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Biomedical subjects

G Skopp

Publications and source records attributed to G Skopp.

At least 19 recordsLinked to original sources
PubMed2004

Preanalytic aspects in postmortem toxicology.

The preanalytic phase has been recognized to have a substantial role for the quality and reliability of analytical results, which very much depend on the type and quality of specimens provided. There are several unique challenges to select and collect specimens for postmortem toxicology investigation. Postmortem specimens may be numerous, and sample quality may be quite variable. An overview is given on specimens routinely collected as well as on alternative specimens that may provide additional information on the route of administration, a long term or a recent use/exposure to a drug or poison. Autolytic and putrefactive changes limit the selection and utility of specimens. Some data from case reports as well as experimental investigations on drug degradation and/or formation during putrefaction are discussed. Diffusion processes as well as postmortem degradation or formation may influence ethanol concentration in autopsy specimens. Formalin fixation of specimens or embalmment of the corpse may cause considerable changes of initial drug levels. These changes are due to alterations of the biological matrix as well as to dilution of a sample, release or degradation of the drug or poison. Most important seems a conversion of desmethyl metabolites to the parent drug. Some general requirements for postmortem sampling are given based on references about specimen collection issues, for a harmonized protocol for sampling in suspected poisonings or drug-related deaths does not exist. The advantages and disadvantages of specimen preservation are shortly discussed. Storage stability is another important issue to be considered. Instability can either derive from physical, chemical or metabolic processes. The knowledge on degradation mechanisms may enable the forensic toxicologist to target the right substance, which may be a major break down product in the investigation of highly labile compounds. Although it is impossible to eliminate all interfering factors or influences occurring during the preanalytic phase, their consideration should facilitate the assessment of sample quality and the analytical result obtained from that sample.

Autolysis↗
PubMed2004

Absinthe: attention performance and mood under the influence of thujone.

OBJECTIVE: The aim of this study was to determine whether the impacts of absinthe on attention performance and mood were different from those experienced with beverages that contain only alcohol. The ingredient causing absinthe's toxicity is believed to be thujone. METHOD: A total of 25 healthy subjects participated in the study. An attention performance test and two questionnaires testing different mood dimensions were used. Three drinks with an identical amount of alcohol but with different amounts of thujone were offered. RESULTS: The results of the present study showed that the simultaneous administration of alcohol containing a high concentration of thujone had a negative effect on attention performance. Under this condition, the subjects tended to direct their attention to signals in the central field of attention and to neglect peripheral signals; the number of correct reactions decreased significantly in the peripheral field of attention, and reaction time and the number of "false alarm" reactions increased significantly. The effects were most prominent at the time of the first measurement. When the subjects were under the influence of alcohol or were administered both alcohol and a low thujone concentration, these effects were not observed. The assessment of mood state dimensions showed that the anxiolytic effect of alcohol was temporarily counteracted by a high thujone concentration. CONCLUSIONS: As they are apparently opposed to the effect of alcohol, the reactions observed here can be explained by the antagonistic effect of thujone on the gamma-aminobutyric acid receptor. Similar alterations were observed for the other mood state dimensions examined.

Absinthe↗
PubMed2003

The role of active metabolites in dihydrocodeine effects.

