Cleo L. Crunelle

Hair ethyl glucuronide levels as a marker for alcohol use and abuse: A review of the current state of the art

BACKGROUND Ethyl glucuronide (EtG) is a minor alcohol metabolite that has been proposed as a stable marker in hair to detect and quantify alcohol consumption over long time periods. METHODS We provide an outline of currently available techniques for EtG hair sample analysis and highlight the pitfalls related to data interpretation. The literature of EtG analysis has been reviewed from January 1980 up to August 2013. In addition, we present an overview of the clinical and forensic studies which have used EtG quantification in hair as a marker for alcohol consumption/abstinence and we provide suggestions for future research. RESULTS EtG is a stable marker in hair that can be used to detect and quantify alcohol consumption over long time periods. This alcohol metabolite remains in hair after complete elimination of alcohol. Currently, there are three main analytical techniques used to quantify EtG in hair: gas chromatography-mass spectrometry (GC-MS), gas chromatography-tandem mass spectrometry (GC-MS/MS), and liquid chromatography-tandem mass spectrometry (LC-MS/MS). No standardized protocols are yet available for the analysis of EtG levels in hair samples, and the current protocols vary in sample preparation and extraction procedures. Variables such as hair length, cosmetic treatment, gender, and pathophysiological conditions influence the final results and should be taken into account. CONCLUSIONS EtG quantification in hair is a useful tool for the objective detection of alcohol consumption over extended time periods, but care should be taken when interpreting the results.

Hair ethyl glucuronide as a biomarker of alcohol consumption in alcohol-dependent patients: Role of gender differences

BACKGROUND Ethyl glucuronide (EtG) is a minor alcohol metabolite that accumulates in hair and is proposed as a stable marker for the detection of chronic and excessive alcohol consumption above a cut-off level of 30pg/mg hair. A correlation between drinking behavior and EtG hair concentrations is observed, but large variability exists. AIMS To investigate the correlation between alcohol consumption and hair EtG concentrations in alcohol dependent patients, and the effect of gender differences as a factor for the variability on this correlation. METHODS EtG was measured by gas chromatography coupled to mass spectrometry in the hairs (first 3cm) of 36 alcohol dependent patients (25 males/11 females) starting and alcohol detoxification program. Factors that possibly influence EtG content in hair (except age and gender) were excluded. Detailed retrospective alcohol consumption was obtained over the last 3 months using the Timeline Follow Back interview. RESULTS Median total alcohol consumption over 3 months was 13,050g pure alcohol (range 60-650g/day). Hair EtG concentrations varied between 32 and 662pg/mg. There was a statistically significant linear and positive correlation between hair EtG and amounts of alcohol consumed (Pearson r=0.83; p<0.001), in both males (Pearson r=0.83; p<0.001) and females (Pearson r=0.76; p=0.007). CONCLUSIONS There is a linear correlation, with no significant effect of gender, between hair EtG concentrations and amounts of alcohol consumed in alcohol-dependent individuals. Analysis of EtG in hair can be applied to estimate retrospective alcohol consumption in both male and female alcohol dependent subjects using the same cut-off.

Advances in detection of antipsychotics in biological matrices

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

Nail analysis for the detection of drugs of abuse and pharmaceuticals: a review

Nails can stably accumulate substances for long periods of time, thus providing retrospective information regarding drugs of abuse and pharmaceutical use. Nails have several advantages over the conventional matrices, such as blood and urine, including a longer detection window (months to years), non-invasive sample collection, and easy storage and transport. These aspects make nails a very interesting matrix for forensic and clinical toxicology. Because of the low concentrations of drugs of abuse and pharmaceuticals present in nails and the complexity of the keratinized matrix, analytical methods need to be more sensitive, and sample preparation is crucial. This review summarizes the literature regarding the detection and quantification of drugs of abuse and pharmaceuticals in nails, as well as the employed pre-analytical and analytical techniques. Additionally, the applications of nail analysis are reviewed. Finally, an overview of the challenges of nail analysis is provided, and guidelines for future research are proposed.

Influence of repeated permanent coloring and bleaching on ethyl glucuronide concentrations in hair from alcohol-dependent patients.

