Vitreous humor in the forensic toxicology of quetiapine and its metabolites

PURPOSE

Τhe aim of the present study was to investigate the use of vitreous humor as an alternative biological material in forensic toxicology for the determination of quetiapine, 7-hydroxy-quetiapine, and nor-quetiapine. The distribution of these substances in vitreous humor was studied by determining and correlating their concentrations in vitreous humor with the respective concentrations in blood.

METHODS

During this study, a method for the determination of these substances was developed, validated and applied to postmortem samples obtained from 16 relative forensic cases. The sample preparation procedure included the isolation of the analytes from vitreous humor and blood samples using solid-phase extraction, with Bond Elut LRC C18 columns followed by derivatization with BSTFA with 1% TMCS prior to GC/MS analysis.

RESULTS

The developed method is characterized by a dynamic range of 10.0-1000.0 ng/mL (R2 ≥ 0.991) for the three substances, with a limit of detection and quantification of 3.0 and 10.0 ng/mL, respectively. Accuracy and precision were below 8.09% and 8.99%, respectively, for both biological materials, while absolute recovery for the three substances was greater than 81%. According to the results, quetiapine, 7-hydroxy-quetiapine, and nor-quetiapine are easily distributed in vitreous humor.

CONCLUSION

The results of the study indicate the usefulness of vitreous humor in toxicological analysis for the determination of these substances, especially when the traditional biological materials are not available. The levels of quetiapine and its metabolites in vitreous humor as well as the vitreous humor to blood concentration ratios can provide important information for a more thorough toxicological investigation of forensic cases.

Driving under the influence of nitrous oxide - A retrospective study of HS-GC-MS analysis in whole blood

Since 2020, our lab has received blood samples from traffic cases involving suspicion of driving under the influence of nitrous oxide (N2O). While N2O analysis by gas chromatography (GC) has been around for decades, quantitative results in blood from drivers have been only scarcely reported. We present a three-year (2020-2022) retrospective study of N2O from traffic cases in Eastern Denmark with suspected involvement of N2O intake. Whole blood samples from traffic cases were analysed for N2O using headspace-GC-MS. Freshly made calibration curves and additions of xenon gas as an internal standard were used for calculation of N2O concentrations. Positive samples have been defined as having concentrations greater than 0.1 mL N2O/L blood. Over a three-year period, we have tested 62 traffic case blood samples for the presence of N2O. Despite the technical challenges associated with the analysis of N2O, we have found N2O in 52 of the samples. Calculated concentrations were in the range 0.1-48 mL N2O/L blood, which are similar to the few cases previously found in the literature.

Novel extraction method using an ISOLUTE PLD+ protein and phospholipid removal column for liquid chromatography-tandem mass spectrometry analysis of 20 psychoactive drugs in postmortem whole blood samples

A novel sample extraction method using an ISOLUTE PLD+ protein and phospholipid removal column was developed for simultaneous quantification of 20 psychoactive drugs, including antidepressants, antipsychotics, sedative-hypnotics, and amphetamines, in postmortem whole blood samples by liquid chromatography-tandem mass spectrometry. The method showed improvement in extract cleanliness compared with traditional protein precipitation and the QuEChERS extraction method. The method was validated for all analytes; the calibration curves showed good linearity, with r² values exceeding 0.991. The intra- and interday accuracies and precisions were 87.6-117.5% and 1.0-18.6%, respectively. The recovery efficiencies were in the range of 64.6-96.8%. Matrix effects were observed in the range of 82.6-116.0%. All analytes were stable under different storage conditions. This method was successfully applied in postmortem forensic sample analysis to quantify psychoactive drugs. The method described in the current study will be useful for forensic toxicological investigations.

Strategic Decision-Making by a Forensic Toxicology Laboratory in Response to an Emerging NPS: Detection, Quantitation and Interpretation of Carfentanil in Death Investigations in Ontario, Canada, July 2017 to June 2018

