Plasma For Therapeutic Drug Monitoring Research Articles

Simultaneous determination of icotinib, osimertinib, aumolertinib, and anlotinib in human plasma for therapeutic drug monitoring by UPLC-MS/MS

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) such as icotinib, osimertinib, and aumolertinib have emerged as promising treatment options for EGFR mutated Non-small cell lung cancer (NSCLC) patients. Additionally, anlotinib, an anti-angiogenic agent targeting VEGFR, FGFR, and PDGFR, has been used in combination with EGFR-TKIs in NSCLC cases. A method utilizing ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed and validated for quantifying icotinib, osimertinib, aumolertinib and anlotinib simultaneously in clinical TDM. The chromatographic separation was performed using a Kinetex C18 column (100 mm × 2.1 mm) and an elution gradient of ammonium acetate in water acidified with 0.1 % formic acid and in acetonitrile. The assay was validated over a linear range of 4–2000 ng/mL for icotinib, 2–1000 ng/mL for osimertinib, 1–500 ng/mL for aumolertinib, and 0.8–400 ng/mL for anlotinib, following the guidelines on bioanalytical methods by FDA. The quantification method exhibited satisfactory performance in terms of selectivity, accuracy (from 91.3 % to 107 %), precision (intra- and inter-day coeffficients of variation ranged from 0.944 % to 7.48 %), linearity, recovery (from 86.0 % to 91.9 %), matrix effect (IS-normalized matrix factors were from 96.7 % to 102 %), and stability. Overall, the method proved to be sensitive, reliable, and straightforward, enabling successful simultaneous determination of blood concentrations of icotinib, osimertinib, aumolertinib, and anlotinib in patients. The validity of the method has been confirmed across various instruments.

Digoxin detection for therapeutic drug monitoring using target-triggered aptamer hairpin switch and nicking enzyme-assisted signal amplification.

Digoxin, a cardiac glycoside drug, is commonly used to treat heart failure and arrhythmias. The therapeutic concentration range of digoxin, with a narrow therapeutic index, is between 0.5 and 2.0 ng mL-1. Hence, it is important for patients to monitor their blood levels after taking medication to achieve effective treatment and reduce the likelihood of experiencing drug side effects. Due to the complex steps and high cost of immunoassays, aptasensors that use aptamers to recognize the targets offer the advantages of low cost and good stability over other analysis methods. Nicking enzyme-assisted signal amplification is a novel isothermal signal amplification technology that relies on nicking enzymes to recognize and cleave restriction sites on one oligonucleotide strand. In this study, we develop a fluorescent aptasensor coupled with target-triggered aptamer hairpin switch and nicking enzyme-assisted signal amplification for digoxin detection in plasma for therapeutic drug monitoring. After optimizing the experimental parameters, we design hairpin probes with ten base pairs of the aptamer sequence and extended sequence complement to react with digoxin in a 10 mM Tris buffer containing 150 mM NaCl and 50 mM MgCl2 (pH 7.4). The signal amplification reactions were performed for 3 hours. The fluorescent aptasensor exhibited high sensitivity with a detection limit of 88 pg mL-1 for detecting digoxin in plasma and a linear range from 0.1 ng mL-1 to 5 ng mL-1. This technology was successfully used for digoxin detection to improve treatment effectiveness and minimize the risk of adverse side effects.

Simple and robust LC–MS/MS method for quantification of colistin methanesulfonate and colistin in human plasma for therapeutic drug monitoring

