Unintentional methadone-related overdose death in New Mexico (USA) and implications for surveillance, 1998-2002

Socioeconomic marginalization and opioid-related overdose: A systematic review

BACKGROUND

Socioeconomic marginalization (SEM) is an important but under-explored determinant of opioid overdose with important implications for health equity and associated public policy initiatives. This systematic review synthesizes evidence on the role of SEM in both fatal and non-fatal overdose among people who use opioids.

METHODS

Studies published between January 1, 2000 and March 31, 2018 were identified through searching electronic databases, citations, and by contacting experts. The titles, abstracts, citation information, and descriptor terms of citations were screened by two team members. Data were synthesized using the lumping technique.

RESULTS

A total of 37 studies met inclusion criteria and were included in the review, with 34 of 37 finding a significant association between at least one socioeconomic factor and overdose. The included studies contained variables related to eight socioeconomic factors: criminal justice system involvement, income, employment, social support, health insurance, housing/homelessness, education, and composite measures of socio-economic status. Most studies found associations in the hypothesized direction, whereby increased SEM was associated with a higher rate or increased likelihood of the overdose outcome measured. The review revealed an underdeveloped evidence base.

CONCLUSIONS

Nearly all reviewed studies found a connection between a socioeconomic variable and overdose, but more research is needed with an explicit focus on SEM, using robust and nuanced measures that capture multiple dimensions of disadvantage, and collect data over time to better inform decision making around opioid overdose.

Prolonged ethanol administration prevents the development of tolerance to morphine-induced respiratory depression

BACKGROUND

Opioid users regularly consume other drugs such as alcohol (ethanol). Acute administration of ethanol can rapidly reverse tolerance to morphine-induced respiratory depression. However, alcohol consumption by opioid users is likely to occur over prolonged time periods. We have therefore sought to determine the effect of prolonged alcohol consumption on the development of tolerance to opioid respiratory depression.

METHODS

Mice were fed control or ethanol (5%) liquid diet for 16 days. On days 9-16 morphine tolerance was induced by administration of 3 priming injections of morphine followed by subcutaneous implantation of a morphine-filled osmotic mini-pump. Control mice received saline. Respiration was measured by plethysmography and the effect of an acute morphine challenge dose was measured on day 16 to assess the development of morphine tolerance.

RESULTS

Prolonged ethanol consumption for 14 days did not alter the respiratory depressant effect of an acute dose of morphine. Control mice treated with prolonged morphine developed tolerance to acute morphine respiratory depression whereas ethanol diet fed mice treated with prolonged morphine showed significant respiratory depression during morphine-pump treatment and remained sensitive to the respiratory depressant effect of the acute challenge dose of morphine. The ethanol consumption did not alter blood or brain levels of morphine, whilst conversely prolonged morphine treatment did not alter blood levels of ethanol.

CONCLUSIONS

Prolonged ethanol consumption prevents the development and maintenance of tolerance to the respiratory depressant effect of morphine. These data suggest that ethanol inhibition of tolerance will greatly increase the risk of fatal heroin overdose in humans.

A Future for Observational Epidemiology: Clarity, Credibility, Transparency

Observational studies are ambiguous, difficult, and necessary for epidemiology. Presently, there are concerns that the evidence produced by most observational studies in epidemiology is not credible and contributes to research waste. I argue that observational epidemiology could be improved by focusing greater attention on 1) defining questions that make clear whether the inferential goal is descriptive or causal; 2) greater utilization of quantitative bias analysis and alternative research designs that aim to decrease the strength of assumptions needed to estimate causal effects; and 3) promoting, experimenting with, and perhaps institutionalizing both reproducible research standards and replication studies to evaluate the fragility of study findings in epidemiology. Greater clarity, credibility, and transparency in observational epidemiology will help to provide reliable evidence that can serve as a basis for making decisions about clinical or population-health interventions.

Current Concepts in Methadone Metabolism and Transport

Methadone is a cornerstone therapy for opioid addiction and a public health strategy for HIV/AIDS and hepatitis C reduction. Methadone is also used for acute and chronic pain. As use for chronic pain has grown, so too have adverse events. Constitutive and acquired (drug interactions) inter- and intraindividual variability in methadone pharmacokinetics and pharmacodynamics confounds reliable clinical use. Identification of enzymes and transporters responsible for methadone disposition has been a long-sought ideal. Initial in vitro studies identified CYP3A4 as metabolizing methadone. Subsequently, by extrapolation, CYP3A4 was long assumed to be responsible for clinical methadone disposition. However, CYP2B6 is also a major catalyst of methadone metabolism in vitro. It has now been unequivocally established that CYP2B6, not CYP3A4, is the principal determinant of methadone metabolism, clearance, elimination, and plasma concentrations in humans. Methadone disposition is susceptible to inductive and inhibitory drug interactions. CYP2B6 genetics also influences methadone metabolism and clearance, which were diminished in CYP2B6*6 carriers and increased in CYP2B6*4 carriers. CYP2B6 genetics can explain, in part, interindividual variability in methadone metabolism and clearance. Thus, both constitutive variability due to CYP2B6 genetics, and CYP2B6-mediated drug interactions, can alter methadone disposition, clinical effect, and drug safety. Methadone is not a substrate for major influx or efflux transporters.

