Estimating antemortem drug concentrations from postmortem blood samples: the influence of postmortem redistribution

Difficulties associated with the interpretation of postmortem toxicology

While postmortem (PM) toxicology results provide valuable information towards ascertaining both the cause and manner of death in coronial cases, there are also significant difficulties associated with the interpretation of PM drug levels. Such difficulties are influenced by several pharmacokinetic and pharmacodynamic factors including PM redistribution, diffusion, site-to-site variability in drug levels, different drug properties and metabolism, bacterial activity, genetic polymorphisms, tolerance, resuscitation efforts, underlying conditions, and the toxicity profile of cases (i.e. single- or mixed-drug toxicity). A large body of research has been dedicated for better understanding and even quantifying the influence of these factors on PM drug levels. For example, several investigative matrices have been developed as potential indicators of PM redistribution, but they have limited practical value. Reference tables of clinically relevant therapeutic, toxic, and potentially fatal drug concentrations have also been compiled, but these unfortunately do not provide reliable reference values for PM toxicology. More recent research has focused on developing databases of peripheral PM drug levels for a variety of case-types to increase transferability to real-life cases and improve interpretations. Changes to drug levels after death are inevitable and unavoidable. As such, guidelines and practices will continue to evolve as we further our understanding of such phenomena.

Preanalytical factors influencing the results of ethanol analysis in postmortem specimens

Excessive drinking and drunkenness are underlying factors in many fatal accidents, which make the quantitative determination of ethanol in postmortem (PM) specimens an essential part of all unnatural death investigations. The same analytical methods are used to determine ethanol in blood taken from living and deceased persons although the interpretation of the results is more complicated in medical examiner cases owing to various preanalytical factors. The biggest problem is that under anaerobic conditions ethanol can be produced naturally in decomposed bodies by microbial activity and fermentation of blood glucose. Ways are needed to differentiate antemortem ingestion of ethanol from PM synthesis. One approach involves the determination of ethanol in alternative specimens, such as bile, cerebrospinal fluid, vitreous humor and/or urine, and comparison of results with blood alcohol concentration (BAC). Another approach involves the analysis of various alcohol biomarkers, such as ethyl glucuronide, ethyl sulfate and/or phosphatidylethanol or the urinary metabolites of serotonin 5-hydroxytryptophol/5-hydroxyindoleacetic acid (5-HTOL/5-HIAA). If ethanol had been produced in the body by microbial activity, the blood samples should also contain other low-molecular volatiles, such as acetaldehyde, n-propanol and/or n-butanol. The inclusion of 1-2% w/v sodium or potassium fluoride, as an enzyme inhibitor, in all PM specimens is essential to diminish the risk of ethanol being generated after sampling, such as during shipment and storage prior to analysis. Furthermore, much might be gained if the analytical cut-off for reporting positive BAC was raised from 0.01 to 0.02 g% when PM blood is analyzed. During putrefaction low BACs are more often produced after death than high BACs. Therefore, when the cadaver is obviously decomposed, a pragmatic approach would be to subtract 0.05 g% from the mean analytical result. Any remaining BAC is expected to give a more reliable indication of whether alcohol had been consumed before death.

Postmortem redistribution of amphetamines and benzodiazepines in humans: Important variables that might be influencing the central blood / peripheral blood ratio

INTRODUCTION

The primary objective of postmortem forensic toxicology is to determine if toxicological substances detected in bodily material of victims have contributed to the death of the victim. Interpretation of postmortem drug concentrations is hindered by the fact that time and site dependent variations in postmortem drug concentrations occur, as a result of postmortem redistribution (PMR). An often-used marker for the occurrence of PMR, is the cardiac blood concentration/peripheral blood concentration ratio (C/P ratio) of a drug. In this study, we investigated the relationship between 13 variables and the C/P ratios of amphetamines and benzodiazepines.

METHOD

Toxicological results of all postmortem cases that were positive for amphetamines (amphetamine, MDMA, MDA) and/or benzodiazepines (diazepam, desmethyldiazepam, temazepam, oxazepam, midazolam, α-hydroxymidazolam) investigated by the Netherlands Forensic Institute between January 1 2010 and July 31 2020 were reviewed. A total of 112 amphetamine positive cases (224 paired specimen) and 179 benzodiazepine positive cases (358 paired specimen) were selected. The C/P ratios were determined for all selected cases. Ratios were compared between subgroups by performing either a Mann-Whitney U test or a Kruskal-Wallis test followed by post-hoc Mann-Whitney U test.

