Pharmacokinetic Variability and Target Attainment of Fluconazole in Critically Ill Patients.

Background: Fluconazole is one of the oldest antifungal drugs. Previous studies have raised concerns considering variability in exposure and inadequate target attainment in critically ill patients. The current study aims to define variability and target attainment for fluconazole exposure in a large group of critically ill patients. Methods: In this pharmacokinetic study, daily plasma trough samples and, if possible, 24 h urine samples were collected to determine fluconazole concentration. A minimum target trough concentration of 10-15 mg/L was selected, corresponding to a free area under the concentration-time curve above the minimum inhibitory concentration (fAUC/MIC) of at least 100 for an MIC of 4 mg/L. Covariates that significantly influenced fluconazole exposure were identified. Results: In total, 288 plasma samples from 43 patients, with a median age of 66 years, were included. The median fluconazole trough concentration was 22.9 mg/L. A notable component of the measured concentrations was below the target trough concentrations (13% <10 mg/L and 27% <15 mg/L). The intra- and intersubject variability were 28.3% and 50.5%, respectively. The main covariates determining fluconazole exposure were the administered dose (mg/kg), augmented renal clearance, and renal replacement therapy. Conclusions: Fluconazole trough concentrations are variable in critically ill patients and a considerable number of these concentrations was below the predefined target trough concentrations.

Validation of an UHPLC/DAD method for the determination of cannabinoids in seized materials: Analysis of 213 samples sold in Belgian CBD shops.

PURPOSE: Nowadays, (-)-cannabidiol (CBD) is gaining popularity for the treatment of various problems and can be found easily in many stores in Belgium. However, such product must comply with the law: if the total tetrahydrocannabinol (THC) content [(-)-Δ9-tetrahydrocannabinol + (-)-Δ9-tetrahydrocannabinolic acid A (THC-A)] is higher than 0.2%, it is considered as narcotic by the Belgian legislation. In this context, we have developed a method to quantify major cannabinoids (THC, THC-A, CBD, cannabidiolic acid, cannabigerolic acid, cannabigerol and cannabinol) in plant material. METHODS: After drying, a liquid-liquid extraction was performed on plant materials, followed by dilutions. Extracts were analyzed by ultra-high-performance liquid chromatography combined with a photodiode array detector. Mobile phases consisted of methanol and 0.1% formic acid in water applied in a 16-minute gradient mode. After validating the method, it was applied to 213 samples seized by the police in CBD shops. RESULTS: The method fulfilled the criteria in terms of specificity, calibration curve, precision, trueness and dosing range. Total THC content ranged from 0.14 to 1.17% (median 0.38%) with 110 samples exceeding the Belgian legal threshold of 0.2%. The amounts measured in the samples varied greatly, some were 6 times below the amount labelled on the packaging, others showed a concentration 4 times higher than stated on the package. Same strain also showed concentration differences from shop to shop. CONCLUSION: Our method was successfully validated and applied to samples seized in CBD shops. Half of the products exceeded the Belgian legal threshold. THC and CBD concentrations discrepancies showed that products sold in CBD shops are not pharmaceutical grade.

Site-, Technique-, and Time-Related Aspects of the Postmortem Redistribution of Diazepam, Methadone, Morphine, and their Metabolites: Interest of Popliteal Vein Blood Sampling.

Sampling site, technique, and time influence postmortem drug concentrations. In 57 cases, we studied drug concentration differences as follows: subclavian vein-dissection/clamping versus blind stick, femoral vein-dissection/clamping versus blind stick, right cardiac chamber, and popliteal vein-dissection and clamping only. Cases were distributed in group #1 (all cases with both techniques), group #2 (dissection/clamping), and group #3 (blind stick). Sampled drugs were diazepam, methadone, morphine, and their metabolites. To assess PMR, mean concentrations and ratios were calculated for each group. Time-dependent variations of blood concentrations and ratios were also assessed. Results indicate that site, method, and time may influence postmortem distribution interpretation in different ways. Popliteal blood seems less subject to PMR. In conclusion, our study is the first to evaluate concurrently three main aspects of PMR and confirms that the popliteal vein may represent a site that is more resistant to the changes seen as a result of PMR.

Postmortem Concentration and Redistribution of Diazepam, Methadone, and Morphine with Subclavian and Femoral Vein Dissection/Clamping.

