The evolution of fentanyl-related substances: Prevalence and drug concentrations in postmortem biological specimens at the Miami-Dade Medical Examiner Department

Since 2014, the Miami-Dade Medical Examiner Department (MDME) has observed a drastic increase in the number of fentanyl and fentanyl analog (fentanyl-related substances (FRSs)) fatalities since its introduction into the heroin and cocaine supply. Due to the prevalence of FRS in Miami-Dade County, the MDME toxicology laboratory began documenting each case in which fentanyl and/or a fentanyl analog was identified. Additional information monitored included demographics (age, race and sex), other drugs identified, cause of death (COD) and manner of death (MOD). From 2014 to 2022, the MDME toxicology laboratory analyzed a total of 1,989 cases that tested positive for FRS, of which 1,707 had detectable and/or quantifiable fentanyl concentrations in postmortem cases. The majority of decedents were white males (62%), and the predominant age range was 25-34 years. The most prevalent MOD was accident (93%) with the most common COD listed as acute combined drug toxicity of fentanyl in combination with other drugs (79%). Other drugs found in combination with fentanyl included heroin, cocaine (most prevalent), synthetic cathinones and ethanol. Of all FRS cases, 9% (170 cases) involved fentanyl alone as a COD, while 2% (38 cases) included only fentanyl analogs. Fentanyl concentrations ranged from 1.0 to 1,646 ng/mL in peripheral blood, 1.2 to 449 ng/mL in central blood, 3.2 to 28 ng/mL in donor blood (obtained during tissue harvesting), 1.1 to 108 ng/mL in antemortem blood, 8.5 to 1,130 ng/g in liver and 2.0 to 471 ng/g in brain. Drug concentrations were also reported for an additional eight fentanyl analogs. Considering the prevalence, high potency and constant evolution of FRS, it is important to continuously monitor trends and report drug concentrations in complex medical examiner casework in an effort to educate pathologists, law enforcement and local governments.

Analysis of over 250 novel synthetic opioids and xylazine by LC-MS-MS in blood and urine

Novel Synthetic Opioids (NSO) are frequently found in postmortem (PM) and human performance (HP) forensic toxicology casework, resulting in impairment and fatal overdoses. Developing a broad NSO method benefits public health, as it can be used to identify trends in potent opioid use to develop risk management programs. This project aimed to design a comprehensive, rapid and routine method for the selective analysis of over 250 novel synthetic opioids in blood and urine. This method rapidly extracted 150 µL of blood or urine via protein precipitation followed by size-exclusion filtration, evaporation and reconstitution. Separation and data acquisition were achieved on a 12 min LC-MS-MS method using an F5 column. Data processing was expedited with a custom built-in query created in-house that automated processing and enhanced quality assurance. Validation according to ASB/ANSI Standard 036 was performed and applicability of the method was assessed using proficiency test and authentic casework samples. Assessed in blood and urine qualitatively were 261 unique analytes including fentanyl analogs (fentalogs), nitazenes and other miscellaneous synthetic opioids. As 59 isomeric target analytes were placed into groups due to co-elution, there were 202 distinct acquired targets or target - groups. To demonstrate applicability, 27 proficiency test blood samples received over an approximate 4-year period were analyzed with 126 expected results assessed comprising 25 unique target analytes. Additionally, 617 fatal accidental overdoses within San Francisco in 2022 were retroactively analyzed by this method with almost 10% of cases containing a new NSO substance(s). Such trends and NSO substances were previously unknown in this community.

Software-assisted automated detection and identification of "unknown" fentanyl analogues

Fentanyl and its non-pharmaceutical analogues (NPFs) are potent synthetic opioids, traditionally used for pain management, with ever-increasing illicit uses. Tightening the regulation for known fentanyls leads to new synthetic analogues in the opioid market. Furthermore, the Organization for the Prohibition of Chemical Weapons (OPCW) has recently issued a decision regarding aerosolized use of central nervous system (CNS)-acting agents, such as fentanyl and its analogues, under the concern that these materials could be misused for terror or war purposes. The ever-increasing development of new fentanyl analogues makes the task of detection and identification of these new, unknown analogues crucial. In this work, we introduce an automated tool for the detection and putative identification of "unknown" fentanyl analogues, using liquid chromatography-mass spectrometry (LC-MS) (high-resolution mass spectrometry [HRMS]) analysis, subsequently followed by data processing using the "Compound Discoverer" software. This software, in our modified use, enabled the automatic detection of various fentanyl analogues, by "digging" out components and comparing them to pre-calculated theoretical molecular ions of possible modifications or transformations on the fentanyl backbone structure (no library or database used). Subsequently, structural elucidation for the proposed component of interest is carried out by automated MS/MS data interpretation, as performed by the software. This method was explored on 12 fentanyl-based "unknown" analogues used as model examples, including chemical modifications such as fluorination and methylation. In all tested compounds, automatic detection and identification were achieved, even at concentrations as low as 1 ng/mL in an environmental soil matrix extract.

A method for the sensitive targeted screening of synthetic cannabinoids and opioids in whole blood by LC-QTOF-MS with simultaneous suspect screening using HighResNPS.com

A sensitive method for the qualitative screening of synthetic cannabinoids and opioids in whole blood was developed and validated using alkaline liquid-liquid extraction (LLE) and liquid chromatography-time-of-flight mass spectrometry (LC-QTOF-MS). Estimated limits of detection for validated compounds ranged from 0.03 to 0.29 µg/L (median, 0.04 µg/L) for the 27 opioids and from 0.04 to 0.5 µg/L (median, 0.07 µg/L) for the 23 synthetic cannabinoids. Data processing occurred in two stages; first, a targeted screen was performed using an in-house database containing retention times, accurate masses and MS-MS spectra for 79 cannabinoids and 53 opioids. Suspect screening was then performed using a database downloaded from the crowd sourced NPS data website HighResNPS.com which contains mass, consensus MS-MS data and laboratory-specific predicted retention times for a far greater number of compounds. The method was applied to 61 forensic cases where synthetic cannabinoid or opioid screening was requested by the client or their use was suspected due to case information. CUMYL-PEGACLONE was detected in two cases and etodesnitazine, 5 F-MDMB-PICA, 4-cyano-CUMYL-BUTINACA and carfentanil were detected in one case each. These compounds were within the targeted scope of the method but were also detected through the suspect screening workflow. The method forms a solid base for expansion as more compounds emerge onto the illicit drug market.

