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Etazene (or etodesnitazene) is a novel and highly active synthetic opioid belonging to the rapidly evolving and emerging group of "nitazenes." Etazene metabolites were identified through analysis of a human urine sample. The sample was obtained from a 25-year-old man who attempted suicide by taking a new psychoactive substances (NPS) cocktail purchased online and was analyzed by ultrahigh performance liquid chromatography-high-resolution mass spectrometry (UHPLC-HRMS). Etazene metabolites were predicted with BioTransformer 3.0, and the exact masses were added to the inclusion list. Eight possible metabolites were identified in the urine sample. N- and O-deethylation were identified as the predominant metabolism routes, resulting in M1 (O-deethylated etazene; most abundant metabolite based on the peak area), M2 (N-deethylated etazene), and M3 (N,O-dideethylated etazene) metabolites. Less abundant hydroxylated products of these deethylated metabolites and etazene were also found. Additionally, in the analysis without β-glucuronidase treatment, M1- and M3-glucuronide phase II metabolites were found. As N- and O-deethylated products seem to be the predominant urinary metabolites, the detection of these metabolites in urine can be useful to demonstrate etazene exposure., (© 2022 John Wiley & Sons Ltd.)

Background: Beta-lactam antimicrobial concentrations are frequently suboptimal in critically ill patients. Population pharmacokinetic (PopPK) modeling is the golden standard to predict drug concentrations. However, currently available PopPK models often lack predictive accuracy, making them less suited to guide dosing regimen adaptations. Furthermore, many currently developed models for clinical applications often lack uncertainty quantification. We, therefore, aimed to develop machine learning (ML) models for the prediction of piperacillin plasma concentrations while also providing uncertainty quantification with the aim of clinical practice., Methods: Blood samples for piperacillin analysis were prospectively collected from critically ill patients receiving continuous infusion of piperacillin/tazobactam. Interpretable ML models for the prediction of piperacillin concentrations were designed using CatBoost and Gaussian processes. Distribution-based Uncertainty Quantification was added to the CatBoost model using a proposed Quantile Ensemble method, useable for any model optimizing a quantile function. These models are subsequently evaluated using the distribution coverage error, a proposed interpretable uncertainty quantification calibration metric. Development and internal evaluation of the ML models were performed on the Ghent University Hospital database (752 piperacillin concentrations from 282 patients). Ensuing, ML models were compared with a published PopPK model on a database from the University Medical Centre of Groningen where a different dosing regimen is used (46 piperacillin concentrations from 15 patients.)., Results: The best performing model was the Catboost model with an RMSE and [Formula: see text] of 31.94-0.64 and 33.53-0.60 for internal evaluation with and without previous concentration. Furthermore, the results prove the added value of the proposed Quantile Ensemble model in providing clinically useful individualized uncertainty predictions and show the limits of homoscedastic methods like Gaussian Processes in clinical applications., Conclusions: Our results show that ML models can consistently estimate piperacillin concentrations with acceptable and high predictive accuracy when identical dosing regimens as in the training data are used while providing highly relevant uncertainty predictions. However, generalization capabilities to other dosing schemes are limited. Notwithstanding, incorporating ML models in therapeutic drug monitoring programs seems definitely promising and the current work provides a basis for validating the model in clinical practice., (© 2022. The Author(s).)

Objectives: In critically ill children, severely altered pharmacokinetics may result in subtherapeutic β-lactam antibiotic concentrations when standard pediatric dosing regimens are applied. However, it remains unclear how to recognize patients most at risk for suboptimal exposure and their outcome. This study aimed to: 1) describe target attainment for β-lactam antibiotics in critically ill children, 2) identify risk factors for suboptimal exposure, and 3) study the association between target nonattainment and clinical outcome., Design: Post hoc analysis of the "Antibiotic Dosing in Pediatric Intensive Care" study (NCT02456974, 2012-2019). Steady-state trough plasma concentrations were classified as therapeutic if greater than or equal to the minimum inhibitory concentration of the (suspected) pathogen. Factors associated with subtherapeutic concentrations and clinical outcome were identified by logistic regression analysis., Setting: The pediatric and cardiac surgery ICU of a Belgian tertiary-care hospital., Patients: One hundred fifty-seven patients (aged 1 mo to 15 yr) treated intravenously with amoxicillin-clavulanic acid, piperacillin-tazobactam, or meropenem., Interventions: None., Measurements and Main Results: Three hundred eighty-two trough concentrations were obtained from 157 patients (median age, 1.25 yr; interquartile range, 0.4-4.2 yr). Subtherapeutic concentrations were measured in 39 of 60 (65%), 43 of 48 (90%), and 35 of 49 (71%) of patients treated with amoxicillin-clavulanic acid, piperacillin-tazobactam, and meropenem, respectively. Estimates of glomerular filtration rate (eGFR; 54% increase in odds for each sd increase in value, 95% CI, 0.287-0.736; p = 0.001) and the absence of vasopressor treatment (2.8-fold greater odds, 95% CI, 1.079-7.253; p = 0.034) were independently associated with target nonattainment. We failed to identify an association between antibiotic concentrations and clinical failure., Conclusions: Subtherapeutic β-lactam concentrations are common in critically ill children and correlate with renal function. eGFR equations may be helpful in identifying patients who may require higher dosing. Future studies should focus on the impact of subtherapeutic concentrations on clinical outcome., Competing Interests: Dr. Van Der Heggen received funding from Clinical Research Fund Ghent University Hospital, Belgium. Dr. De Cock received funding from a Clinical Research fund. The remaining authors have disclosed that they do not have any potential conflicts of interest., (Copyright © 2022 by the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies.)

Objectives: Fast and reliable ethanol assays analysis are used in a clinical context for patients suspected of ethanol intoxication. Mostly, automated systems using an enzymatic reaction based on ethanol dehydrogenase are used. The manuscript focusses on the evaluation of the performance of these assays., Methods: Data included 30 serum samples used in the Belgian EQA scheme from 2019 to 2021 and concentrations ranged from 0.13 to 3.70 g/L. A regression line between target concentrations and reported values was calculated to evaluate outliers, bias, variability and measurement uncertainty., Results: A total of 1,611 results were taken into account. Bias was the highest for Alinity c over the whole concentration range and the lowest for Vitros for low concentrations and Cobas 8000 using the c702 module for high concentrations. The Architect and Cobas c501/c502 systems showed the lowest variability over the whole concentration range. Highest variability was observed for Cobas 8000 using the 702 module, Thermo Scientific and Alinity c. Cobas 8000 using the c702 module showed the highest measurement uncertainty for lower concentrations. For higher concentrations, Alinity c, Thermo Scientific and Vitros were the methods with the highest measurement uncertainty., Conclusions: The bias of the enzymatic techniques is nearly negligible for all methods except Alinity c. Variability differs strongly between measurement procedures. This study shows that the Alinity c has a worse measurement uncertainty than other systems for concentrations above 0.5 g/L. Overall, we found the differences in measurement uncertainty to be mainly influenced by the differences in variability., (© 2022 Walter de Gruyter GmbH, Berlin/Boston.)

