Pharmacokinetic Application Research Articles

Development of a UHPLC-MS/MS Method for the Determination of Moxidectin in Rat Plasma and Its Application in Pharmacokinetics.

The aim of the present study was to establish a simple and reliable ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method and apply it for the determination of pharmacokinetics of moxidectin-loaded microspheres (MOX-MS) in rats. Plasma samples were processed using a simplified liquid-liquid extraction method and were separated using an Agilent Zorbax Eclipse Plus C18 column (50 mm × 2.1 mm, 1.8 μm) with a mobile phase consisting of a 10 mM ammonium formate solution with 0.1% formic acid (A) and acetonitrile (B) at a flow rate of 0.4 mL/min for 5 min. Avermectin B1a was used as an internal standard (IS). The sample was injected at a volume of 10 μL with a column temperature of 35 °C and detected in a positive ion mode. A good linear response across the concentration range of 1.00-200 ng/mL (r2 > 0.99) and a lower limit of quantification (LLOQ) of 1.00 ng/mL were achieved. The extraction recovery of moxidectin exceeded 94.1%, the matrix effect was between 91.2% and 96.2%, the accuracy ranged from 100.1 to 103.6%, and the relative standard deviation (RSD) did not exceed 15% for the intra- and inter-day accuracy and precision. The pharmacokinetic results showed that MOX-MS significantly decreased Cmax, prolonged T1/2, and improved bioavailability. The developed method significantly reduced the assay volume, shortened detection time, simplified sample processing methods and saved assay costs, which may contribute to the development of the new antiparasitic drug.

UPLC-MS/MS analysis of axitinib and pharmacokinetic application in beagle dogs

ObjectiveTo develop a method for determining the concentration of axitinib in beagle dog plasma and utilize this method to investigate the pharmacokinetics of orally administered axitinib in beagle dogs. MethodsPlasma samples were processed using acetonitrile precipitation and analyzed by UPLC-MS/MS with sunitinib as an internal standard (IS). Chromatographic separation was achieved on a Waters Acquisition UPLC BEH C18 column (50 mm × 2.1 mm, 1.7 μm) with a gradient elution of acetonitrile and 0.1 % formic acid. Mass spectrometry uses an electrospray ion source for positive ion detection in a multiple reaction monitoring mode. The monitored ion transitions for axitinib and sunitinib were m/z 387 → 355.96 and m/z 399.3 → 282.96, respectively. Six beagle dogs were administered 0.33 mg/kg of axitinib orally, and venous blood samples were collected at 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12, and 24 h post-dose for pharmacokinetic analysis. ResultsThe assay demonstrated a linear range of 0.5–100 ng/mL (r2 = 0.9992), and the lower limit of quantification was up to 0.5 ng/mL. Precision, as assessed by relative standard deviation (RSD), was within 8.64 % for both intraday and interday variability. The relative error (RE) for precision from −2.77 %–1.20 %. The recovery rate of the analytes exceeded 85.28 % and the matrix effect was approximately 100 %. Plasma samples maintained stability under various conditions, including room temperature storage for 12 h, processed on an automatic sampler at 4 °C for 6 h, three freeze-thaw cycles, and long-term storage at −80 °C for 60 days. Pharmacokinetic parameters were determined using DAS 2.0 software, revealing a half-life (T1/2) of 6.05 h and an area under the curve (AUC (0 →∞)) of 97.13 ng h/mL for axitinib. ConclusionsThe UPLC-MS/MS method developed in this study offers high specificity, rapid analysis, high recovery, excellent linearity, and minimal plasma volume requirements, making it well-suited for pharmacokinetic and drug interaction studies in beagles dogs.

LC-MS/MS method for simultaneous Doxorubicin and Baicalein estimation: formulation and pharmacokinetic applications.

