Development of an LC-MS/MS method for the quantitation of 55 compounds prescribed in combined cardiovascular therapy

A HPLC-MS/MS method for the determination of Nadolol in rat plasma: Development, validation, and application to pharmacokinetic study

A sensitive validated method has been developed for the quantification of Nadolol in rat plasma by high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) using deuterated Nadolol (Nadolol D9) as internal standard (IS). The liquid-liquid extraction method using ethyl acetate was employed for the sample pretreatment. The separation was achieved on the Agilent Zorbax XDB C18 column (150  mm  ×  4.6  mm ID., 3.5  μm). The column temperature was controlled at 30°C. The components were eluted by using mobile phase A (10  mM ammonium formate) and mobile phase B (acetonitrile) in the ratio of 20:80  v/v with a flow rate of 0.5  mL/min. And 15  μL aliquot was injected in an isocratic elution mode with a total run time of 2.5  min. The multiple reactions monitoring transitions, m/z 310.20/254.10 for Nadolol and IS 319.20/255.00 were selected to achieve high selective analysis. The method exhibited great selectivity and linearity over the concentration range of 6 to 3000  ng/mL. The lower limit of quantification was found to be 6  ng/mL. The developed method proved acceptable results on selectivity, sensitivity, precision, accuracy, and stability studies as per Food and Drug Administration guidelines. This HPLC-MS/MS assay was successfully applied to get the pharmacokinetics parameters in rat plasma.

Novel Deconvoluted Synchronous Spectrofluorimetric Method For Simultaneous Determination Of Bisoprolol and Atorvastatin As Single or Co-administrated Drugs in Bulk and Plasma; Green Assessment

Atorvastatin and bisoprolol are two medications often prescribed together for the management of cardiovascular disease and to reduce mortality. Through a simple and direct technique based on deconvolution and synchronous of the spectrofluorometric spectra, the innovative method enables simultaneous quantification of bisoprolol and atorvastatin as single or co-formulated dosage forms in bulk and plasma. The method depends on measuring the amplitudes of bisoprolol and atorvastatin at 298 nm and 363 nm directly after deconvolution where the other drug doesn't show interference. The linearity of the method was 0.02-0.5 µg/mL and 0.3-25 µg/mL for bisoprolol and atorvastatin, respectively. LOD and LOQ were 0.004, 0.085 µg/mL and 0.013, 0.259 µg/mL for bisoprolol and atorvastatin respectively. Furthermore, green assessment of the method using Eco-Scale and GAPI scale. The method was precise, economical, simple, smart, time-saving and eco-friendly, which allowed its application in quality control unit and in lab assessment.

Effect of concomitant oral administration of ethanol on the pharmacokinetics of nicardipine in rats

Ethanol intake can alter pharmacokinetics by increasing the solubility or enhancing the absorption of concomitant drugs. Here, a selective, sensitive and reproducible high-performance liquid chromatography-tandem mass spectrometry method for the quantitative analysis of nicardipine in rat plasma was developed using simple protein precipitation. The calibration curve was linear over a concentration range of 1-2,000 ng/ml (r²  > 0.998). Accuracy ranged from 93.4 to 112.2% and precision was within 12.1% from three independent analytical batches. Stable conditions for the quantification of nicardipine in rat plasma were established in various conditions, including sample storage and handling. The matrix effect was negligible, and recovery was consistent at three different levels of quality control sample. The method was applied to assessment for the effect of ethanol on the pharmacokinetics of nicardipine in rats. The oral bioavailability of nicardipine was increased from 5.4 to 9.4% in Sprague-Dawley rats by concomitant oral administration of ethanol whereas the half-life was not altered. The findings indicated that concomitant ethanol intake can increase systemic drug exposure by increasing gastrointestinal absorption, especially poorly soluble drugs. This study provides an insight for further investigation of the alteration of the pharmacological effect of poorly soluble drugs owing to ethanol intake.