The rise and rise of fentanyl in postmortem casework

Forensic toxicology laboratories are navigating a period of time with increasing drug overdose deaths, an opioid epidemic, the impact of the COVID-19 pandemic, and the illicit drug market flooded with novel psychoactive substances. In New York City, the Department of Forensic Toxicology has experienced a 56% increase in postmortem casework in the past decade with fentanyl detected in 80% of all overdose deaths. Over a period of 2.5 years, 15,638 postmortem cases were tested for the presence of fentanyl and fentanyl analogs using liquid-chromatography tandem mass spectrometry (LCMSMS). Fentanyl was detected in approximately one third of cases and of these 4447 cases with femoral blood. A twofold increase in cases with high concentrations of fentanyl (>100 ng/mL) was observed between 2021 and 2022. The minor metabolite and precursor chemical, 4-ANPP (4-anilino-N-phenethylpiperidine) may help differentiate between illicit and licit fentanyl. 4-ANPP blood concentrations were <10 ng/mL in 98% of the cases and the 4-ANPP:fentanyl ratio was <0.67 for 99.1% of blood specimens. Only six cases had 4-ANPP concentrations higher than the corresponding fentanyl blood concentration. This study also highlights, the changing fentanyl analogs found in postmortem cases since 2016 in NYC with the emergence of fluorofentanyl initially identified in 2020 and continuing to dominate in comparison with the prevalence of other analogs, many of which are no longer detected in casework. The detection of one of the latest drugs to be mixed with fentanyl, namely xylazine, has also increased in prevalence by 36.7% in 2022 compared with 2021.

Review of analytical methods for screening and quantification of fentanyl analogs and novel synthetic opioids in biological specimens

Fentanyl, fentanyl analogs, and other novel synthetic opioids (NSO), including nitazene analogs, prevail in forensic toxicology casework. Analytical methods for identifying these drugs in biological specimens need to be robust, sensitive, and specific. Isomers, new analogs, and slight differences in structural modifications necessitate the use of high-resolution mass spectrometry (HRMS), especially as a non-targeted screening method designed to detect newly emerging drugs. Traditional forensic toxicology workflows, such as immunoassay and gas chromatography mass spectrometry (GC-MS), are generally not sensitive enough for detection of NSOs due to observed low (sub-μg/L) concentrations. For this review, the authors tabulated, reviewed, and summarized analytical methods from 2010-2022 for screening and quantification of fentanyl analogs and other NSOs in biological specimens using a variety of different instruments and sample preparation approaches. Limits of detection or quantification for 105 methods were included and compared to published standards and guidelines for suggested scope and sensitivity in forensic toxicology casework. Methods were summarized by instrument for screening and quantitative methods for fentanyl analogs and for nitazenes and other NSO. Toxicological testing for fentanyl analogs and NSOs is increasingly and most commonly being conducted using a variety of liquid chromatography mass spectrometry (LC-MS)-based techniques. Most of the recent analytical methods reviewed exhibited limits of detection well below 1 μg/L to detect low concentrations of increasingly potent drugs. In addition, it was observed that most newly developed methods are now using smaller sample volumes which is achievable due to the sensitivity increase gained by new technology and new instrumentation.

Mechanisms of Neurorespiratory Toxicity Induced by Fentanyl Analogs—Lessons from Animal Studies

In 2020, fentanyl and its analogs contributed to ~65% of drug-attributed fatalities in the USA, with a threatening increasing trend during the last ten years. These synthetic opioids used as potent analgesics in human and veterinary medicine have been diverted to recreational aims, illegally produced and sold. Like all opioids, central nervous system depression resulting from overdose or misuse of fentanyl analogs is characterized clinically by the onset of consciousness impairment, pinpoint miosis and bradypnea. However, contrasting with what observed with most opioids, thoracic rigidity may occur rapidly with fentanyl analogs, contributing to increasing the risk of death in the absence of immediate life support. Various mechanisms have been proposed to explain this particularity associated with fentanyl analogs, including the activation of noradrenergic and glutamatergic coerulospinal neurons and dopaminergic basal ganglia neurons. Due to the high affinities to the mu-opioid receptor, the need for more elevated naloxone doses than usually required in morphine overdose to reverse the neurorespiratory depression induced by fentanyl analogs has been questioned. This review on the neurorespiratory toxicity of fentanyl and analogs highlights the need for specific research focused on these agents to better understand the involved mechanisms of toxicity and develop dedicated strategies to limit the resulting fatalities.

Novel Applications of Microextraction Techniques Focused on Biological and Forensic Analyses

In recent years, major attention has been focused on microextraction procedures that allow high recovery of target analytes, regardless of the complexity of the sample matrices. The most used techniques included liquid-liquid extraction (LLE), solid-phase extraction (SPE), solid-phase microextraction (SPME), dispersive liquid-liquid microextraction (DLLME), microextraction by packed sorbent (MEPS), and fabric-phase sorptive extraction (FPSE). These techniques manifest a rapid development of sample preparation techniques in different fields, such as biological, environmental, food sciences, natural products, forensic medicine, and toxicology. In the biological and forensic fields, where a wide variety of drugs with different chemical properties are analyzed, the sample preparation is required to make the sample suitable for the instrumental analysis, which often includes gas chromatography (GC) and liquid chromatography (LC) coupled with mass detectors or tandem mass detectors (MS/MS). In this review, we have focused our attention on the biological and forensic application of these innovative procedures, highlighting the major advantages and results that have been accomplished in laboratory and clinical practice.

Ocfentanil testing in hair from a fatality case: Comparative analysis of a lock of hair versus a single hair fiber

In clinical and forensic toxicology, hair analysis offers a larger window for detecting drug exposure than blood or urine. Drug measurements are generally carried out using a segmented lock of hair, but few articles report the use of a single hair to document drug exposure. Nevertheless, single hair analysis can be very useful, particularly if only small amounts of biological matrices are available. More data on analyzing new synthetic opioids (NSOs) in hair are needed to help interpretation in future cases. In this study, segmental single hair analysis is compared with segmental hair lock analysis to document an ocfentanil-related death. The hair lock and single hair analyses were performed using the LC-MS/MS method after decontamination and incubation. Ocfentanil (OcF) concentrations ranged from 42 to 150 pg/mg in the segmented hair lock, depending on the segments. The hair lock and single hair analyses showed similar results: the highest concentrations were measured in the first two centimeters and decreased from root to tip. The similar profiles obtained from both the lock of hair and the single hair demonstrate the relevance of single hair analysis in cases where very few data are available. This article describes OcF concentrations in an authentic hair sample after a documented intake of this molecule in a fatality.

