Fentanyl-related Overdose Deaths Research Articles

“I don’t want to die”: a qualitative study of coping strategies to prevent fentanyl-related overdose deaths among people who inject drugs and its implications for harm reduction policies

BackgroundFentanyl and fentanyl-related analogues are the main drivers of overdose death in the USA, particularly among people who inject drugs (PWID). Despite the fact that non-Hispanic whites exhibit higher population rates of synthetic opioid mortality, overdose deaths have increased among African American and Latinos in urban areas. Yet little attention has been paid to the introduction of fentanyl among rural PWID in Puerto Rico.MethodsWe conducted N = 38 in-depth interviews with PWID in rural Puerto Rico to document participants’ experiences of injection drug use after the arrival of fentanyl and the strategies they implemented to manage overdose death risks.ResultsParticipants suggest that the arrival of fentanyl in large scale happened after Hurricane Maria in 2017; this coincided with a dramatic increase in overdose episodes and deaths. Fear of overdose deaths motivated some participants to substitute intravenous drug use for other forms of substance use or to seek MOUD. PWID that continued injection use resorted to conducting “hit tests,” avoiding injecting alone, using naloxone, and employing fentanyl testing strips.ConclusionsWhile overdose deaths would have been higher without participants’ willingness to adopt harm-reduction strategies, this paper illustrates the limits of these policies to address the current epidemic of fentanyl-related overdose deaths among this population. More studies are needed to understand how health disparities shape overdose risks for minority populations. However, major policy changes, in particular the revision of the harmful role of the War on Drugs and the termination of failed neoliberal economic policies that contribute to deaths of despair, should be addressed if we are to make a dent in this epidemic.

Addressing Methamphetamine Use in Primary Care: Provider Perspectives.

The opioid epidemic has evolved into a combined stimulant epidemic, with escalating stimulant and fentanyl-related overdose deaths. Primary care providers are on the frontlines grappling with patients' methamphetamine use. Although effective models exist for treating opioid use disorder in primary care, little is known about current clinical practices for methamphetamine use. Six semistructured group interviews were conducted with 38 primary care providers. Interviews focused on provider perceptions of patients with methamphetamine use problems and their care. Data were analyzed using inductive and thematic analysis and summarized along the following dimensions: (1) problem identification, (2) clinical management, (3) barriers and facilitators to care, and (4) perceived needs to improve services. Primary care providers varied in their approach to identifying and treating patient methamphetamine use. Unlike opioid use disorders, providers reported lacking standardized screening measures and evidence-based treatments, particularly medications, to address methamphetamine use. They seek more standardized screening tools, Food and Drug Administration-approved medications, reliable connections to addiction medicine specialists, and more training. Interest in novel behavioral health interventions suitable for primary care settings was also noteworthy. The findings from this qualitative analysis revealed that primary care providers are using a wide range of tools to screen and treat methamphetamine use, but with little perceived effectiveness. Primary care faces multiple challenges in effectively addressing methamphetamine use among patients singularly or comorbid with opioid use disorders, including the lack of Food and Drug Administration-approved medications, limited patient retention, referral opportunities, funding, and training for methamphetamine use. Focusing on patients' medical issues using a harm reduction, motivational interviewing approach, and linkage with addiction medicine specialists may be the most reasonable options to support primary care in compassionately and effectively managing patients who use methamphetamines.

Unique Pharmacology, Brain Dysfunction, and Therapeutic Advancements for Fentanyl Misuse and Abuse.

Fentanyl is a fully synthetic opioid with analgesic and anesthetic properties. It has become a primary driver of the deadliest opioid crisis in the United States and elsewhere, consequently imposing devastating social, economic, and health burdens worldwide. However, the neural mechanisms that underlie the behavioral effects of fentanyl and its analogs are largely unknown, and approaches to prevent fentanyl abuse and fentanyl-related overdose deaths are scarce. This review presents the abuse potential and unique pharmacology of fentanyl and elucidates its potential mechanisms of action, including neural circuit dysfunction and neuroinflammation. We discuss recent progress in the development of pharmacological interventions, anti-fentanyl vaccines, anti-fentanyl/heroin conjugate vaccines, and monoclonal antibodies to attenuate fentanyl-seeking and prevent fentanyl-induced respiratory depression. However, translational studies and clinical trials are still lacking. Considering the present opioid crisis, the development of effective pharmacological and immunological strategies to prevent fentanyl abuse and overdose are urgently needed.

