Drug quantitation on a benchtop liquid chromatography-tandem mass spectrometry system

A Highly Sensitive LC–MS/MS Method Development and Validation of Fedratinib in Human Plasma and Pharmacokinetic Evaluation in Healthy Rabbits

Background:

A simple and sensitive quantitation analytical technique by liquid chromatography–tandem mass spectrometry (LC-MS/MS) is essential for fedratinib in biological media with kinetic study in healthy rabbits.

Objective:

The main objectives of the present research work are to LC-MS/MS method development and validate procedure for the quantitation of fedratinib and its application to kinetic study in rabbits.

Methods:

Separation of processed samples were employed on zorbax SB C18 column (50mm×4.6 mm) 3.5µm with a movable phase of methanol, acetonitrile and 0.1% formic acid in the ratio of 30:60:10. The movable phase was monitored through column at 0.8 ml/min flow rate. The drug and ibrutinib internal standard (IS) were evaluated by monitoring the transitions of m/z -525.260/57.07 and 441.2/55.01 for fedratinib and IS respectively in multiple reaction monitoring mode.

Results:

The linear equation and coefficient of correlation (R2) results were y =0.00348x+0.00245 and 0.9984, respectively. Intra and inter-day precision RSD findings of the developed technique were found in the range of 2.4 - 5.3% for the quality control (QC)-samples (252.56, 1804.0 and 2706 ng/ml). The proposed method was subjected to pharmacokinetic study in healthy rabbits and the kinetic study, fedratinib showed mean AUClast 13190±18.1 hr*ng/ml and Cmax was found to be 3550±4.31 ng/ml in healthy rabbits.

Conclusion:

The validated method can be applicable for the pharmacokinetic and toxicokinetic studies in the clinical and forensic analysis of fedratinib in different kinds of biological matrices successfully.

Development of Fast and Simple LC-ESI-MS/MS Technique for the Quantification of Regorafenib; Application to Pharmacokinetics in Healthy Rabbits

Background:

A simple quantification technique by liquid chromatography electrospray ionization- tandem mass spectrometry (LC-ESI-MS/MS) is required for regorafenib in biological matrices with bioavailability studies in healthy rabbits, when compared with reported techniques.

Objective:

The main aim of the research work was to develop a validated LC-ESI-MS/MS technique for the quantification of regorafenib and application to bioavailability studies in healthy rabbits.

Methods:

Chromatographic separation was achieved with hypersil-C18 analytical column (50mm×4.6 mm, 4μm) and mobile phase composition of acetonitrile and 5mM ammonium acetate in the proportion of 70:30. The mobile phase was infused into the column with high pressure to get a 0.7 ml/min flow rate. The total retention time of the analyte is promising when compared with the existed methods for regorafenib. Quantitation was processed by monitoring transitions of m/z -483.0/262.0 and 450.0/260.0 for regorafenib and internal standard respectively in multiple reaction monitoring.

Results:

The linearity equation and correlation coefficient (R2) findings were y =0.9948x+2.6624 and 0.998 respectively. The intra and inter-day precision of the developed technique was found between 1.00 – 8.50% for the QC-samples (2, 4, 240 and 480ng/ml). From bioavailability study, the drug was shown Tmax of 3.688 ± 0.754; average AUC0→α and AUC0→t were 6476.81 ± 259.59 and 6213.845 ± 257.892 respectively and Cmax was found to be 676.91 ± 22.045 in healthy rabbits.

Conclusion:

The developed technique was validated and successfully applied in the pharmacokinetic study of the drug (40 mg tablet) administered through the oral route in healthy rabbits.