Fentanyl, Acetylfentanyl, and Carfentanil in Impaired Driving Cases: A Review of 270 Cases

The detection of fentanyl and fentanyl analogs has been widely communicated throughout the scientific community. While most of the reporting has been in relation to overdose deaths, these drugs are commonly detected in impaired driving cases. A retrospective study of impaired driving cases analyzed between 2017 and 2019 produced 270 cases positive for fentanyl, carfentanil, and/or acetylfentanyl. Fentanyl was the predominant drug found in these 270 cases (65.5%) with concentrations ranging from less than 1.0 ng/mL to 64 ng/mL. Carfentanil was found alone in 6.6% cases with three concentrations above 1.0 ng/mL. Acetylfentanyl was always found when fentanyl was positive with concentrations ranging from less than 1.0 ng/mL to 9.2 ng/mL. Detailed case histories are provided with corresponding toxicology results. Toxicology results show impaired drivers using multiple drugs with a wide range of observed behaviors. The inclusion of these drugs in routine impaired driver toxicology testing is extremely important when attempting to determine their overall prevalence.

A 2017-2019 Update on Acute Intoxications and Fatalities from Illicit Fentanyl and Analogs

The aim of this review was to report the most recent cases of acute intoxication, fatalities and "driving under the influence" cases, involving illicit fentanyl and its newest analogs. When available, information on age, sex, circumstances of exposure, intoxication symptoms, cause of death (if applicable) and toxicology results from biological fluid testing was described. Scientific publications reporting fatalities or acute intoxications involving use of fentanyl derivatives were identified from PubMed, Scopus and institutional/governmental websites from January 2017 up to December 2019. The search terms, used alone and in combination, were as follows: fentanyl, street fentanyl, analogs, compounds, derivatives, abuse, fatality, fatalities, death, toxicity, intoxication and adverse effects. When considered relevant, reports not captured by the initial search but cited in other publications were also included. Of the 2890 sources initially found, only 44 were suitable for the review. Emergent data showed that the most common analogs detected in biological samples and seized materials are acetylfentanyl, acrylfentanyl, butyrfentanyl, carfentanil, cyclopropylfentanyl, fluorofentanyl, 4-fluorobutyrfentanyl, 4-fluoroisobutyrfentanyl, furanylfentanyl, 2-methoxyacetylfentanyl, 3-methylfentanyl and ocfentanil. These compounds were frequently administered in association with other illicit substances, medicinal drugs and/or alcohol; patients and the victims often had a previous history of drug abuse. The trend of fentanyl analogs is rapidly evolving with illicit market fluctuations. Since information about potency and lethal dosage are frequently unknown, it is important to identify the new trends for further investigation on therapeutic use, toxicity and fatal doses, and implement public health measures. Recently marketed fentanyl analogs such as crotonylfentanyl and valerylfentanyl were not involved in intoxications to date, but should be carefully monitored. Many intoxications and fatalities might have gone unnoticed, and research efforts should focus on metabolite identification studies and the implementation of updated and comprehensive analytical methods.

Long-Term Stability of 13 Fentanyl Analogs in Blood

Fentanyl analogs continue to play a major role in proliferating the opioid epidemic in the United States. With high rates of overdose deaths, forensic laboratories experience backlogs, which may lead to false negative results due to drug instability. To address this issue, a quantitative method was validated for fentanyl analogs (3-methylfentanyl, 4-ANPP, 4-fluoro-isobutyrylfentanyl (4-FIBF), acetylfentanyl, acrylfentanyl, butyrylfentanyl, carfentanil, cyclopropylfentanyl, fentanyl, furanylfentanyl, methoxyacetylfentanyl, p-fluorofentanyl, and valerylfentanyl) in blood using liquid chromatography-quadrupole-time-of-flight mass spectrometry (LC-QTOF-MS) and used to assess long-term stability under various temperature conditions (-20°C, 4°C, ~25°C, and 35°C) for 9 months. Authentic specimens were also analyzed 6 months apart for applicability to postmortem blood. Method validation resulted in calibration ranges of 1-100 ng/mL and limits of detection (LOD) of 0.5 ng/mL. Precision and bias were acceptable (within ±7.2%CV and ±15.2%, respectively). Matrix effects exhibited ion enhancement for all analytes, except carfentanil and 4-ANPP in low quality control (>25%). For long-term stability, fentanyl analogs (except acrylfentanyl) remained stable under room temperature and refrigerated conditions at low and high concentrations (81.3-112.5% target) for 9 months. While most fentanyl analogs remained stable frozen, degradation was observed after 2 weeks (4 freeze/thaw cycles). At elevated temperatures, most analytes were stable for 1 week (74.2-112.6% target). Acrylfentanyl was unstable after 24h under elevated (70% loss) and room temperatures (53-60% loss), 48-72h refrigerated (28-40% loss), and 4 weeks frozen (22% loss). In authentic bloods (n=7), initial furanylfentanyl (FuF) and 4-ANPP concentrations were 1.1-3.6 and 1.4-6.4 ng/mL, respectively. Percent loss of FuF and 4-ANPP over 6 months were 16.3-37.4% and 0.2-26.8%, respectively. Samples suspected to contain fentanyl analogs are recommended to be stored refrigerated or frozen with limited freeze/thaw cycles. Due to instability, in the event of an acrylfentanyl overdose, samples should be analyzed immediately or stored frozen with analysis within 1 month.