BACKGROUND Ethyl glucuronide (EtG), a minor metabolite of alcohol, is used as a sensitive marker in hair to detect the retrospective consumption of alcohol. The proximal 0-3 cm hair segment is often used for analysis, providing information on alcohol consumption over the past 3 months. Using more distal segments would allow the detection of alcohol consumption over longer time periods, thereby addressing the chronicity of the consumption. In view of this, permanent coloring and bleaching were shown in vitro to alter EtG concentrations in hair, but no in vivo studies are available to prove or disprove this. AIMS To investigate the influence of repeated bleaching and permanent coloring on EtG concentrations in vivo and to assess the stability of EtG concentrations in distal compared to proximal hair segments. METHODS Hair samples from alcohol-dependent patients with uncolored/unbleached (N=4), permanent coloration (N=5) and bleached hair (N=5) were analyzed in two to six 3 cm long segments for EtG concentrations, and alcohol consumption and hair cosmetic treatments were assessed. RESULTS We observed that hair bleaching and permanent coloring reduces EtG concentrations by 82±11% and 65±24%, respectively, with correlations between the number of cosmetic treatments and the decrease in EtG concentrations. EtG remained stable in untreated hair samples up to 18 cm. CONCLUSIONS EtG is a sensitive marker to assess chronic alcohol consumption up to 18 months in alcohol-dependent patients with no cosmetic hair treatments. However, in alcohol-dependent patients who color or bleach their hair, care should be taken when interpreting EtG measurements.

Gas chromatographic determination of ethyl glucuronide in hair: Comparison between tandem mass spectrometry and single quadrupole mass spectrometry

Ethyl glucuronide (EtG), a minor metabolite of ethanol, accumulates in hair and is currently used as a long-term marker for the detection of chronic and excessive alcohol consumption. Sensitive methods are required to differentiate teetotalers from moderate drinkers according to the established cut-off (i.e., 7 pg/mg hair). The aim of this study was to develop a sensitive method using gas chromatography coupled to tandem mass spectrometry (GC-MS/MS) operated in the negative ion chemical ionization (NICI) mode. The validated method was applied to hair samples from teetotalers, moderate and excessive alcohol consumers, and results were compared to a previously validated GC-NICI-MS method. The developed GC-NICI-MS/MS method showed linearity over a range from 2 to 400 pg/mg hair, with a limit of detection (LOD) of 0.05 pg/mg hair and a lower limit of quantification (LLOQ) of 0.2 pg/mg hair, compared to an LOD of 0.5 pg/mg hair and LLOQ of 1.5 pg/mg hair obtained with GC-NICI-MS. Furthermore, lower background noise was observed using GC-NICI-MS/MS. Comparison of results of hair samples (n=58) obtained by GC-NICI-MS and GC-NICI-MS/MS showed no significant difference between both methods (paired-sample t-test, p>0.05; mean CV=1.0%). The differences between both methods were larger for EtG concentrations<30 mg/pg hair (mean CV=1.7%) than for EtG concentrations>30 mg/pg hair (mean CV=0.7%). This suggests a higher selectivity of GC-NICI-MS/MS at lower concentrations. In conclusion, by using GC-NICI-MS/MS, a higher analytical selectivity and an improved signal to noise ratio, can be achieved. Although GC-NICI-MS would not change the interpretation of the EtG concentrations, the present GC-NICI-MS/MS method should preferentially be used for the determination of EtG in hair, especially when differentiating between teetotalers and moderate drinkers according to the current cut-off (i.e., 7 pg/mg hair).

Relationship between trait impulsivity and cortical volume, thickness and surface area in male cocaine users and non-drug using controls

BACKGROUND Trait impulsivity is commonly associated with cocaine dependence. The few studies that have investigated the relation between trait impulsivity and cortical morphometry, have shown a distinct relation between impulsivity and cortical volume (CV) of temporal, frontal and insula cortex. As CV is the function of cortical surface area (SA) and cortical thickness (CT) impulsivity may be differently associated to SA than to CT. METHOD Fifty-three cocaine users (CU) and thirty-five controls (HC) (males aged 18-55 years) completed the Barrat impulsiveness scale and a structural scan was made on a 3T MRI scanner. CV, SA and CT were measured using Freesurfer. Multivariate analysis was used to test for group differences and group by impulsivity interaction effects in CV, SA and ST across nine regions of interest in the temporal, frontal and insular cortices. Possible confounding effects of drug- and alcohol exposure were explored. RESULTS Compared to HC, CU had a smaller SA of the superior temporal cortex but a larger SA of the insula. There were divergent relations between trait impulsivity and SA of the superior temporal cortex and insula (positive in HC, negative in CU) and CT of the anterior cingulate cortex (negative in HC, positive in CU). Within CU, there was a negative association between monthly cocaine use and CT of the insula and superior temporal cortex. DISCUSSION The distinct relation between trait impulsivity and cortical morphometry in CU and HC might underlie inefficient control over behavior resulting in maladaptive impulsive behaviour such as cocaine abuse.