Mass Spectrometry-Based Biomarkers in Drug Development

Advances in mass spectrometry, proteomics, protein bioanalytical approaches, and biochemistry have led to a rapid evolution and expansion in the area of mass spectrometry-based biomarker discovery and development. The last decade has also seen significant progress in establishing accepted definitions, guidelines, and criteria for the analytical validation, acceptance and qualification of biomarkers. These advances have coincided with a decreased return on investment for pharmaceutical research and development and an increasing need for better early decision making tools. Empowering development teams with tools to measure a therapeutic interventions impact on disease state and progression, measure target engagement and to confirm predicted pharmacodynamic effects is critical to efficient data-driven decision making. Appropriate implementation of a biomarker or a combination of biomarkers can enhance understanding of a drugs mechanism, facilitate effective translation from the preclinical to clinical space, enable early proof of concept and dose selection, and increases the efficiency of drug development. Here we will provide descriptions of the different classes of biomarkers that have utility in the drug development process as well as review specific, protein-centric, mass spectrometry-based approaches for the discovery of biomarkers and development of targeted assays to measure these markers in a selective and analytically precise manner.

Mass spectrometry-based biomarkers in drug development

Advances in mass spectrometry, proteomics, protein bioanalytical approaches, and biochemistry have led to a rapid evolution and expansion in the area of mass spectrometry-based biomarker discovery and development. The last decade has also seen significant progress in establishing accepted definitions, guidelines, and criteria for the analytical validation, acceptance, and qualification of biomarkers. These advances have coincided with a decreased return on investment for pharmaceutical research and development and an increasing need for better early decision making tools. Empowering development teams with tools to measure a therapeutic interventions impact on disease state and progression, measure target engagement, and to confirm predicted pharmacodynamic effects is critical to efficient data-driven decision making. Appropriate implementation of a biomarker or a combination of biomarkers can enhance understanding of a drugs mechanism, facilitate effective translation from the preclinical to clinical space, enable early proof of concept and dose selection, and increase the efficiency of drug development. Here we will provide descriptions of the different classes of biomarkers that have utility in the drug development process as well as review specific, protein-centric, mass spectrometry-based approaches for the discovery of biomarkers and development of targeted assays to measure these markers in a selective and analytically precise manner.

Multiple reaction monitoring (MRM) of plasma proteins in cardiovascular proteomics

Different methodologies have been used through years to discover new potential biomarkers related with cardiovascular risk. The conventional proteomic strategy involves a discovery phase that requires the use of mass spectrometry (MS) and a validation phase, usually on an alternative platform such as immunoassays that can be further implemented in clinical practice. This approach is suitable for a single biomarker, but when large panels of biomarkers must be validated, the process becomes inefficient and costly. Therefore, it is essential to find an alternative methodology to perform the biomarker discovery, validation, and -quantification. The skills provided by quantitative MS turn it into an extremely attractive alternative to antibody-based technologies. Although it has been traditionally used for quantification of small molecules in clinical chemistry, MRM is now emerging as an alternative to traditional immunoassays for candidate protein biomarker validation.

Quantitative mapping of reversible mitochondrial Complex I cysteine oxidation in a Parkinson disease mouse model

Differential cysteine oxidation within mitochondrial Complex I has been quantified in an in vivo oxidative stress model of Parkinson disease. We developed a strategy that incorporates rapid and efficient immunoaffinity purification of Complex I followed by differential alkylation and quantitative detection using sensitive mass spectrometry techniques. This method allowed us to quantify the reversible cysteine oxidation status of 34 distinct cysteine residues out of a total 130 present in murine Complex I. Six Complex I cysteine residues were found to display an increase in oxidation relative to controls in brains from mice undergoing in vivo glutathione depletion. Three of these residues were found to reside within iron-sulfur clusters of Complex I, suggesting that their redox state may affect electron transport function.

