To clarify mechanisms of diazepam/methadone interaction, methadone metabolism was investigated in vitro using rat liver microsomes.

RESULTS

Diazepam/methadone co-administration significantly increased methadone-related effects on inspiratory time (p<0.001) but did not significantly alter the other respiratory parameters when compared with methadone alone, despite significant increase in the area under the curve of plasma R-methadone concentrations measured during 240 min (p<0.05). Diazepam/methadone co-incubation with microsomes in vitro resulted in a significant inhibition of methadone metabolism (p<0.01), with 50%-inhibitory diazepam concentrations of 25.02 ± 0.18 μmol/L and 25.18 ± 0.23 μmol/L for R- and S-methadone, respectively.

CONCLUSION

We concluded that co-administration of high-doses of diazepam and methadone in rats is not responsible for additional respiratory depression in comparison to methadone alone, despite significant metabolic interaction between the drugs. In humans, although our experimental data may suggest the relative safety of benzodiazepine/methadone co-prescription, physicians should remain cautious as other underlying conditions may enhance this drug-drug interaction.

Promethazine misuse among methadone maintenance patients and community-based injection drug users

OBJECTIVE

Promethazine has been reported to be misused in conjunction with opioids in several settings. Promethazine misuse by itself or in conjunction with opioids may have serious adverse health effects. To date, no prevalence data for the nonmedical use of promethazine have been reported. This study examines the prevalence and correlates of promethazine use in 2 different populations in San Francisco, California: methadone maintenance clinic patients and community-based injection drug users (IDUs).

METHODS

We analyzed urine samples for the presence of promethazine and reviewed the clinical records for 334 methadone maintenance patients at the county methadone clinic. Separately, we used targeted sampling methods to recruit and survey 139 community-based opioid IDUs about their use of promethazine. We assessed prevalence and factors associated with promethazine use with bivariate and multivariate statistics.

RESULTS

The prevalence of promethazine-positive urine samples among the methadone maintenance patients was 26%. Only 15% of promethazine-positive patients had an active prescription for promethazine. Among IDUs reporting injection of opiates in the community-based survey, 17% reported having used promethazine in the past month; 24% of the IDUs who reported being enrolled in methadone treatment reported using promethazine in the past month.

CONCLUSIONS

The finding that one-quarter of methadone maintenance patients in a clinic or recruited in community settings have recently used promethazine provides compelling evidence of significant nonmedical use of promethazine in this patient population. Further research is needed to establish the extent and nature of nonmedical use of promethazine.

The use of very-low-dose methadone for palliative pain control and the prevention of opioid hyperalgesia

BACKGROUND

Opioid dose escalation may cause hyperalgesia, mediated by the N-methyl-D-aspartate (NMDA) pathway. Methadone is an atypical opioid that inhibits hyperalgesia through NMDA-blockade, especially at low doses.

OBJECTIVE

To evaluate the efficacy of using very-low-dose methadone as the sole long-acting opioid agent in a hospice practice.

DESIGN

A retrospective, observational study of the use of methadone, ≤15 mg daily, with as-needed short-acting opiates. Adjuvant nonopioid medications included haloperidol, which may have NMDA-blocking effects.

SETTING/SUBJECTS

We reviewed the records of 240 patients admitted to a community-based hospice from July 1, 2011 to April 1, 2012, with data collected until hospice discharge or until April 30, 2012.

MEASUREMENTS

Descriptive statistics were used to summarize patient demographics, medication regimens, and reported pain scores measured on a numeric rating scale from 0 to 10.

RESULTS

All patients received short-acting opiates, in a morphine-equivalent dose of 5 mg every 4 hours as needed, while 40% also received methadone at a median daily dose of 5 mg. Of those on methadone, almost half received scheduled haloperidol. The population had a median reported pain score of 0 and a peak score of 3, with similar results seen for cancer and noncancer groups. Two-thirds of patients never reported a pain score greater than 3.

CONCLUSION

The use of very-low-dose methadone in conjunction with adjuvant haloperidol resulted in excellent pain control without dose escalation or opioid-induced hyperalgesia, for both cancer and noncancer diseases. We conclude that low-dose methadone should be part of first-line treatment in palliative pain management.