Concentrations of para-Fluorofuranylfentanyl (FFF) in Paired Central and Peripheral Blood Collected During Postmortem Death Investigations

The opioid epidemic in the United States (U.S.) has been associated with an increasing mortality rate in large part due to the emergence and proliferation of synthetic opioids over the last fifteen years. Fentanyl and its analogues have played a large part in these statistics due to their potency and toxicity. Fluorofuranylfentanyl (FFF) is a fentanyl analogue that emerged in the U.S. in 2018 and was associated with numerous adverse events and deaths. During this study, a liquid chromatography tandem mass spectrometry (LC-MS/MS) workflow was developed to accurately identify the isomer of FFF present (ortho- vs. meta- vs. para-) in medicolegal death investigation cases from Pinellas County, Florida. FFF was quantified in central and peripheral blood samples collected at autopsy. In addition, the metabolism of FFF was studied using liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS). para-FFF was quantitatively confirmed in 29 postmortem cases; no other isomer of FFF was detected. Central blood concentrations ranged between 0.66 and 73 ng/mL (mean = 11±14 ng/mL, median = 10 ng/mL) and peripheral blood concentrations ranged between 0.53 and 23 ng/mL (mean = 5.7±6.4 ng/mL, median = 2.7 ng/mL). Comparison of central to peripheral blood concentrations were evaluated to determine the possibility of postmortem redistribution (PMR). The metabolism of ortho-FFF was studied and found to undergo metabolic processes similar to fentanyl, producing ortho-fluorofuranyl-norfentanyl, fluoro-4-ANPP, and hydroxylated species. The results of this study demonstrate the toxicity of FFF and its implication in medicolegal death investigations. Laboratories must remain aware of new or re-emerging fentanyl analogues, as they pose significant risks to public health and public safety.

Untargeted Metabolic Profiling of 4-Fluoro-Furanylfentanyl and Isobutyrylfentanyl in Mouse Hepatocytes and Urine by Means of LC-HRMS

The diffusion of new psychoactive substances (NPS) is highly dynamic and the available substances change over time, resulting in forensic laboratories becoming highly engaged in NPS control. In order to manage NPS diffusion, efficient and innovative legal responses have been provided by several nations. Metabolic profiling is also part of the analytical fight against NPS, since it allows us to identify the biomarkers of drug intake which are needed for the development of suitable analytical methods in biological samples. We have recently reported the characterization of two new analogs of fentanyl, i.e., 4-fluoro-furanylfentanyl (4F-FUF) and isobutyrylfentanyl (iBF), which were found for the first time in Italy in 2019; 4F-FUF was identified for the first time in Europe and was notified to the European Early Warning System. The goal of this study was the characterization of the main metabolites of both drugs by in vitro and in vivo experiments. To this end, incubation with mouse hepatocytes and intraperitoneal administration to mice were carried out. Samples were analyzed by means of liquid chromatography-high resolution mass spectrometry (LC-HRMS), followed by untargeted data evaluation using Compound Discoverer software with a specific workflow, designed for the identification of the whole metabolic pattern, including unexpected metabolites. Twenty metabolites were putatively annotated for 4-FFUF, with the dihydrodiol derivative appearing as the most abundant, whereas 22 metabolites were found for iBF, which was mainly excreted as nor-isobutyrylfentanyl. N-dealkylation of 4-FFUF dihydrodiol and oxidation to carbonyl metabolites for iBF were also major biotransformations. Despite some differences, in general there was a good agreement between in vitro and in vivo samples.

Quantitation of Fentanyl and Metabolites from Liver Tissue Using a Validated QuEChERS Extraction and LC-MS-MS Analysis

According to the National Institute on Drug Abuse (NIDA), more than one hundred people die every day from opioid overdose. Overdose fatalities have risen as the availability of potent synthetic opioids, such as fentanyl, has increased. A forensic postmortem toxicological specimen is often in various stages of decomposition, experiencing autolysis and putrefaction, which complicates the extraction, creating a difficult challenge for toxicologists. Isolating the target drug, while creating an efficient and simplified analytical scheme, is a goal for most toxicology laboratories. The validation of a quick, easy, cheap, effective, rugged and safe extraction protocol is presented in this study as an alternative analytical method for efficient extraction and detection of fentanyl and its major metabolites: norfentanyl and despropionyl fentanyl (4-ANPP). The liquid Chromatography with tandem mass spectrometry analysis was validated following the American Academy of Forensic Sciences Standards Board (ASB) standard 036 proposed requirements. Evaluated parameters include selectivity, matrix effects (MEs), linearity, processed sample stability, bias, precision and proof of applicability using liver samples from authentic postmortem cases. MEs (represented as percent ionization suppression or enhancement) at low and high concentrations were -10.0% and 1.4% for fentanyl, -2.1% and -0.3% for 4-ANPP and 3.1% and 2.8% for norfentanyl, respectively. Bias for the three analytes ranged from -8.5% to -19.9% for the low concentrations, -3.6% to -14.7% for the medium concentrations and 1.5% to -16.1% for the high concentrations with all being within the ±20% guideline. Precision for the three analytes ranged from 2.2% to 15.1%. The linear range for the fentanyl and norfentanyl was 0.5-100 and 4-ANPP had a linear range of 0.4-80 μg/kg. The authentic postmortem liver samples ranged in fentanyl concentrations from 56.6 to 462.3 μg/kg with a mean of 149.2 μg/kg (n = 10). The range of norfentanyl concentrations were 1.9 to 50.0 μg/kg with a mean of 14.1 μg/kg (n = 10). The range of 4-ANPP concentrations were 3.2 to 23.7 μg/kg with a mean of 7.5 μg/kg (n = 7).

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.

Carfentanil - from an animal anesthetic to a deadly illicit drug

The use of novel synthetic opioids as recreational drugs has become a public health concern as they are implicated in numerous fatal intoxications across the world. Synthetic opioids have played a major role in the United States opioid crisis and may contribute to a similar opioid epidemic in Europe. The most prominent group of designer opioids consists of fentanyl and its analogues. At present, carfentanil is the most dangerous fentanyl derivative. It was recently detected as an adulterant to other illicit drugs and counterfeit pharmaceuticals, contributing to life-threatening hospital admissions and fatalities. Toxic exposure to carfentanil typically occurs through injection, insufflation or inhalation. Carfentanil produces similar pharmacotoxicological effects to other opioids. However, due to its extraordinary potency, reversing carfentanil-induced severe and recurring respiratory depression requires administration of multiple or higher than standard doses of naloxone. Toxicological reports indicate that carfentanil use is strongly connected to polydrug use. Detection of carfentanil requires specific and sensitive analytical methods that are not commonly available in hospitals. Since abuse of carfentanil is an emerging problem, particularly in the United States, there is an urgent need to develop new techniques for rapid determination of intoxication evoked by this drug as well as new treatment regimens for effective overdose maintenance. This review presents current knowledge on pharmacological activity of carfentanil, prevalence and patterns of use, and analytical methods of its detection. Special emphasis is given to carfentanil-related non-fatal and lethal overdose cases.