Correlation between y-type ions observed in ion trap and triple quadrupole mass spectrometers

Multiple reaction monitoring mass spectrometry (MRM-MS) is a technique for high-sensitivity targeted analysis. In proteomics, MRM-MS can be used to monitor and quantify a peptide based on the production of expected fragment peaks from the selected peptide precursor ion. The choice of which fragment ions to monitor in order to achieve maximum sensitivity in MRM-MS can potentially be guided by existing MS/MS spectra. However, because the majority of discovery experiments are performed on ion trap platforms, there is concern in the field regarding the generalizability of these spectra to MRM-MS on a triple quadrupole instrument. In light of this concern, many operators perform an optimization step to determine the most intense fragments for a target peptide on a triple quadrupole mass spectrometer. We have addressed this issue by targeting, on a triple quadrupole, the top six y-ion peaks from ion trap-derived consensus library spectra for 258 doubly charged peptides from three different sample sets and quantifying the observed elution curves. This analysis revealed a strong correlation between the y-ion peak rank order and relative intensity across platforms. This suggests that y-type ions obtained from ion trap-based library spectra are well-suited for generating MRM-MS assays for triple quadrupoles and that optimization is not required for each target peptide.

MaRiMba: a software application for spectral library-based MRM transition list assembly

Multiple reaction monitoring mass spectrometry (MRM-MS) is a targeted analysis method that has been increasingly viewed as an avenue to explore proteomes with unprecedented sensitivity and throughput. We have developed a software tool, called MaRiMba, to automate the creation of explicitly defined MRM transition lists required to program triple quadrupole mass spectrometers in such analyses. MaRiMba creates MRM transition lists from downloaded or custom-built spectral libraries, restricts output to specified proteins or peptides, and filters based on precursor peptide and product ion properties. MaRiMba can also create MRM lists containing corresponding transitions for isotopically heavy peptides, for which the precursor and product ions are adjusted according to user specifications. This open-source application is operated through a graphical user interface incorporated into the Trans-Proteomic Pipeline, and it outputs the final MRM list to a text file for upload to MS instruments. To illustrate the use of MaRiMba, we used the tool to design and execute an MRM-MS experiment in which we targeted the proteins of a well-defined and previously published standard mixture.

Rapid optimization of MRM-MS instrument parameters by subtle alteration of precursor and product m/z targets

Multiple reaction monitoring (MRM) is a highly sensitive method of targeted mass spectrometry (MS) that can be used to selectively detect and quantify peptides based on the screening of specified precursor peptide-to-fragment ion transitions. MRM-MS sensitivity depends critically on the tuning of instrument parameters, such as collision energy and cone voltage, for the generation of maximal product ion signal. Although generalized equations and values exist for such instrument parameters, there is no clear indication that optimal signal can be reliably produced for all types of MRM transitions using such an algorithmic approach. To address this issue, we have devised a workflow functional on both Waters Quattro Premier and ABI 4000 QTRAP triple quadrupole instruments that allows rapid determination of the optimal value of any programmable instrument parameter for each MRM transition. Here, we demonstrate the strategy for the optimizations of collision energy and cone voltage, but the method could be applied to other instrument parameters, such as declustering potential, as well. The workflow makes use of the incremental adjustment of the precursor and product m/z values at the hundredth decimal place to create a series of MRM targets at different collision energies that can be cycled through in rapid succession within a single run, avoiding any run-to-run variability in execution or comparison. Results are easily visualized and quantified using the MRM software package Mr. M to determine the optimal instrument parameters for each transition.

MRMer, an interactive open source and cross-platform system for data extraction and visualization of multiple reaction monitoring experiments

Multiple reaction monitoring (MRM) mass spectrometry identifies and quantifies specific peptides in a complex mixture with very high sensitivity and speed and thus has promise for the high throughput screening of clinical samples for candidate biomarkers. We have developed an interactive software platform, called MRMer, for managing highly complex MRM-MS experiments, including quantitative analyses using heavy/light isotopic peptide pairs. MRMer parses and extracts information from MS files encoded in the platform-independent mzXML data format. It extracts and infers precursor-product ion transition pairings, computes integrated ion intensities, and permits rapid visual curation for analyses exceeding 1000 precursor-product pairs. Results can be easily output for quantitative comparison of consecutive runs. Additionally MRMer incorporates features that permit the quantitative analysis experiments including heavy and light isotopic peptide pairs. MRMer is open source and provided under the Apache 2.0 license.