OBJECTIVE: The metabolism of dihydrocodeine to dihydromorphine, a high affinity mu-opioid receptor ligand in membrane homogenates, is catalyzed by CYP2D6. However, it is not clear whether an active CYP2D6 enzyme is required for opioid receptor-mediated effects in man after standard dihydrocodeine doses. METHODS: Whole cell opioid-receptor affinity and effects on cAMP accumulation of dihydrocodeine and its metabolites were determined in differentiated SH-SY5Y neuroblastoma cells. In a double-blind, 2-period, placebo-controlled randomized crossover pilot study the pharmacokinetics of dihydrocodeine (60 mg single dose) and its metabolites were examined in 5 phenotyped extensive (EMs) and 4 poor metabolizers (PMs) for CYP2D6, and pharmacodynamics were evaluated using a pain threshold model and dynamic pupillometry. RESULTS: Displacement binding and cAMP accumulation experiments showed clearly higher affinities (100- and 50-fold) and activities (180- and 250-fold) of dihydromorphine and dihydromorphine-6-glucuronide, respectively, whereas the other metabolites had similar or lower affinities and activities as compared to dihydrocodeine. The clinical study revealed no significant difference in plasma or urine pharmacokinetics between EMs and PMs for dihydrocodeine and its glucuronide. Dihydromorphine and its glucuronides were detectable in EMs only. A clear reduction of initial pupil diameters was observed up to 6 hours postdose in both PMs and EMs, with no obvious differences between CYP2D6 phenotypes. In the pain threshold model no effects were observed in either group. CONCLUSION: CYP2D6 phenotype has no major impact on opioid receptor-mediated effects of a single 60 mg dihydrocodeine dose, despite the essential role of CYP2D6 in formation of highly active metabolites.

Analgesics, Opioid↗
PubMed2002

Preliminary approach to elucidate the role of pigment as a binding site for drugs and chemicals in anagen hair: differential uptake of 3H-haloperidol by pigment-producing compared to non-pigment-producing cell lines.

A striking difference was observed for cellular-bound drug in HaCaT and Sk-Mel-1 cells for a fixed drug exposure time of 72 h and varying 3H-haloperidol concentrations in the culture media. Drug uptake was dependent on drug concentration and linearly correlated for both the non-pigment- and the pigment-producing cells which however was different in magnitude. In an additional investigation the time course of drug uptake during 3H-haloperidol exposure (400 pmol/ml; 28 days) revealed increasing drug concentrations in the Sk-Mel-1 population, whereas drug concentrations in the keratinocytes reached a plateau within a short time period. In contrast to the HaCaT cells no tendency to saturation was observed for the pigment-producing cell line. At the end of the experiments 3H-haloperidol concentrations in Sk-Mel-1 were found to be approximately tenfold higher than in HaCaT.

Binding Sites↗
PubMed2002

Preliminary approach to elucidate the role of pigment as a binding site for drugs and chemicals in anagen hairs: pigments as carriers for 3H-haloperidol in HaCaT/Sk-Mel-1 co-cultures.

In view of the melanin-binding characteristics of haloperidol and its differential uptake by pigment- and non-pigment-producing cells, a co-culture of HaCaT with Sk-Mel-1 cell lines was performed to investigate whether melanosomes act as carriers for drug molecules associated with the pigments. Initially, HaCaT and Sk-Mel-1 cells were separately cultivated in the presence of 3H-haloperidol (400 pmol/ml medium ) for 28 days followed by subsequent co-cultivation in the absence of 3H-haloperidol for 5 days. The transfer of pigments into the keratinocytes during co-culture was confirmed by transmission electron microscopy. After the co-culture experiments a striking increase (> or = 50%) of 3H-haloperidol was observed in the pigmented HaCaT cells compared to the unpigmented keratinocytes. The present study proved the role of pigments as carriers for melanin-associated drug molecules. The results supported the hypothesis that hair pigment might be a factor affecting the outcome of hair assays for particular categories of commonly used licit and illicit substances. The chosen cell lines and the developed co-culture system may represent suitable in vitro models to study differential drug uptake into cell populations present in the skin or in the growing hair follicle as well as to elucidate drug uptake due to melanocyte-keratinocyte interactions.

Binding Sites↗
PubMed2001

Saliva testing after single and chronic administration of dihydrocodeine.