N-Piperidinyl etonitazene ('etonitazepipne') represents a recent addition to the rapidly expanding class of 2-benzylbenzimidazole 'nitazene' opioids. Following its first identification in an online-sourced powder and in biological samples from a patient seeking help for detoxification, this report details its in-depth chemical analysis and pharmacological characterization. Analysis of the powder via different techniques (LC-HRMS, GC-MS, UHPLC-DAD, FT-IR) led to the unequivocal identification of N-piperidinyl etonitazene. Furthermore, we report the first activity-based detection and analytical identification of N-piperidinyl etonitazene in authentic samples. LC-HRMS analysis revealed concentrations of 1.21 ng/mL in serum and 0.51 ng/mL in urine, whereas molecular networking enabled the tentative identification of various (potentially active) urinary metabolites. In addition, we determined that the extent of opioid activity present in the patient's serum was equivalent to the in vitro opioid activity exerted by 2.5-10 ng/mL fentanyl or 10-25 ng/mL hydromorphone in serum. Radioligand binding assays in rat brain tissue revealed that the drug binds with high affinity (K i  = 14.3 nM) to the µ-opioid receptor (MOR). Using a MOR-β-arrestin2 activation assay, we found that N-piperidinyl etonitazene is highly potent (EC 50  = 2.49 nM) and efficacious (E max  = 183% versus hydromorphone) in vitro. Pharmacodynamic evaluation in male Sprague Dawley rats showed that N-piperidinyl etonitazene induces opioid-like antinociceptive, cataleptic, and thermic effects, its potency in the hot plate assay (ED 50  = 0.0205 mg/kg) being comparable to that of fentanyl (ED 50  = 0.0209 mg/kg), and > 190 times higher than that of morphine (ED 50  = 3.940 mg/kg). Taken together, our findings indicate that N-piperidinyl etonitazene is a potent opioid with the potential to cause harm in users., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objectives: Fluoropyrimidines such as 5-Fluorouracil (5-FU), capecitabine and tegafur are drugs that are often used in the treatment of maliginancies. The enzyme dihydropyrimidine dehydrogenase (DPD) is the first and rate limiting enzyme of 5-FU catabolism. Genetic variations within the DPYD gene (encoding for DPD protein) can lead to reduced or absent DPD activity. Treatment of DPD deficient patients with fluoropyrimidines can result in severe and, rarely, fatal toxicity. Screening for DPD deficiency should be implemented in practice., Methods: The available methods in routine to screen for DPD deficiency were analyzed and discussed in several group meetings involving members of the oncological, genetic and toxicological societies in Belgium: targeted genotyping based on the detection of 4 DPYD variants and phenotyping, through the measurement of uracil and dihydrouracil/uracil ratio in plasma samples., Results: The main advantage of targeted genotyping is the existence of prospectively validated genotype-based dosing guidelines. The main limitations of this approach are the relatively low sensitivity to detect total and partial DPD deficiency and the fact that this approach has only been validated in Caucasians so far. Phenotyping has a better sensitivity to detect total and partial DPD deficiency when performed in the correct analytical conditions and is not dependent on the ethnic origin of the patient., Conclusion: In Belgium, we recommend phenotype or targeted genotype testing for DPD deficiency before starting 5-FU, capecitabine or tegafur. We strongly suggest a stepwise approach using phenotype testing upfront because of the higher sensitivity and the lower cost to society.

Background: Therapeutic drug monitoring (TDM) of busulfan is recommended for hematopoietic stem cell transplant recipients. Timely reporting of these TDM results is essential given the short administration period and the planned dose adjustments on day 2. The authors evaluated the performance of a new nanoparticle-based competitive immunoassay on two routine clinical chemistry analyzers and compared its performance to that of an in-house high-resolution mass spectrometry (HRMS) method., Methods: The MyCare Oncology Busulfan Assay Kit (Saladax Biomedical) was applied on two routine clinical chemistry analyzers (Abbott Architect c8000 and Roche Cobas c502) with a linearity range of 187-2000 ng/mL. The study evaluation measured imprecision and accuracy, sample probe carry-over, and dilution integrity. Method comparison with liquid chromatography (LC)-HRMS was performed using samples from patients undergoing busulfan treatment., Results: Within- and between-run coefficient of variations for both analyzers were ≤5.23% and ≤8.45%, respectively, across the busulfan concentration range. The obtained biases were ≤10.3%. Both analyzers met the acceptance criteria for sample probe carry-over and dilution integrity. Agreement between the immunoassay and LC-HRMS was high: 92% and 89% of the samples measured on Architect and Cobas, respectively, were within the ±15% limit compared to the corresponding LC-HRMS results., Conclusions: Overall, good analytical performance and high agreement with LC-HRMS results were obtained for the immunoassay installed on both routine clinical chemistry analyzers. Therefore, this assay could be implemented as a valid alternative for LC methods in clinical laboratories on different open-channel clinical chemistry analyzers, resulting in shorter turn-around times for reporting busulfan TDM results with subsequent faster dosage adjustments., Competing Interests: The authors declare no conflict of interest., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Background: There is a trend towards decentralisation of laboratory tests by means of Point-of-Care testing (POCT). Within hospitals, Belgian law requires a POCT policy, coordinated by the clinical laboratory. There is however no legal framework for POCT performed outside the hospital: no reimbursement, no compulsory quality monitoring and no limits nor control on the prices charged to the patient. Uncontrolled use of POCT can have negative consequences for individual and public health., Proposal: We propose that POCT outside hospitals would only be reimbursed for tests carried out within a legal framework, requiring evidence-based testing and collaboration with a clinical laboratory, because clinical laboratories have procedures for test validation and quality monitoring, are equipped for electronic data transfer, are familiar with logistical processes, can provide support when technical issues arise and can organise and certify training. Under these conditions the government investment will be offset by health benefits, e.g. fall in antibiotic consumption with POCT for CRP in primary care, quick response to SARS-CoV2-positive cases in COVID-19 triage centres., Priorities: 1° extension of the Belgian decree on certification of clinical laboratories to decentralised tests in primary care; 2° introduction of a separate reimbursement category for POCT; 3° introduction of reimbursement for a limited number of specified POCT; 4° setup of a Multidisciplinary POCT Advisory Council, the purpose of which is to draw up a model for reimbursement of POCT, to select tests eligible for reimbursement and to make proposals to the National Institute for Health and Disability Insurance ( RIZIV/INAMI ).