Quantitative, multiplexed assays for low abundance proteins in plasma by targeted mass spectrometry and stable isotope dilution

Biomarker discovery produces lists of candidate markers whose presence and level must be subsequently verified in serum or plasma. Verification represents a paradigm shift from unbiased discovery approaches to targeted, hypothesis-driven methods and relies upon specific, quantitative assays optimized for the selective detection of target proteins. Many protein biomarkers of clinical currency are present at or below the nanogram/milliliter range in plasma and have been inaccessible to date by MS-based methods. Using multiple reaction monitoring coupled with stable isotope dilution mass spectrometry, we describe here the development of quantitative, multiplexed assays for six proteins in plasma that achieve limits of quantitation in the 1-10 ng/ml range with percent coefficients of variation from 3 to 15% without immunoaffinity enrichment of either proteins or peptides. Sample processing methods with sufficient throughput, recovery, and reproducibility to enable robust detection and quantitation of candidate biomarker proteins were developed and optimized by addition of exogenous proteins to immunoaffinity depleted plasma from a healthy donor. Quantitative multiple reaction monitoring assays were designed and optimized for signature peptides derived from the test proteins. Based upon calibration curves using known concentrations of spiked protein in plasma, we determined that each target protein had at least one signature peptide with a limit of quantitation in the 1-10 ng/ml range and linearity typically over 2 orders of magnitude in the measurement range of interest. Limits of detection were frequently in the high picogram/milliliter range. These levels of assay performance represent up to a 1000-fold improvement compared with direct analysis of proteins in plasma by MS and were achieved by simple, robust sample processing involving abundant protein depletion and minimal fractionation by strong cation exchange chromatography at the peptide level prior to LC-multiple reaction monitoring/MS. The methods presented here provide a solid basis for developing quantitative MS-based assays of low level proteins in blood.

Protein biomarker discovery and validation: the long and uncertain path to clinical utility

Better biomarkers are urgently needed to improve diagnosis, guide molecularly targeted therapy and monitor activity and therapeutic response across a wide spectrum of disease. Proteomics methods based on mass spectrometry hold special promise for the discovery of novel biomarkers that might form the foundation for new clinical blood tests, but to date their contribution to the diagnostic armamentarium has been disappointing. This is due in part to the lack of a coherent pipeline connecting marker discovery with well-established methods for validation. Advances in methods and technology now enable construction of a comprehensive biomarker pipeline from six essential process components: candidate discovery, qualification, verification, research assay optimization, biomarker validation and commercialization. Better understanding of the overall process of biomarker discovery and validation and of the challenges and strategies inherent in each phase should improve experimental study design, in turn increasing the efficiency of biomarker development and facilitating the delivery and deployment of novel clinical tests.

Liquid chromatography-tandem mass spectrometry assay for human serum testosterone and trideuterated testosterone

A liquid chromatography tandem mass spectrometry assay for serum testosterone (T) and trideuterated testosterone (d(3)T) was developed in order to support clinical research studies that determine the pharmacokinetics, production rate, and clearance of testosterone by administration of trideuterated testosterone. After adding 19-nortestosterone as the internal standard (I.S.), sodium acetate buffer, and ether, to a serum aliquot, the mixture was shaken and centrifuged, and the ether was dried. The extract was reconstituted in methanol and 15 microl was injected into a liquid chromatograph equipped with an autosampler and Applied Biosystems-Sciex API 300 triple quadrupole mass spectrometer operated in the positive ion mode. T, d(3)T, and I.S. were monitored with transitions m/z 289 to m/z 97, m/z 292 to m/z 97, and m/z 275 to m/z 109, respectively. The two calibration curves were linear over the entire measurement range of 0-20 ng/ml for T and 0-2.0 ng/ml for d(3)T. The LOQs for T and d(3)T were 0.5 ng/ml and 0.05 ng/ml. The recoveries for T and d(3)T were 91.5 and 96.4%. For T at 1.25 ng/ml and 4.0 ng/ml, the intra-day precision (RSD, %) was 3.9 and 4.3% and intra-day accuracy 0.01 and 4.5%, respectively. The inter-day precision at these levels was 5.3 and 5.4% and inter-day accuracy was 1.9 and 0.3%. For d(3)T at 0.125 ng/ml and 0.4 ng/ml, the intra-day precision (RSD, %) was 2.8 and 8.3% and intra-day accuracy was 1.8 and 5.6%. The inter-day precision at these levels was 10.0 and 7.6% and inter-day accuracy was 5.7 and 3.4%. The concentrations of T in the 38 healthy subjects ranged from 2.5 to 14.0 ng/ml (mean 6.2 ng/ml).