The Public Health Approach to the Worsening Opioid Crisis in the United States Calls for Harm Reduction Strategies to Mitigate the Harm From Opioid Addiction and Overdose Deaths

The opioid crisis has devastated the U.S. more than any other country, and the epidemic is getting worse. While opioid prescriptions have decreased by more than 40% from its peak in 2010, unfortunately, opioid-related overdose deaths have not declined but continued to increase. With greater scrutiny on prescription opioids, many users switched to the cheaper and more readily available heroin that drove up heroin-related overdose deaths from 2010 to peak in 2016, being overtaken by the spike in synthetic opioid (mostly fentanyl)-related overdose deaths. The surge in fentanyl-related overdose deaths since 2013 is alarming as fentanyl is more potent and deadly. One thing is certain the opioid crisis is not improving but has become dire with the surge in fentanyl-related overdose deaths. Evidence-based strategies have to be implemented in the U.S. to control this epidemic before it destroys more lives. Other countries, including European countries and Canada, have invested more in harm reduction strategies than the U.S. even though they (especially Europe) do not face anywhere near the level of crisis as the U.S. In the long-run, upstream measures (tackling the social determinants of health) are more effective public health strategies to control the epidemic. In the meantime, however, harm reduction strategies have to be employed to mitigate the harm from addiction and overdose deaths.

Quantitation and Validation of 34 Fentanyl Analogs from Liver Tissue Using a QuEChERS Extraction and LC-MS-MS Analysis.

Since 2013, drug overdose deaths involving synthetic opioids (including fentanyl and fentanyl analogs) have increased from 3,105 to 31,335 in 2018. Postmortem toxicological analysis in fentanyl-related overdose deaths is complicated by the high potency of the drug, often resulting in low analyte concentrations and associations with toxicity, multidrug use, novelty of emerging fentanyl analogs and postmortem redistribution. Objectives for this study include the development of a quick, easy, cheap, effective, rugged and safe (QuEChERS) extraction and subsequent liquid chromatography-mass spectrometry--mass spectrometry analysis, validation of the method following the American Academy of Forensic Sciences Standards Board (ASB) standard 036 requirements and application to authentic liver specimens for 34 analytes including fentanyl, metabolites and fentanyl analogs. The bias for all 34 fentanyl analogs did not exceed ±10% for any of the low, medium or high concentrations and the %CV did not exceed 20%. No interferences were identified. All 34 analytes were within the criteria for acceptable percent ionization suppression or enhancement with the low concentration ranging from -10.2% to 23.7% and the high concentration ranging from -7.1% to 11.0%. Liver specimens from 22 authentic postmortem cases were extracted and analyzed with all samples being positive for at least one target analyte from the 34 compounds. Of the 22 samples, 17 contained fentanyl and metabolites plus at least one fentanyl analog. The highest concentration for a fentanyl analog was 541.4 μg/kg of para-fluoroisobutyryl fentanyl (FIBF). The concentrations for fentanyl (n = 20) ranged between 3.6 and 164.9 μg/kg with a mean of 54.7 μg/kg. The fentanyl analog that was most encountered was methoxyacetyl fentanyl (n = 11) with a range of 0.2-4.6 μg/kg and a mean of 1.3 μg/kg. The QuEChERS extraction was fully validated using the ASB Standard 036 requirements for fentanyl, metabolites and fentanyl analogs in liver tissue.

Understanding the increase in opioid overdoses in New Hampshire: A rapid epidemiologic assessment

BackgroundNew Hampshire (NH) has had among the highest rates of fentanyl-related overdose deaths per capita in the United States for several years in a row—more than three times the national average in 2016. This mixed-methods study investigated drug-using practices and perspectives of NH residents who use opioids to inform policy in tackling the overdose crisis. MethodsSeventy-six participants from six NH counties completed demographic surveys and semi-structured interviews focused on drug-using practices and perspectives, including use precursors, fentanyl-seeking behaviors, and experiences with overdose. Rigorous qualitative methods were used to analyze interview data including transcription, coding and content analysis. Descriptive statistics were calculated on quantitative survey data. ResultsEighty-four percent of interviewees had knowingly used fentanyl in their lifetime, 70 % reported overdosing at least once, and 42 % had sought a batch of drugs known to have caused an overdose. The majority stated most heroin available in NH was laced with fentanyl and acknowledged that variability across batches increased overdose risk. Participants reported high availability of fentanyl and limited access to prevention, treatment, and harm reduction programs. There was widespread support for expanding education campaigns for youth, increasing treatment availability, and implementing needle exchange programs. ConclusionsA confluence of factors contribute to the NH opioid overdose crisis. Despite consensus that fentanyl is the primary cause of overdoses, individuals continue to use it and affirm limited availability of resources to address the problem. Policies targeting innovative prevention, harm reduction, and treatment efforts are needed to more effectively address the crisis.