Aim & objective: Combinatorial delivery of Doxorubicin (DOX) and Baicalein (BAC) has a potential to improve breast cancer treatment by mitigating the cardiotoxicity induced by DOX. The nanoformulation has been optimized and subjected to pharmacokinetic studies using LC-MS/MS.Materials & methods: Nanoformulation bearing DOX and BAC was optimized using quality by design approach and method validation was done following USFDA guidelines.Results: The particle size, PDI and zeta potential of developed nanoformulation were 162.56±2.21nm, 0.102±0.03 and -16.5±1.21mV, respectively. DOX-BAC-SNEDDs had a higher AUC0-t values of 6128.84±68.71 and 5896.62±99.31ng/mL/h as compared with DOX-BAC suspension.Conclusion: These findings hold promise for advancing breast cancer treatment and facilitating therapeutic drug monitoring.

Proper retention factor for Avanafil and Dapoxetine Hydrochloride Separation and Validation with RP-HPLC in Bulk, Dosage Form and Rat Plasma; Validation, Degradation, and Pharmacokinetic Application

Proper retention factor for Avanafil and Dapoxetine Hydrochloride Separation and Validation with RP-HPLC in Bulk, Dosage Form and Rat Plasma; Validation, Degradation, and Pharmacokinetic Application

Bioanalytical Method Development and Validation and forced degradation of Sitagliptin and determination of Pharmacokinetic application study in Human Plasma by RP-HPLC method

In the present investigation, an attempt was made for the development, validation, forced degradation and pharmacokinetic application of sitagliptin in the human plasma spiking studies by UV - HPLC method. The experimentation was developed based on the extensive literature survey and ascertained by the statistical parameters of the sampling. A simplified, accurate method was created by the liquid chromatographic system from Shimadazu LC 20AD consisting of manual injection. The optimized chromatogram was obtained with acetonitrile in the isocratic mobile phase method at a 1.0 mL/min flow rate. A thermo C-8 column (4.6X250mm,5μm) was used as a stationary phase, and 265.0nm was selected as the detection wavelength with the aid of a UV-Vis detector. The proposed method was validated as per ICH guidelines. The technique was linear in the range of 10-50μg/mL with correlation coefficient R2 = 0.9746, respectively. Recovery studies postulated that % RSD 19.14, 3 & 9.95 respectively. Injection repeatability values were found to be % RSD 17 & 10.63 for intraday and interday, respectively. Stress degradation studies revealed that sitagliptin degrades more rapidly when subjected to 0.1 NaoH. Human plasma spiking studies reported 3.02 ng/mL at 3.02+/-60 min of C and T max, respectively. Keywords: Sitagliptin, Method development, HPLC, Validation, Stress degradation studies, Human plasma spiking studies

Adapting Fabric Phase Sorptive Extraction as an Innovative Multitool for Sample Transfer and Extraction in Pharmacokinetic Analysis Followed by LC-MS Determination of Levofloxacin in Plasma Samples.

Fabric phase sorptive extraction (FPSE) is a simple microextraction technique that allows analytes to be rescued from matrix components while using a small volume of samples to analyze complex biological systems. This study used FPSE as a microextraction tool and a sample storage and transfer device. Levofloxacin as a model molecule was applied intravenously (IV) to New Zealand male rabbits. The samples were simultaneously extracted by using FPSE and protein precipitation methods. The final solutions were analyzed using LC-MS equipped with an ACE C18 LC Column (150 mm × 4.6 mm, 5 μm) at 25 °C employed in isocratic elution mode using solution A (0.1% formic acid in water)/solution B (0.1% formic acid in acetonitrile) (80:20, v/v). The total analysis time was less than 15 min. The developed method was validated using the ICH M10 bioanalytical method validation and study sample analysis guidelines. The results obtained using FPSE were statistically identical to those obtained using protein precipitation. The plasma samples applied onto FPSE (10 μL onto 1.0 cm × 1.0 cm Biofluid Sampler) were stored in three different temperatures [refrigerator (2-8 °C), at ambient temperature (20 ± 5 °C), and in the stability cabinet (40 °C, 75% humidity)] and three different storage conditions (Eppendorf tubes, plastic containers, and straw paper envelopes). Levofloxacin in plasma samples adsorbed by FPSE biofluid sampler remained stable at 2-8 °C in Eppendorf tubes for at least 1 week. This study showed that FPSE could be used as a sample storage and transfer device for pharmacokinetic applications that need to work with small sample volumes and discard aggressive cold chains to store and transfer the plasma samples.