Classics in Chemical Neuroscience: U-47700

U-47700, 3,4-dichloro-N-((1R,2R)-2-(dimethylamino)cyclohexyl)-N-methyl benzamide, is a novel synthetic opioid (NSO), discovered by the Upjohn company in the late 1970s. With potent in vivo activity, ∼10-times greater than that of morphine, U-47700 has become a drug of widespread abuse due to its ease of synthesis and, until recently, lack of robust detection methods by law enforcement. U-47700 has been found in counterfeit oxycodone tablets and is a key ingredient in "gray death." Due to its emergence worldwide in the past 5 years, it is now a Schedule I drug in the United States and similarly designated around the world; moreover, at autopsy, U-47700 was found to have contributed to the death of the pop artist Prince. This Review will capture the >40 year history of U-47700 and go in-depth regarding the synthesis, medicinal chemistry, in vitro/in vivo pharmacology, drug metabolism (from postmortem overdose cases), and societal impact of this DARK Classic in chemical neuroscience.

Determination of 37 fentanyl analogues and novel synthetic opioids in hair by UHPLC-MS/MS and its application to authentic cases

The recent emergence of new fentanyl analogues and synthetic opioids on the drug market poses a global public health threat. However, these compounds cannot typically be identified using existing analytical methods. In this study, we aimed to develop and validate a rapid and sensitive method based on ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) for the simultaneous determination of 37 fentanyl analogues and novel synthetic opioids in hair samples. Hair samples (20 mg) were extracted by cryogenic grinding in an extraction medium of methanol, acetonitrile, and 2 mmol/L ammonium acetate (pH 5.3). Following centrifugation of the samples, the analytes were separated using a WATERS Acquity UPLC HSS T3 column. The limits of detection (LODs) and limits of quantification (LOQs) ranged from 0.5 to 2.5 pg/mg and from 2 to 5 pg/mg, respectively. The intraday and interday precisions were within 13.32% at LOQ, low, medium, and high levels. The accuracies were within the range of 85.63-116.1%. The extraction recoveries were in the range of 89.42-119.68%, and the matrix effects were within the range of 44.81-119.77%. Furthermore, the method was successfully applied to the detection and quantification of fentanyl and sufentanil in hair samples from two authentic cases. Thus, this method has great potential for detecting fentanyl analogues and novel synthetic opioids in forensic work.

Interpol review of toxicology 2016-2019

This review paper covers the forensic-relevant literature in toxicology from 2016 to 2019 as a part of the 19th Interpol International Forensic Science Managers Symposium. The review papers are also available at the Interpol website at: https://www.interpol.int/content/download/14458/file/Interpol%20Review%20.Papers%202019.pdf.

Challenges Related to Three Cases of Fatal Intoxication to Multiple Novel Synthetic Opioids

In the last two decades, a large increase in opioid overdose death rates has been recorded in North America. This phenomenon, related to the misuse of prescription opioids, has been dubbed an "opioids crisis". Recent years have seen the entrance of novel synthetic opioids (NSO) on the market, compounding the fatal intoxications issue. This brings several challenges for forensic toxicology laboratories: an increased number of cases, a large number of novel structurally similar compounds to include in screening analytical methods, the low concentration of drugs in biological fluids, and the challenging interpretation in the absence of sufficient literature. Three cases of fatal intoxication highlighting those challenges are presented, complete with post-mortem concentrations in cardiac blood, femoral blood and urine. Toxicological screening and quantitative analyses were performed on the biological specimens. In the first and second cases, furanylfentanyl, U-47700 and 4-anilino-N-phenethylpiperidine (4-ANPP) were detected at similar concentrations in cardiac blood. In the third case, a total of seventeen different NSO were detected. All intoxications showed a combination of NSO and other drugs. These three cases appear to be the harbinger of an increased NSO prevalence in the province of Québec, Canada.

Quantification of Furanylfentanyl and its Metabolites in Human and Rat Plasma Using LC–MS-MS

Fentanyl analogs (novel and traditional) continue to impact the ever-growing opioid epidemic. Furanylfentanyl (FuF) is one analog equipotent to fentanyl that has documented involvement in thousands of intoxication and fatality cases around the world. Due to its prevalence, toxicologists need to improve detection and understanding of this analog. A method for the quantification of FuF and its metabolites (4-ANPP, furanyl norfentanyl (FuNorF)) in a small volume (100 μL) of human plasma by LC–MS-MS was developed and validated according to ANSI/ASB Standard. The method was cross validated in rat plasma for a future pharmacokinetic (PK)/pharmacodynamic (PD) study. In human plasma, calibration ranges were 0.025–25 ng/mL (FuF and 4-ANPP) and 0.5–25 ng/mL (FuNorF). Limits of detection were 0.0125 ng/mL (FuF and 4-ANPP) and 0.25 ng/mL (FuNorF). Lower limits of quantification coincided with lowest calibrator concentrations of 0.025 ng/mL (FuF and 4-ANPP) and 0.5 ng/mL (FuNorF). Precision and bias values were determined to be acceptable for all analytes. Matrix effects were acceptable for all analytes (−8.6–25.0%), except FuNorF with suppression &gt;25%. Extraction recoveries ranged from 84.5 to 98.1%. No carryover or endogenous interferences were observed. Qualitative interferences with 4-ANPP were observed from some n-acyl substituted fentanyl analogs predicted to be low-concentration standard impurities. Analytes were stable under all conditions and dilution integrity was sustained. The method was successfully cross validated in rat plasma with acceptable bias (−7.4–8.4%), precision (within-run &lt; 19%CV and between-run &lt; 12.6%CV), matrix effects (−9.3–17.2%, except FuNorF with &gt;25% suppression), recoveries (79.2–94.5%) and dilution integrity (1/2 and 1/10).