In the present study, concentrations of dihydrocodeine and its metabolites in saliva and serum were compared after single low-dose and chronic high-dosage administration of the drug. In the first investigation, blood and saliva were collected periodically from six subjects after oral administration of 60 mg dihydrocodeine. In the second study, 20 subjects on oral dihydrocodeine maintenance provided single samples of blood and saliva simultaneously. Serum protein binding of salivary analytes and their recovery from the adsorbing material of the collection device as well as pH values of saliva samples were determined. The fluids were analyzed for dihydrocodeine and the major metabolites by high-performance liquid chromatography. In the single dose study dihydrocodeine was the only analyte found in saliva for up to 12-24 h post-dose. The half-life of dihydrocodeine in saliva was about twice that found in blood. The ratios of saliva/serum concentrations ranged from 1.2 to 17.0. After chronic high-dosage use, dihydrocodeine was the main salivary analyte and N-nordihydrocodeine was present in a few samples. Saliva/serum concentration ratios of dihydrocodeine were strongly dependent on the pH value of saliva and, to a lesser extent, on serum-protein binding. The saliva/serum ratios were more similar after chronic administration. The data suggest a passive diffusion process as the underlying mechanism for the transport of dihydrocodeine into saliva. After both single and chronic use, the presence of the drug in saliva can be used as evidence of recent substance administration.

Biotransformation↗
PubMed2001

Analysis of cocaine, benzoylecgonine, ecogonine methyl ester, and ecgonine by high-pressure liquid chromatography-API mass spectrometry and application to a short-term degradation study of cocaine in plasma.

A method for the determination of cocaine (COC), benzoylecgonine (BE), ecgonine methyl ester (EME), and ecgonine (ECG) in plasma by liquid chromatography-mass spectrometry (LC-MS-MS) was developed. The analytes were isolated from human plasma by subsequent solid-phase extraction and were separated on a Zorbax Eclipse XDB-C8 narrow-bore column using an ammonium acetate buffer/acetonitrile/methanol gradient. A Turbolonspray source was used for ionization. The analytes were characterized by their particular molecular ion and several fragments. Multiple reaction monitoring (MRM) was used for isolation and quantitation. The assay was rapid, highly sensitive, and reliable. The method was applied to monitor the in vitro degradation of cocaine in plasma. Fresh unpreserved and preserved (0.25% KF) plasma samples were spiked with 1,000 ng cocaine/mL. Aliquots of both series were stored at 4 degrees C and 20 degrees C and were analyzed at selected storage times of up to 15 days. In all samples, degradation of cocaine that was dependent on storage time and temperature and on sample preservation could be observed. The formation of BE did not occur to a significant extent (< 12%, referred to the initial concentration of COC), and its concentration was slightly higher in preserved compared with unpreserved plasma at both storage temperatures chosen. EME was formed in considerably higher amounts compared to BE. As already observed for COC, its formation and degradation were dependent on storage time, temperature, and preservation. EME is suggested to be the major source of ECG, which was detectable in all samples after 1-2 days of storage. Although the degradation of COC was shown to be highly dynamic in nature, the sum of all hydrolysis products of COC accounted for the initial COC concentration at any particular time of storage. Therefore, production of hitherto unknown degradation products of COC seems unlikely. Moreover, the common transformation product of BE and EME appeared to be stable, and ECG is suggested as a promising postcollection artifact.

Artifacts↗
PubMed2001

In vitro stability of cocaine in whole blood and plasma including ecgonine as a target analyte.

The in vitro stability of cocaine (COC) was monitored in fresh whole blood and plasma stabilized with potassium fluoride (0.25%) for as long as 15 days. The samples were stored at 4 degreesC, 20 degreesC and 40 degreesC. Additionally, fresh plasma samples containing either benzoylecgonine (BZE), ecgonine methyl ester (EME) or ecgonine (ECG) were stored at 4 degreesC and 20 degreesC. Data were established using subsequent solid-phase extraction procedures and high-performance liquid chromatography coupled to atmospheric pressure ionization mass spectrometry for isolation and quantitation of COC, BZE, EME, and ECG. COC, BZE, and EME concentrations decreased with increasing storage temperature and time after an apparent first-order reaction kinetic. Only ECG appeared to be stable at storage temperatures as high as 20 degreesC for the entire observation period. At 40 degreesC, the amount of ECG produced from hydrolysis of COC still totalled 80% of the initial COC concentration. Hydrolysis of COC to EME occurred more rapidly in plasma than in blood. The dynamic degradation profiles obtained were dependent on the storage temperature. The conversion of COC to BZE, EME, and ECG appeared to be stoichiometric at all time intervals at storage temperatures of 4 degreesC and 20 degreesC. The presence of any hydrolysis product of COC in blood or plasma constitutes confirmatory evidence of COC incorporation, and determination of ECG seems most promising even in samples stored under unfavorable conditions.