Quantification of rosiglitazone in rat plasma and tissues via LC-MS/MS - method development, validation, and its application in pharmacokinetic and tissue distribution studies

A bioanalytical method for the quantification of rosiglitazone on rat plasma and tissues (adipose tissue, heart, brain, bone, and kidney) using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was developed and validated. Chromatographic separation was achieved on Gemini C₁₈ column (50mm x 4.6mm, 3μm) using mobile phase consists of 10mM ammonium formate (pH 4.0) and acetonitrile (10:90, v/v) at a flow rate of 0.8 mL/min and injection volume of 10μL (Internal standard - Pioglitazone). LC-MS detection was performed with multiple reaction monitoring mode (MRM) using target ions at m/z→358.0 and m/z → 357.67 for rosiglitazone and pioglitazone (IS) respectively. The calibration curve showed a good correlation coefficient (r² ) over the concentration range of 1-10000 ng/mL. The mean percentage recoveries of rosiglitazone were found to be over the range of 92.54-96.64 % with detection and lower quantification limit of 0.6 ng/mL and 1.0 ng/mL, respectively. The developed method was validated as per USFDA guidelines and successfully utilized to measure rosiglitazone in plasma and tissue samples. Further, the developed method can be utilized for validating specific organ targeting delivery systems of rosiglitazone in addition to conventional dosage forms.

A simple and sensitive HPLC-FL method for simultaneous determination of angiotensin II receptor antagonists in human plasma

Angiotensin II receptor antagonists are one of the most widely used classes of antihypertensive drugs. In this study, an HPLC fluorescence method after protein precipitation (PPT) extraction was developed and validated for determination of olmesartan, losartan, irbesartan, and valsartan in human plasma. The separation was carried out on a Luna cyano (250 × 4.6 mm i.d.; 5 μm particle size) column and the mobile phase was composed of acetonitrile and 0.1 % phosphoric acid in gradient elution, at a flow rate of 1.2 mL min^-1. A PPT method was optimized by a two-level factorial design with triplicate at the central point. The parameters that could affect the extraction (sample volume and acetonitrile/plasma volume ratio) were evaluated and the method was compared to microextraction by packed sorbent (MEPS) and liquid-liquid extraction (LLE). The developed method allowed the simultaneous quantification of the analytes employing a simple and cheap sample preparation method and a short chromatographic run (13 min). This method was fully validated showing selectivity, precision, accuracy, and linearity over the range of 25.0-1500.0 ng mL^-1 for olmesartan and valsartan, 25.0-2500.0 ng mL^-1 for irbesartan, and 35.0-2500.0 ng mL^-1 for losartan. Finally, the method was successfully applied in the analysis of human plasma from volunteers.

Rapid Characterizaiton of Chemical Constituents of the Tubers of Gymnadenia conopsea by UPLC-Orbitrap-MS/MS Analysis

Gymnadenia conopsea R. Br. is a traditional Tibetan medicinal plant that grows at altitudes above 3000 m, which is used to treat neurasthenia, asthma, coughs, and chronic hepatitis. However, a comprehensive configuration of the chemical profile of this plant has not been reported because of the complexity of its chemical constituents. In this study, a rapid and precise method based on ultra-high performance liquid chromatography (UPLC) combined with an Orbitrap mass spectrometer (UPLC–Orbitrap–MS/MS) was established in both positive- and negative-ion modes to rapidly identify various chemical components in the tubers of G. conopsea for the first time. Finally, a total of 91 compounds, including 17 succinic acid ester glycosides, 9 stilbenes, 6 phenanthrenes, 19 alkaloids, 11 terpenoids and steroids, 20 phenolic acid derivatives, and 9 others, were identified in the tubers of G. conopsea based on the accurate mass within 3 ppm error. Furthermore, many alkaloids, phenolic acid derivates, and terpenes were reported from G. conopsea for the first time. This rapid method provides an important scientific basis for further study on the cultivation, clinical application, and functional food of G. conopsea.