RESULTS

After dividing cases in quartiles based on their amphetamine concentration in femoral blood, the amphetamine C/P ratio was significantly lower in cases with a high amphetamine concentration (quartile 4) compared to cases with a low amphetamine concentration (quartiles 1 and 2) with median C/P ratios of 1.6, 2.4 and 2.2, respectively (p-value<0.001 and p-value=0.001, respectively). The MDA C/P ratio was significantly higher in cases where trauma was the cause of death compared to cases where intoxication was the cause of death with median C/P ratios of 3.3 and 1.6, respectively (p-value<0.001). The MDA C/P ratio was also significantly lower in cases where resuscitation was attempted compared to cases where no resuscitation was attempted with median C/P ratios of 1.6 and 2.4, respectively (p-value=0.003). However, a significant dependency between the variables cause of death and attempted resuscitation was observed. No significant differences in benzodiazepine C/P ratios were observed between subgroups of any of the investigated variables. However, the low p-value of BMI suggests a potential difference in midazolam C/P ratio between BMI subgroups (p-value=0.027).

CONCLUSION

When interpreting postmortem toxicological results, it might prove useful to take the above-mentioned variables into account.

Postmortem redistribution of cocaine and its metabolites, benzoylecgonine and ecgonine methyl ester in humans: Important variables that might be influencing the central blood / peripheral blood ratio

INTRODUCTION

A big challenge in forensic toxicology is the correct interpretation of the results of quantitative analyses in postmortem cases. Postmortem drug concentrations not necessarily reflect the drug concentrations at the time of death, due to postmortem changes in drug concentrations caused by postmortem redistribution (PMR). Cardiac blood is more prone to PMR related concentration changes than peripheral blood. Because of this difference in susceptibility to PMR related concentration changes, the ratio of cardiac blood concentration/peripheral blood concentration (C/P) of a drug is an often-used marker of PMR. In this study, we investigated the relationship between different potentially significant variables and the C/P ratios of cocaine, benzoylecgonine (BE) and ecgonine methyl ester (EME) in humans. The aim was to elucidate the mechanisms involved in PMR of these substances and potentially provide guidelines aiding forensic toxicologists in the interpretation of postmortem quantitative results of cocaine and its metabolites. To differentiate between postmortem concentration changes due to redistribution versus degradation of cocaine, the relationships between these variables and metabolite/cocaine ratios were investigated as well.

METHOD

Toxicological results of all postmortem cases that were positive for cocaine, BE and/or EME investigated by the Netherlands Forensic Institute between January 1st 2010 and July 31st 2020 were reviewed. The C/P ratios, BE/cocaine ratios and EME/cocaine ratios were determined for all selected cases. Cocaine, BE and/or EME were quantified in both femoral blood and cardiac blood in a total of 148 cases. Ratios were compared between subgroups by performing either a Mann-Whitney U test or a Kruskal-Wallis test followed by post-hoc Mann-Whitney U test.

RESULTS

A statistically significant difference in C/P ratio of EME was observed between trauma and non-trauma cases with median C/P ratios of 2.03 and 1.57, respectively (p value=0.001). A statistically significant difference in EME/cocaine ratio was observed between the BMI subgroups 18.5 - 25.0 kg/m2 and> 25 kg/m2 with median EME/cocaine ratios of 3.79 and 1.58, respectively (p-value<0.001).

CONCLUSION

Postmortem cocaine concentrations should be interpreted with caution, considering the occurrence of both PMR and postmortem degradation. When interpreting postmortem toxicological results in cocaine-related fatalities, it might prove useful to take the above-mentioned variables into account.

Suitability of cardiac blood, brain tissue, and muscle tissue as alternative matrices for toxicological evaluation in postmortem cases

Drug concentrations in peripheral blood are often used to evaluate whether death was caused by drug intoxication. In some cases, peripheral blood is not available, and analytical results of alternative matrices should instead be used in the toxicological evaluation. However, reference concentrations of alternative matrices are few, which makes interpretation of results a challenge. In this study, concentrations of selected benzodiazepines, opioids, illicit drugs, and other commonly used drugs in postmortem femoral blood, cardiac blood, brain tissue, and muscle tissue are presented. Alternative matrix-to-femoral blood drug concentration ratios and correlations of blood and alternative matrix drug concentrations were calculated to examine which of the investigated alternative matrices were most suited to use for toxicological evaluation in cases where peripheral blood is not available. The results showed that concentrations in cardiac blood, brain tissue, and muscle tissue could be useful in the postmortem evaluation of most of the 19 selected analytes. In most cases, analytes were detected in all the alternative matrices. The median concentration ratios for the selected analytes in brain tissue, cardiac blood, and muscle tissue relative to femoral blood ranged from 0.57 to 3.42, 0.59 to 1.87, and 0.67 to 7.04, respectively. Overall, cardiac blood provided the concentrations most comparable with femoral blood concentrations, indicating that cardiac blood can be useful in cases where femoral blood is not available. However, the measured concentrations should be interpreted with caution.

