Drugs In Biological Samples Research Articles

Stability of synthetic cathinones in clinical and forensic toxicological analysis—Where are we now?

Understanding the stability of analyzed drugs in biological samples is a crucial part for an appropriate interpretation of the analytical findings. Synthetic cathinones, as psychoactive stimulants, belong to a major class of new psychoactive substances. As they are subject to several degradation pathways, they are known to clinical and forensic toxicologists as unstable analytes in biological samples. When interpreting analytical data of synthetic cathinones in biological samples, analysts must be aware that the concentration of analytes may not accurately reflect the levels at the time they were acquired owing to many factors. This review provides (i) an overview of the current scientific knowledge on the stability of synthetic cathinones and/or metabolites in various human biological samples with a focus on factors that may deteriorate their stability-such as storage temperature, length of storage, matrix, pH, type of preservatives, concentration of analytes, and the chemistry of the analytes-and (ii) possible solutions on how to avoid such degradation. The PubMed database as well as Google Scholar was thoroughly searched to find published studies on the stability of synthetic cathinones since 2007 by searching specific keywords. A total of 23 articles met the inclusion criteria and were included in this review. Synthetic cathinones that carry methylenedioxy or N-pyrrolidine ring showed higher degradation resistance over other substituted groups. Acidification of samples pH plays a crucial role at increasing the stability of cathinones even with analytes that were frequently considered as poorly stable. This review also provides several recommendations for best practice in planning the experimental design, preservation, and storage conditions in order to minimize synthetic cathinones' degradation in human biological samples.

A Validated Volumetric Absorptive Microsampling-Liquid Chromatography Tandem Mass Spectrometry Method to Quantify Doxycycline Levels in Urine: An Application to Monitor the Malaria Chemoprophylaxis Compliance.

Because of logistics and cost constraints, monitoring of the compliance to antimalarial chemoprophylaxis by the quantitation of drugs in biological samples is not a simple operation on the field. Indeed, analytical devices are fragile to transport and must be used in a perfectly controlled environment. This is also the case for reagents and supplies, and the waste management is constraining. Thus, samples should be repatriated. They should be frozen after collection and transported with no rupture in the cold chain. This is crucial to generate available and interpretable data but often without any difficulties. Hence, to propose an alternative solution easier to implement, a quantitation method of determining doxycycline in urine has been validated using a volumetric absorptive microsampling (VAMS®) device. As blotting paper, the device is dried after collection and transferred at room temperature, but contrarily to dried spot, the collection volume is perfectly repeatable. Analysis of VAMS® was performed with a high-performance liquid chromatography coupled to a mass spectrometer. The chromatographic separation was achieved on a core-shell C18 column. The mean extraction recovery was 109% (mean RSD, 5.4%, n = 6) for doxycycline and 102% (mean RSD, 7.0%) for the internal standard. No matrix effect has been shown. Within-run as within-day precision and accuracy were, respectively, below 14% and ranged from 96 to 106%. The signal/concentration ratio was studied in the 0.25–50 µg/mL range, and recoveries from back-calculated concentrations were in the 96–105% range (RSD < 11.0%). The RSD on slope was 10%. To achieve the validation, this new quantitation method was applied to real samples. In parallel, samples were analyzed directly after a simple dilution. No statistical difference was observed, confirming that the use of VAMS® is an excellent alternative device to monitor the doxycycline compliance.

Review on analytical methods for quantification of ADHD drugs in human biological samples

AbstractAttention deficit hyperactivity disorder (ADHD) is a common neuro-developmental disorder. The symptoms of ADHD include difficulty in attention, memory and impulse control. Many pharmaceutical formulations (stimulants and non-stimulants) are available on the market to treat ADHD symptoms. The most commonly used drugs for treatment are amphetamine, methylphenidate, atomoxetine, bupropion, guanfacine and clonidine. In the field of pharmaceuticals, bioanalysis is an important tool used for the quantification of drugs and their metabolites present in biological samples using various analytical methods. Although a number of analytical methods were reported for the quantification of these drugs in biological samples of experimental animals, due to species differences, it is important to develop analytical methods to quantify these drugs in human biological samples to aid forensic and pharmacokinetic studies. In this review, we compile the bio-analytical methods such as spectrophotometry, spectrofluorimetry, mass spectrometry, electrophoresis, liquid chromatography and gas chromatography used for the quantification of ADHD drugs in human biological samples such as blood, plasma, serum, oral fluids, sweat, hair and urine based on earlier published articles from various journals.