Postmortem redistribution (PMR) concerns blood drug concentration variations after death, depending on many factors such as sampling site and technique. In our study, we focused on sampling method. 30 cases were sampled, each at cardiac, subclavian, femoral, and popliteal sites. Targeted substances were diazepam, methadone, and morphine. Blind stick and dissection/clamping techniques were concomitantly performed at subclavian and femoral sites. Subclavian and femoral concentrations were compared according to technique used. To assess the influence of sampling technique on PMR, central/peripheral ratios were calculated depending on sampling method. Results show that drug concentrations tend to be lower when drawn from a clamped subclavian or femoral vein whereas ratios including subclavian and/or femoral blood concentration are influenced according to the technique used. In conclusion, clamping a subclavian or femoral vessel before sampling tends to result in lower drug concentrations and may influence ratios, suggesting the importance of isolating vessels from thoraco-abdominal viscera.

Popliteal Vein Blood Sampling and the Postmortem Redistribution of Diazepam, Methadone, and Morphine.

Postmortem redistribution (PMR) refers to the site- and time-related blood drug concentration variations after death. We compared central blood (cardiac and subclavian) with peripheral blood (femoral and popliteal) concentrations of diazepam, methadone, and morphine. To our knowledge, popliteal blood has never been compared with other sites. Intracardiac blood (ICB), subclavian blood (SB), femoral blood (FB), and popliteal blood (PB) were sampled in 30 cases. To assess PMR, mean concentrations and ratios were compared. Influence of postmortem interval on mean ratios was also assessed. Results show that popliteal mean concentrations were lower than those for other sites for all three drugs, even lower than femoral blood; mean ratios suggested that the popliteal site was less subject to PMR, and estimated postmortem interval did not influence ratios except for diazepam and methadone FB/PB. In conclusion, our study is the first to explore the popliteal site and suggests that popliteal blood is less prone to postmortem redistribution.

Modelled target attainment after meropenem infusion in patients with severe nosocomial pneumonia: the PROMESSE study.

OBJECTIVES: The objective of this study was to propose an optimal treatment regimen of meropenem in critically ill patients with severe nosocomial pneumonia. PATIENTS AND METHODS: Among 55 patients in intensive care treated with 1 g of meropenem every 8 h for severe nosocomial pneumonia, 30 were assigned to intermittent infusion (II; over 0.5 h) and 25 to extended infusion (EI; over 3 h) groups. Based on plasma and epithelial lining fluid (ELF) concentrations determined at steady-state, pharmacokinetic modelling and Monte Carlo simulations were undertaken to assess the probability of attaining drug concentrations above the MIC for 40%-100% of the time between doses (%T > 1-fold and 4-fold MIC), for 1 or 2 g administered by either method. RESULTS: Penetration ratio, measured by the ELF/plasma ratio of AUCs, was statistically higher in the EI group than in the II group (mean ± SEM: 0.29 ± 0.030 versus 0.20 ± 0.033, P = 0.047). Considering a maximum susceptibility breakpoint of 2 mg/L, all dosages and modes of infusions achieved 40%-100% T > 1-fold MIC in plasma, but none did so in ELF, and only the 2 g dose over EI achieved 40%-100% T > 4-fold MIC in plasma. CONCLUSIONS: The optimum regimen to treat severe nosocomial pneumonia was 2 g of meropenem infused over 3 h every 8 h. This regimen achieved the highest pharmacodynamic targets both in plasma and in ELF.

Identification and structural elucidation of four cannabimimetic compounds (RCS-4, AM-2201, JWH-203 and JWH-210) in seized products.

Since 2008, herbal mixtures with synthetic cannabinoid compounds have been sold as incense throughout the world. Although these new drugs are labeled as not for human consumption, these products are smoked for their cannabis-like effects. This study reports the structural and spectral elucidation of four cannabimimetic compounds seized in Belgium: (4-methoxyphenyl)-1-(pentyl-1H-indol-3-yl)methanone (RCS-4), 1-(5-fluoropentyl)-3-(1-naphtoyl)indole (AM-2201), 2-(2-chlorophenyl)-1-(1-pentylindol-3-yl)ethanone (JWH-203) and 4-ethylnaphthalen-1-yl-(1-pentylindol-3-yl)methanone (JWH-210). Laboratory investigations were conducted by liquid chromatography (LC)-ultraviolet spectroscopy, high-resolution accurate mass detection and nuclear magnetic resonance (NMR) analysis. This combined analytical approach allowed the detection of illicit compounds for which reference materials were not available. To facilitate identification and to complete existing databases, ultraviolet spectra and NMR data of all seized products are presented. Additionally, LC-quadrupole time-of-flight data were recorded to provide absolute identification.

