Postmortem redistribution of fentanyl in the rabbit blood

Postmortem redistribution of fentanyl in the rabbit was investigated after application of the 50-μg/h Durogesic pain patch. Patches were applied for 48 hours. Two cycles of patch administration were used before characterization of the postmortem redistribution. Fentanyl showed marked redistribution into the femoral and pulmonary veins of the rabbit through 48 hours after the animals were humanely killed and the pain patches removed. The plasma concentration of 2.34 ng/mL in the femoral blood before killing the animals increased 5.6-fold by 48 hours after patch removal to 13.2 ng/mL. This postmortem concentration is approximately 3-fold the C(max) determined during antemortem pharmacokinetic analysis, 4 ng/mL, which was achieved 24 hours after the application of the second 50-μg/h Durogesic pain patch. After blood sampling for 48 hours after animal termination with patch removal compared with sampling for 48 hours from animals not terminated and with patch removal, the exposure ratios in the terminated animals were approximately 30-fold, indicating that between the postmortem redistribution of fentanyl and the cessation of hepatic clearance of fentanyl in the rabbit, the postmortem redistribution of fentanyl leads to an elevated measures of postmortem blood concentrations relative to antemortem blood concentrations.     

The extent of postmortem drug redistribution in a rat model.

The aim of this study was to investigate the postmortem redistribution of several drugs in a rat model and to examine if any of the pharmacological properties was related to the extent of this phenomenon. One of the following drugs: phenobarbital (phenobarbitone), acetaminophen (paracetamol), carbamazepine, codeine, verapamil, amphetamine, mianserin, trimeprazine (alimemazine) or chloroquine was administered together with nortriptyline orally to rats 90 min prior to sacrifice. Heart blood was sampled immediately before sacrifice and after 2 h postmortem, as it has previously been shown that this is sufficient time for postmortem concentration changes to occur in heart blood. Blood was also sampled from the clamped abdominal inferior vena cava (representing peripheral blood) and tissue samples were taken from lungs, myocardium, liver, kidney, thigh muscle, forebrain, and vitreous humor together with a specimen from the minced carcass. Drugs were analyzed by high performance liquid or gas chromatography. For phenobarbital, acetaminophen and carbamazepine the postmortem to antemortem blood drug concentration ratios were close to 1.0 and tissue concentrations were low. The postmortem to antemortem heart blood drug concentration ratio for chloroquine (6.9 +/- 1.5) was higher than for nortriptyline (3.5 +/- 0.3), and the remaining drugs (codeine, verapamil, amphetamine, mianserin, and trimeprazine) showed ratios of the same magnitude as nortriptyline. The postmortem to antemortem blood drug concentration ratios for both heart blood and blood from the vena cava and also the lung to antemortem blood drug concentration ratio were closely related to the apparent volume of distribution for the drugs studied (p < 0.001). Accordingly, an apparent volume of distribution of more than 3-4 L/kg is a good predictor that a drug is liable to undergo postmortem redistribution with significant increments in blood levels. The postmortem drug concentration in blood from vena cava was closely related to the antemortem blood level, confirming that among the postmortem samples, the peripheral blood sample was the most representative for the antemortem blood concentration.     

Interpretation of postmortem digoxin levels: evaluating a "corrective factor" for postmortem blood digoxin concentration

Interpretation of postmortem serum digoxin levels is made difficult above all by a possible prefinal or postmortem rise in digoxin concentrations in the blood. To compensate for this postmortem increase, Eriksson et al. (1984) divided the level of postmortem digoxin in femoral venous blood by a factor of 1.5; in the opinion of these authors, postmortem digoxin levels still exceeding "therapeutic levels" after division by 1.5 are an index of digoxin overdose. The diagnostic value of this "correction factor" was investigated. In 56 cases with documented digoxin medication, samples of postmortem femoral venous blood were taken and the level of digoxin determined. In none of the cases had there been a clinical diagnosis of digoxin intoxication. Fifty percent of the measured values were above "therapeutic levels" (0.7 ng/ml to 2.2 ng/ml). Following division by 1.5, 20% of the cases still showed levels exceeding 2.2 ng/ml; the highest "corrected" value was 4.44 ng/ml. Taking into account the length of time between final dosage and death, individual differences in sensitivity to digitalis glycoside, and the complexity of ante- and postmortem dispersion processes, we concluded for the cases we studied that an (undetected) digoxin overdose was not even likely in those cases whose postmortem values after division by 1.5 lie above "therapeutic levels". The "correction factor" proposed by Eriksson et al. (1984) is only of limited diagnostic value; at best the "corrected" values can give an approximate indication of the corresponding antemortem serum digoxin concentrations. In particular, "corrected" values only a little above "therapeutic levels" could not confirm suspicion of an overdose with sufficient certainty.     