Methadone-related deaths in Montpellier and Region, from 2000 to 2010

PURPOSE

The objectives of this analysis were to assess the role of methadone and related substances in death occurring, discussing methadone blood concentrations and the contribution of the autopsy to the accountability of methadone in the death process.

METHOD

We retrospectively analyzed all forensic cases positive for methadone from January 2000 to December 2010, in Montpellier and the region served by our laboratory.

RESULTS

During the study period, 64 cases of deaths (11 women, 53 men) with methadone detection were recorded. A progressive increase between 2001 (2 cases) and 2010 (8 cases) was observed. The median age was 33 years old. An autopsy was available in 56.3% of cases. The most frequent finding at the autopsy was non-specific asphyxia death signs (67.6%). Tolerance to opioids was documented in 21 cases. The methadone blood concentrations ranged from 1 to 2 800 ng/mL (59 cases, median value 330 ng/mL). Most of the cases (88%) were polydrug intoxications. The most commonly associated drugs were benzodiazepines (61%), cannabinoids (28%), opioids (19%) and cocaine (12.5%).

CONCLUSION

During a 11-year period, toxicological analyses related to 1991 death cases were performed at the Toxicology Laboratory of Montpellier University Hospital. Of these patients, 64 deaths were possibly related to methadone. Several relevant elements (biological analysis and autopsy) were used to attribute the deaths to the sole methadone (12 cases) or to methadone and associated substances (8 cases).

Methadone for chronic non-cancer pain in adults

BACKGROUND

Methadone belongs to a class of analgesics known as opioids, that are considered the cornerstone of therapy for moderate-to-severe pain due to life-threatening illnesses; however, their use in chronic non-cancer pain (CNCP) is controversial. Methadone has many characteristics that differentiate it from other opioids, which suggests that it may have a different efficacy and safety profile.

OBJECTIVES

To assess the analgesic effectiveness and safety of methadone in the treatment of CNCP.

SEARCH METHODS

We identified both randomized controlled trials (RCTs) and non-randomized studies of methadone use in chronic pain by searching the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library 2011, issue 11, MEDLINE (1950 to November 2011), and EMBASE (1980 to November 2011), together with reference lists of retrieved papers and reviews.

SELECTION CRITERIA

We included RCTs with pain assessment as either the primary or secondary outcome. Quasi-randomized studies, cohorts and case-control trials were also considered for inclusion because we suspected that the beneficial and harmful effects of methadone in CNCP may not be adequately addressed in RCTs.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted efficacy and adverse event data and assessed risk of bias.

MAIN RESULTS

We included two RCTs and one non-randomized study, involving a total of 181 participants. Both RCTs were cross-over studies, one involving 19 participants with diverse neuropathic pain syndromes, the other involving 76 participants with postherpetic neuralgia. Study phases were 20 days and approximately eight weeks, respectively. The non-randomized study retrospectively evaluated 86 outpatients over an average of 8.8 ± 6.3 months.One RCT reported average pain intensity and pain relief, and found statistically significant improvements versus placebo for both outcomes, with 10 mg and 20 mg daily doses of methadone. The second RCT reported differences in pain reduction between methadone and morphine and found morphine to be statistically superior. The non-randomized study found that in patients initially prescribed methadone it was effective in fewer participants than in those initially prescribed other long-acting opioids (28% versus 42%, 33% and 50% for morphine, oxycodone and transdermal fentanyl, respectively).One RCT compared incidences for several individual adverse events, but found a difference between methadone and placebo for only one event, dizziness (P = 0.041).

AUTHORS' CONCLUSIONS

The three studies provide very limited evidence of the efficacy of methadone for CNCP, and there were too few data for pooled analysis of efficacy or harm, or to have confidence in the results of the individual studies. No conclusions can be made regarding differences in efficacy or safety between methadone and placebo, other opioids, or other treatments.

Use of other opioids during methadone therapy: a population-based study

AIMS

To determine the extent to which other opioids are prescribed to patients receiving methadone in Ontario, Canada.