Sensitive determination of deferasirox in blood of patients with thalassemia using dispersive liquid-liquid microextraction based on solidification of floating organic drop followed by HPLC–UV

Deferasirox is an oral iron chelator that has been on the market since 2005 and has been a suitable replacement for injectable chelators. It is important to check the amount of this drug in the blood of patients due to side effects. In this study, a new dispersive liquid-liquid microextraction based on solidification of floating drganic drop (DLLME − SFO) was applied to the extraction of deferasirox in the blood of patients with thalassemia prior to its analysis by high-performance liquid chromatography–ultraviolet detection (HPLC − UV). In this method, two long alcohols of the normal chain are mixed in a particular ratio, and then it is injected into the sample solution, which is on the magnetic stirrer. In this case, the mixture of the two alcohol changes to new double-solvent aggregate. This new double-solvent system is used as an extractant, which has a higher extraction power than any of its components alone. Under the optimum conditions, the calibration graph was linear in the rage of 0.2–200 μg L−1 with detection limit of 0.06 μg L−1. Repeatability (intra–day) and reproducibility (inter–day) of method based on seven replicate measurements of 100.0 μg L−1of deferasirox were 3.8 % and 5.7 %, respectively. The results showed that DLLME − SFO is a very simple, inexpensive, environmental friendly, sensitive and efficient analytical method for the determination of trace amount of drugs in biological samples and suitable results were obtained.

Determination of four antiepileptic drugs with solvent assisted dispersive solid phase microextraction – Gas chromatography–mass spectrometry in human urine samples

In this paper solvent assisted dispersive solid-phase microextraction (SA-DSPME) as a rapid and comprehensive sample preparation method was developed to extract and cleanup four antiepileptic drugs (AEDs); valproic acid, phenobarbital, levetiracetam, and pregabalin from human urine samples. In the procedure, the dispersion of the sorbent was attained by rapid injection of a mixture of the adsorbent and disperser solvent into the aqueous sample to increase the contact surface and reduce the extraction time and amount of sorbent consumption. Several sorbents such as magnetic Fe3O4, Fe3O4@graphene, Fe3O4@graphene oxide, Fe3O4@MWCNTs, Fe3O4@SiO2, Fe3O4@SiO2@TiO2, Fe3O4@Chitosan, and NiO NPs were tested to extract the target drugs and the results compared. Among them, Fe3O4@SiO2 was chosen as the best sorbent, and its structure characterized using FESEM, FTIR, and EDX. Besides, effective factors in the SA-DSPME, including the type of disperser solvent and desorption solvent, extraction time, desorption time, pH, and disperser solvent and desorption solvent volume, were optimized using one factor at a time and design experiment strategy. Under the optimum conditions, the calibration curves were linear in the range of 0.2–100 ng mL−1 for valproic acid and phenobarbital, and 0.4–120 ng mL−1 for levetiracetam and pregabalin. Limit of detections and limit of quantifications were lower than 0.11 and 0.4 ng mL−1 for the analytes. Besides, the procedure showed suitable relative standard deviations (≤3.8%) and preconcentration factors (≥133.9) for the determination of the antiepilepsy drugs. Analysis of human urine samples confirmed that the SA-DSPME-GC procedure is an appropriate method for measuring the target drugs in biological samples with recoveries between 92.9 and 103.2 % and RSD less than 4.7%.

Review of Chromatographic Methods Coupled with Modern Detection Techniques Applied in the Therapeutic Drugs Monitoring (TDM).

