Thor Hilberg

Postmortem drug redistribution--human cases related to results in experimental animals.

Femoral blood is widely accepted as the most reliable postmortem specimen for drug analysis in forensic toxicology. There is considerable evidence that the drug concentrations in peripheral blood samples are closer to the antemortem level than the concentration in cardiac blood. In the present study drug concentrations measured in postmortem femoral and/or heart blood samples from eight cases were compared with the concentration found in serum samples from the same subject collected antemortem or perimortem. The drugs involved were amitriptyline, nortriptyline, imipramine, verapamil and chloroquine. Two additional cases with very early postmortem blood samples, as well as femoral blood samples from later autopsy, involved amphetamine and tetrahydrocannabinol. The results from the human cases were compared with results from rat experiments on similar drugs. The samples were analyzed by high performance liquid or gas chromatography. The cases with tricyclic antidepressants had a median postmortern femoral blood to antemortem serum drug concentration ratio of 3.3, the 95% reference range being from 1.1 to 6.0 (pooled data). Large variations of the ratios were seen. The extremes noted were a postmortem femoral blood to antemortem serum drug concentration ratio of 0.9 in a case with nortriptyline and 49 in the case with chloroquine. The low ratio in the former case could be due to attempted resuscitation, while the high ratio in the latter case is probably due to the extremely high apparent volume of distribution and a high blood to plasma concentration ratio for chloroquine. Accordingly, it is dubious whether the drug concentration found in femoral blood at autopsy can be accepted as being representative for the antemortem level. The results obtained from the human cases in the present study were generally in reasonable agreement with previous rat experiments, confirming that the animal studies when interpreted carefully, are indicative of the changes observed in man as well as a previous study in pigs. Studies on drug concentrations in pigs are not necessarily more representative for the findings in humans than experiments with a smaller animal like the rat. The postmortem concentration changes observed for tetrahydrocannabinol in man were found to be unpredictable, while in the accompanying experimental rat study there was a significant postmortem decrease in the tetrahydrocannabinol blood concentration measured in blood from the inferior vena cava. In special cases where the diagnosis of overdose is to be used as judicial evidence, a single sample of blood may prove insufficient. In such cases, analyses of several samples of blood and tissue will increase the possibility of reaching a correct conclusion, but reference values on drug concentrations in tissues are often missing.

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.

An animal model of postmortem amitriptyline redistribution.

An experimental rat model was developed to study postmortem changes of drug concentration after an acute overdose. Overnight fasted rats were fed 75 mg of amitriptyline (AMI). Two h after dosing, the rats were anaesthetized and blood samples were drawn from the femoral vein (peripheral blood--PB) and the heart (HB). The rats were sacrificed by CO2 and left at room temperature for either 0.1, 0.5, 1, 2, 5, 10, 24, 48, or 96 hours, when samples of heart blood, blood from the inferior vena cava (PB) and tissue samples from different liver lobes, heart, lungs, kidney, thigh muscle, and brain were taken. Samples were analyzed by high performance liquid chromatography. The AMI concentration in HB increased fairly rapidly within the first 2 h postmortem and from then the average ratio was 6.4 +/- 0.8 (mean +/- sem) (n = 31). In PB, the post/antemortem AMI concentration ratio followed an approximately exponential rise; at 2 h postmortem the ratio was 1.6 +/- 0.3 (n = 5), and at 96 h 55.1 +/- 23.8 (n = 4). For the main metabolite nortriptyline (NOR), the concentration changes followed the same pattern, but to a lesser extent. Among the tissues, the liver lobes had high, but variable drug concentrations; lobes lying closest to the stomach had the highest drug concentrations. The drug concentration in the lungs declined significantly. This animal model demonstrates postmortem drug concentration changes similar to those described in humans. Probable mechanisms include drug diffusion from the stomach and GI tract to the surrounding tissues and blood; and postmortem drug release from the lungs and possibly other drug-rich tissues into the blood.