The proliferation of novel psychoactive substances (NPS) and the current opioid epidemic creates challenges for a toxicology laboratory. Methods capable of detecting and quantitating emerging compounds must be established despite limited information on toxicologically relevant concentrations. This paper will (i) describe how a publicly funded forensic laboratory reacted to the emergence of carfentanil as a public safety concern and (ii) contribute to the existing forensic literature by presenting a series of deaths involving carfentanil between July 2017 and June 2018. The Centre of Forensic Sciences is the primary provider of forensic toxicology testing in medicolegal death investigations in the province of Ontario. When carfentanil was first identified in the illicit drug supply, routine screening methods used by this laboratory were not sufficiently sensitive to detect the drug at concentrations expected in blood samples. Previously validated, multi-target liquid chromatography-tandem mass spectrometry (LC-MS-MS) quantitative methods already in use by the laboratory did show improved detectability for carfentanil. Thus, an existing LC-MS-MS method was adapted to include carfentanil, achieving improved sensitivity while also providing quantitation in suspected drug-related deaths. This approach had the added benefit that the LC-MS-MS method selected for modification was used in all death investigations requiring toxicology analysis in Ontario, thereby providing an opportunity for surveillance. Using this method, 4,953 cases were analyzed with carfentanil detected at a concentration greater than the limit of detection (0.05 ng/mL) in 160 decedents. Postmortem blood carfentanil concentrations ranged from less than 0.1 to 9.2 ng/mL. Of the 160 carfentanil-positive cases, 156 were classified as either mixed drug toxicity or carfentanil overdose. The approach described enabled this laboratory to efficiently implement a quantitative test for carfentanil in all death investigations, providing a useful template for modifying existing methods when a new psychoactive substance becomes available in the population.

Determination of Antidepressants in Human Plasma by Modified Cloud-Point Extraction Coupled with Mass Spectrometry

Cloud-point extraction (CPE) is rarely combined with liquid chromatography coupled to mass spectrometry (LC-MS) in drug determination due to the matrix effect (ME). However, we have recently shown that ME is not a limiting factor in CPE. Low extraction efficiency may be improved by salt addition, but none of the salts used in CPE are suitable for LC-MS. It is the first time that the influences of a volatile salt-ammonium acetate (AA)-on the CPE extraction efficiency and ME have been studied. Our modification of CPE included also the use of ethanol instead of acetonitrile to reduce the sample viscosity and make the method more environmentally friendly. We developed and validated CPE-LC-MS for the simultaneous determination of 21 antidepressants in plasma that can be useful for clinical and forensic toxicology. The selected parameters included Triton X-114 concentration (1.5 and 6%, w/v), concentration of AA (0, 10, 20 and 30%, w/v), and pH (3.5, 6.8 and 10.2). The addition of 10% of AA increased recovery twice. For 20 and 30% (w/v) of AA, three phases were formed that prolonged the extraction process. The developed CPE method (6% Triton X-114, 10% AA, pH 10.2) was successfully validated through LC-MS/MS simultaneous determination of 21 antidepressants in human plasma. The linearity was in the range of 10-750 ng/mL (r2 > 0.990).

Determination of the alcohol biomarker phosphatidylethanol 16:0/18:1 and 33 compounds from eight different drug classes in whole blood by LC-MS/MS

INTRODUCTION

Most bioanalytical LC-MS/MS methods are developed for determination of single drugs or classes of drugs, but a multi-compound LC-MS/MS method that can replace several methods could reduce both analysis time and costs. The aim of this study was to develop a high-throughput LC-MS/MS method for determination of the alcohol biomarker phosphatidylethanol 16:0/18:1 (PEth 16:0/18:1) and 33 other compounds from eight different drug classes in whole blood.

METHODS

Whole-blood samples were prepared by 96-well supported liquid extraction (SLE). Chromatographic separations were performed on a biphenyl core shell column with a mobile phase consisting of 10 mM ammonium formate, pH 3.1 and methanol. Each extract was analyzed twice by LC-MS/MS, injecting 0.4 μL and 2 μL, in order to obtain narrow and symmetrical peaks and good sensitivity for all compounds. Stable isotope-labeled internal standards were used for 31 of the 34 compounds.

RESULTS

A 96-well SLE reversed phase LC-MS/MS method for determination of PEth 16:0/18:1 and 33 other compounds from eight different drug classes was developed and validated. By using an organic solvent mixture of isopropanol/ methyl tert-butyl ether (1:5, v:v), all compounds, including the polar and ampholytic compounds pregabalin, gabapentin and benzoylecgonine, was extracted by 96-well SLE.

DISCUSSION/CONCLUSION

For the first time an LC-MS/MS method for the determination of alcohol biomarker PEth 16:0/18:1 and drugs and metabolites from several different drug classes was developed and validated. The developed LC-MS/MS method can be used for high-throughput analyses and sensitive determinations of the 34 compounds in whole blood.