A Forensic Diagnostic Algorithm for Drug-Related Deaths: A Case Series

The best evidence provided in the literature worldwide suggests the importance of harmonizing the investigation in drug-related fatalities. In this study, the application of a multidisciplinary approach in eight cases of drug-related deaths is presented. Although death scene findings could be highly suggestive of drug intoxication, external examination and toxicological screening test alone are insufficient. There are several variables, and it is not always easy to give the proper interpretation of the drug detection. A complete autopsy is necessary to correctly complete organ and tissues sampling for further histological and toxicological studies and obtain body fluids. The use of peripheral blood is recommended to avoid artifacts. The collection of many specimens is warranted to get more responses. The sampling aims to provide a picture of the distribution of the substance in the body. The sample and the selection of the drugs and the matrices to investigate are case-dependent. The presented diagnostic algorithm provides the coroner with all the elements to investigate drug-related deaths and cooperate with toxicologists. Toxicological forensic diagnosis is still extremely heterogeneous in regional and national contexts. Funding for method development, research, networking, facilities, and technologies improvement is mandatory to standardize the toxicological investigation.

Comparison of Comprehensive Screening Results in Postmortem Blood and Brain Tissue by UHPLC-QTOF-MS

Alternative specimens collected during autopsies can be valuable in postmortem toxicology in cases where peripheral blood is not available. The applicability of brain tissue as an alternative matrix for drug screening by ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry was investigated in this study. Results of the 50 most frequently detected drugs and metabolites of toxicological interest in blood and brain tissue samples from 1,719 autopsy cases were compared. Examination of the results in paired blood and brain tissue samples revealed that the two matrices were in general comparable, as the majority of the 50 analytes were observed in a high number of the examined cases in both blood and brain tissue. This demonstrates the potential of brain tissue as an alternative matrix for drug screening in postmortem toxicology or as a secondary matrix for confirmation.

Postmortem redistribution of morphine in humans: Important variables that might be influencing the central blood/peripheral blood ratio

INTRODUCTION

In the field of forensic toxicology, many unexpected deaths are investigated as to whether toxicological substances may have caused or contributed to someone's death. One of the factors that makes interpretation of the results of quantitative analysis in postmortem toxicology challenging, is that measured postmortem drugs levels may vary according to the sampling site and the interval between death and specimen collection. These site- and time-dependent variations are caused by 'postmortem redistribution' (PMR). Literature shows that there are several factors that determine the degree of PMR, such as cell and tissue changes after death, decomposition and the physicochemical characteristics of drugs. Blood from peripheral sites seems to be less affected by PMR than cardiac blood. Therefore, the ratio of cardiac blood concentration/peripheral blood concentration (C/P) of a drug is often used as a marker of the extent of postmortem redistribution. In this study, we investigated the relationship between different potentially important variables and the C/P ratio of morphine in humans in order to provide new insights that might assist in the interpretation of quantitative results in forensic casework.

METHOD

Toxicological results of all morphine positive postmortem cases investigated by the Netherlands Forensic Institute between January 1, 2010 and July 31, 2020 were reviewed. Morphine was quantified in both femoral and cardiac blood in a total of 103 cases. The C/P ratios were determined for all selected cases. To collect data for this study, all corresponding files were reviewed. C/P ratios were compared between subgroups by performing either a Mann-Whitney U test or a Kruskal-Wallis test, followed by a post-hoc Mann-Whitney U test. Bonferroni correction was performed to correct for the likelihood of a significant result by chance due to multiple testing. After Bonferroni correction, a p-value< 0.004 was considered statistically significant.

RESULTS

The data suggests a relationship between grade of decomposition at autopsy, position of the corpse at discovery, route of administration, attempted resuscitation and the C/P ratio of morphine with p-values of 0.010, 0.026, 0.035 and 0.046, respectively.

CONCLUSION

Grade of decomposition at autopsy, position of the corpse at discovery, route of administration and attempted resuscitation seem to be influencing the C/P ratio of morphine. Of these four variables, the route of administration seems to have the greatest impact.