The Validation and Determination of Empagliflozin Concentration in the Presence of Grapefruit Juice Using HPLC for Pharmacokinetic Applications.

Type 2 diabetes mellitus is a multifactorial disorder whose primary manifestation usually initiates with elevated blood sugar levels. Several antidiabetic agents are used to manage type 2 diabetes mellitus, of which empagliflozin is an oral sodium-glucose co-transporter (SGLT-2) inhibitor in the kidney. This research aims to develop and validate a simple analytical method for determining empagliflozin levels in biological fluid and to further evaluate grapefruit juice's impact on empagliflozin pharmacokinetics in rats. High-Performance Liquid Chromatography (HPLC) was used to establish a simple, rapid, and accurate method for determining empagliflozin levels in rat plasma, in the presence of grapefruit juice. Four groups of rats (n = 10 rats in each) were used in the preclinical study. Group A (healthy rats) received empagliflozin alone; Group B (healthy rats) received empagliflozin with grapefruit; Group C (diabetic rats) received empagliflozin with grapefruit; and Group D (healthy, negative control) received no medication. The rats (n = 10) were given grapefruit juice instead of water for seven days before receiving the empagliflozin dose (0.16 mg/kg). Some pharmacokinetic parameters for each group were determined. The maximum plasma concentration (Cmax) and area under the curve (AUC) of empagliflozin in Group A without grapefruit intake were 730 ng/mL and 9264.6 ng × h/mL, respectively, with Tmax (2 h). In Group B, Cmax was 1907 ng/mL and AUC was 10,290.75 ng × h/mL in the presence of grapefruit, with Tmax (1 h); whereas, in Group C, the Cmax was 2936 ng/mL and AUC was 18657 ng × h/mL, with Tmax (2 h). In conclusion, our results showed that the co-administration of grapefruit with empagliflozin should be cautiously monitored and avoided, in which grapefruit elevates the plasma level of empagliflozin. This may be attributed to the inhibition of the uridine enzyme in the grapefruit by hesperidin, naringin, and flavonoid.

A spectrofluorimetric approach for the quantification of naringin in biological fluids: Method development, validation and pharmacokinetic applications

Naringin (NAR), a 4′,5,7-trihydroxyflavanone-7-rhamnoglucoside, is a prominent flavanone glycoside that has demonstrated promising therapeutic potential in both preclinical studies and clinical trials. However, its limited bioavailability has hindered its clinical translation as a medicine. To advance its therapeutic application and gain insights into its pharmacokinetic behavior in the body, it is essential to investigate the biotransformation of NAR in serum or biological fluids using suitable bioanalytical methods. In this research, we aimed to develop and validate a simple, sensitive, and time-saving 96-well plate spectrofluorometric method for accurately determining NAR levels in a biological fluid. The newly devised quantification method was employed to estimate pharmacokinetic (PK) parameters after administering NAR oral doses of 100 mg/kg to rats. This method demonstrated excellent linearity within the concentration range of 10–100 ng/ml, boasting an impressive r2 value of ≥ 0.9989 for spectrofluorimetric analysis. The study results indicated that NAR exhibited an AUC0-∞ of 73.21 ± 18.42 (ng.hr/ml) and a t1/2 of 4.53± 1.20 hr in plasma. Overall, our research successfully established and validated a reliable spectrofluorimetric method for quantifying NAR in biological fluids.

Bayesian estimation in veterinary pharmacology: A conceptual and practical introduction.