Therapeutic drug monitoring (TDM) of tyrosine kinase inhibitors (TKIs) is not yet performed routinely in the standard care of oncology patients, although it offers a high potential to improve treatment outcome and minimize toxicity. TKIs are perfect candidates for TDM as they show a relatively small therapeutic window, a wide inter-patient variability in pharmacokinetics and a correlation between drug concentration and effect. Moreover, most of the available TKIs are susceptible to various drug-drug interactions and medication adherence can be checked by performing TDM. Plasma, obtained via traditional venous blood sampling, is the standard matrix for TDM of TKIs. However, the use of plasma poses some challenges related to sampling and stability. The use of dried blood microsamples can overcome these limitations. Collection of samples via finger-prick is minimally invasive and considered convenient and simple, enabling sampling by the patients themselves in their home-setting. The collection of small sample volumes is especially relevant for use in pediatric populations or in pharmacokinetic studies. Additionally, working with dried matrices improves compound stability, resulting in convenient and cost-effective transport and storage of the samples. In this review we focus on the different dried blood microsample-based methods that were used for the quantification of TKIs. Despite the many advantages associated with dried blood microsampling, quantitative analyses are also associated with some specific difficulties. Different methodological aspects of microsampling-based methods are discussed and applied to TDM of TKIs. We focus on sample preparation, analytics, internal standards, dilution of samples, external quality controls, dried blood spot specific validation parameters, stability and blood-to-plasma conversion methods. The various impacts of deviating hematocrit values on quantitative results are discussed in a separate section as this is a key issue and undoubtedly the most widely discussed issue in the analysis of dried blood microsamples. Lastly, the applicability and feasibility of performing TDM using microsamples in a real-life home-sampling context is discussed., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Verougstraete, Stove, Verstraete and Stove.)

Background: Therapeutic drug monitoring (TDM) of β-lactam antibiotics may be used to optimize dosing for patients in the intensive care unit (ICU). A noninvasive matrix such as oral fluid may be interesting in selected patient groups. We compared the oral fluid concentrations of piperacillin and meropenem with the respective unbound and total concentrations in plasma. A secondary objective was to evaluate feasibility of the collection of oral fluid samples in this specific patient population., Methods: The study included 20 non-intubated ICU patients, age 22 to 77 y, receiving piperacillin or meropenem via continuous intravenous infusion. The standard protocol consisted of collecting a paired plasma-oral fluid sample for 3 consecutive days. Oral fluid was obtained from the patients using a standardized procedure by spitting in a plastic container after 2 min of gathering oral fluid in the mouth., Results: Antibiotic concentrations of piperacillin and meropenem are measurable, albeit very low, in unstimulated oral fluid of ICU patients. For piperacillin, a poor correlation was found between oral fluid and both total and unbound plasma concentrations (Spearman's correlation coefficients (Rs) 0.46 and 0.48 respectively). For meropenem this correlation was better (Rs for oral fluid versus total and unbound plasma meropenem concentration 0.92 and 0.93 respectively). Dispersion of antibiotic concentrations was greater in oral fluid than in blood. Collecting oral fluid samples was difficult in non-intubated ICU patients., Conclusions: Oral fluid from non-intubated ICU patients, obtained through a standardized procedure, cannot be recommended as an alternative matrix for quantitative meropenem or piperacillin TDM., (Copyright © 2021. Published by Elsevier B.V.)

Beta-lactam antibiotics are of vital importance for the treatment of infections in a broad range of patients. Although most systemically administered antibiotics will be excreted renally, a fraction will reach the gastro-intestinal tract, affecting the intestinal microbiome by eradicating a wide range of bacterial species while facilitating the growth of antimicrobial-resistant species. A better understanding of the kinetics of beta-lactam antibiotics in the gastro-intestinal tract is essential to study their role in the development of antibiotic resistance in bacteria and to help develop future therapies to prevent damage to, or restore, the intestinal microbiome. Analysis of beta-lactam antibiotics in faeces is particularly challenging due to the heterogeneous nature of the matrix, rapid degradation of some beta-lactam antibiotics in faeces and very strong ion suppression when using mass spectrometry. Sample preparation was optimized using a sequential strategy of experimental designs. It resulted in lyophilization, a MOPS buffer system and the addition of the beta-lactamase inhibitor avibactam to minimize degradation of antibiotics allowing sensitive quantification. The developed liquid chromatography method with high-resolution mass spectrometric detection was successfully validated according to bioanalytical EMA guidelines and had a linear range of 1-200 μg g -1 lyophilized faeces for amoxicillin, piperacillin and meropenem; and 0.5-100 μg g -1 lyophilized faeces for tazobactam. Despite the highly complex and heterogeneous composition of faeces, the accuracy (0.1-15%) and precision (1.7-12.1%) were in line with those obtained for quantification methods of beta-lactam antibiotics in plasma, the golden standard matrix for therapeutic drug monitoring. The applicability of the method was illustrated by successful quantification of piperacillin and tazobactam in faeces from an intensive care unit patient receiving piperacillin/tazobactam in a continuous intravenous infusion. Both piperacillin and tazobactam were still present six days after discontinuation of the therapy., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

An ultra-high pressure liquid chromatography high-resolution mass spectrometric (UHPLC-HRMS) method was developed for the simultaneous and sensitive quantification of 10 β-lactam antibiotics (cefepime, meropenem, amoxicillin, cefazolin, benzylpenicillin, ceftazidime, piperacillin, flucloxacillin, cefuroxime and aztreonam), linezolid and β-lactamase inhibitors tazobactam and clavulanic acid in human plasma. Validation according to the EMA guidelines showed excellent within- and between-run accuracy and precision (i.e. between 1.1 and 8.5%) and high sensitivity (i.e. lower limit of quantification between 0.25 and 1 mg/L). The UHPLC-HRMS method enables a short turnaround time and high sensitivity and needs only a small amount of plasma, allowing appropriate routine therapeutic drug monitoring. The short turnaround time is obtained by speeding up the protocol on multiple levels, i.e. fast and workload-efficient sample preparation (i.e. protein precipitation and dilution), short (4 min) instrument run time, simultaneous measurement of all relevant β-lactam antibiotics used in the intensive care unit and the use of the same instrument, column and mobile phases as for the other routine methods in our laboratory., (© 2021 John Wiley & Sons, Ltd.)