Chromatography, High Pressure Liquid↗
PubMed2000

Effect of the shampoo Ultra Clean on drug concentrations in human hair.

The influence of the special shampoo Ultra Clean (Zydot Unlimited, Tulsa, Oklahoma) on the results of hair analyses was investigated. Hair samples from persons (n = 14) with a known history of drug abuse were collected at autopsy. The hair samples were divided into separate strands which were analyzed both after washing with Ultra Clean and without treatment. Hair analyses were performed by methanol extraction under sonication, purification by solid phase extraction and GC/MS in SIM mode according to routine procedures for tetrahydrocannabinol (THC), cocaine, amphetamine, methylenedioxyamphetamine (MDA), methylenedioxymethamphetamine (MDMA), methylenedioxyethylamphetamine (MDE), heroin, 6-monoacetylmorphine (6-MAM), morphine, codeine, dihydrocodeine and methadone. All drugs originally present in the hair fibers were still detected after a single application of Ultra Clean. However, a slight decrease in drug concentrations could mostly be observed e.g. cocaine (n = 10) -5%, 6-MAM (n = 12) -9%, morphine (n = 12) -26%, THC (n = 4) -36%. The findings clearly demonstrated that drug substances had not been sufficiently removed from human hair by a single Ultra Clean treatment to drop their concentrations below the limit of detection of the analytical method applied.

Forensic Medicine↗
PubMed1999

The detection of dihydrocodeine and its main metabolites in cases of fatal overdose.

The levels of dihydrocodeine found in impaired individuals and in fatalities show a wide overlap in the ranges. Among other factors, the genetically controlled metabolism of dihydrocodeine should play an important role in dihydrocodeine toxicity. For the first time, the most important metabolites of dihydrocodeine were investigated in femoral blood from three fatal cases by simultaneous determination using HPLC and native fluorescence for detection. The amount of parent drug always exceeded dihydrocodeine-glucuronide formation and dihydromorphine concentrations ranged from 0.16-0.21 mg/L. The similar binding affinities of dihydromorphine and morphine to mu-opioid receptors suggest similar pharmacological effects and adverse reactions. The determination of the pharmacologically active metabolites should help to clarify the cause of death in fatal cases especially if a relatively low concentration of the parent drug is found.

Adult↗
PubMed1999

Perspiration versus saliva--basic aspects concerning their use in roadside drug testing.

Various aspects concerning the practical application and forensic interpretation of data obtained by saliva drug testing and drug monitoring from the skin surface are discussed. Basic information on the composition of saliva and skin secretions and their particular transport mechanisms, as far as known, are given. For drugs of abuse secretion into saliva is suggested to be by passive diffusion and to depend on lipid solubility, pKa, plasma protein binding and on the pH of saliva. Drug molecules from blood are considered to reach the skin surface by various routes such as by sweat and sebum as well as by inter- and/or transcellular diffusion. The role of the stratum corneum as a temporary drug reservoir exceeding positive drug findings in urine is outlined. Current data on opioids, cocaine metabolites, cannabinoids and amphetamines detected in saliva and on the skin surface are reviewed. Aspects of collection, processing and analysis of the samples for implementation in roadside testing are addressed. The requirement of test sensitivity covering the broad concentration ranges and the importance of test specificity bearing in mind that the parent drug is the main analyte present in those specimens is stressed. Theoretical and practical findings on frequently abused drugs are discussed with regard to the possibilities and limitations of drug monitoring from saliva and perspiration to support a suspicion of actual or recent drug administration.