Therapeutic drug monitoring (TDM) is a tool used to integrate pharmacokinetic and pharmacodynamics knowledge to optimize and personalize various drug therapies. The optimization of drug dosing may improve treatment outcomes, reduce toxicity, and reduce the risk of developing drug resistance. To adequately implement TDM, accurate and precise analytical procedures are required. In clinical practice, blood is the most commonly used matrix for TDM; however, less invasive samples, such as dried blood spots or non-invasive saliva samples, are increasingly being used. The choice of sample preparation method, type of column packing, mobile phase composition, and detection method is important to ensure accurate drug measurement and to avoid interference from matrix effects and drug metabolites. Most of the reported procedures used liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) techniques due to its high selectivity and sensitivity. High-performance chromatography with ultraviolet detection (HPLC-UV) methods are also used when a simpler and more cost-effective methodology is desired for clinical monitoring. The application of high-performance chromatography with fluorescence detection (HPLC-FLD) with and without derivatization processes and high-performance chromatography with electrochemical detection (HPLC-ED) techniques for the analysis of various drugs in biological samples for TDM have been described less often. Before chromatographic analysis, samples were pretreated by various procedures—most often by protein precipitation, liquid–liquid extraction, and solid-phase extraction, rarely by microextraction by packed sorbent, dispersive liquid–liquid microextraction. The aim of this article is to review the recent literature (2010–2020) regarding the use of liquid chromatography with various detection techniques for TDM.

Investigation of sonochemically synthesized sphere-like metal tungstate nanocrystals decorated activated carbon sheets network and its application towards highly sensitive detection of arsenic drug in biological samples

A novel strontium tungstate (SrWO4 NPs) catalyst decorated on graphene oxide (GrO) network (SrWO4 NPs/GrO) was synthesized by direct sonochemical method and characterized its textural property. Transition bimetal oxides are considered as an efficient electrocatalyst in the sector of electrochemical sensor. Subsequently, the composite has coated on a screen-printed electrode to prepare a SrWO4 NPs/GrO modified GCE. Moreover, the X-ray powder diffraction analysis (XRDA), TEM, elemental analysis (EAs) and electrochemical methods (ECMs) were used to confirm composite of SrWO4 NPs/GrO. Electrochemical behaviors (CV and amperometric methods) of cancer toxic chemical (analyte) at amperometric modified electrodes were analyzed. Besides, the effective and enrichment of roxarsone sensor is due to SrWO4 NPs and GrO sheets. Moreover, optimized electrochemical sensor results have showed by amperometric method (i-t) and roxarsone cathodic peak responses are highly linear from 35 nM to 1816.5 μM. Further, the modified sensor detection limit (LOD) is 22.5 nM (S/N = 3). In addition, the modified electrode and sensors were analyzed to calculate the roxarsone concentration in food products. Hence, this sensor strategy has enables and good opportunities for determination of toxic chemicals in various practical and real time applications.

Microextraction and gas chromatography–flame ionization determination of five antiepileptic drugs in biological samples using amino acid-based deep eutectic ionic liquids

This study investigated the use of amino acid-based deep eutectic solvents (AADESs) in the ultrasound assisted reverse-phase emulsification microextraction (UARPEME) of five antiepileptic drugs (AEDs) from biological samples. The extraction was performed by dispersing the AADES into the sample solution using ultrasonic irradiation. After completing extraction, the sample solution was centrifuged. Then, the pre-concentrated AEDs in the AADES (upper phase) were derivatized by adding phenyltrimethylammonium hydroxide solution to it. The derivatized analytes were then eluted with n-hexane and it was injected directly into the gas chromatography–flame ionization detection (GC–FID) system to determine target analytes after the methylation reaction inside the injection chamber. The effective parameters of the proposed AADES–UARPEME method that comprises three consecutive extraction, derivatization and elution steps, were optimized using one Taguchi orthogonal array design and two central composite designs and evaluated by analysis of variance. The optimized method was successfully implemented to analyze AEDs in the human biological samples (serum, urine, breast-milk and hair) and acceptable results were obtained. The resultant calibration curves were linear over the concentration range of 0.5–850 μg/L (R2 > 0.998). The estimated limits of detection and quantification were lower than 0.5 μg/L and the improvement factors were between 1378 and 1409. The intra- and inter-day repeatability values varied below 5.3% (n = 5) and the relative recovery values were calculated between 90 and 110% for all samples.

