Prevalence of xylazine in overdose cases: An analysis of Miami-Dade County medical examiner case data.

Xylazine sedative, muscle relaxant, and analgesic used in a veterinary setting. Although xylazine was never approved for therapeutic use in humans, it has become popular in the street drug market as a cutting or bulking agent in the fentanyl and heroin supply. Recently, there has been a significant increase in the detection of xylazine in postmortem forensic toxicology casework. Xylazine can be identified during routine toxicology screening utilizing instrumentation such as gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry. Using the Miami-Dade Medical Examiner's LIMS system, all cases received between 2015 and 2022 in which xylazine was reported were reviewed. The cases studied include accidental drug overdose deaths in Miami-Dade County as well as Collier County (Naples), Florida. In total, there are 170 cases; the majority are accidental polydrug overdoses involving White males between the ages of 25 and 44 years old. Of the 170 cases, 37% listed xylazine as the cause of death. 13% of cases contained only xylazine and fentanyl while the remaining 87% of deaths were attributed to polydrug toxicity involving two or more substances. The prevalence of xylazine can be attributed to its increasing popularity rather than an increase in caseload. In 2019, xylazine was present in only 4% of all accidental fentanyl overdoses. By 2021, this percentage has increased sixfold, with xylazine present in 24% of all accidental fentanyl overdoses. Despite a decrease in fentanyl overdoses in 2022, the percentage of xylazine detection remained the same.

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.

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.

To Test or Not To Test?: The Value of Toxicology in a Delayed Overdose Death.

A case demonstrating the necessity of thorough death investigation processes where toxicology plays an active role is presented. A 33-year-old white man presented to the emergency room in respiratory distress after an overdose episode where he was revived on the scene by fire rescue. His condition continued to deteriorate and he expired 6 days after the initial incident. No admission specimens were available for testing; however, there were specimens drawn 4 and 5 days after the incident. Drug paraphernalia from the scene was obtained by the laboratory through collaboration with local law enforcement. Drug paraphernalia was initially tested in the laboratory and after obtaining the results, the antemortem and postmortem specimens were tested identifying mitragynine and U-47700, among other drugs. These results indicate the value in obtaining and testing drug paraphernalia, and the value of testing antemortem specimens even in the event of a delay.

Qualitative Identification of Fentanyl Analogs and Other Opioids in Postmortem Cases by UHPLC-Ion Trap-MSn.

Since 2013, the Miami-Dade County Medical Examiner Department has experienced an increase in the number of opioid-related deaths. The majority of cases coincided with the introduction of fentanyl into the local heroin supply. From 2014 to 2015, Miami-Dade County experienced a near 600% increase in fentanyl-related deaths, followed by an additional 200% increase in 2016. In 2015, two novel fentanyl analogs were identified in medical examiner cases: beta-hydroxythiofentanyl and acetyl fentanyl. In 2016, four additional fentanyl analogs emerged: para-fluoroisobutyryl fentanyl, butyryl fentanyl, furanyl fentanyl and carfentanil, as well as the synthetic opioid U-47700. In order to address this epidemic, a method was developed and validated to identify 44 opioid-related and analgesic compounds in postmortem samples using ultra high performance liquid chromatography ion trap mass spectrometry with MSn capabilities. The limit of detection for all compounds ranged from 0.1 to 5 ng/mL, with a majority having MS3 spectral fragmentation. Blood, urine, liver or brain specimens from ~500 postmortem cases were submitted for analysis based on case history and/or initial screening results. Of those cases, 375 were positive for illicit fentanyl and/or one or more fentanyl analogs. Due to the potency of these compounds, they were almost always included in the cause of death. Worth emphasizing and extremely alarming is the detection of carfentanil in 134 cases, 104 of which were initially missed by gas chromatography mass spectrometry. By incorporating this sensitive, highly specific, and evolving screening procedure into the workflow, the toxicology laboratory continues to effectively assist the medical examiners in determining the cause and manner of death of decedents in Miami-Dade County.