[Forecast of the metrological characteristics of the method of the quantitative determination of verapamil in blood in forensic chemical analysis]

The aim of the work is to test theoretical prognosis of metrological characteristics of methods of quantitative determination in forensic chemical analysis on the example of method of determination of verapamil content in blood by thin layer chromatography with computer densitometry. The algorithm of prognostic determination of relative error for methods of quantitative analysis in forensic chemical examination using computer program «ChemMetrEvaluation 1.0» is offered. The implementation of the algorithm is based on a detailed analysis of error estimation of measurements at the stages of sample preparation, measuring the value of the analytical signal.

Screening of cardiovascular agents in plasma with LC-MS/MS: A valuable tool for objective drug adherence assessment

Adherence to cardiovascular preventive agents is important to prevent short and long term cardiovascular events. Recently, qualitatively compound screening using liquid chromatography-tandem mass spectrometry (LC-MS/MS) has gained interest for drug adherence assessment in patients at high risk of cardiovascular events. Therefore, we developed and tested an assay including 52 compounds and metabolites, covering over 95% of the antihypertensive and antithrombotic agents available worldwide. Trichloroacetic acid was used as simple and fast method for protein precipitation. The assay was validated for lower limit of quantification (LLOQ), linearity, stability for freeze/thaw, room temperature, autosampler and matrix effects. The LLOQ for each compound was targeted under the population trough concentration (PTC) as reported in literature to assure high sensitivity for adherence detection. This was accomplished for 50 of 52 compounds with a LLOQ equal or lower compared to the PTC. Linearity was confirmed for all compounds (r² > 0.995), except for acetylsalicylic acid (r² = 0.991). For room temperature stability, 12 compounds showed degradation over 20% after 20 h. 3 compounds suffer from matrix effect with recoveries < 50%. After analytical validation, blood samples from 91 patients with difficult-to-treat hypertension were analyzed. Patients were unaware of adherence assessment. Adherence varied largely per agent and per concentration ratio (CR) (ratio of the detected concentration with LC-MS/MS and the PTC) cut-off value. Additionally, stratification by adherence group showed that the percentage of patients classified as non-adherent increased from 6.6% for qualitative analysis (pos/neg) to 19.8% for a CR cut-off of 0.5. The data imply that using the CR cut off values has a significant and relevant effect on patient adherence classification.

Objective measures of non-adherence in cardiometabolic diseases: a review focused on urine biochemical screening

Cardiometabolic diseases are among the most prevalent and harmful conditions worldwide. They are complex, comorbid conditions that require polypharmacy - a known contributor to non-adherence in cardiovascular disease (CVD) and diabetes mellitus (DM). Suboptimal adherence is associated with poor disease control, which increases the risk of hospitalizations, mortality, and preventable financial implications. However, until recently, the lack of a gold standard for non-adherence testing in cardiometabolic diseases has been the major barrier for understanding true prevalence and mortality consequences. Recent European guidelines have endorsed biochemical testing as the preferred measure for non-adherence in CVD, with urinary screening methods being the most clinically widespread. The diagnostic and therapeutic benefits incurred to health service resources by use of biochemical non-adherence testing are vast, as hospitalizations and associated economic burdens are reduced, and tailored therapies are increased. However, biochemical testing can only signify a snap shot of adherence behavior, and true adherence may be skewed by pharmacokinetic factors. This review summarizes current literature regarding the prevalence, impact, and reasons of non-adherence in cardiometabolic disease. The benefits of current adherence diagnostic tools have been appraised, where urine in biochemical testing has been focused upon and evaluated against other matrices.

LC-MS/MS method for screening of intoxication and drug adherence of angiotensin-converting enzyme inhibitors in plasma

Aim: Intentional and accidental drug intoxication as well as medication adherence require sensitive and reliable analytical screening methods. Such methods are often lacking in children and adults, therefore, a reliable analytical method has been developed by using low plasma volume. Materials & methods: Sample preparation from plasma was achieved by solid-phase extraction process. LC-MS in positive ion mode was performed using X-select CSH™ C18 column. The mobile phase consisted of water and acetonitrile acidified with 1% formic acid using a gradient method with total run time of 10 min. Results: The method showed repeatability for all analytes. The linearity range from 0.78 to 100 ng/ml per analyte was established with recoveries ≥87% and matrix effect for all analytes was within guideline limits. Conclusion: The screening method was successfully validated for monitoring of intoxication and medication adherence of ten analytes in 50 μl residual plasma samples of children and adults.