Risk markers for fatal and non-fatal prescription drug overdose: a meta-analysis

BACKGROUND

Drug overdose is a public health crisis in the United States, due in part to the unintended consequences of increases in prescribing of opioid analgesics. Many clinicians evaluate risk markers for opioid-related harms when prescribing opioids for chronic pain; however, more data on predictive risk markers are needed. Risk markers are attributes (modifiable and non-modifiable) that are associated with increased probability of an outcome. This review aims to identify risk markers associated with fatal and non-fatal prescription drug overdose by synthesizing findings in the existing peer-reviewed and grey literature. Eligible cohort, case-control, cross-sectional, and case-cohort studies were reviewed and data were extracted for qualitative and quantitative synthesis.

FINDINGS

Summary odds ratios (SOR) were estimated from 29 studies for six risk markers: sex, age, race, psychiatric disorders, substance use disorder (SUD), and urban/rural residence. Heterogeneity was assessed and effect estimates were stratified by study characteristics. Of the six risk markers identified, SUD had the strongest association with drug overdose death (SOR = 5.24, 95% confidence interval (CI) = 3.53 - 7.76), followed by psychiatric disorders (SOR = 3.94, 95% CI = 3.09 - 5.01), white race (SOR = 2.28, 95% CI = 1.93 - 2.70), the 35-44 year age group relative to the 25-34 year reference group (SOR = 1.52, 95% CI = 1.31 - 1.76), and male sex (SOR = 1.33, 95% CI = 1.17 - 1.51).

CONCLUSIONS

This review highlights fatal and non-fatal prescription drug risk markers most frequently assessed in peer-reviewed and grey literature. There is a need to better understand modifiable risk markers and underlying reasons for drug misuse in order to inform interventions that may prevent future drug overdoses.

Research gaps on methadone harms and comparative harms: findings from a review of the evidence for an American Pain Society and College on Problems of Drug Dependence clinical practice guideline

Methadone-associated overdose deaths have dramatically increased. In order to inform an evidence-based clinical practice guideline to improve safety of methadone prescribing, the American Pain Society commissioned a systematic review on various aspects related to methadone safety. We searched Ovid MEDLINE, Cochrane Library, and PsycINFO databases through July 2012 to identify studies that addressed 1 or more of 17 Key Questions related to methadone safety; an update search was performed in 2014 for new studies related to methadone-related overdose and risks related to cardiac arrhythmias. A total of 168 studies met inclusion criteria for the review. The purpose of this article is to highlight critical research gaps in the literature related to methadone safety. These include lack of evidence on risk factors associated with methadone-overdose deaths and adverse events, limited evidence to evaluate the comparative mortality of methadone versus other opioids, insufficient evidence to fully understand the harms associated with methadone use during pregnancy, and insufficient evidence to determine effects of risk mitigation strategies such as electrocardiogram monitoring, strategies for managing patients with prolonged QTc intervals on screening, urine drug testing, alternative dosing regimens for initiation and titration of therapy, and timing of follow-up. Therefore, most guideline recommendations are based on weak evidence. More research is needed to guide safe methadone prescribing practices and decrease the adverse events associated with methadone.

PERSPECTIVE

This article summarizes critical research gaps in the literature related to methadone safety, based on a systematic review commissioned by the American Pain Society. Critical research gaps were identified in a number of areas, highlighting the need for additional research to guide safer prescribing and risk mitigation strategies.

Methadone safety: a clinical practice guideline from the American Pain Society and College on Problems of Drug Dependence, in collaboration with the Heart Rhythm Society

Methadone is used for the treatment of opioid addiction and for treatment of chronic pain. The safety of methadone has been called into question by data indicating a large increase in the number of methadone-associated overdose deaths in recent years that has occurred in parallel with a dramatic rise in the use of methadone for chronic pain. The American Pain Society and the College on Problems of Drug Dependence, in collaboration with the Heart Rhythm Society, commissioned an interdisciplinary expert panel to develop a clinical practice guideline on safer prescribing of methadone for treatment of opioid addiction and chronic pain. As part of the guideline development process, the American Pain Society commissioned a systematic review of various aspects related to safety of methadone. After a review of the available evidence, the expert panel concluded that measures can be taken to promote safer use of methadone. Specific recommendations include the need to educate and counsel patients on methadone safety, use of electrocardiography to identify persons at greater risk for methadone-associated arrhythmia, use of alternative opioids in patients at high risk of complications related to corrected electrocardiographic QTc interval prolongation, careful dose initiation and titration of methadone, and diligent monitoring and follow-up. Although these guidelines are based on a systematic review, the panel identified numerous research gaps, most recommendations were based on low-quality evidence, and no recommendations were based on high-quality evidence.