Investigation of Fragmentation Pathways of Fentanyl Analogues and Novel Synthetic Opioids by Electron Ionization High-Resolution Mass Spectrometry and Electrospray Ionization High-Resolution Tandem Mass Spectrometry

The global drug market is characterized by the fast development of new psychoactive substances such as fentanyl analogues and novel synthetic opioids, the detection of which is complicated by the lack of appropriate quality control procedures and references. Herein, we analyze the fragmentation pathways and characteristic ions of 25 novel fentanyl analogues and 5 novel synthetic opioids by electron ionization (EI) and electrospray ionization (ESI) high-resolution mass spectrometry to provide a reference for the identification of these species. In the ESI mode, fentanyl analogues mainly undergo piperidine ring degradation, phenethyl and piperidine ring dissociation, and piperidine ring and amide moiety cleavage, while piperidine ring degradation and phenethyl and piperidine ring dissociation are the major pathways in the EI mode. The five novel synthetic opioids largely undergo amide group dissociation and N-cyclohexyl bond cleavage in the ESI mode. Thus, this work facilitates the detection and quantitation of fentanyl analogues and novel synthetic opioids or other substances with similar structures in forensic laboratories.

Long-term stability of novel synthetic opioids in blood

Recently, there has been an increase in overdose deaths due to novel synthetic opioids (NSO). Due to backlogs experienced by many forensic laboratories, it is important to understand drug stability in a variety of storage conditions. The objective of this study was to investigate the stability of AH-7921, U-47700, U-49900, U-50488, MT-45, W-15, and W-18 in blood at various temperatures over a 36-week period. NSO were generally stable over the 36-week period (66%-118%) at low and high concentrations when blood samples were stored in the refrigerator or freezer. Most analytes were stable for at least 2 weeks at room temperature (77%-120%). At the elevated temperature (35°C), analytes were generally stable for at least 14 days (75%-109%). This study has determined the stability of several NSO at various temperatures over a 36-week period. These results reflect the forensic significance of keeping samples stored at proper temperatures. Blood samples suspected to contain synthetic opioids should be stored refrigerated or frozen, when possible, in order to preserve analyte stability, especially at low concentrations.

Unique Structural/Stereo-Isomer and Isobar Analysis of Novel Fentanyl Analogues in Postmortem and DUID Whole Blood by UHPLC–MS-MS

The presented analytical method enabled the Toxicology Department at the Cuyahoga County Medical Examiner’s Office to identify 26 and quantitatively report 24 compounds in 500 μL of whole blood, including fentanyl analogues (fentalogues) such as methoxyacetyl fentanyl (MeOAF) and cyclopropyl fentanyl (CPF). This second-generation method (FG2) was developed with the objective to improve the existing analysis (FG1) by decreasing sample size, lowering limits of detection (LOD) and lower limit of quantitation, minimizing ion suppression and resolving chromatographic interferences. Interferences may occur in the analysis of fentanyl, MeOAF, CPF, 3-methylfentanyl (3MF), butyryl fentanyl and isobutyryl fentanyl due to isobars and structural or geometric isomerism with another analogue or metabolite. The isomeric and isobaric fentalogues were grouped into three sets. The LOD established for Set 1 [MeOAF, para-methoxyacetyl fentanyl, para-fluoro acryl fentanyl (isobar), fentanyl carbamate], 2-furanyl fentanyl, Set 2 [CPF, (E)-crotonyl fentanyl] and carfentanil was 0.0125 ng/mL. The LOD established for N-methyl norfentanyl, norfentanyl, norcarfentanil, despropionyl fentanyl (4-ANPP), acetyl fentanyl, β-hydroxy fentanyl, benzyl fentanyl, acryl fentanyl, alfentanil, fentanyl, para-fluoro fentanyl, Set 3 [(±)-trans-3MF, (±)-cis-3MF, isobutyryl and butyryl fentanyl], para-fluoroisobutyryl fentanyl, sufentanil, phenyl fentanyl and cyclopentenyl fentanyl was 0.0625 ng/mL. Seven-point linear calibration curves were established between 0.025 and 4.0 ng/mL for the 8 analytes with the lower LOD and 0.125 and 20 ng/mL for the 18 analytes with the higher LOD. 4-ANPP and cyclopentenyl fentanyl met qualitative reporting criteria only. The results for five postmortem and two driving under the influence of drugs authentic case samples are presented. To the authors’ knowledge, FG2 is the first published method that achieved baseline resolution of the nine structural/stereo isomers and one isobar by ultra-high performance liquid chromatography–MS-MS and provided quantitative validation data for nine compounds. FG2 may be used as the new baseline for future isomers that need to be chromatographically separated.

4-Fluoromethylphenidate: Fatal Intoxication Involving a Previously Unreported Novel Psychoactive Substance in the USA

The (±)-threo-4-fluoromethylphenidate (4F-MPH) is a fluorinated analog of the prescription central nervous system stimulant medication, methylphenidate. This novel psychoactive substance was first detected in drug paraphernalia at the Miami-Dade County Medical Examiner Department Toxicology Laboratory in 2016 but was not detected in a biological specimen until 2018. Limited literature is available on 4F-MPH, with predominate literature being published out of Europe, and no known toxicities reported in the USA. Post-mortem specimens were screened using both gas chromatography mass spectrometry and liquid chromatography ion trap mass spectrometry (LC–Ion Trap-MSn). In addition, a validated method for the quantification of 4F-MPH was developed using liquid chromatography–tandem mass spectrometry (LC–MS-MS), with a linear range of 0.01–0.500 mg/L and acceptable validation criteria including precision, bias, carry-over, linearity and endogenous/exogenous interferences. In addition to the detection of 4F-MPH, 3-methoxy-PCP, amphetamine, methamphetamine, 6-monoacetylmorphine, morphine, codeine and tetrahydrocannabinol were also identified in the decedent. A single source of blood was collected (femoral vein) and quantified in all blood tubes used for collection, with concentrations varying from 0.012 to 0.05 mg/L. Additional specimens available for screening included gastric contents and urine. An additional peak having the same targeted ions and transitions as 4F-MPH was identified in both the LC–Ion Trap-MSn screening procedure and the LC–MS-MS quantitative procedure. This peak suggests the presence of a structural isomer, possibly (±)-erythro-4-fluoromethylphenidate, which cannot be confirmed due to there being no available certified reference material. This case report presents the first time that 4F-MPH was detected in a decedent, as well as the first time 4F-MPH has been listed in the official cause of death of a decedent in Florida.