Therapeutic drug monitoring (TDM) of tyrosine kinase inhibitors (TKIs) in cancer therapy offers the potential to improve treatment efficacy while minimizing toxicity. Therefore, a high-throughput, sensitive LC-MS/MS method was developed and validated, to be used for personalized treatment of hematologic malignancies. The assay allows the simultaneous quantification in plasma (EDTA and heparin) and whole blood of eight TKIs, including bosutinib, dasatinib, gilteritinib, ibrutinib, imatinib, midostaurin, nilotinib and ponatinib, which are used in the treatment of chronic and acute myeloid leukemia (CML, AML) and chronic lymphocytic leukemia (CLL). The procedure involves simple protein precipitation of 50 μL of sample, a 4-min chromatographic separation by applying gradient elution on a standard reverse phase column, and tandem mass spectrometric detection. The method was successfully validated based on international guidelines in terms of calibration curves, precision (within-run CV 0.74-16.4%; between-run CV 1.65-17.8%), accuracy (within-run bias 0.07-19.8%; between-run bias 0.05 to -17.6%), carry-over (max 19.4%, for ponatinib), selectivity, matrix-effects, recovery (ranging from 61 to 128%), stability (only issues observed for ibrutinib) and dilution integrity. Furthermore, the accuracy of the method was demonstrated by analyzing external quality controls, with a maximum bias of -11.3%. Assay applicability was demonstrated by analyzing authentic plasma and whole blood samples in order to derive blood-plasma ratios and the variation thereof. The latter are important to allow possible blood-plasma conversion when envisaging possible future implementation of TDM via dried blood microsampling. The presented method can be applied in clinical practice for performing TDM of TKIs in plasma and whole blood samples., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Objective: One third of epilepsy patients do not become seizure-free using conventional medication. Therefore, there is a need for alternative treatments. Preclinical research using designer receptors exclusively activated by designer drugs (DREADDs) has demonstrated initial success in suppressing epileptic activity. Here, we evaluated whether long-term chemogenetic seizure suppression could be obtained in the intraperitoneal kainic acid rat model of temporal lobe epilepsy, when DREADDs were selectively expressed in excitatory hippocampal neurons., Methods: Epileptic male Sprague Dawley rats received unilateral hippocampal injections of adeno-associated viral vector encoding the inhibitory DREADD hM4D(Gi), preceded by a cell-specific promotor targeting excitatory neurons. The effect of clozapine-mediated DREADD activation on dentate gyrus evoked potentials and spontaneous electrographic seizures was evaluated. Animals were systemically treated with single (.1 mg/kg/24 h) or repeated (.1 mg/kg/6 h) injections of clozapine. In addition, long-term continuous release of clozapine and olanzapine (2.8 mg/kg/7 days) using implantable minipumps was evaluated. All treatments were administered during the chronic epileptic phase and between 1.5 and 13.5 months after viral transduction., Results: In the DREADD group, dentate gyrus evoked potentials were inhibited after clozapine treatment. Only in DREADD-expressing animals, clozapine reduced seizure frequency during the first 6 h postinjection. When administered repeatedly, seizures were suppressed during the entire day. Long-term treatment with clozapine and olanzapine both resulted in significant seizure-suppressing effects for multiple days. Histological analysis revealed DREADD expression in both hippocampi and some cortical regions. However, lesions were also detected at the site of vector injection., Significance: This study shows that inhibition of the hippocampus using chemogenetics results in potent seizure-suppressing effects in the intraperitoneal kainic acid rat model, even 1 year after viral transduction. Despite a need for further optimization, chemogenetic neuromodulation represents a promising treatment prospect for temporal lobe epilepsy., (© 2021 International League Against Epilepsy.)

New psychoactive substances continue to appear on the drug market. Until recently, new synthetic opioids, which are among the most dangerous new psychoactive substances, primarily encompassed analogs of the potent analgesic fentanyl. Lately, also other new synthetic opioids have increasingly started to surface. This is the first report on the identification and full chemical characterization of brorphine, a novel potent synthetic opioid with a piperidine benzimidazolone structure. A powder, identified as brorphine, was obtained from a patient seeking medical help for detoxification. Brorphine was also found in a serum sample of the patient. Liquid chromatography-high-resolution mass spectrometry (LC-HRMS) identified an exact mass of m/z 400.1020 and 402.1005 for the compound, corresponding to both bromine isotopes. Further chemical characterization was performed by gas chromatography-mass spectrometry, liquid chromatography-diode array detection and Fourier-transform infrared spectroscopy analyses. Finally, the structure was confirmed by performing 1H-NMR and 13C-NMR spectroscopy. In vitro biological activity of brorphine was determined by a cell-based µ-opioid receptor activation assay, resulting in an EC50 of 30.9 nM (13.5 ng/mL) and an Emax of 209% relative to hydromorphone, confirming the high potency and efficacy of this compound. In a serum sample of the patient, brorphine and a hydroxy-metabolite were found using the LC-HRMS screening method. The presence of opioid activity in the serum was also confirmed via the activity-based opioid screening assay. The occurrence of brorphine is yet another example of how the illicit drug market is continuously evolving in an attempt to escape international legislation. Its high potency poses a serious and imminent health threat for any user., (© The Author(s) 2020. Published by Oxford University Press on behalf of Society of Forensic Toxicologists, Inc. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Metal-on-metal (MoM) prostheses, in which the bearing surfaces are made of a metal alloy, may release metal ions upon wear and corrosion, potentially inducing both local and systemic toxicity. As the systemic cobalt concentration increases with the degree of implant wear, this concentration needs to be monitored as a means of assessing implant function and the risk of adverse effects. Here, we report on the development, validation and application of a method to quantitatively assess these Co concentrations in whole blood, based on the combination of volumetric absorptive microsampling (VAMS) and inductively coupled plasma - mass spectrometry (ICP-MS). This method could allow patients to collect the required samples at home, as VAMS samples are easy to collect and can be transported to the laboratory via regular mail. The extraction procedure utilized an alkaline extraction mixture with yttrium as internal standard and proved to be independent of the hematocrit and age of the VAMS samples. The Co concentrations in the VAMS extracts were measured using quadrupole-based ICP-MS. The analytical method covers a range of 2-300 μg/L and displays excellent accuracy (bias ≤4%) and imprecision (relative standard deviation ≤ 5% and ≤15% at the lower limit of quantitation (LLOQ)). The method was applied to venous VAMS samples of MoM prosthesis patients (n = 78), yielding promising results. The comparison of these results with those obtained on the corresponding liquid whole blood samples, showed a correlation coefficient of 0.99 and 87% of the data fulfilled the criteria proposed by the Royal College of Pathologists of Australasia (RCPA)., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Purpose: Increased renal elimination is the leading cause for subtherapeutic concentrations of renally cleared antibiotics and it has been hypothesized that brain damaged patients in the intensive care unit (ICU) are particularly at risk. The objective of this study is to determine the prevalence of subtherapeutic piperacillin concentrations in neurocritical patients and to investigate if having a neurocritical diagnosis is a risk factor for this., Materials and Methods: Single center retrospective analysis of a prospective cohort study of adult ICU patients receiving continuous infusion piperacillin/tazobactam. Patients were categorized as either having a neurocritical diagnosis or not. An unbound piperacillin concentration > 4× the epidemiologic cut-off value (ECOFF) of Pseudomonas aeruginosa was selected as the PKPD target of choice. Multivariable logistic regression was performed to identify risk factors for subtherapeutic piperacillin concentrations., Results: 356 patients had a measured creatinine clearance (mCrCl) and matched piperacillin concentration, 52 of which had a neurocritical diagnosis. Subtherapeutic piperacillin concentrations were reported significantly more frequent in neurocritical patients. In multivariate analysis, the only risk factor identified for subtherapeutic piperacillin concentration was an increasing mCrCl., Conclusion: Subtherapeutic piperacillin concentrations are common in neurocritical patients yet having a neurocritical admission diagnosis was not identified as an independent risk factor., (Copyright © 2019. Published by Elsevier Inc.)