PERSPECTIVE

This guideline, based on a systematic review of the evidence on methadone safety, provides recommendations developed by a multidisciplinary expert panel. Safe use of methadone requires clinical skills and knowledge in use of methadone to mitigate potential risks, including serious risks related to risk of overdose and cardiac arrhythmias.

Methadone overdose and cardiac arrhythmia potential: findings from a review of the evidence for an American Pain Society and College on Problems of Drug Dependence clinical practice guideline

The number of deaths associated with methadone use increased dramatically in parallel with marked increases in its use, particularly for treatment of chronic pain. To develop a clinical guideline on methadone prescribing to reduce potential harms, the American Pain Society commissioned a review of various aspects related to methadone safety. This article summarizes evidence related to unintentional overdose due to methadone and harms related to cardiac arrhythmia potential. We searched Ovid MEDLINE, the Cochrane Library, and PsycINFO databases through January 2014 for studies assessing harms associated with methadone use; we judged 70 studies to be relevant and to meet inclusion criteria. The majority of studies on overdose and cardiac arrhythmia risk are observational and provide weak evidence on which to base clinical guidelines. In patients prescribed methadone for treatment of opioid dependence, data suggest that mortality benefits related to reduction in illicit drug use outweigh harms. Despite epidemiologic data showing marked increases in the numbers of methadone-related deaths that have been primarily attributed to increased use of methadone for chronic pain, evidence on methadone and mortality risk in this population has been somewhat contradictory. There is some evidence that recent initiation of methadone, psychiatric admissions, and concomitant use of benzodiazepines are associated with a higher risk for overdose. Evidence on cardiac risks is primarily limited to case reports of torsades de pointes, primarily in patients on high doses of methadone, and to studies showing an association between methadone use and prolongation of QTc intervals. Research is needed to understand the effectiveness of dosing methods, electrocardiogram monitoring, and other risk mitigation strategies in patients prescribed methadone.

PERSPECTIVE

This systematic review synthesizes the evidence related to methadone use and risk for overdose and cardiac arrhythmia. Findings regarding the association between methadone use and QTc interval prolongation and risk factors for methadone-associated overdose suggest potential targets for risk mitigation strategies, though research is needed to determine the effectiveness of such strategies at reducing adverse outcomes.

Determinants of increased opioid-related mortality in the United States and Canada, 1990-2013: a systematic review

We review evidence of determinants contributing to increased opioid-related mortality in the United States and Canada between 1990 and 2013. We identified 17 determinants of opioid-related mortality and mortality increases that we classified into 3 categories: prescriber behavior, user behavior and characteristics, and environmental and systemic determinants. These determinants operate independently but interact in complex ways that vary according to geography and population, making generalization from single studies inadvisable. Researchers in this area face significant methodological difficulties; most of the studies in our review were ecological or observational and lacked control groups or adjustment for confounding factors; thus, causal inferences are difficult. Preventing additional opioid-related mortality will likely require interventions that address multiple determinants and are tailored to specific locations and populations.

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.

Forensic Pathology and Epidemiology, Public Health and Population-Based Research

Forensic pathology can play a pivotal role in safeguarding public health. While medicolegal death investigation focuses on certifying cause and manner of individual deaths, taken in aggregate this information provides a powerful tool for epidemiologic research. The published literature provides numerous examples of the utility of forensic pathology in public health research, from describing trends in substance abuse deaths to reducing occupational fatalities and identifying unusual infectious disease deaths. Medical examiner and coroner (ME/C) offices contribute to public health research by participating in surveillance systems, including those for sudden unexplained infant deaths and violent deaths, and by alerting public health agencies to emerging threats. Accessing and utilizing ME/C data for epidemiologic research can be challenging, given the wide variation in types of jurisdictions and the availability of electronic data, but the rewards for researchers justify the endeavor. Mutually beneficial relationships can develop between epidemiologists and ME/Cs, improving both public health and medicolegal death investigation.