Development, validation and application of a novel HPLC-MS/MS method for the quantification of atorvastatin, bisoprolol and clopidogrel in a large cardiovascular patient cohort

Cardiovascular disease is a leading cause of morbidity, mortality, and healthcare expenditure worldwide. Importantly, there is interindividual variation in response to cardiovascular medications, leading to variable efficacy and adverse events. Therefore a rapid, selective, sensitive and reproducible multi-analyte HPLC-MS/MS assay for the quantification in human plasma of atorvastatin, its major metabolites 2-hydroxyatorvastatin, atorvastatin lactone and 2-hydroxyatorvastatin lactone, plus bisoprolol and clopidogrel-carboxylic acid has been developed, fully validated, and applied to a large patient study. Fifty microliter plasma samples were extracted with a simple protein precipitation procedure involving acetonitrile with acetic acid (0.1%, v/v). Chromatographic separation was via a 2.7 μm Halo C18 (50 × 2.1 mm ID, 90 Å) column and gradient elution at a flow rate of 500 μL/min consisting of a mobile phase of water (A) and acetonitrile (B), each containing 0.1% formic acid (v/v), over a 6.0 min run time. The six analytes and their corresponding six deuterated internal standards underwent positive ion electrospray ionisation and were detected with multiple reaction monitoring. The developed method was fully validated with acceptable selectivity, carryover, dilution integrity, and within-run and between-run accuracy and precision. Mean extraction recovery for the analytes was 92.7-108.5%, and internal standard-normalised matrix effects had acceptable precision (coefficients of variation 2.2-12.3%). Moreover, all analytes were stable under the tested conditions. Atorvastatin lactone to acid interconversion was assessed and recommendations for its minimisation are made. The validated assay was successfully applied to analyse 1279 samples from 1024 patients recruited to a cardiovascular secondary prevention prospective study.

Blood plasma level determination using an automated LC-MSn screening system and electronically stored calibrations exemplified for 22 drugs and two active metabolites often requested in emergency toxicology

Fast and comprehensive qualitative and quantitative methods preferably by gas chromatography-mass spectrometry (GC-MS) and/or liquid chromatography-mass spectrometry (LC-MS) are needed to support the (differential) diagnosis of acute poisonings in emergency toxicology. One option is a commercially available qualitative screening solution based on LC-MSⁿ (Bruker Daltonik Toxtyper™, TT). Identified and toxicologically relevant compounds should be quantified to assess severity of poisonings. The aim of the present study was to test the TT system for quantification simultaneous with the screening process in blood plasma exemplified for 22 relevant drugs and two active metabolites. A standard liquid-liquid extraction was used for sample work-up followed by 1:5 dilution of the final extracts. They were analyzed using the TT system consisting of a Bruker amaZon speed ion trap and a Thermo Fisher Dionex Ultimate 3000 LC system. Plasma levels were assessed using full-scan data and an electronically stored five-point calibration. The calibration model was linear for the studied ranges and could be used for at least two months. The method was validated according to international guidelines. The acceptance criteria recommended for emergency toxicology for accuracy and precision were fulfilled for all tested compounds, but bromazepam, lorazepam, oxycodone, and prothipendyl could reliably be determined only above the therapeutic range. In conclusion, the presented procedure allowed the combination of a comprehensive LC-MSⁿ screening with fast automated assessment of plasma levels for emergency toxicology of tested compounds.

Indexed plasma drug concentrations for drug adherence screening in hypertensive patients

AIM

Due to its high sensitivity, qualitative plasma drug screening by liquid chromatography/tandem mass spectrometry may not be able to distinguish same-day drug intake from drug use on preceding days and cause misclassifications of drug adherence in hypertensive patients. Analysis of plasma drug concentrations may provide more accurate results.

