Mixed-mode solid phase extraction combined with LC-MS/MS for determination of empagliflozin and linagliptin in human plasma

Unveiling Pharmacokinetics and Drug Interaction of Linagliptin and Pioglitazone HCl in Rat Plasma Using LC-MS/MS

The linagliptin (LIN) and pioglitazone HCl (PIO) combination, currently undergoing phase III clinical trials for diabetes mellitus treatment, demonstrated significant improvements in glycemic control. However, the absence of an analytical method for simultaneous determination in biological fluids highlights a crucial gap. This underscores the pressing need for sensitive bioanalytical methods, emphasizing the paramount importance of developing such tools to advance diabetes management strategies and enhance patient care. Herein, a sensitive reverse-phase high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry method was developed for simultaneous determination of LIN and PIO in rat plasma using alogliptin as an internal standard. Chromatographic separation was performed on an Agilent Eclipse Plus C18 (4.6 × 100 mm, 3.5 μm) using an isocratic mobile phase system consisting of ammonium formate (pH 4.5) and methanol using an acetonitrile-induced protein precipitation technique for sample preparation. Multiple reaction monitoring in positive ion mode was used for quantitation of the precursor to production at m/z 473.2 → 419.9 for LIN, 357.1 → 134.2 for PIO, and 340.3 → 116.1 for ALO. The linearity range was 0.5 to 100 and 1 to 2000 ng/mL for LIN and PIO, respectively. The developed method was validated as per US-FDA guidelines and successfully applied to clinical pharmacokinetic and drug-drug interaction studies with a single oral administration of LIN and PIO in rat plasma. Pharmacokinetic parameters of LIN were significantly influenced by the concomitant administration of PIO and vice versa. Molecular modeling revealed the significant interaction of LIN and PIO with P-glycoprotein. Therefore, the drug-drug interaction between LIN and PIO deserves further study to improve drug therapy and prevent dangerous adverse effects.

One-Pot Preparation of Mixed-Mode Reversed-Phase Anion-Exchange Silica Sorbent and its Application in the Detection of Cyclopiazonic Acid in Feeds and Agricultural Products

A novel co-bonded octyl and pyridine silica (OPS) sorbent was prepared and applied for the solid phase extraction (SPE) of cyclopiazonic acid (CPA, a type of mycotoxin) in feed and agricultural products for the first time. A simple mixed-ligand one-pot reaction strategy was employed for OPS sorbent preparation. Nitrogen adsorption-desorption measurements, elemental analysis (EI), thermal gravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FT-IR) analysis demonstrated the successful immobilization of octyl and quaternary ammonium groups onto the surface of silica gel. The large specific surface area, high-density functional groups, and mixed-mode anion-exchange characteristics of these silica particles made them the ideal material for the efficient extraction of CPA. Additionally, the OPS sorbents displayed excellent batch-to-batch reproducibility, satisfactory reusability, and low cost. The SPE parameters were optimized to explore the ionic and hydrophobic interactions between CPA and the functional groups, and the ultra-high performance liquid chromatography coupled with triple-quadrupole tandem mass spectrometry (UPLC-MS/MS) parameters were optimized to obtain a desirable extraction efficiency and high sensitivity to CPA. Meanwhile, the OPS sorbent presented a satisfactory extraction selectivity and low matrix effect. Under the optimized conditions, our developed CPA detection method was used to determine CPA level in rice, wheat flour, corn flour, peanut, and feed samples, exhibiting a lower detection limit, better linearity, higher sensitivity, and satisfactory extraction recovery rate than previously reported methods. Therefore, our method can be preferentially used as a method for the detection of CPA in agricultural products and feeds.

The "depict" strategy for discovering new compounds in complex matrices: Lycibarbarspermidines as a case