Electrochemically synthesized NiFe layered double hydroxide modified Cu(OH)2 needle-shaped nanoarrays: A novel sorbent for thin-film solid phase microextraction of antifungal drugs

Herein, we applied a simple electrosynthesis process to deposit nickel-iron layered double hydroxides (NiFe LDH) on the surface of copper hydroxide (Cu(OH)2) needle-shaped nanoarrays and introduce a new sorbent for thin-film solid phase microextraction (TF-SPME). For this purpose, the nanoarrays were grown via electrochemical anodization on a copper foil’s surface and then modified with NiFe LDH. The synthesized sorbent was characterized by field emission-scanning electron microscopy, Brunauer-Emmett-Teller (BET), and Barrett-Joiner-Halenda (BJH) analysis, energy-dispersive X-ray spectroscopy, and X-ray diffraction. The Cu(OH)2–NiFe LDH based TF-SPME method was used to measure antifungal drugs in veterinary plasma samples followed by HPLC-UV analysis. The effects of various parameters in the extraction efficiency, including pH (5.0), extraction time (20 min), stirring rate (500 rpm), and salt effect (5.0%), type of eluent (acetonitrile), eluent volume (100 μL) and desorption time (5 min) were thoroughly optimized. Under the optimum conditions, limits of detection for ketoconazole, clotrimazole, and miconazole were obtained below 10 ng mL−1. Intra-day, inter-day and film-to-film RSDs% were obtained less than 6.2%, 7.3% and 7.0%, respectively. Moreover, calibration plots were linear from 30 to 5000 ng mL−1 for ketoconazole, 8.0–1000 ng mL−1 for clotrimazole, and 15–1000 ng mL−1 for miconazole, with determination coefficients between 0.9937 and 0.9971. Finally, good relative recoveries (%) in the range of 85–97% were obtained for measuring trace amounts of antifungal drugs in dogs’ plasma samples. As a result, the method can be considered as an appropriate alternative to the conventional sample preparation methods for measuring trace amounts of antifungal drugs in biological samples.

Controllable synthesis of bottlebrush-like ZnO nanowires decorated on carbon nanofibers as an efficient electrocatalyst for the highly sensitive detection of silymarin in biological samples

The excessive intake of antioxidant drugs due to veterinary and human medical treatment poses serious health risks to both humans and animals. In this context, the monitoring of antioxidant drugs in animal and human biological systems is important and has provoked a universal scientific challenge. Therefore, it is of the utmost importance to develop cost-effective electrochemical sensing electrode materials for the sensing of bio-analytes and pharmaceutical drugs in biological samples. In this work, electro-etched carbon nanofibers (CNFs) were coated with bottlebrush-like zinc oxide (ZnO) nanowires via a facile hydrothermal method for the preparation of a CNF-ZnO nanocomposite as a promising electrode material for the trace level detection of silymarin. The fabricated CNF-ZnO glassy carbon electrode (GCE) demonstrated a higher anodic peak current, lower peak potential, and excellent sensing performance of silymarin compared to GCEs fabricated with ZnO or CNFs. The CNF-ZnO-GCE exhibited an appreciable linear response range (2–123 nM), good sensitivity (1.728 μA∙nM−1 cm2), and an ultra-low detection limit (1 nM). We also successfully showcased its specific sensing behavior for the sensing of silymarin in the presence of structurally similar compounds and metal ions. Furthermore, the CNF-ZnO-GCE was effectively applied to real biological and pharmacological samples for the efficient determination of silymarin, with which we obtained satisfactory recovery values.

Quantitative detection of nanomolar drug using surface-enhanced Raman scattering combined with internal standard method and two-step centrifugation method

Quantitative detection for nanomolar analytes is a challenge for surface-enhanced Raman scattering (SERS). In this report, a SERS method which combined with an internal standard method and a two-step centrifugation method was established for trace analysis of two drugs using a portable Raman spectrometer. Metformin hydrochloride was used as an internal standard for phenformin hydrochloride to increase the linearity of SERS detection, while, streptomycin sulfate was used for tigecycline. The two-step centrifugation method for sample preparation increased the density of hot spots and the concentration of analyte by accumulating silver nanoparticles. Therefore, the detection sensitivity was significantly improved. Furthermore, the repeatability of SERS signals was increased by adding 200 µL of the sample solution into a slit-type quartz cuvette to make the excitation light transmit through a heavy thickness sample solution. The RSDs of SERS signal intensity ratio of phenformin hydrochloride and tigecycline to internal standard were 1% and 1.6%, respectively. Finally, phenformin hydrochloride and tigecycline exhibited a good linearity in the range of 1–500 nM (R2 = 0.9976) and 10–750 nM (R2 = 0.9926), respectively. In a word, this method greatly improved the lower limit of quantitation of SERS, and laid foundation for rapid and convenient quantitative detection of low concentration drug in biological samples.