The study aimed to evaluate saturation of piperacillin elimination in critically ill adult patients. Seventeen critically ill adult patients received continuous and intermittent infusion of piperacillin/tazobactam. Piperacillin plasma concentrations (n = 217) were analysed using population pharmacokinetic (PopPK) modelling. Post-hoc simulations were performed to evaluate the type I error rate associated with the study. Unseen data were used to validate the final model. The mean error (ME) and root mean square error (RMSE) were calculated as a measure of bias and imprecision, respectively. A PopPK model with parallel linear and non-linear elimination best fitted the data. The median and 95% confidence interval (CI) for the model parameters drug clearance (CL), volume of central compartment (V), volume of peripheral compartment (V p ) and intercompartmental clearance (Q) were 9 (7.69-11) L/h, 6.18 (4.93-11.2) L, 11.17 (7.26-12) L and 15.61 (12.66-23.8) L/h, respectively. The Michaelis-Menten constant (K m ) and the maximum elimination rate for Michaelis-Menten elimination (V max ) were estimated without population variability in the model to avoid overfitting and inflation of the type I error rate. The population estimates for K m and V max were 37.09 mg/L and 353.57 mg/h, respectively. The bias (ME) was -20.8 (95% CI -26.2 to -15.4) mg/L, whilst imprecision (RMSE) was 49.2 (95% CI 41.2-56) mg/L. In conclusion, piperacillin elimination is (partially) saturable. Moreover, the population estimate for K m lies within the therapeutic window and therefore saturation of elimination should be accounted for when defining optimum dosing regimens for piperacillin in critically ill patients., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Introduction: Psychoactive medicines, such as benzodiazepines and Z-drugs (BdZ), antidepressants and antipsychotics (AA) and medical opioids (MO), have an impairing effect on driving ability. In previous epidemiological studies performed on impaired and/or injured drivers, not all relevant psychoactive substances were included in the toxicological assessment, and their prevalence may be underestimated. This study aims to assess the prevalence of a large set of psychoactive substances (n=53) in Italian drivers involved in a road traffic crash and in predefined population subgroups., Materials and Methods: The toxicological analyses were performed on the whole blood of 1026 drivers involved in a road traffic crash in the area of Bologna, Italy, from January 2017 to March 2018. Analyses were performed using GC-FID (alcohol), GCMS (illicit drugs) and LC/HRMS (psychoactive drugs). The population was divided into subgroups according to gender, age and crash time. Descriptive statistics were used in order to assess differences among sub-groups., Results: The highest prevalence was found for alcohol (17.3%), followed by medicinal drugs (13.6%) and illicit drugs (5.5%). The prevalence of BdZ, AA and MO were 7.3%, 7.2% and 3.1%, respectively. The frequency of BDZ and AA was significantly higher in female drivers and showed higher prevalence at increasing age. The presence of medicinal drugs was significantly higher during the week and in crashes occurring during the day., Conclusion: Results for alcohol and illicit drugs partially overlap with those reported in previous European and Italian studies, but the prevalence of BdZ was much higher. We also found a high prevalence of AA, which are rarely investigated in epidemiological studies performed on drivers, but may cause impairment of the ability to drive, especially when taken in combination with alcohol or other drugs. The pattern of medication use differs from that involving drugs of abuse, since it is mainly observed in female subjects and older drivers and does not follow the same weekly trend observed for alcohol and other illicit drugs., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Purpose: To evaluate target attainment of empirically dosed continuous infusion piperacillin/tazobactam (TZP) and meropenem (MER) in critically ill patients., Patients and Methods: Patients were sampled on a daily basis. TZP or MER concentrations were evaluated during the first two days antibiotic therapy. The lower limit of the target range was defined as unbound concentrations equaling 4 times the epidemiological cutoff value of P. aeruginosa. The upper limit of the target range was based on the risk of toxicity, i.e. unbound concentrations >160 mg/L for TZP and > 45 mg/L for MER. Multivariable logistic regression was used to evaluate factors associated with target attainment., Results: Data from 253 patients were analyzed. Overall, 76/205 (37.1%) and 36/48 (75%) of the patients receiving TZP or MER respectively, attained target concentrations. In multivariable analysis, estimated creatinine clearance was identified as a risk factor for target non-attainment (OR 0.988, 95%CI [0.982;0.994]). Patients receiving MER were more likely to attain target concentrations compared with patients receiving TZP (OR 6.02, 95%CI [2.12;18.4])., Conclusion: Target attainment of empiric antibiotic therapy in critically ill patients was low (37%) for TZP and moderate (75%) for MER, despite the use of a loading dose and despite optimization of the mode of infusion., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: Piperacillin is considered a moderately protein-bound antibiotic (20%-40%), with albumin being an important binding protein. Although infrequently used in practice, different methods to measure the fraction unbound (fu) are available, but uncertainty remains as to what the most appropriate method is. The main goal of this study was to estimate the impact of the methodology used to measure unbound piperacillin in plasma on the fu of piperacillin; we compared ultrafiltration (UF) at 4°C and 37°C with the reference method, equilibrium dialysis. In addition, we analyzed the impact of other proteins on the fu., Methods: Anonymized left-over Li-heparin plasma samples (n = 41) from 30 critically ill patients who were treated with piperacillin were used for the analyses., Results: We found that the piperacillin fu, determined by UF, is on average 8% higher at 37°C (91%) than at 4°C (83%). There were no systematic or proportional differences between UF at 4°C and equilibrium dialysis at 4°C. This emphasizes the importance of the temperature during UF, which should therefore be clearly stated in publications that report on the methodology of UF. No significant impact of the albumin-, IgA-, total protein-, or α1-acid glycoprotein concentration on the fu was found. The fu found in this study was higher than the generally assumed fu value of 60%-80%. A possible explanation lies in the studied population or in the temperature used. Based on our results, routine monitoring of unbound piperacillin in intensive care unit patients is not recommended., Conclusions: Based on the prediction model, we can state that in intensive care patients the fu of piperacillin is 91% (SD 7%), determined with UF at 37°C.

Purpose: Measurement of antibiotic concentrations is increasingly used to optimize antibiotic therapy. Plasma samples are typically used for this, but other matrices such as exhaled air could be an alternative., Materials and Methods: We studied 11 spontaneously breathing intensive care unit patients receiving either piperacillin/tazobactam or meropenem. Patients exhaled in the ExaBreath® device, from which the antibiotic was extracted. The presence of antibiotics was also determined in the condensate found in the device and in the plasma., Results: Piperacillin or meropenem could be detected in the filter in 9 patients and in the condensate in 10. Seven patients completed the procedure as prescribed. In these patients the median quantity of piperacillin in the filter was 3083 pg/filter (range 988-203,895 pg/filter), and 45 pg (range 6-126 pg) in the condensate; meropenem quantity was 21,168 pg/filter, but the quantity in the condensate was below the lower limit of quantification. There was no correlation between the concentrations in the plasma and quantities detected in the filter or condensate., Conclusions: Piperacillin and meropenem can be detected and quantified in exhaled air of non-ventilated intensive care unit patients; these quantities did not correlate with plasma concentrations of these drugs., (Copyright © 2019. Published by Elsevier Inc.)