Novel synthetic opioids - toxicological aspects and analysis

Over the past few years, there has been an emerging number of new psychoactive drugs. These drugs are frequently mentioned as "legal highs", "herbal highs", "bath salts" and "research chemicals". They are mostly sold and advertised on online forums and on the dark web. The emerging new psychoactive substances are designed to mimic the effects of psychoactive groups, which are often abused drugs. Novel synthetic opioids are a new trend in this context and represent an alarming threat to public health. Given the wide number of fatalities related to these compounds reported within the last few years, it is an important task to accurately identify these compounds in biologic matrices in order to administer an effective treatment and reverse the respiratory depression caused by opioid related substances. Clinicians dealing with fentanyl intoxication cases should consider that it could, in fact, be a fentanyl analogue. For this reason, it is a helpful recommendation to include synthetic opioids in the routine toxicological screening procedures, including analysis in alternative matrices, if available, to investigate poly-drug use and possible tolerance to opioids. To address this public health problem, better international collaboration, effective legislation, effective investigation, control of suspicious "research chemicals" online forums and continuous community alertness are required. This article aims to review diverse reported fatalities associated with new synthetic opioids describing them in terms of pharmacology, metabolism, posology, available forms, as well as their toxic effects, highlighting the sample procedures and analytical techniques available for their detection and quantification in biological matrices.

Health effects from unintentional occupational exposure to opioids among law enforcement officers: Two case investigations

Recent increases in the rate of drug overdose-related deaths, the emergence of potent opioids such as carfentanil, and media reports of incidents have raised concerns about the potential for work-related exposure to a variety of illicit drugs among law enforcement officers (LEOs), other emergency responders, and other workers in the United States. To characterize the risk associated with unintentional occupational exposure to drugs, we retrospectively investigated two incidents that occurred in 2017 and 2018 where LEOs were exposed to opioid and stimulant drugs and experienced health effects. We interviewed five affected LEOs and others. We reviewed records, including emergency department documentation, incident reports, forensic laboratory results, and when available, body camera footage. Multiple drug types, including opioids and nonopioids, were present at each incident. Potential routes of exposure varied among LEOs and were difficult to characterize with certainty. Health effects were not consistent with severe, life-threatening opioid toxicity, but temporarily precluded affected LEOs from performing their essential job duties. While health risks from occupational exposure to drugs during law enforcement activities cannot currently be fully characterized with certainty, steps to prevent such exposures should be implemented now. The creation and implementation of appropriate controls plus education and training are both important to protecting first responders from these hazardous agents. To more fully characterize potential exposures, timely prospective toxicological evaluation of affected responders is recommended.

Detection of fentanyl and fentanyl analogues in biological samples using liquid chromatography-high resolution mass spectrometry

BACKGROUND

Fentanyl and analogues such as butyrylfentanyl, carfentanil, 4-fluorobutyrylfentanyl, and furanylfentanyl may be either added to, or sold as, heroin. Fentanyl and carfentanil have approximately 100 and 10,000 times the potency of morphine, respectively, and there is thus a high risk of death with the use of these drugs.

METHODS

We looked for fentanyl/fentanyl analogues using liquid chromatography-high resolution mass spectrometry (LC-HRMS) in selected biological samples obtained post-mortem February 2017-end January 2018. Suspicion of fentanyl poisoning arose from the circumstances of death, a history of heroin use, and the geographical area in which the deceased was discovered, supplemented by drugs intelligence data.

RESULTS

Of the 84 deaths investigated, fentanyl and/or a fentanyl analogue were detected in 40 (48%). The fentanyls encountered were carfentanil (N = 17), fentanyl (9), carfentanil and fentanyl together (12), and fentanyl, carfentanil, 4-fluorobutyrylfentanyl, and butyrylfentanyl together (2). The median (range) post-mortem blood fentanyl concentration was 2.66 (0.21-107) μg/L and the median (range) carfentanil concentration was 0.24 (0.03-1.66) μg/L. The most prevalent compounds present together with fentanyls were ethanol [N = 28, median (range) post-mortem blood concentration: 44 (<10-249) mg/dL)], benzoylecgonine [N = 22, 0.64 (<0.05-3.17) mg/L] and free morphine [N = 20, 0.05 (<0.05-0.34) mg/L]. Deaths in hospital excluded, median blood free morphine, and ethanol concentrations were significantly lower in deaths where fentanyl/fentanyl analogues were present, but there was much overlap with the blood concentrations of these analytes in the non-fentanyl related deaths. A routine drugs of abuse assay using LC-HRMS identified fentanyl with 100% sensitivity and carfentanil with 89% sensitivity.

CONCLUSIONS

Given their potency, misuse of fentanyl and its analogues is likely to cause severe toxicity. A simple LC-HRMS method detected all cases in which fentanyl was identified post-mortem and most of the cases in which carfentanil was detected.

Evidence for nonlinear accumulation of the ultrapotent fentanyl analog, carfentanil, after systemic administration to male rats

The current opioid overdose crisis is being exacerbated by illicitly manufactured fentanyl and its analogs. Carfentanil is a fentanyl analog that is 10,000-times more potent than morphine, but limited information is available about its pharmacology. The present study had two aims: 1) to validate a method for quantifying carfentanil and its metabolite norcarfentanil in small-volume samples, and 2) to use the method for examining pharmacodynamic-pharmacokinetic relationships in rats. The analytical method involved liquid-liquid extraction of plasma samples followed by quantitation of carfentanil and norcarfentanil using ultra-high-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). The method was validated following SWGTOX guidelines, and both analytes displayed limits of detection and quantification at 7.5 and 15 pg/mL, respectively. Male Sprague-Dawley rats fitted with jugular catheters and temperature transponders received subcutaneous carfentanil (1, 3 and 10 μg/kg) or saline. Repeated blood specimens were obtained over 8 h, along with pharmacodynamic measures including core temperature and catalepsy scores. Carfentanil produced dose-related hypothermia and catalepsy that lasted up to 8 h. Carfentanil C_max occurred at 15 min whereas metabolite C_max was at 1-2 h. Concentrations of both analytes increased in a dose-related fashion, but area-under-the-curve values were much greater than predicted after 10 μg/kg. Plasma half-life for carfentanil increased at higher doses. Our findings reveal that carfentanil produces marked hypothermia and catalepsy, which is accompanied by nonlinear accumulation of the drug at high doses. We hypothesize that impaired clearance of carfentanil in humans could contribute to life-threatening effects of this ultrapotent opioid agonist. This article is part of the Special Issue entitled 'New Vistas in Opioid Pharmacology'.

Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry Assay for Quantifying Fentanyl and 22 Analogs and Metabolites in Whole Blood, Urine, and Hair

Recently, synthetic opioid-related overdose fatalities, led by illicitly manufactured fentanyl and analogs, increased at an alarming rate, posing a global public health threat. New synthetic fentanyl analogs have been constantly emerging onto the drug marked for the last few years, to circumvent the laws and avoid analytical detection. Analytical methods need to be regularly updated to keep up with the new trends. In this study, we aimed to develop a new method for detecting the newest fentanyl analogs with a high sensitivity, in whole blood, urine, and hair. The method is intended to provide to clinical and forensic toxicologists a tool for documenting consumption. We developed a comprehensive ultra-high-performance liquid chromatography-tandem mass spectrometry method for quantifying fentanyl and 22 analogs and metabolites. Urine samples were simply diluted before injection; a liquid-liquid extraction was performed for blood testing; and a solid phase extraction was performed in hair. The chromatographic separation was short (8 min). The method was validated with a high sensitivity; limits of quantifications ranged from 2 to 6 ng/L in blood and urine, and from 11 to 21 pg/g in hair. The suitability of the method was tested with 42 postmortem blood, urine, or hair specimens from 27 fatalities in which fentanyl analogs were involved. Average blood concentrations (±SD) were 7.84 ± 7.21 and 30.0 ± 18.0 μg/L for cyclopropylfentanyl and cyclopropyl norfentanyl, respectively (n = 8), 4.08 ± 2.30 μg/L for methoxyacetylfentanyl, (n = 4), 40.2 ± 38.6 and 44.5 ± 21.1 μg/L for acetylfentanyl and acetyl norfentanyl, respectively (n = 3), 33.7 and 7.17 μg/L for fentanyl and norfentanyl, respectively (n = 1), 3.60 and 0.90 μg/L for furanylfentanyl and furanyl norfentanyl, respectively (n = 1), 0.67 μg/L for sufentanil (n = 1), and 3.13 ± 2.37 μg/L for 4-ANPP (n = 9). Average urine concentrations were 47.7 ± 39.3 and 417 ± 296 μg/L for cyclopropylfentanyl and cyclopropyl norfentanyl, respectively (n = 11), 995 ± 908 μg/L for methoxyacetylfentanyl, (n = 3), 1,874 ± 1,710 and 6,582 ± 3,252 μg/L for acetylfentanyl and acetyl norfentanyl, respectively (n = 5), 146 ± 318 and 300 ± 710 μg/L for fentanyl (n = 5) and norfentanyl (n = 6), respectively, 84.0 and 23.0 μg/L for furanylfentanyl and furanyl norfentanyl, respectively (n = 1), and 50.5 ± 50.9 μg/L for 4-ANPP (n = 10). Average hair concentrations were 2,670 ± 184 and 82.1 ± 94.7 ng/g for fentanyl and norfentanyl, respectively (n = 2), and 10.8 ± 0.57 ng/g for 4-ANPP (n = 2).

Ten Years of Fentanyl-like Drugs: a Technical-analytical Review

Synthetic opioids, such as fentanyl and its analogues, are a new public health warning. Clandestine laboratories produce drug analogues at a faster rate than these compounds can be controlled or scheduled by drug agencies. Detection requires specific testing and clinicians may be confronted with a sequence of severe issues concerning the diagnosis and management of these contemporary opioid overdoses. This paper deals with methods for biological sample treatment, as well as the methodologies of analysis that have been reported, in the last decade, in the field of fentanyl-like compounds. From this analysis, it emerges that the gold standard for the identification and quantification of 4-anilinopiperidines is LC-MS/MS, coupled with liquid-liquid or solid-phase extraction. In the end, the return to the scene of illicit fentanyls can be considered as a critical problem that can be tackled only with a global multidisciplinary approach.

Carfentanil: a narrative review of its pharmacology and public health concerns

Carfentanil is a synthetic fentanyl analogue approved for veterinary use. It is a mu-opioid receptor agonist with an estimated analgesic potency approximately 10,000 times that of morphine and 20-30 times that of fentanyl, based on animal studies. Since 2016, an increasing number of reports describe detection of carfentanil in the illicit drug supply. Little is known about the pharmacology of carfentanil in humans. Its high potency and presumed high lipophilicity, large volume of distribution, and potential active metabolites have raised concerns about the management of people exposed to carfentanil as well as the safety of first responders. Exposed individuals exhibit features of an opioid toxidrome and respond to opioid antagonists such as naloxone, although empiric dose requirements are unknown and very high doses may be required. Rare reports of suspected accidental poisoning of first responders have not been analytically confirmed and are unlikely to represent true poisoning. General occupational hygiene measures, including regular decontamination with soap and water, basic personal protective equipment (nitrile gloves, N95 mask, and eye goggles), and ready access to naloxone are generally sufficient in most circumstances.

Non-Medical Use of Novel Synthetic Opioids: A New Challenge to Public Health

Background: In the last decade there has been a progressive increase in the use of new psychoactive substances (NPSs) that are not yet under international control. In particular, novel synthetic opioids (NSOs) have reappeared on the recreational drug market in the last few years. As a result, the use of NSOs has increased rapidly. This poses an emerging and demanding challenge to public health. Aim: To raise awareness among clinicians and other professionals about NPSs, especially NSOs, to summarize current knowledge about pharmacological properties, forms of NSO on the market, pattern of use, effects and consequences of use. Methods: An electronic search was carried out on the Medline/PubMed and Google Scholar databases to find selected search terms. Results: Some NPSs are already controlled, while others can be legally sold directly on the drug market (mainly via internet, less so by drug dealers) or be used as precursors for the synthesis of other designer drugs that mimic the psychoactive effects of controlled substances. Potential side-effects of NSOs include miosis, sedation, respiratory depression, hypothermia, inhibition of gastrointestinal propulsion, death (from opioid overdose). Conclusions: The severity of the opioid crisis has intensified with the introduction of highly potent NSOs on the drug market. As long as addicts are dying from overdose or similar causes, there is something more constructive to do than waiting for addicts to overdose on heroin at a place located near a remedy, as if to say, within reach of naloxone.