Developing and Validating a Fast and Accurate Method to Quantify 18 Antidepressants in Oral Fluid Samples Using SPE and LC-MS-MS

Antidepressant drugs are one of the most widely used medicines for treating major depressive disorders for long time periods. Oral fluid (OF) testing offers an easy and non-invasive sample collection. Detection of antidepressants in OF is important in clinical and forensic settings, such as therapeutic drug monitoring and roadside testing for driving under influence. We developed and validated a comprehensive liquid chromatography-tandem mass spectrometry method for 18 antidepressants (amitriptyline, bupropion, citalopram, clomipramine, cyclobenzaprine, desipramine, desvenlafaxine, doxepin, duloxetine, fluoxetine, imipramine, mirtazapine, nortriptyline, paroxetine, sertraline, trazodone, trimipramine, venlafaxine) in oral fluid collected by Quantisal® oral collection devices. One-half milliliter of Quantisal® OF (125 μL of neat OF) was submitted to solid-phase extraction. The chromatographic separation was performed employing a biphenyl column in gradient mode with a total run time of 5 min. The MS detection was achieved by multiple-reaction monitoring with two transitions per compound. The range for linearity of all analytes was from 10 to 1,000 ng/mL, with a limit of detection of 10 ng/mL. Intra and inter-day accuracy and precision (n = 15) were all within acceptable limits, ±20% error and ±15% relative standard deviation. Analyte recovery at 400 ng/mL concentration (n = 15) ranged from 91 to 129%. Matrix effect ranged from 73.7 to 157%. The internal proficiency test detected all antidepressants with accuracy ranging from 83.1 to 112.1%. The authentic patient sample showed a percentage difference compared to the previously calculated concentration of 86.3-111%. This method provides for the rapid detection of 18 antidepressants and metabolites in OF, which is readily applicable to a routine laboratory.

A Validated Method for the Simultaneous Determination of Quetiapine, Clozapine and Mirtazapine in Postmortem Blood and Tissue Samples

Psychotropic drugs are regularly present in cases of sudden, unexpected death. Such drugs also tend to express significant postmortem redistribution. To facilitate further investigation of this phenomenon, reliable quantitative methods applicable to multiple biological matrices are needed. We present a validated ultra-performance liquid chromatography–tandem mass spectrometry method for the simultaneous quantification of quetiapine, clozapine and mirtazapine in postmortem whole blood, skeletal muscle, brain tissue and liver tissue using high-performance liquid chromatography–tandem mass spectrometry. Sample preparation was performed using liquid–liquid extraction. The validated ranges were 3.8–1534, 16–1960 and 13–1060 μg/L for quetiapine, clozapine and mirtazapine, respectively. Within-run and between-run accuracy (87.4–122%) and precision (CV 1.5–8.9%), matrix effects (95–101%) and recovery (35.7–92%) were validated at two concentration levels; 5.8 and 1227 μg/L for quetiapine, 25 and 1568 μg/L for clozapine and 20 and 849 μg/L for mirtazapine. Stability in a 10°C environment was assessed for treated samples of brain, liver and muscle tissue, showing deviations in analyte concentrations ranging from −8% to 9% after 3 days. The analyte concentrations in treated samples of whole blood stored at 4°C deviated by <5% after 5 days. The method was applied in three forensic autopsy cases implicating quetiapine, clozapine and mirtazapine, respectively, in supratherapeutic concentrations.

Amitriptyline accumulation in tissues after coated activated charcoal hemoperfusion-a randomized controlled animal poisoning model

Amitriptyline poisoning (AT) is a common poisoning, and AT possess the ability to promote life-threatening complications by its main action on the central nervous and cardiovascular systems. The pharmacokinetic properties might be altered at toxic levels compared to therapeutic levels. The effect of coated activated charcoal hemoperfusion (CAC-HP) on the accumulation of AT and its active metabolite nortriptyline (NT) in various tissues was studied in a non-blinded randomized controlled animal trial including 14 female Danish Land Race piglets. All piglets were poisoned with amitriptyline 7.5 mg/kg infused in 20 min, followed by orally instilled activated charcoal at 30 min after infusion cessation. The intervention group received 4 h of CAC-HP followed by a 1-h redistribution phase. At study cessation, the piglets were euthanized, and within 20 min, vitreous fluid, liver tissue, ventricle and septum of the heart, diaphragm and lipoic and brain tissues were collected. AT and NT tissue concentrations were quantified by UHPLC-MS/MS. A 4-h treatment with CAC-HP did not affect the tissue accumulation of AT in the selected organs when tested by Mann-Whitney U test (p values between 0.44 and 0.73). For NT concentrations, p values were between 0.13 and 1.00. Although not significant, an interesting finding was that data showed a tendency of increased tissue accumulation of AT and NT in the CAC-HP group compared with the control group. Coated activated charcoal hemoperfusion does not significantly alter the tissue concentration of AT and NT in the AT-poisoned piglet.