Objectives: The antibiotic teicoplanin, used for the treatment of infections caused by Gram-positive bacteria, is highly bound to plasma proteins (percentage protein binding, %PB, around 90%) and therapeutic plasma levels of total teicoplanin are 10-100 mg/L. Because of the low free concentrations (i.e. <1-10 mg/L), current immunoassays are not able to quantify free teicoplanin concentrations, although they might be more relevant in therapeutic drug monitoring than total concentrations., Design and Methods: In this study, an ultra-high performance liquid chromatography - high resolution mass spectrometry (UHPLC-HRMS) method for the quantification of total and free teicoplanin in K 2 EDTA plasma samples was developed and validated. Furthermore, %PB obtained by ultrafiltration was compared with that obtained by equilibrium dialysis using spiked samples from healthy subjects. Analytes were separated using a phenylhexyl column, gradient mobile phase analysis was used, total run time was 4.5 min and teicoplanin was detected by orbitrap MS., Results: The precision and accuracy were below 15% and within ±15%, respectively and teicoplanin was found to be stable for at least 14 days in plasma at 4 °C. The %PB of teicoplanin in spiked plasma from healthy subjects as obtained by ultrafiltration (94.1 ± 1.3%) was in good agreement with that obtained by equilibrium dialysis (93.6 ± 0.4%), whereas mean %PB of teicoplanin in samples from infected patients who received the antibiotic was 87.7 ± 4.2% (range: 79.6-95.4%)., Conclusion: A novel highly sensitive UHPLC-HRMS method was developed and validated for the quantification of total and free teicoplanin in human K 2 EDTA plasma samples. Amongst others, this method is suitable for therapeutic drug monitoring., (Copyright © 2019 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Background: Several population pharmacokinetic (PopPK) models for meropenem dosing in ICU patients are available. It is not known to what extent these models can predict meropenem concentrations in an independent validation dataset when meropenem is infused continuously., Patients and Methods: A PopPK model was developed with concentration-time data collected from routine care of 21 ICU patients (38 samples) receiving continuous infusion meropenem. The predictability of this model and seven other published PopPK models was studied using an independent dataset that consisted of 47 ICU patients (161 samples) receiving continuous infusion meropenem. A statistical comparison of imprecision (mean square prediction error) and bias (mean prediction error) was conducted., Results: A one-compartment model with linear elimination and creatinine clearance as a covariate of clearance best described our data. The mean ± SD parameter estimate for CL was 9.89 ± 3.71 L/h. The estimated volume of distribution was 48.1 L. The different PopPK models showed a bias in predicting serum concentrations from the validation dataset that ranged from -8.76 to 7.06 mg/L. Imprecision ranged from 9.90 to 42.1 mg/L., Conclusions: Published PopPK models for meropenem vary considerably in their predictive performance when validated in an external dataset of ICU patients receiving continuous infusion meropenem. It is necessary to validate PopPK models in a target population before implementing them in a therapeutic drug monitoring program aimed at optimizing meropenem dosing.

The aim of this study is to assess the results of inspections in the last three years of drug abuse testing in medical laboratories according to the latest regulations in Turkey. The on-site inspections of medical laboratories for drugs abuse testing performed in Alcohol and Drug Addiction Treatment Centers during 2014-2016 are described, and laboratory processes and performance evaluated. The performance of 35 laboratories in 2014, 62 laboratories in 2015, and 94 laboratories in 2016 were scored as the sum of the scores for all answers on the inspection form. An inspected laboratory was considered to have an unconformity if the total score was less than 2/3 of maximum score. The total scores of inspections and the number of laboratories with between years were compared using one-way analysis of variance and slope Chi-square for trend test, respectively. Total scores increased statistically significantly from 35.9 ± 16.2 in 2014, to 43.5 ± 16.3 in 2015 and 49.1 ± 1.3 in 2016 (p < 0.001). The laboratories with unconformities decreased statistically significantly from 57% in 2014 to 37% in 2015 and 22% in 2016 (p < 0.001). The published legislation and the inspections contributed to national standardization and improved quality of service in medical laboratories for drug abuse testing., (© 2018 John Wiley & Sons, Ltd.)

Background: Harmonization of units is an important step to improve the comparability of clinical chemistry results, but few examples exist of successful harmonization efforts. We present the results of a pragmatic approach that was implemented in Belgium from 2012., Methods: After a large consultation and information of stakeholders, preferred units were proposed for 140 assays, including the 23 immunoassays discussed in more detail here. The change occurred in two phases, first involving assays for which there was no change in the numerical result, then changes involving a change in numerical results. Laboratories were invited to participate in this harmonization on a voluntary basis. The project was based on a bottom-up approach, large consultation and the pragmatic choice of the proposed units, including conventional and SI units., Results: The large heterogeneity of units was drastically reduced; adoption of the preferred units increased from 3% (insulin) - 45% (HCG) to 70% (insulin) - 96% (LH and FSH). Adoption of the preferred units was higher if it involved no change in numerical values (90%) than when there was a change (76%)., Conclusions: We believe that the harmonization effort has reached its goals. Without aiming at implementing SI units for all parameters, our strategy was successful with a large majority of the laboratories switching to the proposed units. Moreover, the harmonization program is still progressing, with additional laboratories converting to the consensus units.

Dosing recommendations for continuous infusion of piperacillin, a broad-spectrum beta-lactam antibiotic, are mainly guided by outputs from population pharmacokinetic models constructed with intermittent infusion data. However, the probability of target attainment in patients receiving piperacillin by continuous infusion may be overestimated when drug clearance estimates from population pharmacokinetic models based on intermittent infusion data are used, especially when higher doses (e.g. 16 g/24 h or more) are simulated. Therefore, the purpose of this study was to describe the population pharmacokinetics of piperacillin when infused continuously in critically ill patients. For this analysis, 270 plasma samples from 110 critically ill patients receiving piperacillin were available for population pharmacokinetic model building. A one-compartment model with linear clearance best described the concentration-time data. The mean ± standard deviation parameter estimates were 8.38 ± 9.91 L/h for drug clearance and 25.54 ± 3.65 L for volume of distribution. Creatinine clearance improved the model fit and was supported for inclusion as a covariate. In critically ill patients with renal clearance higher than 90 mL/min/1.73 m 2 , a high-dose continuous infusion of 24 g/24 h is insufficient to achieve adequate exposure (pharmacokinetic/pharmacodynamic target of 100% fT >4 x MIC ) against susceptible Pseudomonas aerginosa isolates (MIC ≤16 mg/L). These findings suggest that merely increasing the dose of piperacillin, even with continuous infusion, may not always result in adequate piperacillin exposure. This should be confirmed by evaluating piperacillin target attainment rates in critically ill patients exhibiting high renal clearance., (Copyright © 2017 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.)