Surge in Fentanyl Toxicity Deaths in Jefferson Parish, LA, 2013-2018.

Background: The opioid epidemic in the United States has resulted in a significant increase in fentanyl-related overdoses nationwide since 2013. Because of an increased rate of fentanyl-related overdoses seen in Jefferson Parish, LA, the Jefferson Parish Coroner's Office (JPCO) hypothesized that the opioid epidemic, specifically related to fentanyl, had reached this region. To test this hypothesis, JPCO analyzed fentanyl overdose deaths to determine if the deaths had increased during a 6-year period and if the change met the definition of an epidemic.Methods: In the toxicology laboratory at JPCO, enzyme-linked immunosorbent assay screening and gas chromatography/mass spectrometry are used in-house to determine the presence of drugs. Drug-positive samples are sent to National Medical Services (NMS) Labs to quantify the analyte concentration in each sample. Data for each decedent were extracted from the Medicolegal Death Investigation Log (MDILog) database for the years 2013 through 2018.Results: A slow increase in fentanyl-related deaths during the first 3 years of the study period was followed by a near doubling of cases in 2016, a tripling of cases in 2017, and a 6-fold increase in incidence in 2018. During the 6-year study period, fentanyl-related deaths increased from 6 in 2013, to 8 in 2014, to 14 in 2015. Twenty-five deaths in 2016 spiked to 66 in 2017 and increased to 78 fentanyl-related overdose deaths in 2018. The percentage of fentanyl-related overdose deaths increased from 4% of all drug deaths in 2013 to 45% in 2018.Conclusion: The data validate the hypothesis that the fentanyl epidemic has affected Jefferson Parish in southeast Louisiana.

Sold as Heroin: Perceptions and Use of an Evolving Drug in Baltimore, MD

ABSTRACTSince 2001, heroin-related overdose deaths in the United States have risen six-fold, a rise unaccounted for by the expanding user population. Has heroin become a more dangerous drug? Reports of fentanyl and its analogs, often concealed in or sold as heroin, have also increased sharply. This article investigates heroin injectors’ perceptions and experiences of changes in the heroin supply in the East Coast city of Baltimore, Maryland, currently facing an epidemic in heroin- and fentanyl-related overdose deaths. Unusually, Baltimore’s heroin market is divided between two types: “Raw,” believed to be Colombian in origin and relatively pure, and the more adulterated “Scramble” (raw heroin traditionally blended with quinine and lactose). Users reported that Scramble heroin, while gaining market share, has become a highly unstable product, varying dramatically in appearance, intensity of onset, duration of action, and effect. Some considered that Scramble was no longer “heroin,” but was heavily adulterated or even replaced, mentioning fentanyl, benzodiazepines, and crushed opioid pills as additives. There was intense awareness of overdose as a present danger in users’ lives, which they linked to the recent adulteration of the heroin supply. Responses to this perceived adulteration varied, including information gathering, attraction, avoidance, taking precautions, and acceptance.

The ‘fentanyl epidemic’ in Canada – Some cautionary observations focusing on opioid-related mortality