Simple implementation of muscle tissue into routine workflow of blood analysis in forensic cases - A validated method for quantification of 29 drugs in postmortem blood and muscle samples by UHPLC-MS/MS

Whole blood is most often the matrix of choice for postmortem analysis but it is not always available. In these cases, muscle tissue can be used as an alternative matrix. Therefore, an ultra-high-performance liquid chromatography-tandem mass spectrometry method for the quantification of 29 drugs and metabolites of toxicological interest in postmortem muscle tissue was developed and validated. Additionally, a validation of whole blood was carried out to compare the results from the two matrices. Solid-phase extraction was performed by an automated robotic system to minimize manual labour and risk of human errors, and increase robustness, sample throughput and sample traceability. The method was validated in terms of selectivity, matrix effect, extraction recovery, process efficiency, measuring range, lower limit of quantification, carry-over, stability, precision and accuracy. To correct for any inter-individual variability in matrix effects on analyte accuracy and precision, deuterated analogues of each analyte were used as internal standards. The lower limit of quantification in both blood and muscle homogenate ranged between 0.002 and 0.005 mg/kg, while the upper limit of quantification spanned from 0.20 to 1.0 mg/kg. Corrected with the 4-fold dilution factor, the corresponding concentrations in muscle tissue were 0.008-0.02 mg/kg at the lower limit of quantification and 0.80-4.0 mg/kg at the upper limit of quantification. The method showed acceptable precision and accuracy, with precision below 12% and accuracies ranging from 87% to 115% at up to 6 levels for all analytes in both matrices. In addition, comparison between calibration standards in spiked muscle homogenate and spiked blood showed that analyte concentrations in muscle samples could be quantified by using spiked blood samples as calibration standards with acceptable precision and accuracy when using deuterated analogues as internal standards. The investigation of matrix effects showed no great difference between blood and homogenates of non-decomposed and decomposed muscle tissue for most analytes. In the samples where high ion suppression or enhancement was observed, the results were corrected by the internal standards. Statistical comparison of quality control samples in blood and muscle tissue showed no obvious differences, and therefore muscle tissue was included in the routine method for analysis of blood samples and used in autopsy cases where no blood was available. By adding a semi-automated homogenization step before the remaining automated sample preparation, muscle tissue samples were easily incorporated into the workflow of the existing routine method. The present method has been successfully implemented in routine analysis of blood and muscle tissue since 2019.

Postmortem Drug Redistribution: A Compilation of Postmortem/Antemortem Drug Concentration Ratios

Postmortem drug redistribution (PMR) is a well-known phenomenon in forensic toxicology with implications for medico-legal death investigations. Paired antemortem (AM) specimen and postmortem (PM) mortuary admission femoral blood drug concentrations from 811 coronial cases were used to construct a retrospective compilation of PM/AM drug concentration ratios for 42 parent drugs and metabolites. The median PM/AM ratios for all antidepressants were > 1 and consistent with PMR In contrast, the median PM/AM ratios of most benzodiazepines were < 1. The antipsychotics were varied (0.63-3.3) and suggest the mixed effects of PMR and drug instability. Amphetamines exhibited no trends (0.90-0.95) and are likely confounded by many factors. The PM/AM ratios of cardiovascular drugs, opioids and other drugs are also reported. This research represents an expansive retrospective compilation of paired AM and PM drug concentrations for many toxicologically relevant drugs. While the median PM/AM ratios demonstrate some drug-dependent trends, there was no obvious relationship between AM specimens and PM femoral blood taken at mortuary admission.

Methamphetamine deaths: Changing trends and diagnostic issues

The term 'amphetamine' refers to a class of synthetic drugs which includes methamphetamine. The latter is a globally popular drug of abuse which induces euphoria, affecting cognitive/psychomotor performance and sleep. It also provokes risk taking and violent behaviour. The central effects of methamphetamine are due to the overproduction of neurotransmitters, resulting in high levels of dopamine. In recent years, there have been significant increases in cases of methamphetamine abuse in North and South America, Australia and Asia due to its ready availability and low cost. The following review examines changing trends in methamphetamine use and problems that arise diagnostically in medico-legal cases in determining the significance of post-mortem blood levels, the relationship of these to ante-mortem levels, the possible effects on physical and psychological behaviours and the possible contribution of the drug to a lethal episode.

Dynamic Distribution and Postmortem Redistribution of Tramadol in Poisoned Rats

In the past dozen years, the cases of tramadol intoxication have become frequent in many countries. Most previous studies focused on tramadol's pharmacology, such as pharmacokinetics, pharmacodynamics and pharmacogenetics. However, the dynamic distribution and postmortem redistribution (PMR) of tramadol remain unclear. Our study aimed to investigate these two issues systematically in various specimens of 216 poisoned male rats. A validated gas chromatography-mass spectrometry method was used in this study to measure the concentrations of tramadol. In the first part, 66 tramadol poisoned rats were sacrificed at 11 different time points and their organs were collected separately for the study of tramadol's dynamic distribution, which made it feasible to investigate its PMR later on. The results of this part showed that tramadol's concentrations varied according to the organ and time, and peaked 2 h after intragastric administration in the specimens of liver, kidney, spleen, lung, brain and heart-blood (except stomach and heart). Based on the results of the first part, the concentration of tramadol peaked 2 h in most tissues. Therefore, this time point was used for the study of tramadol's PMR. In the second part, the remaining 150 rats were sacrificed 2 h after intragastric administration of tramadol, and the carcasses were stored under three different conditions (-20, 4 and 20°C). The autopsy was carried out at eight different time points and their organs were collected separately. The results of this part showed that under storage temperatures of -20 and 4°C, the concentrations of tramadol in individual organs showed no significant changes at different time points whereas under a storage temperature of 20°C, the concentrations in certain organs (liver, kidney, spleen, lung, brain and heart-blood) increased significantly at the last few time points. PMR of tramadol was therefore confirmed. The process of PMR of tramadol could be slowed or stopped at lower storage temperatures (-20 or 4°C), which is significant in cases of suspected tramadol poisoning.