Ultra-performance liquid chromatography- tandem mass spectrometry method for the determination of bupropion and its main metabolites in human whole blood.

A selective and sensitive ultra-performance liquid chromatography (UPLC)-electrospray ionization-tandem mass spectrometry (MS) method for simultaneous determination of bupropion and its main metabolites, hydroxybupropion, erythrohydrobupropion, and threohydrobupropion, in human whole blood is presented. The sample preparation consists of cleanup protein precipitation with methanol combined with a solid-phase extraction on Oasis HLB cartridges. Analytes were separated on a Waters Acquity UPLC((R)) BEH phenyl column using a binary mobile phase consisting of ammonium formate buffer (2 mM, pH 4) and acetonitrile. Detection was performed on a Waters Acquity UPLC system coupled to a Quattro Premier triple-quadrupole MS in positive ion selected reaction monitoring. Internal standards were bupropion-d(9) and hydroxybupropion-d(6). Linearity was from 5 to 1000 ng/mL for bupropion and from 10 to 2000 ng/mL for metabolites. Accuracy profiles (80-120%), precision (< 15%), and limits of detection (1 ng/mL for bupropion and 2 ng/mL for metabolites) were also evaluated and responded to all criteria of validation. The aim of this study was to compare this presented method with a previously described method developed on a classic liquid chromatography-tandem MS system.

Combined pharmacokinetic and urodynamic study of the effects of oral administration of phenylpropanolamine in female Beagle dogs.

This study investigated the differences in pharmacokinetic, urodynamic and haemodynamic parameters after administration of two dosages of phenylpropanolamine (PPA) in female Beagle dogs. Blood was collected and urethral pressure profiles were performed over 24 h periods following single or three times daily (T(0),T(6h),T(12h)) administration of PPA. The maximal concentration (C(max)) was reached 2 h after PPA administration (T(max)) and the half-life (T((1/2))) was 4 h. Three times daily administration induced an increase in C(max) due to bioaccumulation. A significant increase in urethral resistance, compared to the control group, was observed at T(max) after 1 week of once daily administrations, but not when PPA was administered every 6 h during the day, despite higher plasma concentrations following more frequent dosing. An increase in mean arterial pressure was compensated by a decreased heart rate. Clinical efficacy with the temporary increase in urethral resistance following single daily administration of PPA in dogs suffering from urethral sphincter mechanism incompetence (USMI) needs to be further investigated in a randomised clinical trial.

Fatal intoxications by acenocoumarol, phenprocoumon and warfarin: method validation in blood using the total error approach.

A simple high-performance liquid chromatography (HPLC) method with ultraviolet (UV) detection has been developed and validated for simultaneous identification and quantification of three antivitamin K drugs (acenocoumarol, warfarin and phenprocoumon) in whole blood. The aim of this development was to propose an analytical technique adapted to the situations of forensic toxicology, i.e. intoxication with massive anticoagulant doses, when the usual coagulation tests could not be used. The blood sample, after spiked with prazepam as an internal standard (IS), was submitted to a liquid-liquid extraction (LLE) prior to HPLC analysis. A chromatographic separation was achieved on a C8 Symmetry column with a mobile phase consisting of an acetonitrile and phosphate buffer (pH 3.8) mixture in a gradient mode. Detection was carried out at a wavelength between 200 and 400 nm. This method has been validated with the concept of total error as decision criterion. Trueness ranged from 99.1% to 105.0% and precision was good with RSD between 1.3% and 6.7%. Consequently, this rapid and simple chromatographic technique is well adapted to focus intoxications with most important coumarinic drugs available on pharmaceutical market and is now routinely used in our laboratory for forensic "general unknown" screening.

Skin protection creams in medical settings: successful or evil?

BACKGROUND: Chronic exposure to mild irritants including cleansing and antiseptic products used for hand hygiene generates insults to the skin. To avoid unpleasant reactions, skin protection creams are commonly employed, but some fail to afford protection against a variety of xenobiotics. In this study, two skin protection creams were assayed comparatively looking for a protective effect if any against a liquid soap and an alcohol-based gel designed for hand hygiene in medical settings. METHODS: Corneosurfametry and corneoxenometry are two in vitro bioessays which were selected for their good reproducibility, sensitivity and ease of use. A Kruskal-Wallis ANOVA test followed by the Dunn test was realized to compare series of data obtained. RESULTS: Significant differences in efficacy were obtained between the two assayed skin protection creams. One of the two tested creams showed a real protective effect against mild irritants, but the other tested cream presented an irritant potential in its application with mild irritants. CONCLUSION: The differences observed for the two tested skin protection creams were probably due to their galenic composition and their possible interactions with the offending products. As a result, the present in vitro bioassays showed contrasted effects of the creams corresponding to either a protective or an irritant effect on human stratum corneum.