In Canada, opioid-related overdose mortality has steeply increased in recent years; as a substantial number of opioid-related deaths are related to fentanyl products, this phenomenon has widely been described as the ‘fentanyl epidemic’, also implying that these deaths are largely caused by clandestinely produced illicit fentanyl products. We examined numbers and rates of opioid- and fentanyl-related deaths in six pan-Canadian provinces with respective (coroner-based) data available from 2010 to 2016. While fentanyl-related deaths are clearly increasing from relatively low levels in all provinces, those increases are strongest in the two Western provinces (e.g., British Columbia, where fentanyl accounts for the majority of opioid deaths in 2016 and Alberta), and, to some extent, Ontario. However, fentanyl-related deaths remain a minority of deaths in Ontario (40%) and the remaining provinces (<25%). Furthermore, it is uncertain what proportion of fentanyl-related deaths is actually related to illicit fentanyl products. We conclude that fentanyl-related overdose deaths have risen – most strongly in the West – due to both a high availability of medical fentanyl products, as well as an influx of illegal fentanyl products. In most provinces, the majority of opioid deaths remain associated with other (non-fentanyl) products. Appropriate (prevention, treatment and policy) interventions need to be targeted at the full range of opioid deaths from different sources. Overall, a realistic framing of the social (e.g., media) discourse about the nature of the ‘opioid overdose death crisis’ is required, which is not exclusively an ‘illicit fentanyl death crisis’ even though this may be a socio-politically appealing image.

Fentanyl and the Evolving Opioid Epidemic: What Strategies Should Policy Makers Consider?

Major policy efforts are being aimed at combating the epidemic of opioid addiction and overdose deaths. In response to the epidemic, the medical community and policy makers have attempted to intervene; to date, these varied approaches have done little to reverse the increase in mortality related to opioid overdose. One factor that has complicated efforts to control overdose deaths has been the emergence of a public health crisis related to illicit fentanyl. The rise in fentanyl-related overdose deaths means that new approaches are needed to combat the opioid epidemic, including adoption of harm reduction strategies. Specific strategies that should be considered as part of efforts to combat the opioid crisis include safe drug consumption sites, anonymous drug-checking services, updated naloxone distribution policies, harm reduction-oriented policing, expansion of evidence-based pharmacological treatments in criminal justice and emergency department settings, and stigma-reduction messaging emphasizing the risks of fentanyl.

Post-mortem review of fentanyl-related overdose deaths among identified drug users in Southern Bavaria, Germany, 2005–2014

BackgroundTwo decades ago, there were only single case reports on deaths in Europe following the consumption of illicitly manufactured fentanyl by problem drug users. Today, lethal fentanyl intoxication is now no longer a rarity. Since 2005, a rapid increase of lethal fentanyl-related intoxications in the drug scene has been observed at the Institute of Legal Medicine, Ludwig Maximilians University, Munich. We hypothesized that this rise is the result of the launch of fentanyl matrix patches in Germany in 2004, their broad acceptance, their diversion from the regulated supply chain, and incautious prescription by medical care providers. MethodsPost-mortem toxicological reports were reviewed for lethal fentanyl-related intoxications between 2004 und 2014. Blood and tissue samples were tested by GC/MS or LC–MS/MS. The results of police investigations, autopsy reports, and the database of the Institute of Legal Medicine, LMU, were analysed to identify problem drug users and to detect the source of fentanyl as well as the routes of administration. ResultsBetween 2005 and 2014, 242 overdose victims with post-mortem toxicological detection of fentanyl were found. In the majority of cases, fentanyl matrix patches were the source of fentanyl. ConclusionThe onset of fentanyl-related deaths coincided with the launch of transdermal fentanyl matrix patches in Germany in 2004. Several approaches, such as providing drug users with information on the possible risks of fentanyl consumption, education of medical caregivers, and also monitoring of the prescription of fentanyl patches, are required to reduce the number of fentanyl-related deaths in drug addicts.

Heroin and fentanyl overdoses in Kentucky: Epidemiology and surveillance

BackgroundThe study aims to describe recent changes in Kentucky's drug overdose trends related to increased heroin and fentanyl involvement, and to discuss future directions for improved drug overdose surveillance. MethodsThe study used multiple data sources (death certificates, postmortem toxicology results, emergency department [ED] records, law enforcement drug submissions, and prescription drug monitoring records) to describe temporal, geographic, and demographic changes in drug overdoses in Kentucky. ResultsFentanyl- and heroin-related overdose death rates increased across all age groups from years 2011 to 2015 with the highest rates consistently among 25–34-year-olds. The majority of the heroin and fentanyl overdose decedents had histories of substantial exposures to legally acquired prescription opioids. Law enforcement drug submission data were strongly correlated with drug overdose ED and mortality data. The 2016 crude rate of heroin-related overdose ED visits was 104/100,000, a 68% increase from 2015 (62/100,000). More fentanyl-related overdose deaths were reported between October, 2015, and September, 2016, than ED visits, in striking contrast with the observed ratio of >10 to 1 heroin-related overdose ED visits to deaths. Many fatal fentanyl overdoses were associated with heroin adulterated with fentanyl; <40% of the heroin overdose ED discharge records listed procedure codes for drug screening. ConclusionsThe lack of routine ED drug testing likely resulted in underreporting of non-fatal overdoses involving fentanyl and other synthetic drugs. In order to inform coordinated public health and safety responses, drug overdose surveillance must move from a reactive to a proactive mode, utilizing the infrastructure for electronic health records.