Acidic Drug Concentrations in Postmortem Vitreous Humor and Peripheral Blood

Vitreous humor is a potential alternative matrix for postmortem toxicology drug screens when peripheral blood is unavailable. It is easily and reliably collected and may not suffer from the same postmortem redistribution as seen in blood. Here, we compared the concentrations of 7 acidic drugs (acetaminophen, ibuprofen, naproxen, salicylic acid, carbamazepine, phenobarbital and phenytoin) in peripheral blood and vitreous fluid collected in 89 autopsy cases. Analysis was done by high-performance liquid chromatography with diode-array detection. Overall, we found that vitreous drug concentrations were significantly lower than peripheral blood with median vitreous to peripheral blood (V/PB) ratios ranging from 0.0 to 0.6 (mean, 0.1-0.6). The correlations between the concentrations of over-the-counter analgesics in peripheral blood versus vitreous fluid were poor, with acetaminophen exhibiting the best linearity (R2 = 0.72). The antiepileptic drugs (carbamazepine, phenytoin and phenobarbital) exhibited good correlations between peripheral blood and vitreous humor, with all exhibiting an R2 ≥ 0.95. Overall, we have demonstrated the potential of vitreous fluid as an alternative matrix for the detection of select acidic drugs.

Position Paper: Recommendations for the Investigation, Diagnosis, and Certification of Deaths Related to Opioid and Other Drugs

The National Association of Medical Examiners convened an expert panel to update the association's evidence-based recommendations for investigating and certifying deaths associated with opioids and other misused substances to improve death certificate and mortality data for public health surveillance. The recommendations are as follows:1. Autopsy provides the best information on a decedent's medical condition for optimal interpretation of toxicology results, circumstances surrounding death, medical history, and scene findings. The panel considers autopsy an essential component of investigating apparent overdose deaths.2. Scene investigation includes reconciling prescription information and medication counts. Investigators should note drug paraphernalia or other evidence of using intoxicating substances.3. Retain blood, urine, and vitreous humor whenever available. Blood from the iliofemoral vein is preferable to blood from more central sites.4. A toxicological panel should be comprehensive, including potent depressant, stimulant, and antidepressant medications. Detecting novel substances present in the community may require special testing.5. When death is attributed to a drug or combination of drugs (as cause or contributing factor), the certifier should list the drugs by generic name in the autopsy report and death certificate.6. The best classification for manner of death in an overdose without any apparent intent of self-harm is "accident."

Sudden Death Associated with Complex Treatment of Acute Mania: Case Report and Toxicological Findings

Background:

Antipsychotic drugs, mood-stabilizers, and sedatives are used routinely to treat acute mania, sometimes in combinations, most of which are poorly evaluated for efficacy and safety.

Objective:

We report a case of sudden death in a 40-year-old man with acute mania treated aggressively with combinations of drugs that resulted in in potentially toxic, high serum drug concentrations.

Method:

After the autopsy, analysis were conducted to determine levels of the administered medications using GC-MS and LC-MS/MS.

Results:

Although dosed within recommended ranges, circulating concentrations of some antipsychotic drugs given were excessive, suggesting possible pharmacokinetic interactions. In particular, valproate may have increased serum levels of haloperidol, clozapine, and promazine. The proposed cause of death was cardiac arrest, to which the high concentrations of antipsychotics may have contributed.

Conclusion:

This case suggests caution in the aggressive treatment of mania with combinations of psychotropic drugs and highlights the need of further clinical studies to identify consequences of drug-drug interactions of antimanic drugs, even when given at recommended doses.

Adherence to psychotropic medication in completed suicide in Sweden 2006-2013: a forensic-toxicological matched case-control study

OBJECTIVE

To investigate the influence of adherence to psychotropic medications upon the risk of completed suicide by comparing person-level prescriptions and postmortem toxicological findings among complete-suicide cases and non-suicide controls in Sweden 2006-2013.