Quantitative high-throughput analysis of drugs in biological matrices by mass spectrometry

To support pharmacokinetic and drug metabolism studies, LC-MS/MS plays more and more an essential role for the quantitation of drugs and their metabolites in biological matrices. With the new challenges encountered in drug discovery and drug development, new strategies are put in place to achieve high-throughput analysis, using serial and parallel approaches. To speed-up method development and validation, generic approaches with the direct injection of biological fluids is highly desirable. Column-switching, using various packing materials for the extraction columns, is widely applied. Improvement of mass spectrometers performance, and in particular triple quadrupoles, also strongly influences sample preparation strategies, which remain a key element in the bioanalytical process.

Fourier transform ion cyclotron resonance mass spectrometry using atmospheric pressure photoionization for high-resolution analyses of corticosteroids

Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS) was coupled with atmospheric pressure photoionization (APPI) for the first time and used for the analysis of several corticosteroids.1 The analytes showed excellent response using APPI when compared with both electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI). APPI has the advantage of requiring less heat for desolvation, resulting in less thermal degradation of the analytes and higher signal-to-noise than APCI. In terms of ultimate sensitivity, APPI is more efficient than either ESI or APCI for the analysis of corticosteroids. With some compounds, the high-resolution capability of FTICRMS was necessary to obtain an accurate mass due to contributions of the M(+.) (13)C isotope in the [M+H](+) ion peak.

Examination of structurally selective derivatization of vitamin D(3) analogues by electrospray mass spectrometry

The structural specificity of vitamin D derivatization by PTAD (4-phenyl-1,2,4-triazoline-3,5-dione) was probed using synthetic analogues and ion trap mass spectrometry. EB 1089, a vitamin D(3) analogue which contains a second site for Diels--Alder cycloaddition on its side-chain, allowed the examination of derivatization modes and comparisons of ion fragment structures. The origins of a PTAD-vitamin D(3) ion fragment, commonly used in metabolite characterization and quantitation of vitamin D(3) analogues (m/z 314), were established; ion trap mass spectrometry revealed that the PTAD comprises a portion of this diagnostic fragment, and is not lost by a retro-Diels--Alder step. Furthermore, the unique structure of the EB 1089 side-chain also permits facile determination of its side-chain metabolism. Use of PTAD derivatization and detection of metabolite-specific ion fragments identify hydroxylation at the end of the EB 1089 sidechain. It is believed that the results from these studies provide a clearer understanding of the mass spectrometry of triazolinedione derivatives, not only in the specific case of EB 1089, but also in their application to other vitamin D compounds.

Liquid chromatography-mass spectrometry: potential in forensic and clinical toxicology