The comprehensive detection and identification of active ingredients in complex matrices is a crucial challenge. Liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS) is the most prominent analytical platform for the exploration of novel active compounds from complex matrices. However, the LC-HRMS-based analysis workflow suffers from several bottleneck issues, such as trace content of target compounds, limited acquisition for fragment information, and uncertainty in interpreting relevant MS2 spectra. Lycibarbarspermidines are vital antioxidant active ingredients in Lycii Fructus, while the reported structures are merely focused on dicaffeoylspermidines due to their low content. To comprehensively detect the new structures of lycibarbarspermidine derivatives, a "depict" strategy was developed in this study. First, potential new lycibarbarspermidine derivatives were designed according to the biosynthetic pathway, and a comprehensive database was established, which enlarged the coverage of lycibarbarspermidine derivatives. Second, the polarity-oriented sample preparation of potential new compounds increased the concentration of the target compounds. Third, the construction of the molecular network based on the fragmentation pathway of lycibarbarspermidine derivatives broadened the comprehensiveness of identification. Finally, the weak response signals were captured by data-dependent scanning (DDA) followed by parallel reaction monitoring (PRM), and the efficiency of acquiring MS2 fragment ions of target compounds was significantly improved. Based on the integrated strategy above, 210 lycibarbarspermidine derivatives were detected and identified from Lycii Fructus, and in particular, 170 potential new compounds were structurally characterized. The integrated strategy improved the sensitivity of detection and the coverage of low-response components, and it is expected to be a promising pipeline for discovering new compounds.

Empagliflozin: Validation of Stability-Indicating LC Method and in silico Toxicity Studies

A new stability-indicating liquid chromatography method was developed for the quantification of empagliflozin and two synthetic impurities. The chromatographic conditions included Spherisorb® RP-18 column (150 × 4.6 mm, 5 μm) with a PDA detector, using acetonitrile and formic acid (pH 4.0) as mobile phase in gradient elution and flow-rate of 1.2 mL·min-1. The gradient increasing from 51 to 100% acetonitrile until 11.00 min, followed by decreasing the solvent from 100% to the initial ratio from 11.01 to 15.00 min. The method was validated according to International Council of Harmonization guidelines. The LOD and LOQ values for impurities A and B were 35 and 15 ng·mL-1, respectively, (for LOD) and 115 and 35 ng.mL-1, respectively (for LOQ). The method was linear in the range of 80-140, 115-1150 and 35-350 ng·mL-1 for EMPA, impurities A and B, respectively, and the correlation coefficient were > 0.999 in all situations, indicating the method good linearity. The developed method showed a good recovery for empagliflozin and added impurities. The method has proven to be precise, demonstrated values less than 2.0% to empagliflozin and 5.0% to synthetic impurities, robust and selective with no interference from other products in the determination of analytes. The in silico toxicity prediction suggested that the impurities do not present any toxicity risk for the parameters evaluated.

Development and validation of Empagliflozin and Linagliptin simultaneous estimation in rat plasma using freezing lipid precipitation and SCX-SPE assisted HPLC-MS/MS method and its application in pharmacokinetic studies

A quick and sensitive liquid chromatography-mass spectrometry technique was designed, improved, and validated for simultaneous determination of Empagliflozin (EPG) and Linagliptin (LNG) using Empagliflozin-d4 (EPG-d4) and linagliptin-d4 (LNG-d4) as internal standards (IS) in rat plasma. Target analytes and the IS were extracted using freezing lipid precipitation (FLP) and optimized using the strong cation exchange solid phase extraction (SCX-SPE) method to achieve the maximum sample clean-up. In particular, when combined with SPE clean-up, FLP can efficiently eliminate the plasma sample's high lipid content. More than 84.14% of plasma lipids were rapidly removed during the FLP procedure, with minimal loss of EPG and LNG. We used LC-atmospheric chemical ionization (APCI)-mass spectrometry was employed to assess the efficiency of FLP in lipid removal. The SCX-SPE cartridges removed the remaining impurities from EPG and LNG, allowing for further purification. The samples were chromatographically separated using a Spherisorb RP/Cyano column by pumping a gradient mobile phase comprised of acetonitrile and 25 mM ammonium acetate buffer (pH 8.1) in positive ion mode at a flow rate of 0.8 mL/min. The selected reaction monitoring technique was performed using a Waters triple-stage quadrupole tandem mass spectrometer equipped with an electrospray ionization (ESI) source. The chromatographic separation was accomplished using a Waters Acquity® high-performance liquid chromatography (HPLC) system. Mass transition (m/z) of 451.15/71.12 for EPG, m/z 473.27/419.94 for LNG; m/z 455.19/71.12 for EPG-d4, and 477.27/423.94 for LNG-d4 was successfully achieved. This study successfully examined the concentration ranges of 25-1050 ng/mL for EPG and 0.35-15 ng/mL for LNG. The results showed that the linearity of EPG ranged from 25.14 to 985.26 ng/mL, while the linearity of LNG ranged from 0.59 to 14.86 ng/mL. The relative standard deviation (RSD) for both EPG and LNG, within and between days, were below 3.83%, indicating that they fall within acceptable limits. This novel approach demonstrated favourable outcomes in a pharmacokinetic study involving healthy rats, where EPG and LNG were co-administered. This study found that the co-administration of both drugs did not have a significant impact on their pharmacokinetic behavior, suggesting the absence of any drug-drug interactions.