METHODS

Using national registries with full coverage on dispensed prescriptions, results of medico-legal autopsies, causes of death, and diagnoses from inpatient care, estimated continuous drug use for 30 commonly prescribed psychotropic medications was compared with forensic-toxicological findings. Subjects who had died by suicide (cases) were matched (1:2) with subjects who had died of other causes (controls) for age, sex, and year of death. Odds ratios were calculated using logistic regression to estimate the risk of completed suicide conferred by partial adherence and non-adherence to pharmacotherapy. Adjustments were made for previous inpatient care and the ratio of initiated and discontinued dispensed prescriptions, a measure of the continued need of treatment preceding death.

RESULTS

In 5294 suicide cases and 9879 non-suicide controls, after adjusting for the dispensation ratio and other covariates, partial adherence and non-adherence to antipsychotics were associated with 6.7-fold and 12.4-fold risks of completed suicide, respectively, whereas corresponding risk estimates for antidepressant treatment were not statistically significant and corresponding risk increases for incomplete adherence to antidepressant treatment were lower (1.6-fold and 1.5-fold, respectively) and lacked statistical significance.

CONCLUSION

After adjustment for the need of treatment, biochemically verified incomplete adherence to antipsychotic pharmacotherapy was associated with markedly increased risks of completed suicide.

Range of therapeutic prothipendyl and prothipendyl sulfoxide concentrations in clinical blood samples

Due to a lack of reference blood concentrations in the literature, the forensic evaluation of prothipendyl findings in blood samples is difficult. Interpretations with regard to the assessment of blood concentrations as well as an estimation of the ingested prothipendyl amounts were often vague. To describe a concentration range in clinical samples, prothipendyl and prothipendyl sulfoxide concentrations were determined in serum samples of 50 psychiatric patients receiving 40 mg, 80 mg, or 160 mg doses of prothipendyl. The analyses of prothipendyl and prothipendyl sulfoxide were carried out using validated methods of high performance liquid chromatography coupled to triple quadrupole mass spectrometry (LC-QQQ-MS), respectively. 40 mg doses caused average prothipendyl serum concentrations of 18.0 ng/mL (1 hour after intake) and 7.9 ng/mL (10.5 hours after intake), while 80 mg doses caused averages of 42.6 ng/mL and 15.2 ng/mL at the mentioned times of sampling. Irrespective of the given dose, prothipendyl concentrations below 30 ng/mL were observed in 80% of the patient samples taken 1 hour after ingestion as well as in 90% of the samples collected 10.5 hours after administration. Serum concentrations of the Phase I metabolite prothipendyl sulfoxide averaged 4.3 ng/mL (1 hour after intake) and 3.6 ng/mL (10.5 hours after intake). Possible drug-drug interactions regarding absorption and metabolism of prothipendyl are discussed. Results of the herein presented study are useful for the interpretation of analytical prothipendyl findings in forensic toxicology. The utility of the described concentration range is demonstrated by discussing two death cases involving prothipendyl findings.

Analytical data supporting the "theoretical" postmortem redistribution factor (Ft ): a new model to evaluate postmortem redistribution

The concepts of postmortem redistribution (PMR, F) factor, and "theoretical" PMR (Ft ) - based upon a drug's characteristic L/P ratio - have been defined to express the direct relationship between postmortem peripheral blood and the corresponding antemortem whole-blood concentration. This paper applies recent data describing liver/peripheral blood (L/P) ratios for many commonly detected drugs to assess these models, and provide a ranking of drugs' propensity for (and degree of) PMR.

Postmortem redistribution of olanzapine following intramuscular administration of olanzapine pamoate in dogs

The potential for postmortem redistribution of olanzapine was investigated in beagle dogs. Olanzapine pamoate monohydrate was administered once every 14 days by intramuscular injection for 3 months to fed male dogs (n=15) at a dose of 20 mg/kg olanzapine (equivalent to 46 mg/kg olanzapine pamoate monohydrate). Blood samples were collected after the fifth (Day 57) and sixth (Day 71) doses to determine olanzapine and N-oxide olanzapine concentrations. On Day 71 at 72 h postdose, dogs were euthanized and placed on their backs without additional manipulation and held for postmortem blood, urine, and tissue collection at room temperature for up to 168 h postdose (96 h after euthanasia). Concentrations of olanzapine and N-oxide olanzapine were determined by liquid chromatography-mass spectroscopy/mass spectroscopy (LC-MS/MS). Postmortem olanzapine concentrations in blood increased up to seven-fold compared to the last quantified antemortem blood concentration. Olanzapine concentrations in vein tissue samples (surrogates for peripheral blood) also increased, whereas other tissue concentrations, such as myocardium, lung, liver, and kidney decreased over the postmortem period. An increase in blood concentration of olanzapine after death was observed in all but one animal, suggesting that postmortem redistribution may occur in dogs following biweekly intramuscular administration of olanzapine pamoate monohydrate. The rise in olanzapine concentrations in blood after death in this study may potentially be attributed to diffusion from multiple tissues to blood and, to a lesser extent, reduction of the N-oxide olanzapine metabolite back to olanzapine. However, the generalizability of these results to humans cannot be confirmed by the present study.