Background: The precise monitoring of everolimus, an immunosuppressant drug, is vital for transplant recipients due to its narrow therapeutic range. This study evaluated the analytical performance of a new electrochemiluminescence immunoassay (ECLIA) for everolimus concentrations in whole blood., Methods: Accuracy, imprecision, and sensitivity studies for the Roche Elecsys everolimus ECLIA were performed at 5 European laboratories. The ECLIA was compared with liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods, as well as the Quantitative Microsphere System everolimus assay., Results: Everolimus ECLIA accuracies were within the range 100% ± 9%. Coefficients of variation (CVs) across the target range were ≤4.8% for repeatability and ≤8.4% for intermediate imprecision, whereas multisite reproducibility at lower (2.71 mcg/L) and higher everolimus concentrations (3.0-30.0 mcg/L) resulted in CVs of ≤13.7% and ≤12.4%, respectively. The CV at the assay's lower limit of quantification without considering bias was excellent, estimated as ≤9.3% at 0.5 mcg/L. The weighted Deming regression analysis, used for comparison of the results obtained by everolimus ECLIA and by LC-MS/MS methods, yielded a slope of 1.21 [95% confidence interval (CI): 1.15-1.26], intercept of 0.478 mcg/L (95% CI: 0.241-0.716), and a Pearson correlation coefficient (r) of 0.91. A single-site comparison between the ECLIA and the Quantitative Microsphere System assay revealed a slope of 1.05 (95% CI: 0.917-1.17), intercept of 1.03 mcg/L (95% CI: 0.351-1.70), and r of 0.91., Conclusions: Based on these results, the Roche Elecsys everolimus ECLIA can be considered suitable for routine therapeutic drug monitoring. A positive bias was observed with respect to LC-MS/MS methods, suggesting that it may be necessary to rebaseline individual patients when switching from LC-MS/MS to the ECLIA; however, this must also be considered for any change of method for everolimus measurement.

Objectives: Antibiotic therapy is of vital importance for the control of infectious exacerbations in cystic fibrosis (CF) patients. However, very little is known regarding the fraction of systemically administered antibiotics reaching the lower respiratory tract secretions. We developed and validated a method to measure the concentrations of piperacillin, ceftazidime, meropenem and aztreonam in CF sputum, and present the validation data., Methods: Ultra-performance LC coupled to tandem MS was used. A single sample can be measured in 2.5 min with multiple reaction monitoring in positive electrospray ionization mode. Deuterated internal standards were used and a concentration range of 0.7-160 mg/L was covered. The method was validated according to the EMA guideline on analytical method validation., Results: The boundaries within which a reliable measurement in CF sputum can be performed were determined. A few constraints are linked to the instability of the antibiotics in sputum. Piperacillin showed limited stability at room temperature and during freeze-thaw cycles. Autosampler instability was observed after 15 h for aztreonam at low concentrations., Conclusions: The method allows a reliable measurement of the selected antibiotics, if precautions are taken regarding the limited stability of piperacillin at room temperature. Due to freeze-thaw instability, piperacillin should always be analysed on the day of sampling. Quick review of the analytical data and reanalysis are needed as low concentrations of aztreonam are not stable in the autosampler., (© The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Objectives: To characterize the population pharmacokinetics of piperacillin and tazobactam in critically ill infants and children, in order to develop an evidence-based dosing regimen., Patients and Methods: This pharmacokinetic study enrolled patients admitted to the paediatric ICU for whom intravenous piperacillin/tazobactam (8:1 ratio) was indicated (75 mg/kg every 6 h based on piperacillin). Piperacillin/tazobactam concentrations were measured by an LC-MS/MS method. Pharmacokinetic data were analysed using non-linear mixed effects modelling., Results: Piperacillin and tazobactam blood samples were collected from 47 patients (median age 2.83 years; range 2 months to 15 years). Piperacillin and tazobactam disposition was best described by a two-compartment model that included allometric scaling and a maturation function to account for the effect of growth and age. Mean clearance estimates for piperacillin and tazobactam were 4.00 and 3.01 L/h for a child of 14 kg. Monte Carlo simulations showed that an intermittent infusion of 75 mg/kg (based on piperacillin) every 4 h over 2 h, 100 mg/kg every 4 h given over 1 h or a loading dose of 75 mg/kg followed by a continuous infusion of 300 mg/kg/24 h were the minimal requirements to achieve the therapeutic targets for piperacillin (60% f T >MIC >16 mg/L)., Conclusions: Standard intermittent dosing regimens do not ensure optimal piperacillin/tazobactam exposure in critically ill patients, thereby risking treatment failure. The use of a loading dose followed by a continuous infusion is recommended for treatment of severe infections in children >2 months of age., (© The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Background: Measurement of hair cortisol concentration (HCC) may be used as a biomarker for chronic stress. However, the association between stress and HCC has rarely been investigated in a working population., Aims: To explore associations between (i) HCC and various stress measures and (ii) HCC and symptoms of depression in Belgian workers., Methods: Hair samples were collected from workers in two production companies and cortisol content was determined by liquid chromatography tandem mass spectrometry. Participants completed a questionnaire including socio-demographics, health behaviours and standardized measures for assessing stress., Results: After excluding those workers suffering from a psychiatric or neuroendocrine disease and those treated with glucocorticoids, there were a total of 102 workers with both questionnaire, cortisol results and anthropometric measures. Median HCC was 5.73 pg/mg hair (interquartile range = 4.52-9.06). No significant associations were found between cortisol and the standardized measures related to several work psychosocial risk factors. A significantly lower mean HCC was found in shift workers compared with dayworkers, adjusted for age. Additionally, a significant higher mean HCC was found in workers with symptoms of depression compared with those without symptoms of depression, after adjustment for age., Conclusions: HCC showed a limited applicability as a biomarker for job stress in this sample, although the results suggest this method may be a suitable marker for detecting early symptoms of depression. Further research is needed to investigate the applicability of HCC in the working environment and within job stress research., (© The Author 2016. Published by Oxford University Press on behalf of the Society of Occupational Medicine. All rights reserved. For Permissions, please email: journals.permissions@oup.com)

Objectives: Δ(9)-Tetrahydrocannabinol (THC) can be measured in exhaled breath by using an aerosol particle collection device. The sampling procedure is simple, non-invasive and takes only 2-3min. In the present study we measured the amount of THC in exhaled breath of cannabis users at specific time intervals up to 3h after smoking one cannabis cigarette., Design and Methods: The breath concentration-effect relationship was studied by measuring the pulse rate and the pupil diameter to assess physiological changes. THC and the main metabolite 11-nor-9-carboxy-Δ(9)-tetrahydrocannabinol were analyzed in exhaled breath by a liquid chromatography-tandem mass spectrometry method. Thirteen subjects (9 males and 4 females, aged 23-24years) participated. Five of those were using cannabis more frequently than monthly., Results: THC was detected in most subjects already at baseline, concentrations increased following smoking and remained detectable for over 3h (mean THC concentration in breath at 3h: 1479pg/sample). Pulse rate (p=0.015) and pupil diameter (p=0.044) were significantly altered up to 30min after smoking. The detection window of cannabis in breath after smoking one cannabis cigarette in occasional and chronic smokers was at least 3h. Only THC was detected, and not the metabolite. The THC concentration in exhaled breath was related to the physiological changes that occur over time., Conclusions: Exhaled breath can be used to detect recent cannabis exposure., (Copyright © 2016 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