Validation of a Bioanalytical Method for the Determination of Synthetic and Natural Cannabinoids (New Psychoactive Substances) in Oral Fluid Samples by Means of HPLC-MS/MS.

New psychoactive substances (NPS) represent an important focus nowadays and are continually produced with minimal structural modifications in order to circumvent the law and increase the difficulty of identifying them. Moreover, since there are a high number of different compounds, it is arduous to develop analytical screening and/or confirmation methods that allow the identification and quantification of these compounds. The aim of this work is to develop and validate a bioanalytical method for detecting new synthetic drugs in biological samples, specifically oral fluid, using high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS/MS) with minimal sample pretreatment. Oral fluid samples were simply centrifuged and denaturized with different rapid procedures before injection into the LC-MS/MS system. Calibration curves covered a linear concentration range from LOQ to 100 ng/mL. Validation parameters such as linearity, precision, accuracy, selectivity, matrix effect and thermal stability were evaluated and showed satisfactory results, in accordance with US Food & Drug Administration guidelines. The inter-day analytical bias and imprecision at two levels of quality control (QC) were within ±15% for most compounds. This method was able to identify and calculate the concentration of 10 NPS validated in this biological sample, even in the presence of matrix effect.

Analysis of basic drugs in biological samples using dynamic single-interface hollow fiber liquid-phase microextraction combined with fast electromembrane extraction

In this study, a combination of single-interface hollow fiber liquid-phase microextraction and electromembrane extraction was applied for the extraction of some basic drugs from biological samples. The extraction process was followed by the HPLC-UV instrument. In this dynamic system, 1-octanol was impregnated into the pores of hollow fiber wall as an acceptor phase, the sample solution (pH = 12.0) was pumped into the lumen of hollow fiber by a syringe pump, the extraction efficiency was improved by filling and emptying (25 times) of sample solution (step-1). The extracted analytes in the organic acceptor phase were back-extracted by a fast electromembrane extraction procedure (step-2). Effective parameters on the extraction efficiency of both methods were investigated and optimized. Under optimized conditions (organic acceptor phase: 1-octanol, sample solution volume: 1500 µL, flow rate: 2.0 mL min−1, the number of filling and emptying cycles: 25, voltage: 100 V, back-extraction time: 2 min, and aqueous acceptor phase: 100 mM HCl), the proposed method provided good linearity with determination coefficients ranging from 0.992 to 0.996 over a concentration range of 2.5–1000 ng mL−1. Extraction recoveries were obtained in the range of 65.1 and 88.8%, which resulted in preconcentration factors in the range of 32.6–44.4. The limits of detection were found to be within the range of 0.12–0.36 ng mL−1, while the corresponding repeatability ranged from 3.7 to 9.3% (n = 3). Finally, the optimized method was applied for the quantification of propranolol, diltiazem and, lidocaine in urine and, plasma samples with relative recoveries ranged between 94.1 and 105.4%, indicating the reliability of the method.

Polyoxomolybdate368 /polyaniline nanocomposite as a novel fiber for solid‐phase microextraction of antidepressant drugs in biological samples

A novel solid-phase microextraction fiber was synthesized by coating a stainless steel wire with polyoxomolybdate368 /polyaniline as a sorbent aimed at extraction of amitriptyline, nortriptyline, and doxepin as antidepressant drugs from urine and blood samples. The polyoxomolybdate368 /polyaniline composite coating was applied using electropolymerization process under constant potential. This composition leads to enhanced extraction efficiency of the fiber. Scanning electron microscopy images show that huge three-dimensional structures of polyoxomolybdate368 in composite induced more non-smooth and porous fiber. In order to optimize of the extraction process, a series of variables including concentration of the composite materials, coating thickness, pH, extraction time, salt addition, and stirring rate was investigated and optimum conditions were determined. Analysis of surface morphology and chemical composition was performed. High-performance liquid chromatography was used for separation and evaluation of mentioned antidepressant drugs from the matrixes. The experiments indicated a detection limits of <0.2ng/L and a linear dynamic range of 0.3-100ng/L (R2 >0.994). The relative recovery values were found to be in the range of 92-98%. It was concluded that the purposed fiber is highly efficient in analyzing traces of antidepressant drugs in urine and blood.