PATIENTS AND METHODS

We describe dose-dependent indexing of plasma drug concentrations for expected peak concentrations to define individual screening thresholds for same-day drug use. To explore its utility, plasma samples from 9 hypertensive patients without major comorbidity were prospectively analyzed on two occasions. All were on hydrochlorothiazide with either amlodipine (n=7) and/or valsartan (n=6) at different doses. Drugs were quantitated by mass spectrometry. Non-adherence was defined if an indexed drug concentration was below the expected trough level at 24-hour dosing interval.

RESULTS

All patients were adherent by qualitative plasma screening (spectrometric sensitivity). On the first visit (random sampling time), mean plasma concentrations of the drugs were 102±70, 15.4±6.7 and 2529±1608ng/mL, and mean indexes 84±57%, 85±35% and 60±38%, respectively. Using the study criterion, non-adherence was suspected in three. Intraindividual cross-checking retained two. On the second visit (fixed sampling time), amlodipine concentration was 15.6±8.5ng/mL (88±52% after indexing). Two patients were non-adherent according to the study criterion.

CONCLUSION

Indexing of plasma drug concentrations appears practicable and useful for drug adherence screening under clinical conditions. With this technique, same-day drug intake can be easily distinguished which reduces the risk of false positive results associated with qualitative drug screening.

Bioanalytical methods for the detection of antidiabetic drugs: a review

Type 2 diabetes mellitus, a disease which prevalence has been progressively increasing worldwide, is characterized by chronic hyperglycemia resulting from the combination of inappropriate insulin secretion and/or resistance to insulin action. If left uncontrolled, diabetes is associated with complications such as dysfunction and failure of various organs, and even premature death. Along with lifestyle-modification strategies, several classes of oral antidiabetic agents can be employed for glycemic control. Thus, therapeutic drug monitoring of these drugs is essential to maintain appropriate treatment. This review discusses the most frequently employed analytical techniques and sample preparation systems to obtain a reliable and trustworthy method to quantify antidiabetic drugs in biological matrices. An adequate choice of internal standard, ideal chromatography conditions and most suitable analytical detector are reported.

Development of SPME-LC-MS method for screening of eight beta-blockers and bronchodilators in plasma and urine samples

The current work describes the development and validation of a simple, efficient, and fast method using solid phase microextraction coupled to liquid chromatography-tandem mass spectrometry (SPME-LC-MS/MS) for the concomitant measurement of eight beta-blockers and bronchodilators in plasma and urine. The presented assay enables quantitative determination of acebutolol, atenolol, fenoterol, nadolol, pindolol, procaterol, sotalol, and timolol. In this work, samples were prepared on a high-throughput platform using the 96-well plate format of the thin film solid phase microextraction (TFME) system, and a biocompatible extraction phase made of hydrophilic-lipophilic balance particles. Analytes were separated on a pentafluorophenyl column (100mm×2.1mm, 3μm) by gradient elution using an UPLC Nexera coupled with an LCMS-8060 mass spectrometer. The mobile phase consisted of water-acetonitrile (0.1% formic acid) at a flow rate of 0.4mLmin(-1). The linearity of the method was checked within therapeutic blood-plasma concentrations, and shown to adequately reflect typically expected concentrations of future study samples. Post-extraction addition experiments showed that the matrix effect ranged in plasma from 98% for procaterol to 115% for nadolol, and in urine, from 85% for nadolol and pindolol to 119% for atenolol. The method was successfully validated using Food and Drug Administration (FDA) guidelines, and met all acceptance criteria for bioanalytical assays at five concentration levels for all selected drugs. The final protocol can be successfully applied for monitoring concentrations of the selected drugs in both plasma and urine matrices obtained from patients or athletes.