A rapid, simple, and robust LC–MS/MS method was developed and validated for the quantitation of colistin and colistin methanesulfonate (CMS) in human plasma. The method also prevented overestimation of colistin concentration by establishing the stability of CMS under sample preparation conditions, including blood and plasma storage conditions. Polymyxin B1 was used as an internal standard, and positive-ion electrospray ionization in multiple reaction monitoring mode was used for quantification. Chromatographic separation was achieved using a Zorbax eclipse C18 column (3.5 µm, 2.1 mm i.d. × 100 mm), with a flow rate of 0.5 mL/min, 5 μL injection volume, and gradient elution with a mixture of acetonitrile-water (containing 0.1 % trifluoroacetic acid). The method had a quantifiable range of 0.043–8.61 and 0.057–11.39 μg/mL for colistin A and B in human plasma, respectively, under a total runtime of 6.0 min. Further, it demonstrated appropriate extraction efficiency, no significant interference from co-eluting endogenous compounds, and satisfactory intraday and interday precision and accuracy. The proposed procedure for sample preparation successfully addressed the issue of CMS instability, consequently diminishing the probability of overestimating the concentration of colistin. Therefore, this simple and robust LC-MS/MS method for CMS and colistin quantification in human plasma is a valuable tool for clinicians to accurately monitor colistin treatment in patients with infections caused by multidrug-resistant (MDR) Gram-negative bacteria.

Development and Validation of an Ecofriendly, Rapid, Simple and Sensitive UPLC-MS/MS Method for Entrectinib Quantification in Plasma for Therapeutic Drug Monitoring

Entrectinib is an oral selective inhibitor of the neurotrophic T receptor kinase (NTRK). It is used in the treatment of solid tumors in NTRK gene fusion lung cancer. The study aimed to develop and validate an analytical method for quantifying entrectinib plasma by UPLC-MS/MS using quizartinib as an internal standard. The method involves liquid–liquid extraction of entrectinib from plasma using tert butyl methyl ether. The mass-to-charge transitions were 561.23 → 435.1 for entrectinib and 561.19 → 114.1 for quizartinib. The method was successfully validated according to ICH and FDA guidelines. The method has a low quantification limit of 0.5 ng/mL, and the calibration curves constructed over a wide range of 0.5–1000 ng/mL showed good linearity (≥0.997). This method exhibits a tenfold increase in sensitivity compared with the previous method. The method is also accurate, precise, and reproducible, as evidenced by the inter-day and intra-day accuracy and precision values of 82.24–93.33% and 3.64–14.78%, respectively. Principles of green analytical chemistry were considered during all analytical steps to ensure safety. The greenness of the methods was evaluated using two assessment tools. These tools are the Analytical Eco-Scale and the analytical greenness metric approach (AGREE). The results were satisfactory and compatible with the criteria of these tools for green assessment. This method is green, accurate, precise, and reproducible. The method can be used to quantitate entrectinib in plasma and its pharmacokinetics in preclinical, and therapeutic drug monitoring.

Development and Bioanalytical Validation of RP-HPLC Method for the Simultaneous Determination of Perampanel and Carbamazepine in Human Plasma for Therapeutic Drug Monitoring

Development and Bioanalytical Validation of RP-HPLC Method for the Simultaneous Determination of Perampanel and Carbamazepine in Human Plasma for Therapeutic Drug Monitoring

Simultaneous determination of eight antiepileptic drugs and two metabolites in human plasma by liquid chromatography/tandem mass spectrometry

AbstractEpilepsy is one of the most prevalent neurological conditions and antiepileptic drugs are the mainstay of epilepsy treatment. High variation in pharmacokinetic profiles of several antiepileptic drugs highlights the importance of therapeutic drug monitoring to estimate pharmacokinetic properties and consequently individualize drug posology. In this work, a simple, rapid and robust liquid chromatography-tandem mass spectrometry method was developed for simultaneous quantification of carbamazepine and its metabolite carbamazepine-10,11-epoxide, gabapentin, levetiracetam, lamotrigine, oxcarbazepine and its metabolite mono-hydroxy-derivative metabolite, phenytoin, topiramate, and valproic acid in human plasma for therapeutic drug monitoring. d6-Levetiracetam, d4-gabapentin and d6-valproic acid were used as internal standards. After addition of internal standards along with two-step protein precipitation and dilution sample preparation, plasma samples were analyzed on a C18 column using a gradient elution in 5 min without interference. The calibration curves were linear over a 100-fold concentration range, with determination coefficients (r2) greater than 0.99 for all analytes. The limit of quantification was 0.5 μg mL−1 (0.1 μg mL−1 for oxcarbazepine, 2 μg mL−1 for levetiracetam, and 10 μg mL−1 for valproic acid) with precision and accuracy ranging from 3% to 9% and from 94% to 112%, respectively. Intra- and inter-day precision and accuracy values were within 15% at low, medium and high quality control levels. No significant matrix effect was observed in the normal, hemolyzed, lipemic, and hyperbilirubin blood samples. This method was successfully used in the identification and quantitation of antiepileptic drugs in patients undergoing mono- or polytherapy for epilepsy.