DESIGN

Retrospective cohort study.

SETTING

Ontario, Canada from 1 April 2003 to 31 March 2010.

PARTICIPANTS

We studied patients aged 15-64 years with publically funded drug coverage who received at least 30 days of continuous methadone maintenance therapy (MMT).

MEASUREMENTS

The proportion of patients who received more than 7 days of a non-methadone opioid during MMT. A secondary analysis examined the extent to which non-methadone opioids were prescribed by physicians or dispensed by pharmacies not involved in a patient's MMT.

FINDINGS

Among 18,759 patients treated with methadone, 3456 (18.4%) received at least one prescription for non-methadone opioids of more than 7 days' duration. In this group, the median number of non-methadone opioid prescriptions dispensed per year was 11.9 (interquartile range 4.1-25.0). The most frequently prescribed opioids were codeine and oxycodone. Of the 73,520 non-methadone opioid prescriptions of more than 7 days' duration, nearly half (45.8%) originated from non-MMT prescribers and pharmacies.

CONCLUSIONS

Many patients receiving methadone maintenance therapy in Ontario receive overlapping prescriptions for other opioids, often for extended periods. The associated prescribing patterns suggest that many such prescriptions may be duplicitous. The prescribing and dispensing of non-methadone opioids to patients receiving methadone maintenance therapy is likely to be observed in jurisdictions outside Ontario, Canada.

The source of methadone in overdose deaths in Western Virginia in 2004

OBJECTIVES

Methadone-related overdose deaths increased in the United States by 468% from 1999 to 2005. Current studies associate the nonmedical use of methadone with methadone-related deaths. This study describes medical examiner cases in rural Virginia in 2004 with methadone identified by toxicology and compares cases according to source of methadone.

METHODS

In 2004, all intentional and unintentional poisoning deaths from the Office of The Chief Medical Examiner, Western District of Virginia, were reviewed to identify cases in which methadone was a direct or contributing cause of death. The Virginia Prescription Monitoring Program was reviewed for prescription opioids in the name of these identified decedents. Decedent participation in local opioid treatment programs (OTP) was also assessed.

RESULTS

The source of methadone in the 61 methadone-related overdose deaths was mostly nonprescribed (67%), although 28% of decedents were prescribed methadone for analgesia. Only 5% of decedents were actively enrolled in an OTP. The majority of deaths were attributed to polysubstance overdose.

CONCLUSIONS

The majority of methadone overdose deaths in this study were related to illicit methadone use, rather than prescribed or OTP uses. Interventions to decrease methadone-related deaths should focus on reduction of nonprescription use of methadone.

CYP2B6 and OPRM1 gene variations predict methadone-related deaths

The largest proportion of methadone-associated deaths occurs during the drug induction phase. We analysed methadone-related fatalities for gene variations linked with methadone action. A significant association between high methadone concentrations and the CYP2B6*6 allele characteristic of the slow metabolizer phenotype was identified. We suggest that the risk of methadone fatality may be predetermined in part by the CYP2B6*6 allele. A significant correlation was also observed between post-mortem benzodiazepine concentrations and the OPRM1 A118G allele GA in methadone-related fatalities. Screening for these susceptibility variations prior to methadone prescription could assist in reducing the potential for serious adverse effects.

Trends in methadone-related deaths in Zurich

Methadone has a long and successful history in the treatment of opioid addiction. In recent years, it has become popular again--as potent and inexpensive analgesic in patients with chronic pain. Since methadone has been used fatalities have been reported. In our study all methadone-associated deaths in Zurich from 1998 to 2007 were analysed. Most of the 146 detected deaths of the past 10 years occurred during substitution programmes or illicit intake of methadone while only three of them could be attributed to methadone used as an analgesic. Noticeable in our study was the high percentage of cases of combined drug intoxication (76%). The most frequent co-intoxicants were alcohol and cocaine. Mortalities attributed to methadone intoxication alone were a rare finding and could only be detected in five cases of deceased who had received methadone maintenance treatment. The aim of our study is to assess the trends in the number and nature of methadone-related fatalities in Zurich during the last 19 years. For this purpose a previous study from Zurich (1989-1997) was included, whereby a very long observation period and large number of cases resulted.