A fatal case of bupropion (Zyban) overdose.

A sensitive and reproducible method for the identification and the quantitative determination of bupropion (BUP) and its major metabolites, hydroxybupropion (OH-BUP) and threohydrobupropion (T-BUP), was developed in blood and urine. The three compounds were extracted with a solid-phase extraction procedure followed by LC-ESI-MS-MS separation and quantification using decadeuterated lidocaine as internal standard. BUP and its metabolites were satisfactorily identified by multiple reactions monitoring detection. The limits of detection and quantification were determined at 5 and 10 microg/L, respectively, for each analyte. The intraday and interday coefficients of variability were lower than 11.9% for BUP and its metabolites. This method was applied to the forensic case of a 35-year-old male who died after a suspected ingestion of 30 slow-release tablets of Zyban. As samplings were performed at least 72 h after the drug intake, BUP had disappeared from blood, but OH-BUP and T-BUP were present at the concentrations of 5.8 and 30.4 mg/L, respectively. In urine, concentrations ranged from 42.9 mg/L for BUP to 617 mg/L for T-BUP. These results agree with the hypothesis of a successful suicide attempt.

Simultaneous determination of five beta-lactam antibiotics (cefepim, ceftazidim, cefuroxim, meropenem and piperacillin) in human plasma by high-performance liquid chromatography with ultraviolet detection.

Monitoring of plasma antibiotic drugs is useful for better clinical management in infected patients, particularly in intensive care units. A simple and sensitive high-performance liquid chromatography (HPLC) method with ultraviolet (UV) detection has been developed and validated for simultaneous quantification of five beta-lactam antibiotics in human plasma: cefepim, ceftazidim, cefuroxim, meropenem and piperacillin. The plasma sample, after spiked with ceforanid as an internal standard (IS), was submitted to a solid-phase extraction (SPE) prior to HPLC analysis. A chromatographic separation was achieved on a C8 symmetry column with a mobile phase consisting of an acetonitrile and phosphate buffer (pH 7.4) mixture in a gradient mode. Detection was carried out at a wavelength between 200 and 400 nm. The method developed was linear over the concentration range of 2.5-60 microg/mL for each antibiotic in the plasma samples. Accuracy ranged from 93.2 to 107.1% and precision was between 0.9 and 12.2%. The method has been applied to plasma samples obtained from patients treated with beta-lactam antibiotics and is appropriated for easy determination of plasma concentrations for therapeutic monitoring applications.

Mechanisms of interaction of endocrine-disrupting chemicals with glutamate-evoked secretion of gonadotropin-releasing hormone.

In previous studies, we detected a dichlorodiphenyltrichloroethane (DDT) derivative in the serum of children with sexual precocity after migration from developing countries. Recently, we reported that DDT stimulated pulsatile gonadotropin-releasing hormone (GnRH) secretion and sexual maturation in the female rat. The aim of this study was to delineate the mechanisms of interaction of endocrine-disrupting chemicals including DDT with GnRH secretion evoked by glutamate in vitro. Using hypothalamic explants obtained from 15-day-old female rats, estradiol (E2) and DDT caused a concentration-related increase in glutamate-evoked GnRH release while p,p'-dichlorodiphenyldichloroethene and methoxychlor had no effect. The effective DDT concentrations in vitro were consistent with the serum concentrations measured in vivo 5 days after exposure of immature rats to 10 mg/kg/day of o,p'-DDT. Bisphenol A induced some stimulatory effect, whereas no change was observed with 4-nonylphenol. The o,p'-DDT effects in vitro were prevented partially by a selective antagonist of the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) subtype of glutamate receptors. A complete prevention of o,p'-DDT effects was caused by an estrogen receptor (ER) antagonist as well as an aryl hydrocarbon receptor (AHR) antagonist and inhibitors of protein kinases A and C and mitogen-activated kinases. While an intermittent incubation with E2 caused no change in amplification of the glutamate-evoked GnRH release for 4 h, continuous incubation with E2 or o,p'-DDT caused an increase of this amplification after 3.5 h of incubation. In summary, DDT amplifies the glutamate-evoked GnRH secretion in vitro through rapid and slow effects involving ER, AHR, and AMPA receptor mediation.