Determination of Osimertinib, Aumolertinib, and Furmonertinib in Human Plasma for Therapeutic Drug Monitoring by UPLC-MS/MS.

The third-generation epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs), osimertinib, aumolertinib, and furmonertinib represent a new treatment option for patients with EGFR p.Thr790 Met (T790 M)-mutated non-small cell lung cancer (NSCLC). Currently, there are no studies reporting the simultaneous quantification of these three drugs. A simple ultra-performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for the simultaneous quantitative determination of osimertinib, aumolertinib, and furmonertinib concentrations in human plasma, and it was applied for therapeutic drug monitoring (TDM). Plasma samples were processed using the protein precipitation method (acetonitrile). A positive ion monitoring mode was used for detecting analytes. D3-Sorafenib was utilized as the internal standard (IS), and the mobile phases were acetonitrile (containing 0.1% formic acid) and water with gradient elution on an XSelect HSS XP column (2.1 mm × 100.0 mm, 2.5 µm, Waters, Milford, MA, USA) at a flow rate of 0.5 mL·min−1. The method’s selectivity, precision (coefficient of variation of intra-day and inter-day ≤ 6.1%), accuracy (95.8–105.2%), matrix effect (92.3–106.0%), extraction recovery, and stability results were acceptable according to the guidelines. The linear ranges were 5–500 ng·mL−1, 2–500 ng·mL−1, and 0.5–200 ng·mL−1 for osimertinib, aumolertinib, and furmonertinib, respectively. The results show that the method was sensitive, reliable, and simple and that it could be successfully applied to simultaneously determine the osimertinib, aumolertinib, and furmonertinib blood concentrations in patients. These findings support using the method for TDM, potentially reducing the incidence of dosing blindness and adverse effects due to empirical dosing and inter-patient differences.

Development of a Novel Analytical Method for Determining Trazodone in Human Plasma by Liquid Chromatography Coupled With Mass Spectrometry Coupled With Automatic 2-Dimensional Liquid Chromatograph-Mass Spectrometer Coupler 9500 and Its Application to Therapeutic Drug Monitoring.

Trazodone (TZD) is a tetracyclic serotonin antagonist and reuptake inhibitor that is used as a second-generation phenylpiperazine antidepressant. However, the plasma concentrations of TZD have shown individual variations in clinical practice. Quantification of TZD plasma concentrations may be an effective and valuable method to balance the clinical efficacy and adverse reactions. This study aimed to establish a novel liquid chromatography coupled with mass spectrometry (LC-MS) assay for measuring TZD concentrations in human plasma for therapeutic drug monitoring (TDM). After protein precipitation with acetonitrile, LC-MS quantification of TZD was performed in the multiple reaction monitoring mode with chromatographic separation using a mobile phase of MeOH and 0.1% formic acid in water. This method validation intends to investigate specificity, sensitivity, linearity, precision, accuracy, recovery, matrix effect, and stability according to United states food and drug administration guidelines. This method showed good selectivity because no interfering peaks were observed in the plasma samples during the 2-minute run time. The range of the calibration curve was 1-3000 ng/mL. The detection and quantification limits were 0.3 and 1 ng/mL, respectively. The intraday and interday accuracies were 96.5%-103.4%, with precision relative SD% values of <5%, except for the limit of quality. The mean TZD recovery from human plasma was 95.4%-104.5%. Finally, this method was successfully applied to TDM in 20 patients. The TZD plasma concentrations of the patients ranged between 21.5 and 2267.3 ng/mL. A novel analytical method was established to measure TZD by LC-MS coupled with an automatic 2-dimensional liquid chromatograph mass spectrometer coupler 9500 (LC-MS/MS-Mate 9500), which is superior to the ordinary LC-MS system in separation, transport, anti-interference, sensitivity, and quantitative analysis stability.