Sophisticated mathematical and computational tools have become widespread and important in veterinary pharmacology. Although the theoretical basis and practical applications of these have been widely explored in the literature, statistical inference in the context of these models has received less attention. Optimization methods, often with frequentist statistical inference, have been predominant. In contrast, Bayesian statistics have not been widely applied, but offer both practical utility and arguably greater interpretability. Veterinary pharmacology applications are generally well supported by relevant prior information, from either existing substantive knowledge, or an understanding of study and model design. This facilitates practical implementation of Bayesian analyses that can take advantage of this knowledge. This essay will explore the specification of Bayesian models relevant to veterinary pharmacology, including demonstration of prior selection, and illustrate the capability of these models to generate practically useful statistics, including uncertainty statements, that are difficult or impossible to obtain otherwise. Case studies using simulated data will describe applications in clinical trials, pharmacodynamics, and pharmacokinetics, all including multilevel modeling. This content may serve as a suitable starting point for researchers in veterinary pharmacology and related disciplines considering Bayesian estimation for their applied work.

Development of an UPLC-MS/MS method for quantitative analysis of abexinostat levels in rat plasma and application of pharmacokinetics

Broad-spectrum histone deacetylase inhibitors (HDACi) have excellent anti-tumor effects, such as abexinostat, which was a novel oral HDACi that was widely used in clinical treatment. The purpose of this study was to establish a rapid and reliable method for the detection of abexinostat concentrations in rat plasma using ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). The mobile phase we used was acetonitrile and 0.1% formic acid, and the internal standard (IS) was givinostat. Selective reaction monitoring (SRM) was used for detection with ion transitions at m/z 397.93 → 200.19 for abexinostat and m/z 422.01 → 186.11 for givinostat, respectively. The intra-day and inter-day precision of abexinostat were less than 11.5% and the intra-day and inter-day accuracy ranged from − 10.7% to 9.7% using this method. During the analysis process, the stability of the test sample was reliable. In addition, the recovery and matrix effects of this method were within acceptable limits. Finally, the method presented in this paper enabled accurate and quick determination of abexinostat levels in rat plasma from the pharmacokinetic study following gavage at a dose of 8.0 mg/kg abexinostat.

Optimized LC-MS/MS method for quantifying insulin degludec and liraglutide in rat plasma and Tissues: Application in pharmacokinetics and biodistribution

We present an ultra-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for simultaneous detection of insulin degludec (I-Deg) and liraglutide (LIRA) in rat plasma and tissues, characterized by its sensitivity and selectivity. Chromatographic separation was achieved using an Acquity UPLC BEH C18 column, leveraging a mobile phase of acetonitrile and water (both with 0.1 % formic acid) under gradient elution over a run time of 7.5 min. The mass spectrometer operated in positive electrospray ionization multiple reaction monitoring (MRM) mode, tracking transitions of m/z 1221.6 → 641.6 for I-Deg, m/z 938.7 → 1064.1 for LIRA, and m/z 1184.7 → 454.4 for the internal standard. Validation ranged from 5 to 100 ng/mL, exhibiting robust linearity (r2 > 0.99) and limits of detection (LOD) of 1.63–2.02 ng/mL for I-Deg and 0.96–1.62 ng/mL for LIRA. Limits of quantification (LOQ) were 2.38–4.76 ng/mL for I-Deg and 3.22–4.40 ng/mL for LIRA. Notably, no significant matrix effects were detected. Stability was confirmed under various conditions, and precision metrics (intraday RSD 1.68–8.05 % for I-Deg and 1.11–7.69 % for LIRA; interday RSD 1.39–8.61 % for I-Deg and 1.06–8.83 % for LIRA) alongside accuracy (90.5–114.9 % for I-Deg and 92.7–113.7 % for LIRA) were within acceptable ranges. The method was successfully applied to pharmacokinetic and biodistribution studies following simultaneous subcutaneous administration of LIRA and I-Deg in rats.

Decitabine enclosed biotin-zein conjugated nanoparticles: synthesis, characterization, in vitro and in vivo evaluation.