Reference Brain/Blood Concentrations of Citalopram, Duloxetine, Mirtazapine and Sertraline

Postmortem blood samples may not accurately reflect antemortem drug concentrations, as the levels of some drugs increase due to postmortem redistribution (PMR). The brain has been suggested as an alternative sampling site. The anatomically secluded site of the brain limits redistribution and prolongs the detection window, thereby enabling sampling from deceased individuals where blood is no longer suitable for analysis. We report concentrations in brain tissue and blood from 91 cases for the four antidepressants citalopram, duloxetine, mirtazapine and sertraline. The cases were classified according to their role in the cause of death, as follows: (A) concentrations where the drug was the sole cause of fatal intoxication; (B) concentrations where the drug contributed to a fatal outcome; and (C) concentrations where the drug was not related to the cause of death. The analytical method was successfully validated in brain tissue in terms of linearity, process efficiency, precision and accuracy. Quantification of analytes was performed by ultra-performance liquid chromatography with tandem mass spectrometry. Correlations between blood and brain concentrations were achieved with R2-values between 0.67 and 0.91. The following median brain-blood ratios were obtained: 3.71 for citalopram (range: 1.4-5.9), 11.0 for duloxetine (range: 5.0-21.6), 1.53 for mirtazapine (range: 1.02-4.71) and 7.38 for sertraline (range: 3.2-14.2). The S/R ratio of racemic citalopram was the same in brain (0.80) and blood (0.85), whereas the median citalopram/N-desmethylcitalopram ratio was higher in brain (9.1) than blood (4.1). The results of this study may serve as reference concentrations in brain for forensic cases.

Post-mortem quetiapine concentrations in hair segments of psychiatric patients - Correlation between hair concentration, dose and concentration in blood

Drug analysis in hair is useful when seeking to establish drug intake over a period of months to years. Segmental hair analysis can also document whether psychiatric patients are receiving a stable intake of antipsychotics. This study describes segmental analysis of the antipsychotic drug quetiapine in post-mortem hair samples from long-term quetiapine users by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) analysis. The aim was to obtain more knowledge on quetiapine concentrations in hair and to relate the concentration in hair to the administered dose and the post-mortem concentration in femoral blood. We analyzed hair samples from 22 deceased quetiapine-treated individuals, who were divided into two groups: natural hair colour and dyed/bleached hair. Two to six 1cm long segments were analyzed per individual, depending on the length of the hair, with 6cm corresponding to the last six months before death. The average daily quetiapine dose and average concentration in hair for the last six months prior to death were examined for potential correlation. Estimated doses ranged from 45 to 1040mg quetiapine daily over the period, and the average concentration in hair ranged from 0.18 to 13ng/mg. A significant positive correlation was observed between estimated daily dosage of quetiapine and average concentration in hair for individuals with natural hair colour (p=0.00005), but statistical significance was not reached for individuals with dyed/bleached hair (p=0.31). The individual coefficient of variation (CV) of the quetiapine concentrations between segments ranged from 3 to 34% for individuals with natural hair colour and 22-62% for individuals with dyed/bleached hair. Dose-adjusted concentrations in hair were significantly lower in females with dyed/bleached hair than in individuals with natural hair colour. The quetiapine concentrations in post-mortem femoral blood and in the proximal hair segment, segment 1 (S1), representing the last month before death were also investigated for correlation. A significant positive correlation was observed between quetiapine concentrations in blood at the time of death and concentrations in S1 for individuals with natural hair colour (p=0.003) but not for individuals with dyed/bleached hair (p=0.31). The blood concentrations of quetiapine ranged from 0.006 to 1.9mg/kg, and the quetiapine concentrations in S1 ranged from 0.22 to 24ng/mg. The results of this study suggest a positive correlation of quetiapine between both concentrations in hair and doses, and between proximal hair (S1) and blood concentrations, when conditions such as hair treatments are taken into consideration.