Determination of lercanidipine in human plasma by an improved UPLC-MS/MS method for a bioequivalence study

An improved and reliable ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) method has been developed and validated for the determination of lercanidipine in human plasma. Plasma samples with lercanidipine-d3 as an internal standard (IS) were prepared by solid phase extraction on Phenomenex Strata-X cartridges using 100 µL of human plasma. Chromatographic analysis was performed on UPLC BEH C₁₈ (50 mm×2.1 mm, 1.7 µm) column under isocratic conditions. Linear calibration curves were obtained over a wide dynamic concentration range of 0.010-20.0 ng/mL. Matrix effect was assessed by post-column infusion, post-extraction spiking and standard-line slope methods. The mean extraction recovery was >94% for the analyte and IS. Inter-batch and intra-batch precision (% CV) across five quality controls was <5.8%. Bioequivalence study was performed with 36 healthy subjects after oral administration of 10 mg of lercanidipine and the assay reproducibility was evaluated by reanalysis of 133 incurred samples.

Cardiovascular drug determination in bioanalysis: an update

The great impact of cardiovascular diseases in human health has led to the development of a huge number of drugs and therapies to improve the treatment of these diseases. Cardiovascular drug analysis in biological fluids constitutes an important challenge for analytical scientists. There is a clear need for reliable methods to carry out both qualitative and quantitative analysis in a short time of analysis. Different problems such as drug monitoring, analysis of metabolites, study of drugs interactions, drugs residues or degradation products, chiral separation, and screening and confirmation of drugs of abuse in doping control must be solved. New trends in sample preparation, instrumental and column technology advances in LC and innovations in MS are described in this work.

Chromatographic behavior of co-eluted plasma compounds and effect on screening of drugs by APCI-LC-MS(/MS): Applications to selected cardiovascular drugs

Chromatographic behavior of co-eluted compounds from un-extracted drug-free plasma samples was studied by LC–MS and LC–MS/MS with positive APCI. Under soft gradient, total ion chromatogram (TIC) consisted of two major peaks separated by a constant lower intensity region. Early peak (0.15–0.4 min) belongs to polar plasma compounds and consisted of smaller mass ions (m/z<250); late peak (3.6–4.6 min) belongs to thermally unstable phospholipids and consisted of fragments with m/z<300. Late peak is more sensitive to variations in chromatographic and MS parameters. Screening of most targeted cardiovascular drugs at levels lower than 50 ng/mL has been possible by LC–MS for drugs with retention factors larger than three. Matrix effects and recovery, at 20 and 200 ng/mL, were evaluated for spiked plasma samples with 15 cardiovascular drugs, by MRM–LC–MS/MS. Average recoveries were above 90% and matrix effects expressed as percent matrix factor (% MF) were above 100%, indicating enhancement character for APCI. Large uncertainties were significant for drugs with smaller masses (m/z<250) and retention factors lower than two.

Bioanalytical chromatographic method validation according to current regulations, with a special focus on the non-well defined parameters limit of quantification, robustness and matrix effect

Method validation is a mandatory step in bioanalysis, to evaluate the ability of developed methods in providing reliable results for their routine application. Even if some organisations have developed guidelines to define the different parameters to be included in method validation (FDA, EMA); there are still some ambiguous concepts in validation criteria and methodology that need to be clarified. The methodology to calculate fundamental parameters such as the limit of quantification has been defined in several ways without reaching a harmonised definition, which can lead to very different values depending on the applied criterion. Other parameters such as robustness or ruggedness are usually omitted and when defined there is not an established approach to evaluate them. Especially significant is the case of the matrix effect evaluation which is one of the most critical points to be studied in LC-MS methods but has been traditionally overlooked. Due to the increasing importance of bioanalysis this scenario is no longer acceptable and harmonised criteria involving all the concerned parties should be arisen. The objective of this review is thus to discuss and highlight several essential aspects of method validation, focused in bioanalysis. The overall validation process including common validation parameters (selectivity, linearity range, precision, accuracy, stability…) will be reviewed. Furthermore, the most controversial parameters (limit of quantification, robustness and matrix effect) will be carefully studied and the definitions and methodology proposed by the different regulatory bodies will be compared. This review aims to clarify the methodology to be followed in bioanalytical method validation, facilitating this time consuming step.