Aim: This study focuses on biotinylated nanocarriers designed to encapsulate amphiphilic molecules with self-biodegradable properties for enhanced drug delivery.Methods: Biotin-zein conjugated nanoparticles were synthesized and tested in C6 cell lines to evaluate their viability and cellular uptake. Optimization was achieved using a acentral composite design. The nanoparticles underwent thermogravimetric analysis, and their pharmacokinetics and biodistribution were also studied.Results: The optimized nanoparticles displayed 96.31% drug encapsulation efficiency, a particle size of 95.29nm and a zeta potential of -17.7mV. These nanoparticles showed increased cytotoxicity and improved cellular uptake compared with free drugs. Thermogravimetric analysis revealed that the drug-loaded nanocarriers provided better protection against drug degradation. Pharmacokinetic and biodistribution studies indicated that the formulation had an extended brain residence time, highlighting its effectiveness.Conclusion: The biotin-zein conjugated nanoparticles developed in this study offer a promising nano-vehicle for in vivo biodistribution and pharmacokinetic applications. Their high drug encapsulation efficiency, stability and extended brain residence time suggest they are effective for targeted drug delivery and therapeutic uses.

394. Consistency of AZD7442 (Cilgavimab/Tixagevimab) Pharmacokinetics Across Prophylaxis and Treatment and Adult and Pediatric Participants: Application of Population Pharmacokinetics to Enable Rapid Decision-Making During the COVID-19 Pandemic

Abstract Background AZD7442 is a combination of two half-life extended monoclonal antibodies, tixagevimab and cilgavimab. A population pharmacokinetic (popPK) model for AZD7442 included interim data from phase 3 trials in pre-exposure prophylaxis (PreP; PROVENT), post-exposure prophylaxis (STORMCHASER), and treatment of mild-to-moderate COVID-19 (TACKLE) in adults. This popPK model facilitated inclusion of adolescents in the AZD7442 label, the decision to increase the recommended PreP dose of AZD7442 in response to evolving SARS-CoV-2 variants, and selection of doses for a pediatric study (TRUST). Upon completion of the adult phase 3 studies, the popPK model was updated to include data from eight studies. Methods The final popPK analysis included 4940 adult participants from North and South America, Europe, and Asia. To predict the PK of AZD7442 in pediatric patients, the effect of post-menstrual age on clearance was incorporated into the model. Results The PK of AZD7442, tixagevimab, and cilgavimab were very similar and dose-proportional. PopPK analyses found no difference in AZD7442 PK between PreP and treatment (Figure 1). The final AZD7442, tixagevimab, and cilgavimab models included body weight, sex, age, BMI, Black race, and site of intramuscular administration as covariates; none of these were clinically relevant nor required dose adjustment. When interim TRUST (pediatric) data became available, popPK predictions were compared to observed serum PK data (Figure 2). Good agreement was observed, confirming appropriateness of dosing adolescents ≥40kg with the same dosing regimen as adults, and adequate characterization of AZD7442 PK in pediatric participants. Safety data from TRUST and adult studies were comparable. Conclusion The PK of AZD7442, cilgavimab, and tixagevimab are comparable and follow linear kinetics with an extended half-life, allowing for prolonged duration of protection. AZD7442 PK is comparable across indications and between adults and pediatric populations. PopPK analyses facilitated rapid decision-making during the COVID-19 pandemic, including accelerating access to AZD7442 by adolescent patients ahead of the availability of pediatric clinical data. Disclosures Lindsay E. Clegg, PhD, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds Oleg Stepanov, MS, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds Henning Schmidt, PhD, AstraZeneca: Employed by IntiQuan, which received payment from AstraZeneca for work involved in this analysis Ventakesh Pilla Reddy, PhD, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds Weifeng Tang, MD, PhD, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds Michael Gibbs, PhD, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds Sangeeta Sedani, MSc, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds Antonella Nadia Tuillio, MD, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds Sam Sadow, MA, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds Nuria Martinez-Alier, PhD, AstraZeneca: Employee|AstraZeneca: Employement|AstraZeneca: Stocks/Bonds|AstraZeneca: Stocks/Bonds Taylor Cohen, PhD, AstraZeneca: Employement|AstraZeneca: Stocks/Bonds Saul N. Faust, FRCPCH PhD, AstraZeneca, Janssen, Pfizer, Moderna, GlaxoSmithKline, Novavax, Sanofi, Seqirus, Medimmune, Merck, MSD, Iliad and Valneva: Advisor/Consultant|AstraZeneca, Janssen, Pfizer, Moderna, GlaxoSmithKline, Novavax, Sanofi, Seqirus, Medimmune, Merck, MSD, Iliad and Valneva: Investigator Mark T. Esser, PhD, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds Mats Någård, PhD, AstraZeneca: Employee|AstraZeneca: Stocks/Bonds