A novel and robust analytical method for the quantification of perospirone in human plasma using an LC–MS/MS system with self-internal standard calibration

ObjectivesThis study aims to establish a novel method for measuring perospirone in human plasma for therapeutic drug monitoring (TDM) by liquid chromatography–mass spectrometry (LC–MS) coupled with an automatic liquid chromatograph mass spectrometer coupler 9500 (LC–MS/MS-Mate 9500), which has been equipped with self-internal standard (SIS) calibration technology. Design & methodsA novel and attractive analytical calibration method designed for perospirone, calibration with SIS, was reported. After protein precipitation with acetonitrile-cyclopentanol (9:1, v/v) containing 1% NH3·H2O, LC–MS quantification of perospirone was performed by multiple reaction monitoring in the positive mode with quantitative and qualitative analysis of the ion pairs m/z 427.30 → 177.15 and 427.30 → 166.15 for perospirone and SIS. Chromatographic separation was accomplished in < 2.0 min on an Hypersil GOLDTM C18 column (2.1 mm × 50 mm, 3.0 μm) using a mobile methanol phase and 0.1% formic acid in water. ResultsThis method showed good selectivity because no interfering peaks were observed in the plasma samples during the 2.0-min run time. The calibration curve range was 0.05–20 ng/mL, with a correlation coefficient of ≥ 0.9995. Intraday and interday accuracies were 98.3%–107.9%, respectively, with precision relative standard deviation values of < 10%. The matrix effects ranged from 92.7% to 96.1%, and extraction recoveries were between 97.3% and 108.8%. Finally, this method was successfully applied to routine clinical TDM for 142 patients. The perospirone plasma concentrations of the patients ranged between 0.07 and 10.96 ng/mL. ConclusionsThis bioanalytical method can be used for the quantification of perospirone in human plasma by LC–MS/MS-Mate 9500 using perospirone itself as the SIS.

A rapid, simple and sensitive LC-MS/MS method for lenvatinib quantification in human plasma for therapeutic drug monitoring.

Lenvatinib (LENVA) is an oral antineoplastic drug used for the treatment of hepatocellular carcinoma and thyroid carcinoma. LENVA therapeutic drug monitoring (TDM) should be mandatory for a precision medicine to optimize the drug dosage. To this end, the development of a sensitive and robust quantification method to be applied in the clinical setting is essential. The aim of this work was to develop and validate a sensitive, rapid, and cost-effective LC-MS/MS method for the quantification of LENVA in human plasma. On this premise, sample preparation was based on a protein precipitation and the chromatographic separation was achieved on a Synergi Fusion RP C18 column in 4 min. The method was completely and successfully validated according to European Medicines Agency (EMA) and Food and Drug Administration (FDA) guidelines, with good linearity in the range of 0.50–2000 ng/mL (R≥0.9968). Coefficient of variation (CV) for intra- and inter-day precision was ≤11.3% and accuracy ranged from 96.3 to 109.0%, internal standard normalized matrix effect CV% was ≤2.8% and recovery was ≥95.6%. Successful results were obtained for sensitivity (signal to noise (S/N) ratio >21) and selectivity, dilution integrity (CV% ≤ 4.0% and accuracy 99.9–102%), and analyte stability under various handling and storage conditions both in matrix and solvents. This method was applied to quantify LENVA in patient’s plasma samples and covered the concentration range achievable in patients. In conclusion, a sensitive and robust quantification method was developed and validated to be applied in the clinical setting.

Quantification of sorafenib, lenvatinib, and apatinib in human plasma for therapeutic drug monitoring by UPLC-MS/MS