Development and Validation of a LC-MS/MS Method for the Simultaneous Estimation of Amlodipine and Valsartan in Human Plasma: Application to a Bioequivalence Study

A reliable, simple, and robust liquid chromatography-tandem mass spectro-metric (LC-MS/MS) method has been developed and validated that employs solid-phase extraction for the simultaneous estimation of amlodipine and valsartan in human K₃EDTA plasma using amlodipine-d4 and valsartan-d9 as internal standards. Chromatographic separation of amlodipine and valsartan was achieved on the Luna C18 (2)100A (150 × 4.6 mm, 5 μm) column using acetonitrile: 5 mM ammonium formate solution (80:20, v/v) as the mobile phase at a flow rate of 0.8 mL/min in isocratic mode. Quantification was achieved using an electrospray ion interface operating in positive mode, under multiple reaction monitoring (MRM) conditions. The assay was found to be linear over the range of 0.302–20.725 ng/mL for amlodipine and 6.062–18060.792 ng/mL for valsartan. The method has shown good reproducibility, as intra- and interday precisions were within 10% and accuracies were within 8% of nominal values for both analytes. The method was successfully applied for the bioequivalence study of amlodipine and valsartan after oral administration of a fixed dose of the combination. Additionally, as required by the current regulatory bodies, incurred sample reanalysis was performed and found to be acceptable.

Simultaneous determination of a broad range of cardiovascular drugs in plasma with a simple and efficient extraction/clean up procedure and chromatography-mass spectrometry analysis

A simple, easy to use and efficient method was described for simultaneous determination of ten cardiovascular drugs with a broad range of physicochemical properties in rat plasma via online SPE and HPLC-MS/MS.

Analysis of Sartans: a review

The risk of cardiovascular diseases is closely related to hypertension, high cholesterol levels, and diabetes. When these risk factors appear together they are referred to as a metabolic syndrome. In the treatment of cardiovascular diseases, a combination of antihypertensive, hypolipemiant, and antidiabetic drugs is often applied. Diuretics (chlortalidone, hydrochlorothiazide, etc.) and angiotensin II receptors antagonist (sartans) are used to control hypertension, whereas statins (fluvastatin, simvastatin, etc.) are used to reduce cholesterol levels. This review is concerned with methods for the analysis of sartans in various matrices, such as pharmaceutical formulations, environmental and biological samples, and discusses the current status of stability studies of sartans . It also presents analytical methods for the simultaneous determination of sartans, diuretics, and statins.

An LC-MS assay for the screening of cardiovascular medications in human samples

Cardiovascular drugs are the most commonly prescribed medications. Some prior assays successfully detect cardiovascular drugs among multiple classes using a single sample. Here, we develop an assay to detect a broad range of cardiovascular drug classes to include commonly used cardiovascular drugs and evaluate the assay's analytical and statistical properties in a clinical setting. We describe a protocol for drug detection that encompasses 34 commonly prescribed cardiovascular drugs or drug metabolites with a single LC-MS/MS method using 100μL of serum or plasma. Drug classes monitored by this assay include: anticoagulants, angiotensin converting enzyme inhibitors (ACEI), angiotensin II receptor blockers (ARB), beta blockers, calcium channel blockers, diuretics, statins, and vasodilators, as well as digoxin, fenofibrate, and niacin. Analytical accuracy and precision for each drug were evaluated by repeating the assay on spiked samples at low, medium, and high concentrations. In 294 clinical samples obtained from hospitalized patients for whom medication administration was recorded, we evaluated the assay's statistical sensitivity, specificity, and accuracy. For the 34 drugs or drug metabolites, the assay was statistically sensitive (>0.90) for all drugs except captopril (0.25), isosorbide (0.81), and niacin (0.89). The assay was statistically specific for all drugs, with a minimum specificity of 0.94 (aspirin). To our knowledge, this method is the first method of simultaneous analysis of 34 cardiovascular drugs or drug metabolites from nine drug classes evaluated using clinical samples from hospitalized patients.