A Novel Milli-fluidic Liver Tissue Chip with Continuous Recirculation for Predictive Pharmacokinetics Applications

A crucial step in lead selection during drug development is accurate estimation and optimization of hepatic clearance using in vitro methods. However, current methods are limited by factors such as lack of physiological relevance, short culture/incubation times that are not consistent with drug exposure patterns in patients, use of drug absorbing materials, and evaporation during long-term incubation. To address these technological needs, we developed a novel milli-fluidic human liver tissue chip (LTC) that was designed with continuous media recirculation and optimized for hepatic cultures using human primary hepatocytes. Here, we characterized the LTC using a series of physiologically relevant metrics and test compounds to demonstrate that we could accurately predict the PK of both low- and high-clearance compounds. The non-biological characterization indicated that the cyclic olefin copolymer (COC)–based LTC exhibited negligible evaporation and minimal non-specific binding of drugs of varying ionic states and lipophilicity. Biologically, the LTC exhibited functional and polarized hepatic culture with sustained metabolic CYP activity for at least 15 days. This long-term culture was then used for drug clearance studies for low- and high-clearance compounds for at least 12 days, and clearance was estimated for a range of compounds with high in vitro-in vivo correlation (IVIVC). We also demonstrated that LTC can be induced by rifampicin, and the culture age had insignificant effect on depletion kinetic and predicted clearance value. Thus, we used advances in bioengineering to develop a novel purpose-built platform with high reproducibility and minimal variability to address unmet needs for PK applications.Graphical

Low-dimensional neural ODEs and their application in pharmacokinetics

Machine Learning (ML) is a fast-evolving field, integrated in many of today’s scientific disciplines. With the recent development of neural ordinary differential equations (NODEs), ML provides a new tool to model dynamical systems in the field of pharmacology and pharmacometrics, such as pharmacokinetics (PK) or pharmacodynamics. The novel and conceptionally different approach of NODEs compared to classical PK modeling creates challenges but also provides opportunities for its application. In this manuscript, we introduce the functionality of NODEs and develop specific low-dimensional NODE structures based on PK principles. We discuss two challenges of NODEs, overfitting and extrapolation to unseen data, and provide practical solutions to these problems. We illustrate concept and application of our proposed low-dimensional NODE approach with several PK modeling examples, including multi-compartmental, target-mediated drug disposition, and delayed absorption behavior. In all investigated scenarios, the NODEs were able to describe the data well and simulate data for new subjects within the observed dosing range. Finally, we briefly demonstrate how NODEs can be combined with mechanistic models. This research work enhances understanding of how NODEs can be applied in PK analyses and illustrates the potential for NODEs in the field of pharmacology and pharmacometrics.