Morbus Fahr--considerations on a case of sudden death

This paper presents 21 cases related to cyanide intoxication by oral ingestion. Cyanide concentrations in biological specimens are especially different from the type of postmortem specimens, and very important in interpreting the cause of death in postmortem forensic toxicology. Besides the detection of cyanide in autopsy specimens, the autopsy findings were unremarkable. Biological samples (0.2mL or equal to less than 10μg of cyanide) were analyzed colorimetrically for cyanide. In a series of 21 cyanide fatalities, the concentration ranges (mean±SD) of cyanide in heart blood, peripheral blood and gastric contents were 0.1-248.6mg/L (38.1±56.6mg/L), 0.3-212.4mg/L (17.1±45.1mg/L) and 2.0-6398.0mg/kg (859.0±1486.2mg/kg), respectively. The ranges of the heart/peripheral blood concentration ratio and gastric contents/peripheral blood concentration ratio were 0.3-10.6 (mean 3.4) and 3.4-402.4 (mean 86.0), respectively. From the difference of cyanide concentration and the concentration ratio of cyanide in different types of postmortem specimens, the possibility of the postmortem redistribution of cyanide and death by oral ingestion of cyanide could be confirmed. We reported cyanide fatal cases along with a review of literature.     

Digoxin, magnesium, and potassium levels in a forensic autopsy material of sudden death from ischemic heart disease

In 91 cases where the cause of death was heart disease, digoxin, Mg and K concentrations in serum and ventricular myocardium were measured post mortem. Forty per cent were positive for digoxin in both serum and myocardium. The mean serum level was 5.1 +/- 2.4 nmol/l and the mean myocardial level was 42.6 +/- 27.5 ng/g. Correlation could be established between serum and myocardial concentrations of digoxin. There were statistically significant differences in serum as well as in myocardial digoxin levels in persons on 0.13 mg and 0.25 mg per day, respectively. Myocardial levels of Mg and K were low as generally found in persons with ischemic heart disease. There was no correlation between these levels and myocardial digoxin concentrations. Caution must be exercised in the assessment of digoxin results from cadaver samples because of the postmortem rise of digoxin serum concentrations. Considering this fact, the results still indicate that the prevalence of toxic digoxin concentrations might be more common than previously thought.     

An Examination of the Postmortem Redistribution of Fentanyl and Interlaboratory Variability,

Fentanyl is a synthetic opioid agonist used for pain control. Often administered as a transdermal patch, it is an interesting drug for study of postmortem redistribution. We hypothesized that fentanyl concentrations would increase over time after death, as measured in blood drawn on the day prior to autopsy and in blood drawn at the time of autopsy in ten cases where fentanyl patches were identified at the scene. Concentrations were compared, and heart blood to femoral blood ratios were calculated as markers of postmortem redistribution. Fentanyl concentrations measured in peripheral blood drawn the day of autopsy (peripheral blood 2 [PB2]) were higher than those drawn the day prior to autopsy (peripheral blood 1 [PB1]) with a mean ratio (PB2/PB1) of 1.80. The ratio of heart blood concentrations (HB) to femoral blood concentrations drawn at autopsy (PB2) had a mean ratio (HB/PB2) of 1.08. Some cases had blood from the same source analyzed at two different laboratories, and concentrations of fentanyl in those samples showed inter‐ and intralaboratory differences up to 25 ng/mL. Postmortem fentanyl concentrations may be affected by antemortem factors, postmortem redistribution, and laboratory variability. Forensic pathologists must use caution in interpreting fentanyl levels as part of death investigation.     

Distribution of digoxin, digitoxin and their cardioactive metabolites in human heart and kidney tissue. A postmortem study

A method was developed for the specific determination of digoxin and digitoxin, as well as their semisynthetic derivatives and dependent cardioactive metabolites, in autopsy samples of heart and kidney. A collective of six patients on long-term treatment with therapeutic doses of beta-acetyldigoxin had a mean myocardial digoxin content of 46.1 +/- 25.0 ng/g (SD); kidney: 50.3 +/- 30.3 ng/g. Digoxigenin bisdigitoxoside represented the second most important metabolite in heart and kidney; digoxigenin monodigitoxoside and digoxigenin follow, respectively. In a collective of seven patients on maintenance treatment with digitoxin, the mean tissue levels were higher but the metabolic pattern was similar (myocardial digitoxin content: 78.9 +/- 38.4 ng/g, renal content: 104.1 +/- 44.1 ng/g). The amount of digoxin formed by hydroxylation under long-term treatment with digitoxin in heart and kidney were approximately 10 ng/g. A case of digoxin intoxication differed both in the tissue content and in the metabolic distribution.     