Postmortem memantine concentration in a non-intoxication case, and the possibility of postmortem redistribution: A case report

In this case study, we measured the concentration of memantine in the heart blood, peripheral blood, urine, liver, thigh muscle, and subcutaneous fat of a 64-year-old woman who was prescribed memantine for early-onset Alzheimer's disease. She died in hospital after an altercation with her husband. Cause of death was clearly not drug intoxication or overdose, so we investigated the postmortem redistribution (PMR) of memantine in the various tissues and blood ratios of the postmortem samples. Memantine concentrations detected were 1.31 μg/mL in the peripheral blood, 3.95 μg/mL in central blood, 2.09 μg/mL in the urine, 25.54 μg/g in the liver, 1.16 μg/g in the thigh muscle and 2.13 μg/g in the subcutaneous fat. In all samples, the concentrations were higher than the accepted therapeutic range (which is approximately 0.09-0.15 μg/mL). The central blood to peripheral blood (C/P) memantine ratio was 3.01 while the liver to peripheral blood (L/P) ratio was 19.5. It is documented that a C/P ratio exceeding 2 and L/P ratio exceeding 20 highlight a propensity for significant PMR. Although this is a single case study, our data suggest that memantine exhibits PMR. Additionally, a lowered pH was found in peripheral blood (pH 6.2) and central blood (pH 6.1). This postmortem reduction in blood pH may also promote the PMR of memantine. Because there is very little available postmortem toxicological data on memantine, our case study will serve as a foundation to assist in future forensic investigations.

Evaluation of postmortem drug concentrations in cerebrospinal fluid compared with blood and pericardial fluid

In forensic toxicology, body fluids are important materials not only as alternatives to blood but also for investigation of postmortem drug redistributions and pharmaco-/toxicokinetic analysis; however, there are limited data on postmortem drug distributions in cerebrospinal fluid (CSF). The present study reviewed toxicological data of autopsy cases (n=103), in which drugs were detected in CSF using gas chromatography/mass spectrometry (GC/MS), to investigate drug concentrations in CSF, compared with blood and pericardial fluid (PCF) concentrations. Oral/injected amphetamines (n=23) showed similar CSF and blood/PCF concentrations with partly lower CSF concentrations (about ×0.5-1.1). CSF concentrations of the venous anesthetic midazolam (n=7) were lower with poor correlations. Oral caffeine (n=15), acetaminophen (n=7), chlorpheniramine (n=6), dihydrocodeine (n=6), and phenobarbital (n=21) showed equivalent to lower CSF concentrations (about ×0.2-1.2), compared with blood and PCF concentrations; however, CSF phenobarbital concentrations were high in a fatal intoxication case. CSF concentrations of phenothiazine derivatives (n=29) were markedly lower (about ×0.1) than blood/PCF concentrations. The distribution of the local anesthetic lidocaine used in critical medical care (n=49) markedly varied by case. These findings suggest that CSF is useful in routine forensic toxicology as an alternative to blood as well as for investigating pharmaco-/toxicokinetics and postmortem redistributions.

Polycyclic aromatic hydrocarbon residues in serum samples of autopsied individuals from Tennessee

This study reports the concentrations of Polycyclic Aromatic Hydrocarbons (PAHs) in human blood sera samples (n = 650) obtained at autopsy from individuals who died of drug abuse, alcohol toxicity, homicide, suicide and other unknown causes. The analyzed samples from decedents revealed the presence of PAHs of which B(a)P was the most predominant one, followed by benzo(b)fluoranthene and benzo(k)fluoranthene. The other PAHs detected sporadically and measured were benzo(g,h,i)perylene, acenaphthene, anthracene, phenanthrene, and fluoranthene The mean concentrations of PAHs were greater in the twenties to fifties age groups compared to others. The PAH residue levels detected were high in African Americans compared to Caucasians, Asians, and Hispanics. It appears that environmental exposure, dietary intake and in some cases occupational exposure may have contributed to the PAH body burden. While the PAH residue concentrations measured fall within the range of those reported for healthy adults elsewhere, in isolated cases, the concentrations detected were high, calling the need for a reduction in PAH emissions and human biomonitoring studies for purposes of risk assessment.