Sorafenib, lenvatinib, and apatinib, as multi-targeted tyrosine kinase inhibitors with anti-proliferative and anti-angiogenic effects, are widely used for systemic therapy in advanced hepatocellular carcinoma patients. Nevertheless, insufficient efficacy or adverse effects often appear due to the significant inter-individual variability of plasma concentration for these drugs. In order to carry out therapeutic drug monitoring of these drugs and then ensure the effectiveness and safety of the medical treatment, the first method allowing to quantify sorafenib, lenvatinib, and apatinib simultaneously in human plasma was developed in this study. The analysis was performed by UPLC-MS/MS system and the chromatographic separation was achieved on a C18 column using a gradient elution of water-acetonitrile in 3.5 min. This method presented satisfactory results in terms of specificity, precision (coefficient of variation of intra-day and inter-day:1.4–6.6 %), accuracy (92.6–105.4 %), matrix effects (96.9–107.2 %), extraction recovery (90.5–99.4 %), as well as stability in human plasma and even whole blood under certain conditions. This sensitive, rapid and simple method was successfully applied to the analysis of sorafenib, lenvatinib and apatinib for therapeutic drug monitoring in hepatocellular carcinoma patients, and it was expected to be applied to further study about clarifying the concentration- efficacy and concentration-toxic relationship of sorafenib, lenvatinib, and apatinib in hepatocellular carcinoma patients.

A novel GC–MS assay method for the therapeutic drug monitoring of the atomoxetine

Atomoxetine is used commonly treatment of attention deficit hyperactivity disorder in children, adolescents, and adults. A validated GC–MS assay for the quantitation of atomoxetine in human plasma is presented in the study. The assay method is the first GC–MS-based method reported for the analysis of atomoxetine in plasma for therapeutic drug monitoring. The method has rapid analysis time and simple sample preparation. Atomoxetine and internal standard (IS) pseudoephedrine were extracted from plasma using a liquid-liquid extraction method. The assay method was validated according to the European Medicines Agency (EMA) Guideline on bioanalytical method validation. The lower limit of quantitation of the developed method was 200 ng/mL for atomoxetine. The calibration curve of atomoxetine was between 200 and 2000 ng/mL with showing correlation coefficients >0.99. Also, the method was applied to real patient’s plasma.

Method Development and Validation for Simultaneous Determination of Six Tyrosine Kinase Inhibitors and Two Active Metabolites in Human Plasma Using UPLC–MS/MS for Therapeutic Drug Monitoring

Over the past decades, therapeutic drug monitoring (TDM) of tyrosine kinase inhibitors (TKIs) and their main active metabolites has shown benefits in improving treatment efficacy and safety. Therefore, a sensitive, simple and economical ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for the determination of six oral tyrosine kinase inhibitors (TKIs) and two active metabolites, including imatinib (IMA), N-desmethyl imatinib (NDIMA), sunitinib (SUNI), N-desethyl sunitinib (NDSUNI), regorafenib (REGO), nilotinib (NILO), dasatinib (DASA) and osimertinib (OSI) in human plasma for therapeutic drug monitoring. The plasma samples were deproteinated with acetonitrile after spiking with two deuterated internal standards (ISs, [ 2 H 8 ]-imatinib and [ 2 H 10 ]-sunitinib) and separated on a 40 °C ACQUITY UPLC® BEH C 18 column (1.7 μm, 2.1 mm×50 mm). The mobile phase was composed of acetonitrile (solution A) and water-formic acid-ammonium acetate (1M)(994:1:5, v/v/v, solution B). Gradient elution was applied at a flow rate of 0.4 mL/min. Detection was carried out using a Triple Quad 5500 tandem mass spectrometer coupled with an electrospray ionization (ESI) source in positive mode. The method was validated over the calibration curve (CV) range of 2-400 ng/mL for NDSUNI and DASA, 2.5-500 ng/mL for SUNI, 10-2000 ng/mL NDIMA and OSI, 20-4000 ng/mL for NILO, 30-6000 ng/mL for REGO and 50-10000 ng/mL for IMA using linear regression and 1/x 2 weighting. No difference was observed in the matrix effect (ME) among blank human plasma, hemolytic plasma and lipemic plasma samples in general. And the intra- and inter-batch precision and accuracy of all eight components were acceptable. To provide a clinical reference for the operation, the stability of the whole process from sample collection to drug detection was verified. SUNI and NDSUNI showed obvious photoisomerization under light exposure. Therefore, strict light protection was applied for all sample collection and handling steps of SUNI and NDSUNI. Compared with heparin anticoagulant tubes, the stability of the eight compounds in both whole blood and plasma was better in K3-EDTA and sodium citrate anticoagulant tubes. Given that all the analytes were stable in plasma at 4 °C for 48 h and in whole blood at room temperature for 48 h but OSI and REGO were unstable in whole blood and plasma at room temperature, samples should be centrifuged as soon as possible to be preserved as plasma at 4 °C when OSI or REGO is detected. In conclusion, this validated method can provide support for clinical practice, such as therapeutic drug monitoring (TDM) and pharmacokinetic studies of these six TKIs and two active metabolites.