A Characterization of Sources of Isopropanol Detected on Postmortem Toxicologic Analysis

Abstract: Isopropanol is an important chemical to forensic pathologists in that intoxication can result in death yet presence does not necessarily indicate intoxication. Several reports have been published, which indicate that isopropanol can be created endogenously in certain situations including diabetes mellitus, starvation, dehydration, and chronic ethanol use; however, a large‐scale analysis addressing all of the possible causes of postmortem isopropanol detection has not been performed. A retrospective review of all cases examined at the Bexar County Medical Examiner’s Office between 1993 and 2008 in which isopropanol was detected in routine alcohol screening was undertaken. The cases were categorized by the source of the isopropanol, and the concentrations of isopropanol and acetone were analyzed. Analysis revealed isopropanol concentrations to be low (<100 mg/dL) in cases of antemortem and postmortem creation and in postmortem contamination and high (>100 mg/dL) in cases of antemortem exposure. These results are consistent with other published reports.     

Postmortem atropine concentrations in resuscitation cases

The medications used during resuscitation are often in and of themselves toxic. Several reports have been published regarding toxicities of these drugs, including lidocaine, procainamide, and atropine. But how does a forensic pathologist or toxicologist differentiate a possible intoxication from therapeutic or resuscitory use especially given that the concentrations of such drugs, when used in the setting of resuscitation, have not been studied? Concentrations of a well-known resuscitation medication, atropine, were assessed in cases where it was administered before death during attempted resuscitation in an effort to address this deficiency. A review of deaths occurring in 2009 was undertaken to identify cases where drugs known to be used during resuscitation were present on toxicological analysis. Autopsy reports and medical records were examined to determine how much atropine was administered, the timing and route of administration, the time the sample was drawn (antemortem and postmortem), the source of the sample, and the ultimate cause of death. Eighty-nine cases were identified in which atropine was given before death during attempted resuscitation and was detected in the blood on postmortem toxicological screening; 11 cases were identified in which atropine was administered before death yet was not detected on the postmortem toxicological screening. Mean age was 41 years, and there were 65 males and 35 females. The overall median dose of atropine given was 3 mg, the median difference between the time of last administration of the atropine to the time of death (or draw for antemortem samples) was 15 minutes, and the median atropine concentration was 0.1 mg/L. Analysis failed to reveal significant differences in the atropine concentration based on the route of administration (intravenous or intraosseus), the cause of death, or the time since administration (within the first 2 hours). Analysis did reveal a difference between the atropine concentrations in peripheral versus central blood sources and with prolonged postmortem interval (>24 hours) suggesting postmortem redistribution.     

Experimental Study on the Postmortem Redistribution of the Substituted Phenethylamine, 25B‐NBOMe

2‐(4‐Bromo‐2,5‐dimethoxyphenyl)‐N‐(2‐methoxybenzyl)ethanamine (25B‐NBOMe) is a substituted phenethylamine, which has become highly prevalent worldwide since 2014. Recently, in an autopsy case involving fatal 25B‐NBOMe intoxication, we found the postmortem increase of 25B‐NBOMe concentration in the cardiac blood approximately 2 days after death. The aim of this study was to investigate the distribution of 25B‐NBOMe and reproduce the postmortem redistribution using a rat model. Sprague‐Dawley rats were killed 30 min after intraperitoneal injection of 25B‐NBOMe (0.5 mg/kg) and left for 0, 3, 6, 9, 15, or 24 h (six rats at each time point). Postmortem 25B‐NBOMe concentrations in the cardiac blood increased by more than 10‐fold at 6‐h postmortem. 25B‐NBOMe accumulated primarily in the lung. Moreover, this postmortem redistribution occurred even in rats that had died 1 week following the 25B‐NBOMe administration. These findings indicate that attention should be paid to sample collection and data interpretation in the toxicological analysis of 25B‐NBOMe.     

Correlation of antemortem and postmortem digoxin levels.

Postmortem serum digoxin levels from any source routinely exceed antemortem values. Variation resulting from site of sampling gave a mean postmortem to antemortem ratio of 1.96 for heart, 1.63 for subclavian vein, and 1.42 for femoral vein samples. No correlation could be made between the postmortem interval and the increase in post-mortem serum values, irrespective of the site of sampling. A combination of femoral venous serum and vitreous humor values gave the best information for determining possible antemortem digoxin toxicity.     