Postmortem distribution of guaifenesin concentrations reveals a lack of potential for redistribution

Therapeutic (or non-toxic) postmortem guaifenesin blood and liver concentrations have not been previously described. Peripheral blood guaifenesin concentrations were compared to central blood and liver concentrations in eight medical examiner cases. Specimens were initially screened for alcohol and simple volatiles, drugs of abuse, alkaline, and acid/neutral drugs. Guaifenesin, when detected by the acid/neutral drug screen, was subsequently confirmed and quantified by a high performance liquid chromatography procedure. Data suggest that postmortem guaifenesin peripheral blood concentrations may be considered non-toxic to at least 5.4mg/L with liver concentrations to at least 7.0mg/kg. Overall, guaifenesin concentrations ranged from 1.9 to 40mg/L in peripheral blood, 2.2-150mg/L in central blood, and 2.6-36mg/kg in liver. The median guaifenesin central blood to peripheral blood ratio was 1.1 (N=8). Similarly, liver to peripheral blood ratios showed a median value of 0.9L/kg (N=5). Given that a liver to peripheral blood ratio less than 5L/kg is consistent with little to no propensity for postmortem redistribution, these data suggest that guaifenesin is not prone to substantial postmortem redistribution.

Distribution of enantiomers of methadone and its main metabolite EDDP in human tissues and blood of postmortem cases

Knowledge concerning the distribution of methadone in postmortem human tissue and the effect of postmortem redistribution on methadone is today limited making the choice of a suitable substitute for femoral blood difficult when this is not available. Cardiac blood, femoral blood, muscle, and brain tissue concentrations of the enantiomers of methadone and its metabolite 2-ethyl-1,5-dimethyl-3,3-diphenylpyrrolinium were recorded for 155 postmortem cases. Brain and muscle tissue concentrations exceeded the femoral blood concentrations with a median fold of 2.3 and 1.6, respectively, but both had a better correlation than cardiac blood to femoral blood concentrations. The Kruskal-Wallis test showed a significant dependency on time and body mass index for some of the matrix ratios over femoral blood. We conclude brain or muscle tissue may constitute a better alternative for measurement of methadone than cardiac blood for situations in which femoral blood is not available, despite concentrations in both matrices being systematically higher.

Applying quantitative structure-activity relationship (QSAR) methodology for modeling postmortem redistribution of benzodiazepines and tricyclic antidepressants

Postmortem redistribution (PMR) constitutes a multifaceted process, which complicates the interpretation of drug concentrations by forensic toxicologists. The present study aimed to apply quantitative structure-activity relationship (QSAR) analysis for modeling PMR data of structurally related drugs, 10 benzodiazepines and 10 tricyclic antidepressants. For benzodiazepines, an adequate QSAR model was obtained (R(2) = 0.98, Q(2) = 0.88, RMSEE = 0.12), in which energy, ionization and molecular size exerted significant impact. For tricyclic antidepressants, an adequate QSAR model with slightly inferior statistics (R(2) = 0.95, Q(2) = 0.87, RMSEE = 0.29) was established after exclusion of maprotiline, in which energy parameters, basicity character and lipophilicity exerted significant contribution. Thus, QSAR analysis could be used as a complementary tool to provide an informative illustration of the contributing molecular, physicochemical and structural properties in PMR process. However, the complexity, non-static and time-dependent nature of PMR endpoints raises serious concerns whether QSAR methodology could predict the degree of redistribution, highlighting the need for animal-derived PMR data.

Complete republication: National Association of Medical Examiners position paper: Recommendations for the investigation, diagnosis, and certification of deaths related to opioid drugs

The American College of Medical Toxicology and the National Association of Medical Examiners convened an expert panel to generate evidence-based recommendations for the practice of death investigation and autopsy, toxicological analysis, interpretation of toxicology findings, and death certification to improve the precision of death certificate data available for public health surveillance. The panel finds the following: 1. A complete autopsy is necessary for optimal interpretation of toxicology results, which must also be considered in the context of the circumstances surrounding death, medical history, and scene findings. 2. A complete scene investigation extends to reconciliation of prescription information and pill counts. 3. Blood, urine, and vitreous humor, when available, should be retained in all cases. Blood from the femoral vein is preferable to blood from other sites. 4. A toxicological panel should be comprehensive and include opioid and benzodiazepine analytes, as well as other potent depressant, stimulant, and anti-depressant medications. 5. Interpretation of postmortem opioid concentrations requires correlation with medical history, scene investigation, and autopsy findings. 6. If death is attributed to any drug or combination of drugs (whether as cause or contributing factor), the certifier should list all the responsible substances by generic name in the autopsy report and on the death certificate. 7. The best classification for manner of death in deaths due to the misuse or abuse of opioids without any apparent intent of self-harm is "accident." Reserve "undetermined" as the manner for the rare cases in which evidence exists to support more than one possible determination.