Validation of a fully automated solid-phase extraction and ultra-high-performance liquid chromatography-tandem mass spectrometry method for quantification of 30 pharmaceuticals and metabolites in post-mortem blood and brain samples

In this study, we present the validation of an analytical method capable of quantifying 30 commonly encountered pharmaceuticals and metabolites in whole blood and brain tissue from forensic cases. Solid-phase extraction was performed by a fully automated robotic system, thereby minimising manual labour and human error while increasing sample throughput, robustness, and traceability. The method was validated in blood in terms of selectivity, linear range, matrix effect, extraction recovery, process efficiency, carry-over, stability, precision, and accuracy. Deuterated analogues of each analyte were used as internal standards, which corrected adequately for any inter-individual variability in matrix effects on analyte accuracy and precision. The lower limit of quantification (LLOQ) spanned from 0.0008 to 0.010 mg/kg, depending on the analyte, while the upper LOQ ranged between 0.40 and 2.0 mg/kg. Thus, the linear range covered both therapeutic and toxic levels. The method showed acceptable accuracy and precision, with accuracies ranging from 80 to 118% and precision below 19% for the majority of the analytes. Linear range, matrix effect, extraction recovery, process efficiency, precision, and accuracy were also tested in brain homogenate and the results agreed with those from blood. An additional finding was that the analyte concentrations in brain samples could be quantified by calibration curves obtained from spiked blood samples with acceptable precision and accuracy when using deuterated analogues of each analyte as internal standards. This method has been successfully implemented as a routine analysis procedure for quantification of pharmaceuticals in both blood and brain tissue since 2015.

In vitro studies on flubromazolam metabolism and detection of its metabolites in authentic forensic samples

Flubromazolam is a triazole benzodiazepine with high potency and long-lasting central nervous system depressant effects; however, limited data about its pharmacokinetics are available. Here, we report in vitro studies of the human flubromazolam metabolism analyzed by liquid chromatography high-resolution mass spectrometry (LC-HRMS). In vitro investigations were carried out in pooled human liver microsomes (pHLM) and recombinant cytochrome P450 (CYP)-enzymes. To confirm those metabolites detected in vitro, authentic samples obtained from two forensic cases were also analyzed by LC-HRMS. Additionally, determination of the unbound fraction of flubromazolam in pHLM and in plasma was performed by equilibrium dialysis with subsequent prediction of its hepatic clearance (CL_H ) using well-stirred and parallel-tube models. Additional findings obtained by routine screening methods of these forensic cases are also reported. Studies using incubations with nicotinamide adenine dinucleotide phosphate-fortified pHLM with or without uridine 5'-diphosphoglucuronic acid and incubations with CYP-enzymes identified the main metabolic pathway of flubromazolam as hydroxylation on the α- and/or 4-position mediated by CYP3A4 and CYP3A5, with subsequent glucuronidation of the hydroxylated metabolites as well as of the parent drug. Further, α-hydroxy-flubromazolam and its corresponding glucuronide were detected in vivo together with the N-glucuronide of flubromazolam. The predicted CL_H of flubromazolam using the well-stirred and parallel-tube models were 0.42 and 0.43 mL/min/kg, respectively. Based on the data presented here, flubromazolam is primarily metabolized by CYP3A4/5 with a high protein-binding and a predicted low clearance. Analysis of authentic samples suggested that analytical targets for flubromazolam should be the compound itself and α-hydroxy-flubromazolam. Copyright © 2016 John Wiley & Sons, Ltd.

The significance of sampling time in therapeutic drug monitoring of clozapine

OBJECTIVE

Therapeutic drug monitoring (TDM) of clozapine is standardized to 12-h postdose samplings. In clinical settings, sampling time often deviates from this time point, although the importance of the deviation is unknown. To this end, serum concentrations (s-) of clozapine and its metabolite N-desmethyl-clozapine (norclozapine) were measured at 12 ± 1 and 2 h postdose.

METHOD

Forty-six patients with a diagnosis of schizophrenia, and on stable clozapine treatment, were enrolled for hourly, venous blood sampling at 10-14 h postdose.

RESULTS

Minor changes in median percentage values were observed for both s-clozapine (-8.4%) and s-norclozapine (+1.2%) across the 4-h time span. Maximum individual differences were 42.8% for s-clozapine and 38.4% for s-norclozapine. Compared to 12-h values, maximum median differences were 8.4% for s-clozapine and 7.3% for s-norclozapine at deviations of ±2 h. Maximum individual differences were 52.6% for s-clozapine and 105.0% for s-norclozapine. The magnitude of s-clozapine differences was significantly associated with age, body mass index and the presence of chronic basophilia or monocytosis.

CONCLUSION

The impact of deviations in clozapine TDM sampling time, within the time span of 10-14 h postdose, seems of minor importance when looking at median percentage differences. However, substantial individual differences were observed, which implies a need to adhere to a fixed sampling time.