Postmortem release of amitriptyline from the lungs; a mechanism of postmortem drug redistribution

An experimental rat model was used to study postmortem redistribution of amitriptyline (AMI). Two hours after a subcutaneous injection with 20 mg of amitriptyline, the rats (n = 40) were anaesthetized and blood samples were drawn from the femoral vein and the heart. The rats were then sacrificed by CO2 and left at room temperature for either 0.1, 1, 2, 5, 24, 48, or 96 h. Postmortem blood samples from the heart and the inferior vena cava, and tissue samples from the lungs, heart, liver, right kidney, thigh muscle, the wall of the abdominal vena cava and brain were analyzed by high performance liquid chromatography. A significant increase was observed within 2 h postmortem in heart blood and later also in blood from the inferior vena cava. At 96 h postmortem the concentration increase was 4.4 +/- 0.5-fold (P < 0.01) and 3.0 +/- 1.1-fold (P < 0.05) as compared to the antemortem values observed in heart blood and blood from the inferior vena cava, respectively (mean +/- SEM). In the lungs there was a fall in the concentration of AMI from 148 +/- 16.7 mumol/kg at 0.1 h to 49.1 +/- 7.8 mumol/kg at 96 h postmortem (P < 0.01). In the vessel wall of the abdominal vena cava there was also a significant fall in drug concentration, while in heart muscle and liver an increase in drug concentration was observed. In animals where the lungs were removed agonally (n = 7), the drug concentration in heart blood had increased significantly less at 2 h postmortem.(ABSTRACT TRUNCATED AT 250 WORDS)

Diffusion as a mechanism of postmortem drug redistribution: An experimental study in rats

SummaryIn some cases of drug overdose there is a reservoir of unabsorbed drug in the stomach and gut. Furthermore, agonal aspiration might establish a second reservoir in the lungs. Two experimental rat models were used to study if diffusion from these reservoirs could contribute to the phenomenon of postmortem drug redistribution. Overnight fasted rats were sacrificed by CO2 and 75 mg of amitriptyline (AMI) was administered by a gastric tube. In the first series (n = 19), the tubes were removed after AMI administration. In the second series (n = 17), the trachea was ligated and cut prior to drug administration to prevent airways contamination. The rats were left at room temperature on their back for a period of 5, 10, 24, 48, 96 up to 192 h and samples of heart blood, blood from the inferior vena cava, tissue samples from heart, lungs, different liver lobes, kidney and psoas muscle were taken. In both series of rats we observed that as early as 5 h postmortem increasing concentrations of amitriptyline were found in the liver lobes lying closest to the stomach. In rats where the trachea was not ligated, drug contamination of the lungs also resulted in an increase in drug concentration within 5 h in heart blood and heart muscle. In rats where the trachea had been ligated, amitriptyline was found in the lungs after 96 h postmortem. The main metabolite nortriptyline was also detected. We concluded that postmortem diffusion from the gastrointestinal tract could be a major mechanism behind the phenomenon of postmortem redistribution of drugs in human case material, and that agonal aspiration may be followed by a rapid increase in postmortem drug concentration in autopsy samples.ZusammenfassungIn einigen Fällen von Medikamenten-Dosierung gibt es ein Reservoir nicht-resorbierter Wirkstoffe im Magen und im Darm. Außerdem könnte eine agonale Aspiration zur Entstehung eines weiteren Reservoirs in den Lungen führen. Zwei experimentelle Tiermodelle mit Ratten wurden benutzt, um zu untersuchen, ob die Diffusion von diesen Reservoirs einen Beitrag leistet zu dem Phänomen der postmortalen Wirkstoff-Umverteilung. Während der Nacht hatten die Ratten keine Nahrung und wurden mit CO2 getötet, und zusätzlich wurde eine Dosis von 75 mg Amitriptylin (AMI) durch einen Magenschlauch gegeben. In der ersten Serie (n = 19) wurden die Schläuche nach der AMI-Zuführung entfernt. In der zweiten Serie (n = 17) wurde die Trachea vor der Zuführung des Wirkstoffs ligiert und durchtrennt, um eine Kontaminierung der Luftwege zu verhindern. Die Ratten wurden bei Raumtemperatur auf dem Rücken liegen gelassen für Zeiträume von 5, 10, 24, 48, 96 bis zu 192 Stunden, und Proben des Herzblutes, von der unteren Hohlvene, Gewebsproben vom Herzen, den Lungen, verschiedenen Leberlappen, von der Niere und vom Psoasmuskel wurden entnommen. In beiden Serien beobachteten wir, daß bereits 5 Stunden postmortem ansteigende Konzentrationen von Amitriptylin in den Leberlappen gefunden wurden, welche am nächsten zum Magen liegen. Bei den Ratten, bei welchen die Trachea nicht ligiert wurde, führte die Kontamination der Lungen mit Wirkstoff innerhalb von 5 Stunden zu einem Anstieg des Medikamentes im Herzblut und im Herzmuskel. Bei Ratten, bei welchen die Trachea ligiert worden war, wurde Amitriptylin nach 96 Stunden in den Lungen gefunden. Der Hauptmetabolit Nortriptylin wurde auch gefunden. Wir schlußfolgern, daß die postmortale Diffusion vom Gastrointestinaltrakt ein Hauptmechanismus sein könnte, welcher verantwortlich ist für die postmortale Umverteilung von Wirkstoffen in menschlichen Todesfällen und daß eine agonale Aspiration von einem raschen Anstieg der postmortalen Wirkstoffkonzentration in Autopsieproben gefolgt wird.