Hyphenated mass spectrometry techniques for assessing medication adherence: advantages, challenges, clinical applications and future perspectives.

Nonadherence to prescribed pharmacotherapy is an understated public health problem globally and is costing many patients their chance to return to good health and healthcare systems billions. Clinicians need an accurate assessment of adherence to medications to aid the clinical decision-making process in the event of poor patient progress and to maximise the patient health outcomes from the drug therapies prescribed. An overview of indirect and direct methods used to measure medication adherence is presented, highlighting the potential for accurate measuring of drugs in biological samples using hyphenated mass spectrometry (MS) techniques to provide healthcare professionals with a reliable evidence base for clinical decision making. In this review we summarise published applications of hyphenated MS techniques for a diverse range of clinical areas demonstrating the rise in the use of such direct methods for assessing medication adherence. Although liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods using plasma, serum and urine samples are the most popular, in recent years increased attention has been given to liquid chromatography high-resolution mass spectrometry (LC-HRMS) methods and alternative biosample matrices including hair, saliva and blood microsamples. The advantages and challenges of using hyphenated MS techniques to address this healthcare problem are also discussed alongside future perspectives.

Hollow fiber-based liquid-phase microextraction and HPLC-UV determination of lovastatin in biological fluids

In this study, a hollow fiber liquid-phase microextraction (HF-LPME) method coupled with high-performance liquid chromatography (HPLC) was successfully developed for the determination of trace levels of lovastatin in urine and plasma samples. Lovastatin was extracted from 15 mL of the acidic sample solution with a pH of 2 into an organic extracting solvent (n-octanol) impregnated in the pores of a hollow fiber and then back extracted into an acidified aqueous solution in the lumen of the hollow fiber. After extraction, 10 µL of the acceptor phase was injected into HPLC system. To obtain high extraction efficiency, the parameters affecting the HF-LPME, including pH of the sample and extractant phases, type of organic phase, ionic strength, stirring rate, extraction time, and temperature, were studied and optimized. Under the optimized conditions (solvent 1-octanol, pH = 2, 45 min stirring at 45°C with 750rpm), the relative recovery percentage was 85.2–97, which shows the capability of the method to analyze the analyte concentration. This technique provided preconcentration factor 199, 185, and 170 for water, urine, and plasma, respectively. Good precisions values (with relative standard division ≤ 10.5%) were obtained. The results indicated that the HF-LPME method has an excellent cleanup capacity and a high preconcentration factor and could serve as a simple and sensitive method for monitoring the drug in biological samples.

Nitrogen-doped carbon quantum dots embedded Co3O4 with multiwall carbon nanotubes: An efficient probe for the simultaneous determination of anticancer and antibiotic drugs

The simultaneous determination of anticancer and antibiotic drugs in biological samples with fast and sensitive methods is an essential task for the effective monitoring of drug therapy. A novel electrochemical sensor for the simultaneous determination of anticancer drug Flutamide (FLU) and antibiotic drug Nitrofurantoin (NF) was developed based on the glassy carbon electrode (GCE) modified with N-CQD@Co3O4/MWCNTs hybrid nanocomposite. The electro-kinetics of the developed sensor was studied using cyclic voltammetry (CV). The electrochemical performance of FLU and NF on the N-CQD@Co3O4/MWCNTs/GCE surface was examined using CV and differential pulse voltammetry (DPV) techniques. At an optimized condition, the developed sensor exhibits excellent performance in simultaneous determination of FLU and NF with a linear range of 0.05–590 μM and 0.05–1220 μM and detection limit of 0.0169 μM and 0.044 μM respectively. Furthermore, the developed sensor exhibits satisfactory results in the real sample analysis.