The methadone epidemic: methadone-related deaths on the rise in Vermont

The prevalence of methadone-related overdose deaths is increasing worldwide and has been a topic of recent debate. Methadone-related deaths, to this point, have not been systematically reviewed in the state of Vermont. All of the methadone-related fatalities from 2001 to 2006 (total, 76 cases), which were examined by the Vermont Office of the Chief Medical Examiner were retrospectively reviewed. The mean age of the decedents was 36 years (range, 16-74 years), and 72% were male. The manners of death were classified as follows: 84% accident, 12% undetermined, and 4% suicide. The mean level of methadone was 457 ng/mL (range, 50-3793 ng/mL). The substances causing death were determined to be methadone alone in 26 (34%), methadone with only other prescribed medications in 29 (38%), methadone with only illicit drugs (excluding tetrahydrocannabinol) in 13 (17%), methadone with both illicit and prescribed medications in 5 (7%), and methadone with ethanol in 3 (4%). The methadone was obtained by illegal diversion (sale, gift, or theft) in 67% of cases. In the remaining cases (33%), the methadone was obtained by physician's prescription for chronic pain (60%), acute pain or injury (8%), methadone maintenance therapy for heroin dependence (8%), and unknown reasons (24%). The number of overdose deaths has increased 4-fold from 2001 (17 deaths) to 2006 (79 deaths). The proportion of methadone-related deaths has increased by 300% from 2001 (0.6% of reported deaths, 12% of overdose deaths) to 2006 (3% of reported deaths, 37% of overdose deaths). Methadone maintenance therapy for heroin dependence in our population comprises an insignificant number of the methadone-related deaths (3% of the decedents). In Vermont, the populations most at risk are those taking methadone for chronic pain and those obtaining diverted methadone for abuse. Education of clinicians regarding the increasing number of methadone-related deaths, the potential for abuse and diversion, and the pharmacokinetics of methadone may help halt this epidemic and reduce the number of fatalities from this drug.

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.

Elevated overdose mortality rates among First Nations individuals in a Canadian setting: a population-based analysis

AIMS

To determine the total burden of illicit drug overdose mortality over the study period in the province of British Columbia and investigate possible population-level determinants by estimating rates among subgroups including First Nations individuals.

DESIGN

Review of coroner case files.

SETTING

The province of British Columbia, Canada.

PARTICIPANTS

Individuals dying from an illicit drug overdose between 2001 and 2005.

MEASUREMENTS

Age-adjusted mortality rates, standardized mortality ratios (SMR) and years of potential life lost (YPLL), stratified by major population groups.

FINDINGS

Over the study period, 909 individuals died from illicit drug overdoses, including 104 (11.4%) First Nations individuals. Compared to the general population, First Nations males and females suffered from substantially elevated SMR and YPLL. In a multivariate logistic regression analysis, First Nations deaths were significantly more likely to be among women, related to injection drug use and to have occurred in the Downtown Eastside area of Vancouver, the local epicentre of human immunodeficiency virus infection and open drug use (all P< 0.05).

CONCLUSIONS

This report found highly elevated overdose death rates and levels of premature mortality among First Nations Canadians in British Columbia compared to the general population. While previously unidentified, these findings are consistent with the poorer population health profile of First Nations Canadians. Although further research is needed to identify the causes of the elevated death rates, our findings support increased availability of evidence-based overdose prevention measures.

Increase in unintentional medication overdose deaths: Oklahoma, 1994-2006

BACKGROUND

During 1999-2006, rates of unintentional drug-related deaths increased 120% in the U.S.

PURPOSE

This report describes demographics and trends of unintentional medication overdose deaths among Oklahoma residents to target prevention strategies.

METHODS

Oklahoma medical examiner data regarding fatal unintentional poisonings involving at least one prescription or over-the-counter medication during 1994-2006 and opioid retail sales data during 1997-2006 were analyzed during 2008-2009 to determine demographic-specific rates of overdose deaths and changes in 3-year mean death rates.

RESULTS

A total of 2112 fatal unintentional medication overdoses were identified (4.7 deaths/100,000 population) involving a median of two substances/decedent. The highest fatality rates occurred among men (5.9/100,000) and people aged 35-54 years (11/100,000). Crude overdose death rates increased sevenfold during the investigation period, peaking at 11/100,000 in 2006. Death rates increased more for women (ninefold) than men (sixfold); rates among residents of rural counties increased more (eightfold) than urban county rates (sixfold). Leading drug types involved in fatalities were opioids and anxiolytics. The individual drugs contributing most frequently included methadone (31%); hydrocodone (19%); alprazolam (15%); and oxycodone (15%). During 1997-2006, Oklahoma prescription opioid sales increased fourfold. Methadone was associated with the highest number of deaths per equianalgesic dose sold (23.3), whereas hydrocodone and oxycodone had the highest increases in deaths per equianalgesic dose sold (threefold increase each).