Acute Benztropine Intoxication and Fatality

A woman was found unresponsive with an empty bottle of Cogentin^® prescribed to another. Admitted to an area hospital, her condition steadily declined until death 29 h after admission. Following toxicological screening on hospital (admission) whole blood, the only significant compound detected was benztropine. Benztropine was confirmed at 0.28 mg/L – the highest antemortem blood concentration recorded in a case of toxicity or fatality uniquely associated with benztropine. A second serum antemortem specimen showed a benztropine concentration of 0.19 mg/L. Despite over 24 h in the hospital, benztropine was also found in the postmortem specimens collected at autopsy. Peripheral blood, central blood, liver, and gastric concentrations were 0.47 mg/L, 0.36 mg/L, 9.6 mg/kg, and 44 mg, respectively. These results indicate that benztropine exhibited a potential difference between whole‐blood and serum (plasma) concentrations. Additionally, in consideration of literature data, benztropine was found indicative of a compound prone to at least some postmortem redistribution.     

Postmortem disposition of morphine in rats

The antemortem and postmortem distribution of morphine was studied in rats for the purpose of establishing whether drug distribution is altered after death. Samples were examined for free and total morphine concentration, pH and water content at 0-96 h after death. Morphine was administered antemortem at various intervals. All groups of rats studied showed a significant (P less than 0.05) increase in postmortem cardiac blood morphine concentrations. These changes, which are detectable within 5 min after death are likely to be related to an observed, rapid decrease in cardiac blood pH from 7.34 +/- 0.02 to 6.74 +/- 0.05. Significant increases in free morphine levels were, also, observed 24 and 96 h after death in liver, heart and forebrain while urine morphine levels decreased. The liver showed the greatest increase (20-fold) in free morphine levels 96 h after death, while hindbrain levels did not significantly change. Bacterial hydrolysis of morphine glucuronides accounted only in part for the observed increase in free morphine concentration. Postmortem fluid movement and pH-dependent drug partitioning was detected. It would appear that several mechanisms are responsible for postmortem drug distribution. Understanding the mechanisms and patterns responsible may eventually lead to better choices of postmortem tissue which may better represent antemortem drug levels.     

Fatal Fentanyl Patch Misuse in a Hospitalized Patient with a Postmortem Increase in Fentanyl Blood Concentration

Opioid‐related mortality happens, even in healthcare settings. We describe serial postmortem fentanyl blood concentrations in a hospital inpatient who fatally abused transdermal fentanyl. This is a single‐patient case report. A 42‐year‐old man with lymphoma was started on transdermal fentanyl therapy while hospitalized for chronic abdominal pain. The patient was last seen awake 1.3 h prior to being found apneic and cyanotic. During the resuscitation attempt, a small square‐shaped film was removed from the patient's oropharynx. Femoral blood was collected 0.5 and 2 h postmortem, and the measured fentanyl concentration increased from 1.6 to 14 ng/mL. Study limitations include potential laboratory or collection errors and missing data. (i) Providers must be vigilant for signs of fentanyl patch abuse. (ii) Postmortem blood concentrations are not static postmortem, likely secondary to decreasing pH, increased aqueous solubility, and tissue redistribution, and are therefore unlikely to accurately represent antemortem blood concentrations.     

Investigation of Postmortem Absorption and Redistribution After the Application of a Fentanyl Patch

Fentanyl deaths have increased with availability of transdermal patches. Interpretation of postmortem fentanyl levels may be complicated by postmortem redistribution and absorption of fentanyl from a patch. We applied an unused 100‐μg/h fentanyl patch onto the lower abdomen of a decedent with no premortem fentanyl exposure. Ocular fluid, blood, and urine were collected prior to placement, and the decedent was refrigerated for 23 h. Prior to the autopsy, urine, subcutaneous tissue under the patch, and samples from the same anatomic sites were obtained. We observed no fentanyl in any postpatch placement samples (LOD: 0.1 ng/mL for blood and vitreous fluid, 1.0 ng/mL urine, 2.0 ng/g for tissues). Although we observed no postmortem absorption of fentanyl, this was only a single case; therefore, we recommend that patches be removed after receipt of a cadaver before initiation of an autopsy, with the location of removed patch documented.     

Timely antemortem and postmortem concentrations in a fatal carbamazepine overdose.