Kinetic modeling and long‐term test‐retest reproducibility of the mGluR5 PET tracer 18F‐FPEB in human brain

18F‐FPEB is a promising PET tracer for studying the metabotropic glutamate subtype 5 receptor (mGluR5) expression in neuropsychiatric disorders. To assess the potential of 18F‐FPEB for longitudinal mGluR5 evaluation in patient studies, we evaluated the long‐term test‐retest reproducibility using various kinetic models in the human brain. Nine healthy volunteers underwent consecutive scans separated by a 6‐month period. Dynamic PET was combined with arterial sampling and radiometabolite analysis. Total distribution volume (VT) and nondisplaceable binding potential (BPND) were derived from a two‐tissue compartment model without constraints (2TCM) and with constraining the K1/k2 ratio to the value of either cerebellum (2TCM‐CBL) or pons (2TCM‐PONS). The effect of fitting different functions to the tracer parent fractions and reducing scan duration were assessed. Regional absolute test‐retest variability (aTRV), coefficient of repeatability (CR) and intraclass correlation coefficient (ICC) were computed. The 2TCM‐CBL showed best fits. The mean 6‐month aTRV of VT ranged from 8 to 13% (CR < 25%) with ICC > 0.6 for all kinetic models. BPND from 2TCM‐CBL with a sigmoid fit for the parent fractions showed the best reproducibility, with aTRV ≤ 7% (CR < 16%) and ICC > 0.9 in most regions. Reducing the scan duration from 90 to 60 min did not affect reproducibility. These results demonstrate for the first time that 18F‐FPEB brain PET has good long‐term reproducibility, therefore validating its use to monitor mGluR5 expression in longitudinal clinical studies. We suggest a 2TCM‐CBL with fitting a sigmoid function to the parent fractions to be optimal for this tracer. Synapse, 2016.

Time resolved analysis of quetiapine and 7-OH-quetiapine in hair using LC/MS-MS.

Hair analysis is a powerful tool for retrospective drug analysis and has a wide application window. This article describes the simultaneous determination and quantification of the short-acting atypical antipsychotic drug quetiapine and its main metabolite 7-OH quetiapine in hair. A sensitive and accurate method for the determination of these two compounds was developed using high-performance liquid chromatography coupled to tandem mass spectrometry detection (LC-MS/MS). The method was applied to 10 real case samples. For five patients, a time resolved hair analysis was done. Results varied from 0.35 ng/mg to 10.21 ng/mg hair for quetiapine and from 0.02 ng/mg to 3.19 ng/mg hair for 7-OH-quetiapine.

Ethyl glucuronide in keratinous matrices as biomarker of alcohol use: A correlation study between hair and nails

To quantify alcohol use, objective, specific and sensitive long-term alcohol markers are necessary. Ethyl glucuronide (EtG), a direct metabolite of alcohol, accumulates in keratinous matrices such as hair and nails, and is a specific and sensitive long-term biomarker for the detection of chronic alcohol consumption. So far, research has primarily focused on the detection of EtG in hair, and studies on its measurement in nails are scarce. In this article, we assessed EtG concentrations in hair, finger- and toenails from the same individuals in order to evaluate the direct correlation between the matrices. To this end, a total amount of 45 hair, 41 fingernail, and 13 toenail samples were collected from patients treated for alcohol use disorders at two psychiatric centers in Belgium. Samples were analyzed by gas chromatography-tandem mass spectrometry. Hair EtG concentrations ranged from <LLOQ to 1149pg/mg (median=164pg/mg, IQR [42; 283]). Fingernail EtG concentrations ranged from <LLOQ to 4090pg/mg (median=250pg/mg, IQR [74; 645]). Toenail EtG concentrations ranged from 127 to 3792pg/mg (median=687pg/mg, IQR [379; 1370]). EtG levels in hair and nails were significantly and positively correlated (p-values<0.001, r=0.70 and r=0.62, respectively). Higher concentrations were present in finger- and toenails compared to hair, which might be attributed to the slower growth rate of nails, resulting in increased accumulation of EtG. Hence, nail analysis may be interesting when low concentrations of EtG are expected, e.g. to discriminate between teetotalers and social drinkers. In addition, the current study proposes preliminary cut-off values for EtG concentrations in fingernails: >123pg/mg for chronic excessive alcohol consumption, 59-123pg/mg for moderate alcohol consumption, and <59pg/mg for alcohol abstinence. In light of these results, nails may be a useful alternative to hair samples for monitoring of long-term alcohol consumption, e.g., in cases where hair is not available. Further studies are needed to establish cut-off values for EtG levels in nails.