Measurement of apixaban concentrations in different human biological fluids by UHPLC-MS/MS. Clinical pharmacokinetic application in a subject with chronic kidney disease and nonvalvular atrial fibrillation on haemodialysis

BackgroundApixaban’s technical sheet does not recommend its use in clinical practice for patients with chronic kidney disease undergoing haemodialysis. However, recent studies indicate that apixaban could be a safe oral anticoagulant in these kinds of patients who do not present valvular atrial fibrillation. We developed and validated ultra–high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) procedures for measuring apixaban concentrations in plasma, dialysate liquid, and urine. Material and methodsSimple protein precipitation was implemented to prepare samples. Chromatographic separations were achieved on an Acquity®-UPLC®-BEHTM (2.1x100 mm id, 1.7 µm) reverse-phase C18 column using a water/acetonitrile non-linear gradient containing 0.1 % formic acid at a 0.4 mL/min flow rate. Apixaban and its internal standard (apixaban-d3) were detected by electrospray ionisation mass spectrometry in positive and multiple reaction monitoring modes, using transitions of 460.3 → 199.0/443.2 and 463.3 → 202.0, respectively. ResultsNo significant interferences and carry-overs were observed. Precisions, absolute relative biases, normalised-matrix factors, and normalised recoveries were ≤ 12.2%, ≤8.0%, 94.3–105.1%, and 93.9–105.4%, respectively. Linearity was observed between 5 and 500 μg/L for plasma/dialysate liquid and 5–1000 μg/L for urine. ConclusionsThe validated UHPLC-MS/MS procedures could help support a pharmacokinetic study in non-valvular atrial fibrillation subjects with chronic kidney disease undergoing haemodialysis and apixaban-based anticoagulant therapy.

"Off/On” Fluorescent Probe based on Aggregation-Induced Quenching of ZnO-Quantum dots for Determination of Ara-C: Pharmacokinetic Applications, Adsorption Kinetics & Green Profile Assessment

Herein, a turn “Off/On” fluorescence probe based on ZnO quantum dots (ZnO-QDs) has been proposed and successfully utilized for the determination of Ara-C (cytarabine) using ceric ions (Ce4+) as quencher and ethylenediamine (ED) as a linker. The probe is based initially on the quenching effect of Ce4+ ions on the strong native fluorescence of ZnO-QDs forming the Turn Off system (Ce@ZnO-QDs) that believed to occur due to the aggregation-induced quenching (AIQ) mechanism. The second step is the addition of Ara-C in the presence of ethylenediamine (ED) that encourages the formation of Ara-C/ED/Ce4+ as well as the release of the free ZnO-QDs, leading to the recovery of the fluorescence intensity. The developed sensing platform shows a linear response towards Ara-C over the range of 10 to 1000 ng mL−1 giving a limit of detection (LOD) and limit of quantitation (LOQ) of 1.22 ng mL−1 and 3.70 ng mL−1, respectively. A dispersive magnetic solid phase micro-extraction (dMSPE) method was developed and optimized for the extraction of Ara-C in spiked human plasma using thiol-modified magnetite nanoparticles (S-MNPs). The proposed platform exhibits good sensitivity toward Ara-C in the presence of different interfering substances. Excellent recoveries are obtained after spiking different concentrations of Ara-C into rabbit plasma samples. The validated experimental parameters have been successfully applied to monitor the pharmacokinetic profile of Ara-C in rabbit plasma. A detailed adsorption kinetics study has been carried out to provide a deep insight into the adsorption behavior of Ara-C on the thiol-doped-magnetite nanoparticles. The greenness assessment of the proposed method was achieved and compared with other reported methods using two tools of greenness; the green analytical procedure index (GAPI) and the analytical greenness calculator AGREE.

Development of a robust UPLC-MS/MS method for the quantification of riluzole in human plasma and its application in pharmacokinetics.

Introduction: The aim of the present study was to establish a simple method for the determination of riluzole in human plasma by ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and apply it for the determination of riluzole in amyotrophic lateral sclerosis (ALS) patients. Methods: Samples were prepared by protein precipitation and were then gradient-eluted on a column of ACQUITY UPLC® HSS T3 by using 0.1% formic acid acetonitrile and 0.1% formic acid water as the mobile phase. Detection was performed on a Xevo TQ-S tandem mass spectrometer in the multiple-reaction monitoring mode using positive electrospray ionization. Validation was performed in the range of 5-800ng/mL. Results and discussion: Three batches of precision accuracy, selectivity, matrix effects, extraction recovery, and stability were also verified and met the requirements. The results showed that the method was reliable and successfully applied to the pharmacokinetics study of riluzole in Chinese amyotrophic lateral sclerosis patients. Meanwhile, in comparison with other prior published methods, our method has the advantages of simple sample preparation, relatively short running time, and small plasma sample consumption, which represented a high-throughput sample determination potential.