Postmortem Amitriptyline Pharmacokinetics in Pigs after Oral and Intravenous Routes of Administration

In this study we have evaluated the postmortem pharmacokinetics of amitriptyline (Ami) and metabolites in pigs after oral and intravenous administration, and the results are compared with previous studies in rats and humans. In addition a meticulous investigation of blood and tissue concentrations after postmortem intravenous infusion of Ami was undertaken. Of a total of 9 over-night fasted pigs, 3 were given 25 mg/Kg Ami orally, and another 3 pigs received an intravenous infusion lasting 1 h of 3.3 mg/Kg Ami prior to death. The final 3 pigs were sacrificed and then given the intravenous infusion after death. After approximately 5 h at room temperature, all carcasses were subsequently stored at 4-5 degrees C. Postmortem blood samples were collected at 0.25, 1, 2, 4, 8, 24, 48, and 96 h through an indwelling intracardial needle. Postmortem examination with blood and tissue sampling was performed 96 h after death. Analysis was carried out by high performance liquid chromatography with ultraviolet detection. Postmortem blood samples from the heart of the orally dosed animals revealed large and variable concentration increases of 99(30-243)% for Ami and 96(52-429)% for the main metabolite 10-OH-Ami at 96 h. In the intravenously infused live pigs heart blood Ami increased by 55(33-69)% and 10-OH-Ami increased by 232(76-240)%. Blood from the atria had significantly higher Ami concentrations than blood from both ventricles in the animals dosed while alive, and the drug concentration in femoral blood was higher than in heart blood (p < 0.01). In the orally dosed pigs the left lobe of the liver had significantly higher Ami levels than the right lobe. Tissue/blood Ami concentration ratios were generally lower than previously reported in rats and approximating the levels reported in humans. The animals infused intravenously after death demonstrated high drug levels in blood samples from central vessels, heart, lungs as well as cerebrospinal fluid and vitreous humour. This implies that the presence of a lethal concentration of a drug in just one sample of heart blood can prove worthless in a case where agonal drug infusion may have occurred.

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.

Fatal Overdose of Zopiclone in an Elderly Woman with Bronchogenic Carcinoma

The death of a 72-year-old woman with respiratory debilitation due to bronchogenic carcinoma is described. She overdosed herself with probably 200 to 350 mg of zopiclone. Zopiclone, quantitated by HPLC in femoral postmortem blood, was found to be 1.9 mg/L (4.8 micromol/L). This level is higher than many other zopiclone fatalities reported. We report a case where only zopiclone was detected.

Pharmacology Portal: An Open Database for Clinical Pharmacologic Laboratory Services

PURPOSE More than 50 Norwegian public and private laboratories provide one or more analyses for therapeutic drug monitoring or testing for drugs of abuse. Practices differ among laboratories, and analytical repertoires can change rapidly as new substances become available for analysis. METHODS The Pharmacology Portal was developed to provide an overview of these activities and to standardize the practices and terminology among laboratories. The Pharmacology Portal is a modern dynamic web database comprising all available analyses within therapeutic drug monitoring and testing for drugs of abuse in Norway. Content can be retrieved by using the search engine or by scrolling through substance lists. The core content is a substance registry updated by a national editorial board of experts within the field of clinical pharmacology. This ensures quality and consistency regarding substance terminologies and classification. FINDINGS All laboratories publish their own repertoires in a user-friendly workflow, adding laboratory-specific details to the core information in the substance registry. The user management system ensures that laboratories are restricted from editing content in the database core or in repertoires within other laboratory subpages. The portal is for nonprofit use, and has been fully funded by the Norwegian Medical Association, the Norwegian Society of Clinical Pharmacology, and the 8 largest pharmacologic institutions in Norway. IMPLICATIONS The database server runs an open-source content management system that ensures flexibility with respect to further development projects, including the potential expansion of the Pharmacology Portal to other countries.