For many drugs, there is a poor correlation between the plasma and oral fluid (OF) concentrations, due to differences in OF pH, oral contamination, stimulation of OF flow and variability of the volume of sample taken. The aim of this study was to evaluate the OF/plasma ratio and variability in drug concentration in OF sampled by two commercially available collection systems: Saliva Collection System (SCS) and Quantisal. Blood and OF samples were collected from 12 volunteers after intake of 19.5 mg codeine phosphate. Six persons were sampled by SCS first, followed by Quantisal; six other participants used Quantisal before SCS. The OF content of SCS tubes was measured spectrophotometrically. The Quantisal devices were weighed to correct for the effectively obtained OF volume. Codeine was measured by gas chromatography-mass spectrometry. The mean codeine concentration at 1 h was 29.8 ± 18.8 μg/L in plasma, 72.8 ± 63.9 μg/L in SCS OF and 85.3 ± 72.6 μg/L in Quantisal OF. The mean OF/plasma ratio was 2.30 ± 0.77 (SCS) and 2.69 ± 1.94 (Quantisal). Pearson's correlation coefficient between OF and plasma codeine concentrations was statistically significantly (P = 0.005) higher for SCS (R(2) = 0.745) than for Quantisal (R(2) = 0.403). The variability in ratios with Quantisal was markedly reduced when used after SCS. Codeine concentrations measured in OF taken with SCS correlate better with plasma concentrations than in OF obtained with Quantisal, particularly when Quantisal was used first., (© The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Background: The aim of this study was to compare the usefulness of 3 different screening instruments (questionnaires) for the detection of cannabis use (CU) with biological markers in blood and hair., Methods: Ninety-four students were recruited in October 2013. Participants filled out the Severity of Dependence Scale (SDS), the CAGE-AID ("Cut down Annoyed Guilty Eye-opener"-Adapted to Include Drugs), and ProbCannabis-DT questionnaires concerning their possible CU. Blood and hair samples were taken and analyzed by gas chromatography-mass spectrometry. Logistic regression (Nagelkerke R(2)) and receiver operating characteristic (ROC) curve analyses were performed. THCCOOH (Δ(9)-tetrahydrocannabinoic acid) plasma of ≥5 ng/mL and THC (Δ(9)-tetrahydrocannabinol) hair concentrations of ≥0.1 and ≥0.02 ng/mg were used as the gold standard for CU. The questionnaire results were compared with different concentration ranges for THCCOOH in plasma (<5, 5-75, and >75 ng/mL, indicating the intensity of use) and THC in hair (≥0.02 ng/mg, ≥0.1 ng/mg)., Results: The Nagelkerke R(2) for comparing the SDS, CAGE-AID, and ProbCannabis-DT with THCCOOH in plasma was 0.350, 0.489, and 0.335, respectively. The area under the ROC curve (95% confidence interval) was 0.772 (0.662-0.882), 0.797 (0.710-0.884), and 0.769 (0.669-0.870), respectively. Corresponding sensitivity/specificity were 70%/84%, 100%/59%, and 87%/67%, respectively. These values were similar to those compared to a 0.02 ng/mg THC cutoff in hair., Conclusions: Moderate agreement was found between all questionnaires and biomarkers of CU. The CAGE-AID and probCannabis-DT questionnaires were very sensitive, but less specific. SDS was less sensitive, but more specific.

A very rare case of acetylsulfapyridine nephrolithiasis is presented in a 54-year-old female patient who had been prescribed sulfasalazine (6 x 500 mg/day) because of psoriatic arthritis for the last 9 years. The patient's renal function was only slightly impaired. Reflectance infrared spectroscopy and gas chromatography-mass spectrometry allowed the identification of the chemical nature of the stone. As acetylsulfapyridine is a metabolite of sulfasalazine, administration of the latter drug was the cause of the nephrolithiasis.

There is little data available to guide amoxicillin-clavulanic acid dosing in critically ill children. The primary objective of this study was to investigate the pharmacokinetics of both compounds in this pediatric subpopulation. Patients admitted to the pediatric intensive care unit (ICU) in whom intravenous amoxicillin-clavulanic acid was indicated (25 to 35 mg/kg of body weight every 6 h) were enrolled. Population pharmacokinetic analysis was conducted, and the clinical outcome was documented. A total of 325 and 151 blood samples were collected from 50 patients (median age, 2.58 years; age range, 1 month to 15 years) treated with amoxicillin and clavulanic acid, respectively. A three-compartment model for amoxicillin and a two-compartment model for clavulanic acid best described the data, in which allometric weight scaling and maturation functions were added a priori to scale for size and age. In addition, plasma cystatin C and concomitant treatment with vasopressors were identified to have a significant influence on amoxicillin clearance. The typical population values of clearance for amoxicillin and clavulanic acid were 17.97 liters/h/70 kg and 12.20 liters/h/70 kg, respectively. In 32% of the treated patients, amoxicillin-clavulanic acid therapy was stopped prematurely due to clinical failure, and the patient was switched to broader-spectrum antibiotic treatment. Monte Carlo simulations demonstrated that four-hourly dosing of 25 mg/kg was required to achieve the therapeutic target for both amoxicillin and clavulanic acid. For patients with augmented renal function, a 1-h infusion was preferable to bolus dosing. Current published dosing regimens result in subtherapeutic concentrations in the early period of sepsis due to augmented renal clearance, which risks clinical failure in critically ill children, and therefore need to be updated. (This study has been registered at Clinicaltrials.gov as an observational study [NCT02456974].)., (Copyright © 2015, American Society for Microbiology. All Rights Reserved.)

Aim: To assess whether analysis of oral fluid can be used to identify individual drivers with drug concentrations in blood above 25ng/mL for amphetamine and methamphetamine, 10ng/mL for cocaine and 1.0ng/mL for tetrahydrocannabinol (THC), which are the cut-off concentrations used in the European DRUID Project, by calculating the diagnostic accuracies when using the analytical cut-off concentrations in oral fluid as well as for the optimal cut-off concentrations., Methods: Paired samples of whole blood and oral fluid collected with the Statsure SalivaSampler were obtained from 4080 drivers in four European countries and analysed for amphetamine, methamphetamine, cocaine and THC using GC-MS or LC-MS. The vast majority (89%) were random drivers not suspected of drug-impaired driving. Receiver-Operating Characteristic analysis was used to evaluate the analytical results., Results: The prevalence of drug findings above the cut-off concentrations in blood was 1.3% for amphetamine, 1.0% for methamphetamine, 0.6% for cocaine and 1.3% for THC. The cut-off concentrations in oral fluid that gave the highest diagnostic accuracy were for amphetamine 130ng/mL (accuracy 99.8%), methamphetamine 280ng/mL (accuracy 99.9%), cocaine 570ng/mL (accuracy 99.6%), and THC 38ng/mL (accuracy 98.3%). The proportion of false positives were 0.2%, 0.1%, 0.1% and 0.9%; and the proportion of false negatives were 0.1%, 0.0%, 0.3% and 0.8%, respectively, when using those cut-offs. The positive predictive values were 87.9%, 92.9%, 84.6% and 35.7% for amphetamine, methamphetamine, cocaine and THC, respectively., Conclusions: Analysis of concentrations of illicit drugs in oral fluid could not be used to accurately identify drivers with drugs concentrations above the selected cut-offs in blood in a cohort of drivers with low prevalence of drugs., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)