An HPLC-MS/MS method for determination of sulbactam in human plasma and its pharmacokinetic application in critically ill patients with augmented renal clearance.

A simple, rapid, and specific method has been developed and validated to measure sulbactam in human plasma using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The pharmacokinetic characteristics of sulbactam in critically ill patients with augmented renal clearance were investigated after the repeated administration of cefoperazone-sulbactam (3 g, q8, IV drip, combination ratio of 2:1). Sulbactam plasma concentration was determined using LC-MS/MS with tazobactam used as an internal standard (IS). The method was fully validated with a sensitivity of 0.20 μg/mL, the linear concentration was ranged from 0.20 to 30.0 μg/mL. The intra-batch precision (RSD%) was less than 4.9%, and the accuracy deviation (RE%) ranged from -9.9 to 1.0%; the inter-batch precision (RSD%) was less than 6.2%, and the accuracy deviation (RE%) ranged from -9.2% to 3.7%. The value of the mean matrix factor at the low and high quality control (QC) concentration was 96.8 and 101.0%, respectively. The extraction recovery for QCL and QCH of sulbactam were 92.5 and 87.5%, respectively. Plasma samples and clinical data were collected at 0 (pre dose), 0.25, 0.5, 1, 2, 3, 6, and 8 hours (post dose) from 11 critically ill patients. Pharmacokinetic parameters were determined by non-compartmental analysis (NCA) using Phoenix WinNonlin software. This method was successfully applied to study the pharmacokinetics of sulbactam for critically ill patients. The main pharmacokinetic parameters of sulbactam in augmented renal function and normal renal function groups were summarized as follows: half-life, 1.45 ± 0.66 and 1.72 ± 0.58 hours, area under the concentration-time curve from 0 to 8 hours, 59.1 ± 20.1 and 111.4 ± 23.2 μg × h/mL, drug plasma clearance at steady state, 18.9 ± 7.5 and 9.32 ± 2 .03 L/h, respectively. These results suggested that a higher dose of sulbactam should be used in critically ill patients with augmented renal clearance.

Determination of rosmarinic acid and its N-substituted analog A1 in rat plasma using high-performance liquid chromatography-tandem mass spectrometry and its application in pharmacokinetics.

The aim of this study was to determine the concentration of rosmarinic acid (RA) and its analog (E)-3-(3,4-dihydroxyphenyl)-2-(3-(3,4-dihydroxyphenyl)acrylamido)propanoic acid (A1) in rat plasma following oral administration. The significance of this study lies in the development of a rapid, sensitive, and alternative method using liquid chromatography-tandem mass spectrometry for the accurate quantification and identification of RA and A1 in vivo. Liquid chromatography-tandem mass spectrometry was employed to analyze RA and A1 in rat plasma. A C18 column (1.9 µm, 2.1 × 100 mm) with a C18 guard column (5 µm, 2.1 × 10 mm) and a triple-quadrupole mass spectrometer combined with an electrospray ionization source were utilized. Sample pretreatment involved a one-step protein precipitation using isopropanol:ethyl acetate (20:80, v/v) as the solvent. Pseudoephedrine hydrochloride served as a standard. The developed method exhibited a linear relationship within the concentration ranges of 5-750 ng/ml for both RA and A1. Relative standard deviations in daily courses were less than 15%, and the relative errors recorded were within 15%. This is the first study to concentrate on determining A1 and RA in rat plasma through oral administration. The liquid chromatography-tandem mass spectrometry method developed in this study offers a rapid, sensitive, and alternative approach for the accurate quantification and identification of RA and A1 in vivo. The findings serve as a significant foundation for evaluating the clinical applications of the medicine.