A relatively limited number of papers concerning applications of liquid chromatography-mass spectrometry (LC-MS) to forensic or clinical toxicology, or analytical methods directly applicable to these topics have been published so far, but their number have greatly increased in the past two years, probably due to technical improvements and to a decrease in the price of such instruments. After a brief presentation and exemplary applications of the interfaces and/or sources proposed in the past for coupling HPLC to mass spectrometry (direct liquid inlet, moving belt, fast atom bombardment and thermospray interfaces), this paper describes electrospray-type and atmospheric pressure chemical ionisation interfaces and their most recent applications in forensic or clinical toxicology. In a third section, the different LC-MS solutions proposed for typical applications in human toxicology, such as the determination of morphine metabolites, LSD and its metabolites and corticosteroids in blood or urine, are reviewed in detail in order to highlight the strengths and weaknesses of each ionisation device and/or analytical method. The last section envisages the new analytical fields opened up by LC-MS in toxicology, regarding mainly peptides, proteins and large molecules, as well as the possible use of LC-MS as a complement to GC-MS for "general unknown" screenings; it also deals with the perspectives concerning technical improvements in ionisation interfaces/sources or mass spectrometers, as well as in sample preparation and liquid chromatography techniques applied to this type of coupling. Though LC-MS is still a relatively new technique in toxicology, on taking into consideration its success so far and owing to the simplification of instruments and concept handling thanks to user-friendly software, it is the authors' opinion that it will become a major success in analytical toxicology in the next few years.

LC/MS applications in drug development

The combination of high-performance liquid chromatography and mass spectrometry (LC/MS) has had a significant impact on drug development over the past decade. Continual improvements in LC/MS interface technologies combined with powerful features for structure analysis, qualitative and quantitative, have resulted in a widened scope of application. These improvements coincided with breakthroughs in combinatorial chemistry, molecular biology, and an overall industry trend of accelerated development. New technologies have created a situation where the rate of sample generation far exceeds the rate of sample analysis. As a result, new paradigms for the analysis of drugs and related substances have been developed. The growth in LC/MS applications has been extensive, with retention time and molecular weight emerging as essential analytical features from drug target to product. LC/MS-based methodologies that involve automation, predictive or surrogate models, and open access systems have become a permanent fixture in the drug development landscape. An iterative cycle of "what is it?" and "how much is there?" continues to fuel the tremendous growth of LC/MS in the pharmaceutical industry. During this time, LC/MS has become widely accepted as an integral part of the drug development process. This review describes the utility of LC/MS techniques for accelerated drug development and provides a perspective on the significant changes in strategies for pharmaceutical analysis. Future applications of LC/MS technologies for accelerated drug development and emerging industry trends are also discussed.

Quantitative subfemtomole analysis of alpha-tocopherol and deuterated isotopomers in plasma using tabletop GC/MS/MS

A rapid, high-selectivity method with subfemtomole sensitivity is reported for quantification of alpha-tocopherol in plasma-based gas chromatography/tandem mass spectrometry (GC/MS/MS) using a tabletop quadrupole ion trap mass spectrometer. Sample workup is rapid, consisting of protein precipitation followed by liquid/liquid extraction and O-trimethylsilyl derivatization of alpha-tocopherol (alpha-T-TMS) and an internal standard, 2,2,5,7,8-pentamethyl-6-chromanol (PC-TMS). Rudimentary chromatography was carried out using an 8-m DB-5 capillary column resulting in an analyte retention time of 7.2 min. No interferences from the plasma matrix were observed. The assay has a detection limit of 178 amol (89.6 fg) and a lower limit of quantification of 700 amol (350 fg) of derivatized alpha-tocopherol in diluted plasma; < 30 pL of plasma is estimated to yield sufficient alpha-tocopherol for quantitative analysis at typical concentrations found in humans. A calibration curve constructed from National Institute of Standards and Technology serum standards was linear in the working range of 1.9-1073 ng/mL (0.95-0.54 ng). Within- and between-day precision averaged 5.8% and did not exceed 11.3% for three concentrations of quality control (QC) solutions. The overall accuracy for the QC samples was within 7.2%. Storage studies showed that, alpha-T-TMS and PC-TMS are stable under conditions that might be encountered during analyses. In a test study, plasma kinetic curves for alpha-tocopherol-d6 and alpha-tocopherol-d3 were obtained for a catheterized pregnant ewe and her fetus who were simultaneously given a bolus injection of alpha-tocopherol-d6, to the ewe and alpha-tocopherol-d3 to the fetus. These data show that a tabletop GC ion trap can determine alpha-T-TMS and its isotopomers quantitatively at high selectivity in a complex matrix.