Increases in self-reported fentanyl use among a population entering drug treatment: The need for systematic surveillance of illicitly manufactured opioids

Background/purposeRecent reports indicate a sharp increase in fentanyl-related overdose deaths across the United States, much of which is likely related to the introduction of cheap, illicitly manufactured fentanyl derivatives. In this study, we sought to estimate the magnitude of illicit fentanyl use from 2012 to 2016 using a national opioid abuse surveillance system. MethodsThe study program surveyed 10,900 individuals entering substance abuse treatment for opioid use disorder, with participants asked to endorse past month ‘use to get high' of fentanyl drugs, stratified by identifiable (i.e., branded) fentanyl formulations or a ‘type unknown' drug alleged to contain fentanyl. Main findingsTotal past-month fentanyl-use rose modestly from 2012 to 2016. While use of known fentanyl products remained relatively stable (mean=10.9%; P=0.25), endorsements of ‘unknown’ fentanyl products nearly doubled from 9% in 2013 to 15.1% by 2016 (P<0.001). Data show no discernable indication that this increase is diminishing or stabilizing. ConclusionsThis first attempt to assess the prevalence of illicit fentanyl use shows that recent increases in fentanyl use seem to be due almost entirely to ‘unknown' fentanyl presumed to be illicitly manufactured. Given that it is difficult to assess the extent to which fentanyl may have been substituted for another drug (i.e., oxycodone, alprazolam, etc.) or was used as a heroin admixture, our data likely represent an underestimation of the full magnitude of illicit fentanyl abuse. As such, this growing public health problem requires immediate attention and more systematic efforts to identify and track its abuse.

Erratum: Vol. 65, No. 33.

In the report, "Increases in Fentanyl-Related Overdose Deaths - Florida and Ohio, 2013-2015," on page 845, in "FIGURE. Number of fentanyl-related law enforcement submissions* and overdose deaths, and rate of fentanyl prescriptions - Florida and Ohio, January 2013-June 2015," in the Florida line chart, the second and third labels in the legend should be reversed. The second label should read "Fentanyl-related overdose deaths," and the third label should read "Fentanyl-related law enforcement submissions."

Increases in Fentanyl-Related Overdose Deaths - Florida and Ohio, 2013-2015.

In March and October 2015, the Drug Enforcement Administration (DEA) and CDC issued nationwide alerts identifying fentanyl, particularly illicitly manufactured fentanyl (IMF), as a threat to public health and safety (1,2). IMF is pharmacologically similar to pharmaceutical fentanyl (PF), but is unlawfully produced in clandestine laboratories, obtained via illicit drug markets, and includes fentanyl analogs. Fentanyl is a synthetic opioid 50-100 times more potent than morphine and approved for the management of surgical/postoperative pain, severe chronic pain, and breakthrough cancer pain.* DEA's National Forensic Laboratory Information System (NFLIS) collects drug identification results from drug cases analyzed by federal, state, and local forensic laboratories throughout the United States.(†) In 2014, 80% of fentanyl submissions (i.e., drug products obtained by law enforcement that tested positive for fentanyl) in NFLIS were identified from 10 states, including Florida and Ohio (2), and seven of these 10 states reported sharp increases in fentanyl-related overdose deaths (fentanyl deaths) (3). This report presents findings of increased fentanyl deaths during 2013-2015 from investigations conducted by the University of Florida and the Ohio Department of Public Health, in collaboration with CDC. Analyses examined the association between trends in fentanyl-related law enforcement submissions and fentanyl deaths and describes groups at risk for fentanyl death using medical examiner and coroner reports. The marked increases in fentanyl death in Florida and Ohio during 2013-2015 were closely associated with parallel increases in fentanyl submissions, with the largest impact on persons who use heroin, consistent with reports that IMF is commonly mixed with or sold as heroin (1,4). In Ohio, circumstances associated with fentanyl deaths included a current diagnosed mental health disorder(§) and recent release from an institution such as a jail, rehabilitation facility, or hospital.