Evaluation of the dose-related concentration approach in therapeutic drug monitoring of diuretics and \u03b2-blockers \u2013 drug classes with low adherence in antihypertensive therapy

Detection of antihypertensive drugs in biological samples is an important tool to assess the adherence of hypertensive patients. Urine and serum/plasma screenings based on qualitative results may lead to misinterpretations regarding drugs with a prolonged detectability. The aim of the present study was to develop a method that can be used for therapeutic drug monitoring (TDM) of antihypertensive drugs with focus on adherence assessment. Therefore, a method for quantification of four diuretics and four β-blockers using high-performance liquid chromatography-mass spectrometric analysis (LC-MS/MS) of combined acidic and basic serum extracts was developed and validated. The method was applied to 40 serum samples from 20 patients in a supervised medication setting (trough and peak serum samples). Literature data on therapeutic concentration ranges, as well as dose-related drug concentrations (calculated from data of pharmacokinetic studies) were used to evaluate adherence assessment criteria. Concentrations were measured for bisoprolol (n = 9 patients), metoprolol (n = 7), nebivolol (n = 1), canrenone (n = 2, metabolite of spironolactone), hydrochlorothiazide (n = 10) and torasemide (n = 8). The measured concentrations were within the therapeutic reference ranges, except for 24% of the samples (mainly β-blockers). In contrast, all measured concentrations were above the lower dose-related concentration (DRC), which appears superior in evaluating adherence. In conclusion, the quantitative analysis of antihypertensive drugs in serum samples and its evaluation on the basis of the individually calculated lower DRC is a promising tool to differentially assess adherence. This method could possibly detect a lack of adherence or other causes of insufficient therapy more reliably than qualitative methods.

Optimization of morphine extraction method for the assay of its urinary 3-glucuronideconjuguate by gas chromatography-mass spectrometry

In the field of doping, a great interest is carried for the analysis of morphine, a powerful narcotic analgesic opiate which use is prohibited during competitions. In order to confirm the abnormal analytical result in our anti-doping laboratory, a sensitive and selective gas chromatography-mass spectrometry (GC-MS) method was performed for the quantification of urinary morphine. As sample preparation is a key step for the determination of drugs in biological samples, the aim of this work consists of the optimization of the urinary human sample pretreatment conditions before quantification by GC/MS. Enzymatic hydrolysis associated with liquid-liquid extraction constitute the major pre-treatment steps. Our study has first focused on the optimization of the extraction solvents then to enzymatic hydrolysis which morphine is released from its glucuronide conjugated form. Onboard premiums, a study involving the effect of "amount of enzyme", "incubation temperature" and "duration of hydrolysis" was conducted. This univariate study has enabled us to evaluate the influence of each of these operating variables on the area ratio of morphine to the internal standard (Amorphine/AIS) response and to set the experimental fields for each one of them. Based on these results, an experimental design was established using the Box-Behnken model to determine, by multivariate analysis, the optimal operating conditions maximizing the "Amophine/AIS" response. After validation, the analysis of response surface makes it possible to set the optimum operating conditions, which the ratio "Amorphine/AIS" is maximized. The retained conditions for enzymatic hydrolysis are 160μl of Escherichiacoli glucuronidase enzyme during 6hours of incubation at a temperature of 36°C.The solvent mixture Methyl-t-Butyl Ether/isopropanol (4:1, v/v) was selected since it has improved morphine extraction from the urinary matrix allowing a gain of 50% when compared to that used in our routine laboratory. Our developed extraction method can be successfully applied for our forensic anti-doping analysis of morphin in human sample urine.

Quadrupole Time-of-Flight Mass Spectrometry: A Paradigm Shift in Toxicology Screening Applications.

The screening of biological samples for the presence of illicit or legal substances is an important frontline tool in both clinical and forensic toxicology. In the clinical setting, drug screening is a useful tool for the clinician in improving patient care and guiding treatment. Analytical approaches for the screening of drugs in biological samples are extensive and well documented, though many rapid screening techniques often lack appropriate sensitivity and specificity, requiring careful clinical interpretation. The continuous emergence of new psychoactive substances presents a considerable analytical challenge in maintaining up-to-date methods for the detection of relevant drugs. Adapting and validating methods for the detection of new substances can be a complicated and costly undertaking. There is also a considerable lag time between the emergence of new drugs and the release of commercial assays for detection. Quadrupole time-of-flight mass spectrometry (Q-TOF-MS) has gained considerable attention over the last decade as an analytical technique that is capable of meeting the challenges of a rapidly changing drug landscape. Exhibiting both high sensitivity and specificity in drug detection, Q-TOF-MS also allows methods to be rapidly updated for newly emerging psychoactive agents. The coupling of Q-TOF-MS with techniques such as liquid or gas chromatography can provide both rapid and comprehensive screening solutions that are gaining popularity in the clinical laboratory setting.