A novel microextraction technique aided by air agitation using a natural hydrophobic deep eutectic solvent for the extraction of fluvastatin and empagliflozin from plasma samples: application to pharmacokinetic and drug-drug interaction study

This study focuses on the interaction between the antihyperlipidemic drug fluvastatin (FLV) and the antidiabetic drug empagliflozin (EMP), which are commonly co-administered medications. EMP's impact on FLV levels is attributed to its inhibition of organic anion transporting polypeptide 1B1 (OATP1B1), responsible for FLV liver uptake, consequently elevating FLV concentrations in blood. Traditional extraction methods for FLV faced difficulties due to its high hydrophobicity. In this study, a hydrophobic natural deep eutectic solvent (NDES) using air assisted dispersive liquid-liquid microextraction (AA-DLLME) was utilized as an excellent choice for achieving the highest extraction recovery, reaching 96% for FLV and 92% for EMP. The NDES was created through the combination of menthol and hippuric acid in a 4 : 1 ratio, making it a green and cost-effective pathway. Liquid phase microextraction followed by spectrofluorometric measurements of FLV at λem = 395 nm and EMP at λem = 303 nm, with excitation at a single wavelength of 275 nm was carried out. Response surface methodology (RSM) relying on central composite design (CCD) was used to optimize the variables affecting the AA-NDES-DLLME. The optimized conditions for extraction are: NDES volume of 200 μL, centrifugation time of 15 minutes, air-agitation cycle of 6 cycles, and sample pH of 4.0. Under these optimized conditions, the developed method exhibited good linearity and precision. The method showed good recoveries from rabbit plasma samples spiked at varying concentrations of the analyzed compounds. To assess the applicability and effectiveness of the hydrophobic DES, the validated method was applied to extract the studied drugs from rabbit plasma samples after oral administration of FLV alone and in combination with EMP. The pharmacokinetic parameters of FLV were calculated in both cases to investigate any changes and determine the need for dose adjustment.

The potential off-target neuroprotective effect of sister gliflozins suggests their repurposing despite not crossing the blood-brain barrier: From bioanalytical assay in rats into theory genesis

Gliflozins are successfully marketed antidiabetic agents with a reported neuroprotective effect, and this study tests their blood-brain barrier crossing ability. Henceforward, a computational hypothesis interpreting their effects was reasonable after failure to cross into the brain. A chromatographic bioassay for canagliflozin, dapagliflozin, and empagliflozin was developed, validated, and applied to the rat's and rat's plasma and brain. HPLC method robustness was tested over two levels using Design of Experiment on MINITAB. It is the first method for gliflozins' detection in rats' brain tissue. The method was applied on 18 rats and six for each drug. Concentrations in plasma were determined but neither of them was detected in brain at the described chromatographic conditions. A computational study for the three drugs was endorsing two techniques. First, ligand-based target fishing reveals possible targets for gliflozins. They showed an ability to bind with human equilibrative nucleoside transporter 1, a regulator of adenosine extracellularly. Second, a docking study was carried out on this protein receptor. Results showed perfect alignment with a minimum of one hydrogen bond. Dapagliflozin achieved the lowest energy score with two hocking hydrogen bonds. This is proposing gliflozins ability to regulate equilibrative nucleoside transporter 1 receptors in peripheries, elevating the centrally acting neuroprotective adenosine.