CONCLUSIONS

Unintentional medication-related deaths are increasing in Oklahoma and often involve multiple substances. Substances most frequently contributing to deaths were prescription opioid analgesics. Prevention strategies should target people aged 35-54 years and emphasize the dangers of coingesting substances and misusing prescription pain medications.

Indicators of buprenorphine and methadone use and abuse: what do we know?

Abuse of prescription opioids is a growing problem. The number of methadone pain pills distributed now exceeds liquid methadone used in opioid treatment, and the increases in buprenorphine indicators provide evidence of the need to monitor and intervene to decrease the abuse of this drug. The need for additional and improved data to track trends is discussed, along with findings as to the characteristics of the users and combinations of drugs. Data on toxicities related to methadone or buprenorphine, particularly in combination with other prescribed drugs, are presented and clinical implications and considerations are offered. These findings underscore the need for physicians to be aware of potential toxicities and to educate their patients regarding these issues.

Clinical Characteristics of Central European and North American Samples of Pregnant Women Screened for Opioid Agonist Treatment

BACKGROUND

Little comparable information is available regarding clinical characteristics of opioid-dependent women from different countries. In the present study, women from the USA, Canada and a Central European country, Austria, screened for participation in the Maternal Opioid Treatment Human Experimental Research study, were compared with respect to their demographic and addiction histories.

METHODS

Pregnant women (n = 1,074) were screened for study participation using uniformed clinical criteria and instruments. The screening results were compared with regard to exclusion, demographics, drug use, and psychosocial and treatment histories.

RESULTS

Compared to the screened US and Canadian women, Austrian women were more likely to be younger (p < 0.001), white (p < 0.001), had significantly lower levels of educational attainment (p < 0.001), were less likely to use opioids daily (p < 0.001) and more likely to have been prescribed buprenorphine (p < 0.001). Compared to both rural and urban US groups, the Austrian group was less likely to have legal issues (p < 0.001) and was younger when first prescribed agonist medication (p < 0.001).

CONCLUSION

The differences between North American and European groups may offer unique insights concerning treatment and pregnancy outcomes for opioid-dependent pregnant women.

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.

Methadone pharmacokinetics are independent of cytochrome P4503A (CYP3A) activity and gastrointestinal drug transport: insights from methadone interactions with ritonavir/indinavir

BACKGROUND

Methadone clearance is highly variable, and drug interactions are problematic. Both have been attributed to CYP3A, but actual mechanisms are unknown. Drug interactions can provide such mechanistic information. Ritonavir/indinavir, one of the earliest protease inhibitor combinations, may inhibit CYP3A. We assessed ritonavir/indinavir effects on methadone pharmacokinetics and pharmacodynamics, intestinal and hepatic CYP3A activity, and intestinal transporters (P-glycoprotein) activity. CYP3A and transporters were assessed with alfentanil and fexofenadine, respectively.

METHODS

Twelve healthy human immunodeficiency virus-negative volunteers underwent a sequential three-part crossover. On three consecutive days, they received oral alfentanil/fexofenadine, intravenous alfentanil, and intravenous plus oral (deuterium-labeled) methadone, repeated after acute (3 days) and steady-state (2 weeks) ritonavir/indinavir. Plasma and urine analytes were measured by mass spectrometry. Opioid effects were assessed by miosis.

RESULTS

Alfentanil apparent oral clearance was inhibited more than 97% by both acute and steady-state ritonavir/indinavir, and systemic clearance was inhibited more than 90% due to diminished hepatic and intestinal extraction. Ritonavir/indinavir increased fexofenadine area under the plasma concentration-time curve four- to five-fold, suggesting significant inhibition of gastrointestinal P-glycoprotein. Ritonavir/indinavir slightly increased methadone N-demethylation, but it had no significant effects on methadone plasma concentrations or on systemic or apparent oral clearance, renal clearance, hepatic extraction or clearance, or bioavailability. Ritonavir/indinavir had no significant effects on methadone plasma concentration-effect relationships.

CONCLUSIONS

Inhibition of both hepatic and intestinal CYP3A activity is responsible for ritonavir/indinavir drug interactions. Methadone disposition was unchanged, despite profound inhibition of CYP3A activity, suggesting little or no role for CYP3A in clinical methadone metabolism and clearance. Methadone bioavailability was unchanged, despite inhibition of gastrointestinal P-glycoprotein activity, suggesting that this transporter does not limit methadone intestinal absorption.

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.