Drug Monitoring↗
PubMed1999

The influence of the route of administration: a comparative study at steady state of oral sustained release morphine and morphine sulfate suppositories.

Steady state pharmacokinetics of morphine (M), morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) were investigated in 6 patients with intractable cancer pain administered orally with MST (Mundipharma, Limburg, Germany) and, subsequently, rectally with MSR to make a judgment whether orally administered morphine can be replaced by rectally administered morphine. The parent drug and glucuronide metabolites were measured simultaneously using high-performance liquid chromatography (HPLC) and native fluorescence detection. The mean morphine area under the curve (AUC) value (0-8 h) was smaller (434.3 +/- 170.2 nmolL(-1)h) in the oral administration than in the rectal administration (574.8 +/- 285.0 nmolL(-1)h) (p < 0.05). The rectal administration resulted in less production of M3G and M6G. There were no significant differences in the mean steady state concentrations (C(ss)) of morphine, M3G, and M6G between the oral and rectal administrations (p > 0.05). The median AUC ratio--M3G/M and M6G/M, 12.58 and 1.85--following MSR rectal administration was smaller than following MST oral administration in 6 patients (19.97 and 2.59; p < 0.05), whereas the median AUC ratio M3G/M6G in the rectal dosing was 6.24 (range 5.2-7.6) was almost the same as the median ratio M3G/M6G in the oral dosing was 6.49 (range 5.8-8.5; p > 0.1). Four of the 6 patients had a greater Cmax of M3G and M6G after oral administration than after rectal administration. The same 4 had lower fluctuation rates for morphine, M3G (p < 0.05), and M6G (p < 0.05) after rectal administration. Therefore, during chronic morphine treatment, it still seems difficult to decide whether oral administration can be replaced by rectal administration.

Administration, Oral↗
PubMed1999

Report on intrauterine drug exposure during second trimester of pregnancy in a heroin-associated death.

A 17-year-old girl was found dead in a public toilet with fresh needle puncture marks. She was 18-20 weeks pregnant with a male fetus. Drug screening of her blood and urine indicated recent heroin use. Chronic drug use was confirmed by hair analysis. Amniotic fluid as well as fetal and maternal tissues and body fluids were analyzed by GC/MS and HPLC. All the fetal specimens were investigated, and the following levels of drugs were found: 6-monoacetyl-morphine (blood: 152 ng/g; amniotic fluid: 128 ng/g; brain: 140 ng/g; lung: 110 ng/g; liver: 2 ng/g; kidney: 40 ng/g), morphine (blood: 1360 ng/g; amniotic fluid: 604 ng/g; brain: 710 ng/g; lung: 1030 ng/g; liver: 2060 ng/g; kidney: 1100 ng/g), codeine (blood: 70 ng/g; brain: 60 ng/g; lung: 60 ng/g; liver: 90 ng/g; kidney: 70 ng/g), and morphine-3-glucuronide (amniotic fluid: 209 ng/g; brain: 170 ng/g; lung: 325 ng/g; kidney: 231 ng/g). Morphine-6-glucuronide was present in the maternal circulation but could not be detected in the fetal circulation.

Adolescent↗
PubMed1998

Postmortem distribution of dihydrocodeine and metabolites in a fatal case of dihydrocodeine intoxication.

A report of a fatal dihydrocodeine ingestion under substitution therapy is given. Quantitation of dihydrocodeine, dihydromorphine, N-nordihydrocodeine, dihydrocodeine-6-, dihydromorphine-6- and dihydromorphine-3-glucuronide was performed simultaneously after solid-phase extraction prior to HPLC analysis, and the analytes were detected using their native fluorescence. Postmortem concentrations of blood samples from different sampling sites as well as from liver, kidney and cerebrum are reported. A hair sample was investigated to prove long-term use of the substitute drug. Site-to-site differences of the analytes from blood samples were very small. The partition behavior of the opioid glucuronides depended on the hematocrit value of the particular blood sample. Most important findings seemed that dihydromorphine and dihydromorphine-6-glucuronide concentrations decisively contributed to the toxicity of dihydrocodeine. This case report outlines that in dihydrocodeine related deaths the concentrations of the pharmacologically active metabolites should additionally be determined for reliable interpretation.