Rising Fentanyl-related Overdose Deaths in British Columbia

There has been a surge in the number of fentanyl-detected overdoses in 2014 among people who use drugs in British Columbia. Provisional data indicates a constant increase in the number of fentanyl-detected overdoses over the past 3 years. A green pill, ‘fake oxy’ tablets, which resemble Oxycontin 80mg (oxycodone) have been found to contain variable amounts of fentanyl and not oxycodone. The physiological effects, symptoms and signs of fentanyl overdose are largely indistinguishable from that of heroin. This can complicate the management of overdoses in emergency settings. Emergency room physicians may find that the standard protocol dose of 0.4 - 0.8 mg of naloxone for heroin overdoses insufficient to reverse fentanyl overdoses. In such cases, in addition to investigations to rule out other potential use of other substances, larger doses of naloxone are often necessary to reverse the overdose. Take home naloxone programs are one harm reduction approach which is available in many jurisdictions in US1 and was initiated in British Columbia in 2012 and it is currently available at 62 sites throughout the province of British Columbia. Il y a eu une vague d'overdoses liées à la présence de fentanyl en 2014 parmi les personnes qui consomment des drogues en Colombie-Britannique. Des données provisoires indiquent une augmentation constante du nombre d'overdoses liées au fentanyl au cours des trois dernières années. Des comprimés verts, “fake oxy”, ressemblant à des comprimés d'Oxycontin 80mg (oxycodone), ont été identifiés comme contenant des quantités variables de fentanyl et non d'oxycodone. Les effets physiologiques, signes et symptômes d'une overdose par fentanyl s'apparentent à ceux de l'héroïne. Ce tableau complexifie la gestion des overdoses en situations d'urgence. Les médecins en salles d'urgence pourraient faire face à des situations où la dose standard de naloxone (0,4 - 0,8 mg) pour overdose d'héroïne soit insuffisante pour renverser les effets d'une overdose de fentanyl. Devant pareilles situations, en plus de chercher à éliminer la présence d'autres substances, de plus grandes doses de naloxone sont souvent nécessaires pour renverser l'overdose. Les programmes de naloxone à emporter sont une approche de réduction des méfaits disponible dans plusieurs juridictions aux États-Unis1 et en Colombie-Britannique depuis 2012. Ils sont présentement disponibles dans 62 sites à travers la province.

Fentanyl Concentrations in 23 Postmortem Cases from the Hennepin County Medical Examiner’s Office*

The purpose of this study was to compare blood fentanyl concentrations in fentanyl-related deaths with fentanyl concentrations found incidentally at autopsy, as well as with fentanyl concentrations found in hospitalized patients receiving fentanyl. Between the years 1997 to 2005, 23 fentanyl-positive postmortem cases were identified. Nineteen of 23 (82.6%) cases were deemed to be drug overdoses. Fentanyl alone was responsible for 8 of the 19 (42.1%) overdose deaths. Mean and median fentanyl concentrations were 36 (SD 38) microg/L and 22 microg/L, respectively, range 5-120 microg/L. Seven of the cases were accidental, one undetermined. The remaining 11 of the 19 (57.9%) cases were mixed drug overdoses. Fentanyl concentrations in these cases were 31 (SD 46) microg/L, range 5-152 microg/L. All of the mixed drug overdoses were determined to be accidental. Four cases where fentanyl was considered an incidental postmortem finding were determined to be natural deaths. In hospitalized inpatients (n = 11) receiving fentanyl 2 of the patients receiving fentanyl for chronic pain for more than 3 months had concentrations of 8.5 microg/L and 9.9 microg/L. The other nine inpatient concentrations were less than 4 microg/L. In conclusion, blood fentanyl concentrations found in cases where fentanyl alone was determined to be the cause of death were similar to cases where fentanyl was part of a mixed drug overdose. There was also considerable overlap between fentanyl concentrations in fentanyl-related overdose deaths compared to hospitalized patients being treated for chronic pain. Fentanyl concentrations in postmortem cases must be interpreted in the context of the deceased's past medical history and autopsy findings.