Hepatitis infection in the treatment of opioid dependence and abuse

Many new and existing cases of viral hepatitis infections are related to injection drug use. Transmission of these infections can result directly from the use of injection equipment that is contaminated with blood containing the hepatitis B or C virus or through sexual contact with an infected individual. In the latter case, drug use can indirectly contribute to hepatitis transmission through the dis-inhibited at-risk behavior, that is, unprotected sex with an infected partner. Individuals who inject drugs are at-risk for infection from different hepatitis viruses, hepatitis A, B, or C. Those with chronic hepatitis B virus infection also face additional risk should they become co-infected with hepatitis D virus. Protection from the transmission of hepatitis viruses A and B is best achieved by vaccination. For those with a history of or who currently inject drugs, the medical management of viral hepatitis infection comprising screening, testing, counseling and providing care and treatment is evolving. Components of the medical management of hepatitis infection, for persons considering, initiating, or receiving pharmacologic therapy for opioid addiction include: testing for hepatitis B and C infections; education and counseling regarding at-risk behavior and hepatitis transmission, acute and chronic hepatitis infection, liver disease and its care and treatment; vaccination against hepatitis A and B infection; and integrative primary care as part of the comprehensive treatment approach for recovery from opioid abuse and dependence. In addition, participation in a peer support group as part of integrated medical care enhances treatment outcomes. Liver disease is highly prevalent in patient populations seeking recovery from opioid addiction or who are currently receiving pharmacotherapy for opioid addiction. Pharmacotherapy for opioid addiction is not a contraindication to evaluation, care, or treatment of liver disease due to hepatitis virus infection. Successful pharmacotherapy for opioid addiction stabilizes patients and improves patient compliance to care and treatment regimens as well as promotes good patient outcomes. Implementation and integration of effective hepatitis prevention programs, care programs, and treatment regimens in concert with the pharmacological therapy of opioid addiction can reduce the public health burdens of hepatitis and injection drug use.

Estimating heroin epidemics with data of patients in methadone maintenance treatment, collected during a single treatment day

AIMS

Effects of differing drug policies are difficult to evaluate, because time trends in the spread of heroin use, the most problematic illicit drug world-wide, are unknown in almost all countries. We aimed to develop a simple method to estimate these dynamics with data that can be gathered from patients in substitution treatment within a single day.

DESIGN

We tested the assumption that being in substitution treatment on any day depends solely upon individual time since onset of regular heroin use (following a 'general inclusion function'). We used data from the case register for substitution treatments in the canton of Zurich (1992--2004), comprising 9518 patients, to model a 'general inclusion function'. Applying this function, we calculated 30 incidence curves for heroin dependence, each with data of one of 30 randomly chosen treatment days between 1992 and 2004.

FINDINGS

Incidence modelling led to 30 similar curves, and therefore our hypothesis was corroborated. Additionally, our approach also revealed a restricted access to substitution treatment in the early 1990s and a decline in demand due to the introduction of heroin-assisted treatment from 1994 onwards.

CONCLUSIONS

In the canton of Zurich, the probability of being in substitution treatment can be described by a 'general inclusion function', and therefore dynamics of heroin epidemics can be estimated based on data of a single treatment day. Adaptation of our function to areas with a more restricted access to substitution treatment may permit these estimations also in other regions or countries. Thus, our approach facilitates the urgently needed assessment of the effects of different drug policies.

Benzodiazepine prescription for patients in opioid maintenance treatment in Norway

BACKGROUND

Opioid maintained patients report high levels of anxiety, but the use of benzodiazepines among these patients has been associated with negative outcomes such as increased risk of overdose and death and poorer retention in programmes. Previous research has used interview or urine analysis to assess benzodiazepine use. In this study a prescription database was applied.

METHODS

The Norwegian Prescription Database covers all prescriptions for the entire population from 1 January 2004. Benzodiazepine prescriptions to patients receiving methadone (N=1364) or buprenorphine (N=805) in 2004 and 2005 were studied. Type and amount of drugs received were investigated.

RESULTS

Overall 40% of the patients received at least one prescription for a benzodiazepine drug. Oxazepam was the most frequently prescribed drug. Female patients, methadone-maintained patients and patients in the liberal programmes received a prescription more often. Prescribed doses were high and highest in the liberal programmes. Older patients received more hypnotics. Dose of maintenance drug was positively related to amount of anxiolytics prescribed.

CONCLUSIONS

This study showed that more benzodiazepines were prescribed to opioid maintenance treatment patients than previously shown by investigations using interview or urine analysis. The doses prescribed were generally high. In light of the negative outcomes following benzodiazepine use in these patients, Norwegian doctors need to review their prescription practices.

An in vitro approach to potential methadone metabolic-inhibition interactions

OBJECTIVE

The aim of this study was to assess the drug interaction potential of psychotropic medication on methadone N-demethylation using cDNA-expressed cytochrome P450 CYP enzymes.