Adult↗
PubMed1998

A preliminary study on the stability of benzodiazepines in blood and plasma stored at 4 degrees C.

An approach to determine the stability of benzodiazepines and some of their metabolites (n = 13) by means of a routinely applied gas chromatographic method using electron capture detection was made in this preliminary study. Validation data of the method are given. Spiked blood and plasma samples were stored at 4 degrees C and analysed at selected times up to 240 days. The concentrations of all analytes had decreased to at least 60% of the original levels at the end of the observation period. A clear pattern of breakdown could not be established. The data obtained suggest that results from long-term stored samples should be interpreted cautiously. Further investigations concerning the stability of drugs in blood and plasma samples, additional methods of identification and determination as well as the establishment of optimal storage conditions seem necessary.

Benzodiazepines↗
PubMed1998

Hemoglobin diffusion across a venous wall: an experimental study.

The aim of this study was to investigate the permeation behavior of a large molecule through a venous wall; hemoglobin was chosen as a model substance. In vitro experiments were performed using a Chien-Valia diffusion chamber. Postmortem, hemolyzed, and fresh nonhemolyzed blood samples were investigated as permeants. Vein patches from vena cava inferior and vena jugularis interna were used as diffusion barriers. Applying this technique, extravasation of hemoglobin was detectable. The portion of hemoglobin molecules passing through the vascular wall depended on time, vein type, and graduation of hemolysis. The passage of hemoglobin across the wall of a large vein suggests intravascular changes in drug concentrations from postmortem blood samples not to be restricted on the unbound portion of the particular drug.

Diffusion↗
PubMed1998

Formation and clearance of active and inactive metabolites of opiates in humans.

The results of recent investigations of the analgesic and the nonanalgesic effects of opioid glucuronides are relevant to the research on drug abuse in forensic toxicology. As has been shown for heroin, knowledge of the state of distribution and elimination of active and inactive metabolites and glucuronides offers new possibilities in forensic interpretation of analytic results. Because of similar metabolic degradation, calculation of the time-dependent ratio of the concentration of morphine and its glucuronide metabolites in blood or serum allows a rough estimation of increased dosage and of time elapsed since the last application. Drug effects can be examined with respect to individual case histories, including overdose and survival time if the patient died. However, different methods of administration and the strong influence of different volumes or compartments of distribution of parent compounds and metabolites on concentrations in human body tissues require careful use of glucuronide concentration data. In Germany, dihydrocodeine (DHC) is prescribed as a heroin substitute, and relative overdoses are needed to be effective. DHC metabolism was studied in three patients who died from overdoses. All metabolites (dihydrocodeine-6-glucuronide [DHC6], nor-DHC [NDHC], dihydromorphine [DHM], nor-DHM [NDHM], and DHM-3- and 6-glucuronide [DHM3G, DHM6G]) were determined using HPLC and fluorescence detection. Concentrations of DHM (0.16 mg/L to 0.22 mg/L serum) were found. The DHM glucuronide ratios were similar to those of morphine. Receptor binding studies showed that the binding affinity of DHM to porcine mu-receptor was higher than that of morphine, and DHM6G's binding affinity was as high as that of morphine-6-glucuronide (M6G). Metabolites may play an important role in the effectiveness of DHC in substitution and toxicity. Because of enzyme polymorphism, the formation of DHC poses a risk for proper dosage in patients who are either poor or extensive metabolizers. The distribution of opioid glucuronides in cerebral spinal fluid in relation to transcellular transport in central nervous tissue is discussed with respect to the receptor binding of opiates and drug effect.

Analgesics, Opioid↗