Rapid determination of remdesivir (SARS-CoV-2 drug) in human plasma for therapeutic drug monitoring in COVID-19-Patients

To tackle the harmful consequences of the widespread COVID-19 pandemic, a broad-spectrum anti-viral drug remdesivir (RDV) has gained the utmost attention recently due to its promising application in treating COVID-19 patients. However, a fast and sensitive analytical methodology is important to monitor RDV drug profile in human plasma for pharmacokinetics (PK) and therapeutic drug monitoring (TDM). In this study, we demonstrate an improved vortex-assisted salt-induced liquid-liquid microextraction (VA-SI-LLME) technique coupled with UHPLC-PDA and UHPLC-MS/MS for rapid determination of RDV in human plasma. This technique involves simple one-step protein precipitation with hydrochloric acid and subsequent extraction with acetonitrile for analysis. Under the optimal VA-SI-LLME conditions (500 μL of acetonitrile with 2.5 g ammonium sulfate under 2 min vortex extraction), method validation results indicated an excellent correlation coefficient of 0.9969 for UHPLC-PDA (monitored at 254 nm) and 0.9990 for UHPLC-MS/MS (monitored at electrospray ionization with + ion mode transitions of m/z 603.1→m/z 402.20 and m/z 603.1→ m/z 199.90). The detection and quantification limits were 1.5 and 5 ng/mL for UHPLC/PDA, and 0.3 and 1 ng/mL for UHPLC-MS/MS, respectively. The developed method showed excellent extraction recoveries between 90.79–116.74 % and 85.68–101.34 % with intraday and interday precision ≤ 9.59 for both methods. These results proved that the developed method is a simple, fast, and sensitive analytical method that can be applied as a standard analytical tool for PK and TDM studies of RDV in clinical trials during the current worldwide outbreak.

Development and Validation of a Quantitative Determination Method for Meropenem in Blood Plasma for Therapeutic Drug Monitoring

The development of an HPLC method for quantitative determination of meropenem in human blood plasma for therapeutic drug monitoring in clinics is reported. Spectrophotometric detection was made at 298 nm. The chromatography time was 12 min. The method was validated for the basic parameters and was linear over a wide concentration range (from 0.2 to 150 ig/mL). The lower limit of quantitation was 0.2 ig/mL, which provided the required method sensitivity. The correlation coefficient of the calibration curve was 0.9998. The developed method was shown to be applicable for real-time monitoring of the meropenem content in patient blood plasma, which allowed the dose to be personalized and the efficacy and rationality of the antibacterial therapy to be increased.

Ready for TDM: Simultaneous quantification of amikacin, vancomycin and creatinine in human plasma employing ultra-performance liquid chromatography-tandem mass spectrometry

BackgroundAmikacin (AMI) and vancomycin (VAN) are antibiotics largely used in intensive care in the empiric treatment of severe infections by multi-resistant gram-negative and gram-positive bacteria. AMI and VAN are eliminated untransformed by glomerular filtration, showing depuration ratio highly correlated with creatinine (CRE) clearance. AMI, VAN and CRE are highly polar structures, presenting poor retention in reversed-phase liquid chromatography when using conventional stationary phases. ObjectiveThis study aimed to develop and validate a simple UPLC-MS/MS method for simultaneous determination of AMI, VAN, and CRE in human plasma for therapeutic drug monitoring. ResultsSamples were prepared by protein precipitation, followed by dilution. Heptafluorobutyric acid (HFBA) was added to the mobile phase at low concentration (0.01%), and separation was performed in an ultra-performance reversed-phase column (particle diameter of 1.8 μm). These conditions allowed retention times of 0.92, 0.93, 2.12, 2.17 and 2.27 min for CRE, CRE-D3, AMI, KAN and VAN, respectively. The assay was linear from 0.5 to 100 mg L−1 for AMI and VAN and 5 to 100 mg L−1. Precision, accuracy and stability assays were acceptable according to bioanalytical validation guidelines. Suitable results. Matrix effects were in the range of +10.5 to +11.6% for AMI, −4.3 to −4.5% for VAN, and − 1.7 to +0.7 for CRE. ConclusionThe first assay for the simultaneous determination of AMI, VAN and CRE in plasma by liquid chromatography-tandem mass spectrometry was reported. This assay allows the obtention of the necessary analytical data for the clinical application of population pharmacokinetic methods for therapeutic drug monitoring of AMI and VAN.