METHODS

Methadone was incubated with various drugs (n = 10) and cDNA-expressed CYP3A4, CYP2D6, CYP2B6, CYP2C19 and CYP1A2 enzymes to screen for their inhibition potency. The nature of enzyme selective activity for inhibition was further investigated for potent inhibitors. To test for a mechanism-based component in inhibition, all substances were tested with preincubation and without. 2-Ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) concentration was determined by liquid chromatography/tandem mass spectrometry following liquid/liquid extraction.

RESULTS

Formation of EDDP was catalysed by CYP3A4, CYP2D6 and CYP2C19. The N-demethylation of methadone was preferentially inhibited by amitriptyline, buprenorphine, methylenedioxymethamphetamine (MDMA) and zolpidem. Both amitriptyline and buprenorphine were strong, reversible inhibitors of CYP3A4. Similarly, amitriptyline and MDMA were identified as inhibitors of CYP2D6. Zolpidem revealed a mechanism-based inhibition of CYP3A4.

CONCLUSION

Amitriptyline, MDMA and zolpidem are likely to slow down conversion of methadone and to increase its area under the curve (AUC). A consideration of the in vitro evidence of drug-methadone interactions should help to improve patient care during methadone maintenance treatment.

Risk factors for methadone outside treatment programs: implications for HIV treatment among injection drug users

BACKGROUND

Diversion of methadone outside treatment programs occurs, yet reasons for use of 'street methadone' are characterized poorly. Self-medication for withdrawal symptoms is one plausible hypothesis. Among HIV-infected drug users, some antiretroviral medications can reduce potency of methadone, yet any association between such effects and the use of supplemental methadone sources remains undetermined.

OBJECTIVE

To estimate the frequency and risk factors for use of street methadone.

METHODS

Injection drug users (IDUs) recruited through extensive community outreach in 1988-89 and 1994 were followed semi-annually with questionnaires about health history, use of licit and illicit drugs including methadone and HIV-related assays. Analyses were performed using generalized estimating equation logistic regression.

RESULTS

Of 2811 IDUs enrolled and eligible for analysis, 493 people reported use of street methadone over 12 316 person-years of follow-up (4.0/100 person-years). In multivariate analyses, street methadone use was more common among women, whites, those 40-59 years old, those who reported withdrawal symptoms, past methadone program attendance (6-12 months before visit), recent heroin injection with or without cocaine (but not cocaine alone), smoking or sniffing heroin and reported trading sex. Street methadone was not associated with HIV infection or treatment.

CONCLUSION

The results suggest that older IDUs still using heroin may be using street methadone to treat signs of withdrawal. The absence of a higher rate of street methadone use in HIV seropositive IDUs reveals that antiretroviral/methadone interactions are not a primary determinant of use outside of treatment settings.

One-year mortality rates of patients receiving methadone and buprenorphine maintenance therapy: a nationally representative cohort study in 2694 patients

Mortality rates in drug-dependent patients in substitution treatment remain a matter of debate. Although several retrospective toxicological or forensic postmortem studies on this issue have been conducted, few prospective studies have addressed this problem. In a nationally representative sample of 2694 opioid dependent patients in substitution treatment either with methadone or buprenorphine at baseline were monitored over a 12-month period (response rate, 91%). A total number of 1629 (60.4%) were still in treatment after 12 months. The overall mortality rate was 1.04%. In total, 28 patients of the initial sample deceased within the 1-year follow-up period. Eleven (0.4%) of these deaths are due to a fatal intoxication. Three patients (0.1%) died of human immunodeficiency virus/acquired immunodeficiency syndrome, and 3 (0.1%) committed suicide. Thirteen of these patients (4 with overdose/polyintoxication) were not in substitution treatment at the time of death. Other reasons included accidents and deaths due to other medical conditions. Only in one case the reason could not be ascertained. The mortality rate was similar in methadone as compared with buprenorphine patients. Taking into account the high comorbidity of opioid dependent patients and the severity of dependence, the mortality rate of approximately 1% confirms that maintenance treatment could be regarded as a fairly safe treatment.

Recent trends in narcotic deaths

The prevalence of overdose deaths from opioids is still generally increasing throughout the world. Heroin is still the predominant illicit opioid of interest to toxicology laboratories because of its continuing widespread availability and its ability to elicit respiratory depression and coma. In many countries methadone continues to play a major role in cases of drug toxicity because of its large-scale use to treat opioid dependency and its high potency and long duration of action. Increasingly, buprenorphine is being used as an alternative pharmacotherapy, and although apparently safer than methadone, it still has an inherent risk of toxicity when used with CNS depressants such as benzodiazepines or when injected. Morphine continues to be the dominant analgesic; however, oxycodone, hydromorphone, hydrocodone, and fentanyl are increasingly being used and will require increasing efforts by toxicology laboratories to ensure that these substances are adequately covered by testing programs.