Drug interactions of clinical importance among the opioids, methadone and buprenorphine, and other frequently prescribed medications: a review

Drug interactions are a leading cause of morbidity and mortality. Methadone and buprenorphine are frequently prescribed for the treatment of opioid addiction. Patients needing treatment with these medications often have co-occurring medical and mental illnesses that require medication treatment. The abuse of illicit substances is also common in opioid-addicted individuals. These clinical realities place patients being treated with methadone and buprenorphine at risk for potentially toxic drug interactions. A substantial literature has accumulated on drug interactions between either methadone or buprenorphine with other medications when ingested concomitantly by humans. This review summarizes current literature in this area.

Methadone: a new old drug with promises and pitfalls

Although methadone is not a new medication, its use in pain management has increased rapidly over the past decade. This article reviews the unique pharmacologic properties of methadone, including its long-acting nature, highly variable clearance rate, and its antagonism of the N-methyl-D-aspartate receptor. We discuss potential benefits and risks of methadone over other opioid medications. Preclinical studies suggest methadone may reduce abuse potential, tolerance development, and sensitization of nociceptive pathways. Pharmacologic properties of methadone suggest potential greater risk of dangerous or fatal side effects from overdose, QT interval prolongation, and drug interactions. However, clinical studies have yet to confirm that methadone produces either better clinical outcomes or higher rates of adverse events than other opioid analgesics. Clinicians who understand the special properties of methadone and follow recommended precautionary prescribing and monitoring practices can safely and effectively use methadone for pain treatment.

A comparison of drug overdose deaths involving methadone and other opioid analgesics in West Virginia

AIMS

To describe all people dying from unintentional overdoses of methadone or other opioid analgesics (OOA) in West Virginia in 2006.

DESIGN

We analyzed medical examiner data supplemented by data from the state prescription drug monitoring program. We compared people whose deaths involved methadone with those whose deaths involved OOA.

FINDINGS

The methadone group included 87 decedents, and the OOA group included 163 decedents. Most were male. Decedents in the methadone group were significantly younger than those in the OOA group: more than a quarter were 18-24 years of age. For both groups, approximately 50% had a history of pain, and 80% had a history of substance abuse. There was no intergroup difference in the prevalence of benzodiazepines at post-mortem. Methadone was significantly less likely to have ever been prescribed than OOA. Among those with prescriptions, the proportion prescribed within 30 days of death was significantly greater for methadone than for hydrocodone, but not for oxycodone. Ten (11.5%) of the methadone decedents were enrolled in an opiate treatment program (OTP) at the time of death.

CONCLUSIONS

The high prevalence of a substance abuse history and lack of prescriptions suggest that most of the deaths in both groups are related to substance abuse. There was no indication of a harmful effect from methadone's metabolic interaction with benzodiazepines, but provider or patient unfamiliarity with methadone may have been a risk factor. Prescribing methadone, especially to young males, requires extra care. Providers, OTPs and coroners/medical examiners should use state prescription drug monitoring programs to monitor the use of controlled substances by their patients.

Correlates of illicit methadone use in New York City: a cross-sectional study

BACKGROUND

Despite growing concern about illicit methadone use in the US and other countries, there is little data about the prevalence and correlates of methadone use in large urban areas. We assessed the prevalence and examined correlates of lifetime and recent illicit methadone use in New York City (NYC).

METHODS

1,415 heroin, crack, and cocaine users aged 15-40 years were recruited in NYC between 2000 and 2004 to complete interviewer-administered questionnaires.

RESULTS

In multivariable logistic regression, non-injection drug users who used illicit methadone were more likely to be heroin dependent, less than daily methamphetamine users and to have a heroin using sex partner in the last two months. Injection drug users who used illicit methadone were more likely to use heroin daily, share injection paraphernalia and less likely to have been in a detoxification program and to have not used marijuana in the last six months.

CONCLUSION

The results overall suggest that illicit (or street) methadone use is likely not a primary drug of choice, but is instead more common in concert with other illicit drug use.