Rapid Homogeneous Immunoassay to Quantify Gemcitabine in Plasma for Therapeutic Drug Monitoring

Gemcitabine (2',2'-difluoro-2'-deoxycytidine) is a nucleoside analog used as a single agent and in combination regimens for the treatment of a variety of solid tumors. Several studies have shown a relationship between gemcitabine peak plasma concentration (Cmax) and hematological toxicity. An immunoassay for gemcitabine in plasma was developed and validated to facilitate therapeutic drug monitoring (TDM) by providing an economical, robust method for automated chemistry analyzers. A monoclonal antibody was coated on nanoparticles to develop a homogenous agglutination inhibition assay. To prevent ex vivo degradation of gemcitabine in blood, tetrahydrouridine was used as a sample stabilizer. Validation was conducted for precision, recovery, cross-reactivity, and linearity on a Beckman Coulter AU480. Verification was performed on an AU5800 in a hospital laboratory. A method comparison was performed with (LC-MS/MS) liquid chromatography tandem mass spectrometry using clinical samples. Selectivity was demonstrated by testing cross-reactivity of the major metabolite, 2',2'-difluorodeoxyuridine. Coefficients of variation for repeatability and within-laboratory precision were <8%. The deviation between measured and assigned values was <3%. Linear range was from 0.40 to 33.02 μ/mL (1.5-125.5 μM). Correlation with validated LC-MS/MS methods was R = 0.977. The assay was specific for gemcitabine: there was no cross-reactivity to 2',2'-difluorodeoxyuridine, chemotherapeutics, concomitant, or common medications tested. Tetrahydrouridine was packaged in single-use syringes. Gemcitabine stability in whole blood was extended to 8 hours (at room temperature) and in plasma to 8 days (2-8°C). The assay demonstrated the selectivity, test range, precision, and linearity to perform reliable measurements of gemcitabine in plasma. The addition of stabilizer improved the sample handling. Using general clinical chemistry analyzers, gemcitabine could be measured for TDM.

Rapid liquid chromatography tandem mass spectrometry determination of rivaroxaban levels in human plasma for therapeutic drug monitoring

Abstract A rapid, sensitive, high-throughput liquid chromatography coupled with tandem mass spectrometry method for the quantification of rivaroxaban from human plasma has been developed and validated. For the analytical separation a Zorbax SB-C18 column with isocratic flow of mobile phase composed of 0.2% formic acid in water and acetonitril (65:35, V/V) with a flow rate of 1 mL/min at a temperature of 45ºC was used. Detection of rivaroxaban was performed using positive electrospray ionization and MS/MS mode (sum of m/z 231.1; 289.2 and 318.2 from m/z 436.3). Plasma samples were prepared using single-step protein precipitation with methanol. Method validation was performed with regards to selectivity, linearity (r &gt;0.9927), within-run and between-run precision (CV&lt; 13.1 %) and accuracy (bias&lt; 9.4 %) over a concentration range of 24.00 - 960.00 ng/mL plasma. Recovery was between 96.5 - 108.5% and the lower limit of quantification of rivaroxaban was 24.00 ng/mL. The developed method is simple, rapid, and selective, requires small plasma sample volumes, and was successfully applied for therapeutic drug monitoring of rivaroxaban in treated patients.