There are no published reports that include both timely antemortem and postmortem carbamazepine concentrations after massive overdose. We report a fatal overdose of carbamazepine with both timely antemortem and postmortem carbamazepine concentrations. Carbamazepine concentrations were 47.7 mcg/mL 2 h antemortem and 53 mcg/mL at 9 h postmortem. The slight rise in drug concentration may reflect continued absorption of the drug in the last 2 h before death. Postmortem carbamazepine concentrations drawn from a peripheral vessel in this patient appeared to reflect drug concentrations at the time of death.     

Fatal combined intoxication with new antidepressants. Human cases and an experimental study of postmortem moclobemide redistribution.

Three cases are presented in which death was caused by suicidal intoxication with moclobemide in combination with a selective serotonin reuptake inhibitor. Both antidepressant drug types are considered to be relatively safe with regard to lethal overdose. However, the combination may cause the serotonin syndrome, a condition with a high mortality rate. In one of the cases, there was clinical information consistent with the serotonin syndrome, in the two other cases, there was no information of the clinical course. Postmortem redistribution of the selective monoamine oxidase inhibitor moclobemide was investigated in a rat model. Postmortem concentrations in blood from the vena cava and the heart were found to be in good accordance with antemortem concentrations. Postmortem concentrations in vitreous humour and various tissues were also measured. The apparent volume of distribution was calculated to be 0.95 +/- 0.10 l/kg, which is in the same range as that reported in man.     

References for determining the time of death by potassium in vitreous humor

The different statements concerning the slope and intercept of the regression line and the 95% limits of confidence are the reason that potassium in vitreous humor is not used (at least in Germany) as an aid in estimating the time of death. The relationship between the concentration of potassium and the time of death is mainly influenced by antemortem electrolyte imbalances caused by disease and/or duration of terminal episode. The influence of terminal episode is best identified by its duration (Adelson et al., J. Forensic Sci., 8 (1963) 503-514). In order to have a method suitable for every case and to be as precise as possible we looked therefore for parameters in vitreous humor which were stable postmortem and indicating antemortem electrolyte imbalance. Urea is such a parameter, being stable postmortem (Coe, Am. J. Clin. Pathol, 51 (1969) 741-750) and useful as a marker of antemortem electrolyte imbalance. Our investigations on potassium in vitreous humor, including sudden and hospital deaths after chronic lingering disease, revealed 95% limits of confidence of +/- 34 h up to 120 h postmortem. Reviewing only cases with urea less than 100 mg/dl the 95% limits of confidence could be reduced to +/- 22 h. Considering the duration of terminal episode (less than 6 h) the precision was +/- 20 h. In this way our modified procedure is suitable for every case with the resulting precision of estimation being determined only by the duration of the terminal episode and urea concentration.     

The analysis of an intracerebral hematoma for drugs of abuse

Toxicological investigations were performed on an intracerebral hematoma, antemortem blood, and postmortem blood of an individual who was found unresponsive in his home. The hematoma was found to have ethanol at a concentration of 0.05% (w/v), and benzoylecgonine (a cocaine metabolite) was also confirmed at a concentration of 0.43 mg/L by specific analysis using gas chromatography/mass spectrometry (GC/MS). These results enabled the pathologist to record the cause of death as intracerebral hemorrhage due to acute cocaine intoxication.     

Influence of blood loss on the pharmacokinetics of citalopram

Extended blood loss results in several compensatory physiological mechanisms, including transfer of extravascular fluid into the blood circulation. If drugs are present in the body, this fluid exchange may imply that blood drug concentrations found in a trauma victim may differ from the concentrations present at the time of the trauma. To address this issue, an animal model was used to investigate the influence of blood loss on pre-existing levels of the antidepressant drug citalopram and its demethylated metabolites. Rats were administered citalopram either acutely (40 mg/kg, orally) or chronically (20 mg/kg daily, subcutaneously) for 6 days using osmotic pumps. In the experimental rats, blood loss was accomplished by withdrawing 0.8 mL blood at 10 min intervals during 70 min. In the control rats, blood was withdrawn at 0 and 70 min only. Blood, brain and lung drug concentrations were analyzed with an enantioselective HPLC method. In the chronically treated rats, the ratios between final and initial citalopram concentrations were 1.08 +/- 0.15 and 1.01 +/- 0.09 in the experimental rats and controls, respectively, indicating no major effect of blood loss. In contrast, acute oral administration resulted in increased ratios in the exsanguinated rats as compared to controls (1.84 +/- 0.50 versus 0.73 +/- 0.07; p = 0.0495). In conclusion, the observation of increased blood drug levels in the acute oral rats indicates that absorption of fluid from the gastrointestinal tract may be important in the intravascular refill. Further, in the interpretation of post-mortem blood levels of drugs, these physiological mechanisms should be taken into account.