Simultaneous Quantification of Antidiabetic Agents in Human Plasma by a UPLC-QToF-MS Method

Optimized Box-Behnken experimental design based response surface methodology and Youden's robustness test to develop and validate methods to determine nateglinide using kinetic spectrophotometry

Selective and straightforward kinetic spectrophotometric methods were developed to quantify nateglinide (NTG) in pharmaceutical dosage forms. Fixed time (ΔA) and the equilibrium methods utilized the reaction of NTG with 1-chloro-2,4-dinitrobenzene (CDNB) in dimethyl sulfoxide (DMSO) with heating at 80 °C for 25 min to form a stable yellow-coloured Meisenheimer complex, which absorbs maximally at 421 nm. The optimization was achieved by utilizing the Box-Behnken experimental design (BBD) combined with response surface methodology (RSM). In which three significant factors were studied, namely, CDNB volume (A), heating temperature (B) and heating time (C) against the absorbance as a response. Method validation presented the International Conference on Harmonisation (ICH) parameters such as specificity, selectivity, linearity, precision, accuracy, limit of detection (LOD), limit of quantitation (LOQ), robustness and solution stability. The LOD and LOQ values were 0.48, 1.46, and 0.21, 0.62 µg/ml, respectively, for a fixed time (ΔA) and equilibrium methods with the linear dynamic range of 1-15 µg/ml. Furthermore, Youden's robustness test using factorial combinations of the selected analytical parameters was performed and investigated its influence with alternative conditions. All results were reproducible and quickly adopted for routine analysis of NTG in pharmaceutical formulations and laboratory preparations.

Qualification and application of liquid chromatography-quadrupole time-of-flight mass spectrometric method for the determination of carisbamate in rat plasma and prediction of its human pharmacokinetics using physiologically based pharmacokinetic modeling

Carisbamate is an antiepileptic drug and it also has broad neuroprotective activity and anticonvulsant reaction. In this study, a liquid chromatography-quadrupole time-of-flight mass spectrometric (LC-qTOF-MS) method was developed and applied for the determination of carisbamate in rat plasma to support in vitro and in vivo studies. A quadratic regression (weighted 1/concentration²), with an equation y = ax² + bx + c, was used to fit calibration curves over the concentration range from 9.05 to 6,600 ng/mL for carisbamate in rat plasma. Preclinical in vitro and in vivo studies of carisbamate have been studied through the developed bioanalytical method. Based on these study results, human pharmacokinetic (PK) profile has been predicted using physiologically based pharmacokinetic (PBPK) modeling. The PBPK model was optimized and validated by using the in vitro and in vivo data. The human PK of carisbamate after oral dosing of 750 mg was simulated by using this validated PBPK model. The human PK parameters and profiles predicted from the validated PBPK model were similar to the clinical data. This PBPK model developed from the preclinical data for carisbamate would be useful for predicting the PK of carisbamate in various clinical settings.

Bioanalytical Method Using Ultra-High-Performance Liquid Chromatography Coupled with High-Resolution Mass Spectrometry (UHPL-CHRMS) for the Detection of Metformin in Human Plasma

Metformin is the first-line medicine for the treatment of type 2 diabetes. Drug interactions between metformin and other drugs, food, or beverages cannot only cause changes in the pharmacokinetic profiles but also affect the efficacy of metformin. The purpose of this study was to develop a rapid and reliable bioanalytical method for the detection of plasma metformin concentration in humans. To remove interfering substances in plasma, acidified acetonitrile (acetonitrile containing 0.1% formic acid) was added to samples. Ultra-high-performance liquid chromatography (UHPLC) coupled with high resolution mass spectrometry (HRMS) was used to analyze metformin and its internal standard (metformin-d6). Analyte separation was performed on a BEH HILIC analytical column (100 × 2.1 mm, 1.7 μm) using a gradient elution of 0.1% formic acid (A) and acetonitrile with 0.1% formic acid (B). The total chromatographic run time was 2 min. The developed method was validated for its linearity, accuracy and precision, selectivity (signal of interfering substance; analyte, lower limit of quantification (LLOQ) ≤ 20%; IS, IS ≤ 5%), sensitivity (LLOQ, 5 ng/mL; S/N ratio ≥ 10), stability (low quality control (LQC, 15 ng/mL), 2.95–14.19%; high quality control (HQC, 1600 ng/mL), −9.49–15.10%), dilution integrity (diluted QC (4000 ng/mL); 10-folds diluted QC (400 ng/mL); 5-folds diluted QC (800 ng/mL); accuracy, 81.30–91.98%; precision, ≤4.47%), carry-over (signal of double blank; analyte, LLOQ ≤20%; IS, IS ≤5%), and matrix effect (LQC, 10.109%; HQC, 12.271%) under various conditions. The constructed calibration curves were shown linear in the concentration range of 5–2000 ng/mL, with within- and between-run precision values of <8.19% and accuracy in the range of 91.13–105.25%. The plasma metformin concentration of 16 healthy subjects was successfully measured by applying the validated bioanalytical method.

A HILIC-MS/MS assay for the quantification of metformin and sitagliptin in human plasma and urine: A tool for studying drug transporter perturbation

This article describes the development and validation of a HILIC-MS/MS method for the simultaneous quantification of metformin and sitagliptin from human plasma and urine. The presented method uses quick sample preparation and fast chromatography allowing for high sample throughput. The quantification is performed using multi-reaction monitoring and ESI positive mode with stable isotope labelled internal standards for both metformin and sitagliptin. Excellent linearity in the selected calibrations ranges, low inter-day variability (CV% <6.7%), and high accuracy (95.5-104.1%) were obtained. Adequate retention was attained for both analytes by hydrophilic interaction liquid chromatography using a plain silica column in combination with a mobile phase composed of ammonium formate, acetonitrile, formic acid and water in gradient separation mode.

Hydrophilic Interaction Liquid Chromatography-Electrospray Ionization Mass Spectrometry for Therapeutic Drug Monitoring of Metformin and Rosuvastatin in Human Plasma

In this work a hydrophilic interaction liquid chromatography/positive ion electrospray mass spectrometric assay (HILIC/ESI-MS) has been developed and fully validated for the quantitation of metformin and rosuvastatin in human plasma. Sample preparation involved the use of 100 μL of human plasma, following protein precipitation and filtration. Metformin, rosuvastatin and 4-[2-(propylamino) ethyl] indoline 2 one hydrochloride (internal standard) were separated by using an X-Bridge-HILIC BEH analytical column (150.0 × 2.1 mm i.d., particle size 3.5 μm) with isocratic elution. A mobile phase consisting of 12% (v/v) 15 mM ammonium formate water solution in acetonitrile was used for the separation and pumped at a flow rate of 0.25 mL min⁻¹. The linear range of the assay was 100 to 5000 ng mL⁻¹ and 2 to 100 ng mL⁻¹ for metformin and rosuvastatin, respectively. The current HILIC-ESI/MS method allows for the accurate and precise quantitation of metformin and rosuvastatin in human plasma with a simple sample preparation and a short a chromatographic run time (less than 15 min). Plasma samples from eight patients were further analysed proving the capability of the proposed method to support a wide range of clinical studies.