ANALYSIS OF 4-HYDROXYCYCLOPHOSPHAMIDE IN CANCER PATIENTS PLASMA FOR THERAPEUTIC DRUG MONITORING OF CYCLOPHOSPHAMIDE

&lt;p&gt;&lt;strong&gt;Objective&lt;/strong&gt;&lt;strong&gt;:&lt;/strong&gt;&lt;strong&gt; &lt;/strong&gt;To quantify 4-hydroxycyclophosphamide in cancer patients’ plasma for therapeutic drug monitoring of cyclophosphamide.&lt;strong&gt;&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods&lt;/strong&gt;&lt;strong&gt;:&lt;/strong&gt;&lt;strong&gt; &lt;/strong&gt;The blood was collected at 0.5 and 1 h after administration of chemotherapy. Prior to analysis, 4-OHCP in plasma was derivatized with semicarbazide HCl, then was extracted using 4 ml ethyl acetate and finally was determined by Ultra High-Performance Liquid Chromatography–tandem mass spectrometry. Chromatographic separation was conducted using waters acquity BEH C18 column (1.7 μm; 50 mm x 2.1 mm). The mobile phase consisted of formic acid 0.1% and methanol (50: 50, v/v), column temperature 30 °C and flow rate of 0.3 ml/min. Mass detection was performed on waters xevo TQD equipped with an electrospray ionization (ESI) source at positive ion mode in the multiple reaction monitoring (MRM). Cyclophosphamide was detected at m/z 260.968&amp;gt;139.978, 4-hydroxycyclophosphamide-semicarbazide at m/z 338.011&amp;gt;224.97, and hexamethylphosphoramide as internal standard at m/z 180.17&amp;gt;92.08.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results&lt;/strong&gt;&lt;strong&gt;:&lt;/strong&gt;&lt;strong&gt; &lt;/strong&gt;The method was linear in the range of 5–1000 ng/ml for cyclophosphamide and also for 4-hydroxycyclophosphamide. The results showed that the level of 4-OHCP in 39 cancer patients was in the range of 5.02 ng/ml to 832.44 ng/ml.&lt;strong&gt;&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusion: &lt;/strong&gt;4-hydroxycyclophosphamide was detected on 39 patient samples with the lowest level of 5.40ng/ml and the highest level was 832.44 ng/ml. This can be a parameter that the regiment of cyclophosphamide was effective.&lt;/p&gt;

Simultaneous determination of seven β-lactam antibiotics in human plasma for therapeutic drug monitoring and pharmacokinetic studies.

There is strong evidence in literature supporting the benefit of monitoring plasma concentrations of β-lactam antibiotics in the critically ill to ensure appropriateness of dosing. The objective of this work was to develop a method for the simultaneous determination of total concentrations piperacillin, benzylpenicillin, flucloxacillin, meropenem, ertapenem, cephazolin and ceftazidime in human plasma. Sample preparation involved protein precipitation with acetonitrile containing 0.1% formic acid and subsequent dilution of supernatant with 0.1% formic acid in water. Chromatographic separation was achieved on a reversed phase column (C18, 2.6 μm, 2.1 × 50 mm) via gradient elution using water and acetonitrile, each containing 0.1% formic acid, as mobile phase. Tandem mass spectrometry (MSMS) analysis was performed, after electrospray ionization in the positive mode, with multiple reaction monitoring (MRM). The method is accurate with the inter-day and intra-day accuracies of quality control samples (QCs) ranging from 95 to 107% and 95 to 108%, respectively. It is also precise with intra-day and inter-day coefficient of variations ranging from 4 to 12% and 5 to 14%, respectively. The lower limit of quantification was 0.1 μg/mL for each antibiotic except flucloxacillin (0.25 μg/mL). Recovery was greater than 96% for all analytes except for ertapenem (78%). Coefficients of variation for the matrix effect were less than 10% over the six batches of plasma. Analytes were stable over three freeze-thaw cycles, and for reasonable hours on the bench top as well as post-preparation. This novel liquid chromatography tandem mass spectrometry method proved accurate, precise and applicable for therapeutic drug monitoring and pharmacokinetic studies of the selected β-lactam antibiotics.