Unintentional prescription drug overdose deaths in New Mexico, 1994-2003

BACKGROUND

New Mexico has the highest rate of drug-induced mortality in the United States. The contribution of prescription drugs to the total overdose death rate has not been adequately described.

METHODS

A total of 1,906 unintentional drug overdose deaths occurring in 1994 to 2003 in New Mexico were analyzed. Unintentional drug overdose death was defined as death caused by prescription, illicit, or a combination of drugs, as determined by a pathologist. Deaths were investigated annually by the medical examiner and data were analyzed in 2004-2005. Rates and trends of total and prescription drug overdose death were calculated, decedent characteristics were analyzed, and common drug combinations causing death were described.

RESULTS

The rate of unintentional prescription drug overdose death increased by 179% (1.9 to 5.3/100,000) from 1994 to 2003. A high percentage of prescription drug overdose decedents were white non-Hispanic (63.2%) and female (43.9%). These decedents were older and less frequently had alcohol listed as an additional cause of death than decedents of other drug overdose categories. Of all deaths caused by prescription drug(s) (n =765), 590 (77.1%) were caused by opioid painkillers, 263 (34.4%) by tranquilizers, and 196 (25.6%) by antidepressants.

CONCLUSIONS

The rate of prescription drug overdose death in New Mexico increased significantly over the 10-year study period. Comprehensive surveillance of drug overdose deaths is recommended to describe their occurrence in the context of both medical and diverted use of prescription drugs. Understanding decedent profiles and the potential risk factors for prescription drug overdose death is crucial for effective drug overdose prevention education among healthcare providers.

Do young heroin users in Madrid, Barcelona and Seville have sufficient knowledge of the risk factors for unintentional opioid overdose?

To identify the self-perceived reasons for unintentional opioid overdose of young heroin users in three Spanish cities and their agreement with objective risk factors for overdose. Computer-Assisted Personal Interviews (CAPI) were held with 991 street-recruited current heroin users aged 18-30. The general reasons for overdose and the reasons for the last overdose suffered were explored with open-ended (OEQs) and pre-coded questions (PCQs). Limited knowledge of overdose risk factors was defined as mention of fewer than two objective risk factors for unintentional overdose in the OEQ. Univariate, bivariate, and logistic regression methods were used. 77.8% (Seville), 64.9% (Madrid) and 57.2% (Barcelona) of participants have limited knowledge of overdose risk factors. Residence in Seville and not having attended courses or meetings on overdoses were significantly associated with limited knowledge, after adjusting for other factors. The most frequently identified general reasons in OEQ or PCQ were using heroin in large amounts (66.8%), together with tranquilizers (62.0%), adulterated (60.7%), or purer than usual (57.6%). Most reasons were selected more frequently in PCQ than in OEQ, especially rapid injection of the entire dose and using heroin shortly after using tranquilizers or alcohol, by injection, or after a period of abstinence. The results were similar for overdoses suffered by participants. Most young heroin users do not have sufficient knowledge of overdose risk factors, especially the use of heroin by injection, after a period of abstinence, or together with alcohol or methadone. Specific informational or educational programs adapted to the local context are critically needed.

Fast gas chromatography/mass spectrometric assay for the validated quantitative determination of methadone and the primary metabolite EDDP in whole blood

A toxicological analysis was developed and validated for simultaneous screening and quantification of methadone (METH) and its primary metabolite 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP). The method employs microscale liquid-liquid extraction (microLLE) and direct injection of a separated aliquot of the organic layer into a gas chromatography/mass spectrometric (GC/MS) system without any other pre-treatment stages. A fast GC/MS runtime (total 5.8 min; METH, Rt = 3.55 min; EDDP, Rt = 3.40 min) combined with rapid sample preparation allowed cost-efficient and routinely applicable performance with a low amount of manual work. The validated parameters included: linearity (25-1000 ng mL(-1) both; R(METH)2 = 0.998 and R(EDDP)2 = 0.997), accuracy (Bias(METH): from -0.05 to 11.3%, Bias(EDDP): from 1.11 to 4.37%); intra and inter-assay precision (RSD(METH): from 2.4 to 3.9%, from 4.89 to 10.3%; RSD(EDDP): from 4.50 to 6.20%, from 4.57 to 15.2%), extraction efficiency (METH = 95.5%; EDDP = 90.6%), LOQ(Meth,EDDP) = 25 ng mL(-1). Samples were stable for at least 25 h and no selectivity problems or baseline interference were observed. The method should be applicable for identifying and quantitative confirmation of possible misuse and/or illegal use of METH in toxicological cases.