Evaluation of poly-drug use in methadone-related fatalities using segmental hair analysis

In Denmark, fatal poisoning among drug addicts is often related to methadone. The primary mechanism contributing to fatal methadone overdose is respiratory depression. Concurrent use of other central nervous system (CNS) depressants is suggested to heighten the potential for fatal methadone toxicity. Reduced tolerance due to a short-time abstinence period is also proposed to determine a risk for fatal overdose. The primary aims of this study were to investigate if concurrent use of CNS depressants or reduced tolerance were significant risk factors in methadone-related fatalities using segmental hair analysis. The study included 99 methadone-related fatalities collected in Denmark from 2008 to 2011, where both blood and hair were available. The cases were divided into three subgroups based on the cause of death; methadone poisoning (N=64), poly-drug poisoning (N=28) or methadone poisoning combined with fatal diseases (N=7). No significant differences between methadone concentrations in the subgroups were obtained in both blood and hair. The methadone blood concentrations were highly variable (0.015-5.3, median: 0.52mg/kg) and mainly within the concentration range detected in living methadone users. In hair, methadone was detected in 97 fatalities with concentrations ranging from 0.061 to 211ng/mg (median: 11ng/mg). In the remaining two cases, methadone was detected in blood but absent in hair specimens, suggesting that these two subjects were methadone-naive users. Extensive poly-drug use was observed in all three subgroups, both recently and within the last months prior to death. Especially, concurrent use of multiple benzodiazepines was prevalent among the deceased followed by the abuse of morphine, codeine, amphetamine, cannabis, cocaine and ethanol. By including quantitative segmental hair analysis, additional information on poly-drug use was obtained. Especially, 6-acetylmorphine was detected more frequently in hair specimens, indicating that regular abuse of heroin was common among the deceased. In conclusion, continuous exposure of methadone provide by segmental hair analysis suggested that reduced tolerance of methadone was not a critical factor among methadone-related fatalities. In contrast, a high abundance of co-ingested CNS depressants suggested that adverse effects from drug-drug interactions were more important risk factors for fatal outcome in these deaths.

Advances in detection of antipsychotics in biological matrices

Measuring antipsychotic concentrations in human matrices is important for both therapeutic drug monitoring and forensic toxicology. This review provides a critical overview of the analytical methods for detection and quantification of antipsychotics published in the last four years. Focus lies on advances in sample preparation, analytical techniques and alternative matrices. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is used most often for quantification of antipsychotics. This sensitive technique makes it possible to determine low concentrations not only in serum, plasma or whole blood, but also in alternative matrices like oral fluid, dried blood spots, hair, nails and other body tissues. Current literature on analytical techniques for alternative matrices is still limited and often requires a more thorough validation including a comparison between conventional and alternative results to determine their actual value. Ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) makes it possible to quantify a high amount of compounds within a shorter run time. This technique is widely used for multi-analyte methods. Only recently, high-resolution mass spectrometry has gained importance when a combination of screening of (un)known metabolites, and quantification is required.

Evaluation of metabolite/drug ratios in blood and urine as a tool for confirmation of a reduced tolerance in methadone-related deaths in Denmark

BACKGROUND

Methadone blood concentrations in fatal cases are highly variable and there is an appreciable overlap between therapeutic methadone concentrations and the concentrations detected in fatalities. As with other opioids, the background of these methadone-related deaths is unclear. The aim of this study was to investigate if short-time abstinence was contributing to the cause of death in methadone-related deaths by evaluation of the EDDP/methadone ratio in blood and urine.

METHODS

Samples of blood and urine were collected from 103 autopsy cases and analysed for the concentrations of methadone and its main metabolite EDDP. The cases were divided into three groups according to the cause of death: cases where methadone was the cause of death (N=67), cases where poly-drug poisoning including methadone was the cause of death (N=24) and cases where death were caused by other factors (N=12). Urine samples from 11 living persons receiving methadone were also included.

RESULTS

In general, a substantial overlap of the methadone concentrations in blood and urine was seen between the groups. There was a tendency of lower median EDDP/methadone urinary ratios in the methadone poisoning group (median: 1.0), poly-drug poisoning group (median: 0.94) and in the fatalities not related to methadone (median: 1.1) compared to the living subjects in methadone treatment (median: 1.6), although the differences were not significant.

CONCLUSION

It was not possible to reveal a possible abstinence period prior to death by using the EDDP/methadone ratio in blood and urine in methadone-related deaths.