Determination of torasemide by fluorescence quenching method with some dihalogenated fluorescein dyes as probes

A novel fluorescence quenching method for the determination of torasemide (TOR) with some dihalogenated fluorescein dyes as fluorescence probes was developed. In acidulous medium, TOR could interact with some dihalogenated fluorescein dyes such as dichlorofluorescein (DCF), dibromofluorescein (DBF) and diiodofluorescein (DIF) to form binary complexes, which could lead to fluorescence quenching of above dihalogenated fluorescein dyes. The maximum fluorescence emission wavelengths were located at 532 nm (TOR-DCF), 535 nm (TOR-DBF) and 554 nm (TOR-DIF). The relative fluorescence intensities (ΔF=F0-F) were proportional to the concentration of TOR in certain ranges. The detection limits were 4.8 ng mL(-1) for TOR-DCF system, 9.8 ng mL(-1) for TOR-DBF system and 35.1 ng mL(-1) for TOR-DIF system. The optimum reaction conditions, influencing factors were studied; and the effect of coexisting substances was investigated owing to the highest sensitivity of TOR-DCF system. In addition, the reaction mechanism, composition and structure of the complex were discussed by quantum chemical calculation and Job's method. The fluorescence quenching of dihalogenated fluorescein dyes by TOR was a static quenching process judging from the effect of temperature and the Stern-Volmer plots. The method was satisfactorily applied to the determination of TOR in tablets and human urine samples.

How can analytical diagnostics in clinical toxicology be successfully performed today?

This article discusses current strategies for efficient analytical diagnostics in clinical toxicology. The tasks for such diagnostics, different analytical strategies and various methods were reviewed. They cover mainly gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry procedures for target or comprehensive screening for drugs (of abuse) and poisons, and for quantification in blood. Quality control aspects and strategies for competent interpretation of the analytical result in correlation with the clinical signs presented by the patient are discussed.

Challenges in the development of bioanalytical liquid chromatography-mass spectrometry method with emphasis on fast analysis

The development of bioanalytical methods has become more and more challenging over the past years due to very demanding requirements in terms of method reliability, sensitivity, speed of analysis and sample throughput. LC-MS/MS has established itself as a method of choice for routine analysis of biological materials. A development of such method consists of several steps including sample preparation and clean-up step, efficient chromatographic separation, sensitive and selective detection of analytes in complex matrices, a choice of convenient data processing and calibration approach and finally method validation. Each of these steps has its own constraints and challenges, which are discussed in detail in this review. Novel and modern approaches in sample preparation, chromatography and detection are especially emphasized. Attention is paid to proper calibration approach and matrix effects that can seriously affect method accuracy and precision.

Towards a universal LC-MS screening procedure - can an LIT LC-MS(n) screening approach and reference library be used on a quadrupole-LIT hybrid instrument?

In contrast to libraries with highly reproducible gas chromatography electron ionization mass spectra, current liquid chromatography (LC-MS) libraries are limited to specific instrument types. Therefore, the aim of the study was to prove whether a recently developed linear ion trap (LIT) LC-MS(n) screening approach and reference library can be transferred to an LC-MS/MS system with a quadrupole-LIT hybrid mass analyzer using SmileMS, a sophisticated search algorithm. The LIT reference library was built with MS² and MS³ wideband spectra recorded on a ThermoFisher LXQ LIT with electrospray ionization in positive mode and full-scan data-dependent acquisition (DDA). Collision parameter optimizations, including different scan types and energies, were performed on an Applied Biosystems QTRAP 4000 system using electrospray ionization in positive mode and full-scan DDA. Modified library sets were generated to improve the detection of a compound by the used search algorithm. Additionally, 100 authentic human urine samples were screened by both systems for proof of applicability. In the applicability study, 533 compounds were detected by the LXQ and 477 by the QTRAP system using enhanced product ion scan and a modified database. The presented data showed that the LIT screening approach and reference library could be used successfully on a QTRAP instrument with some limitations. These should be overcome by further optimizations regarding DDA settings for better sensitivity and further library modifications to reduce spectra mismatches.