Greenness Assessment of Chromatographic Methods Used for Analysis of Empagliflozin: A Comparative Study

The analytical chemistry community is attempting to incorporate green chemistry concepts in the development of analytical techniques to redefine analytical methods and dramatically modify the philosophy of analytical technique development. Each greenness assessment method has its own benefits and drawbacks, as well as its own procedures. The results of each greenness assessment method produce numerous deductions regarding the selection of a greenest chromatographic method on which the determination of a greenness assessment tool depends. The current study examined the greenness behavior of 26 reported chromatographic methods in the literature for the evaluation of the medicine empagliflozin using three evaluation methods: the national environmental methods index (NEMI), the eco-scale assessment (ESA), and the green analytical procedure index (GAPI). This comparative study discussed the value of using more than one greenness evaluation methods while evaluating. The findings showed that the NEMI was a less informative and misleading tool. However, the ESA provided reliable numerical assessments out of 100. Despite the GAPI being a complex assessment compared to the others, it provided a fully descriptive three-colored pictogram and a precise assessment. The findings recommended applying more than one greenness assessment tool to evaluate the greenness of methods prior to planning laboratory-based analytical methods to ensure an environment friendly process.

Economic Spectrofluorometric Bioanalysis of Empagliflozin in Rats' Plasma

A simple, economic, green, and sensitive bioanalytical method for empagliflozin bioassay in rats' plasma was employed successfully owing to the empagliflozin native fluorescence behavior. Enhanced liquid-liquid extraction, using diethyl ether (DEE), was successfully employed for the improved extraction of empagliflozin from rats' plasma based on its high value of logP as 1.8 that boosted the drug migration from plasma to the organic layer. The relative fluorescence intensity for empagliflozin was recorded at emission (299.4 nm) after excitation at 226.5 nm. The method was validated with satisfactory results for linearity (500-5000 ng/mL), trueness, precision, the matrix effect, and extraction recovery. The matrix effect ranged between 15.63% and 23.10% for LQC and HQC samples, respectively. Extraction recovery ranged between 54.61% and 62.54% for LQC and HQC samples, respectively. Bias values for the trueness ranged between -10.62 and +14.95, while %RSD values for the precision ranged between 5.39% and 9.33%. The method was successfully applied to rats' plasma samples that included six rats, and the drug concentration was determined in their plasma after 1 hour (estimated Cmax based on literature) following oral administration of empagliflozin with a concentration of 10 mg/Kg, p.o.. The developed cost-effective spectrofluorimetric method in the present work will be of beneficial use in further pharmacokinetic studies that include rats' plasma and biological fluids. Moreover, with the suitable modifications, the described novel extraction of empagliflozin could be adopted to human plasma samples and future clinical studies. Moreover, development of new simple cost-effective methods is necessary to give the researchers a set of "varieties" that they can use according to the laboratory limitations, especially in the developing countries in addition of being a greener method due to the lower consumption of toxic solvents and lower waste production.

Determination of linagliptin and empagliflozin by UPLC and HPTLC techniques aided by lean six sigma approach

Two chromatographic techniques were developed and validated for simultaneous determination of the newly co-formulated antidiabetic combination linagliptin and empagliflozin in their pure form and film-coated tables. The first technique was UPLC; the separation and resolution of both analytes were achieved using a Zorbax eclipse plus C₁₈ column applying an isocratic elution based on phosphate buffer pH 4-acetonitrile (65:35, v/v) as a running mobile phase at flow rate 1.5 ml/min and the effluent was monitored at 220 nm. Augmentation of Lean Six Sigma with UPLC and HPTLC methods had a major impact on the development of robust specifications to ensure that the quality at six sigma level has a high level of statistical confidence and target performance. On the chromatogram, empagliflozin and linagliptin appeared at retention times of 1.417 and 2.453 min, respectively. The second technique was HPTLC; both analytes were fairly well resolved and separated using a developing mobile phase composed of ethyl acetate-chloroform-acetonitrile (55:25:20 by volume). The values of retention factor (R_F ) were 0.29 and 0.53 for linagliptin and empagliflozin, respectively. All variables were investigated to adjust the whole conditions.

Optimization of chromatography to overcome matrix effect for reliable estimation of four small molecular drugs from biological fluids using LC-MS/MS

The article describes a systematic study to overcome the matrix effect during chromatographic analysis of gemfibrozil, rivastigmine, telmisartan and tacrolimus from biological fluids using LC-ESI-MS/MS. All four methods were thoroughly developed by the appropriate choice of analytical column, elution mode and pH of mobile phase for improved chromatography and overall method performance. Matrix effect was assessed by post-column analyte infusion, slope of calibration line approach and post-extraction spiking. The best chromatographic conditions established were: Acquity BEH C₁₈ (50 × 2.1 mm, 1.7 μm) column with 5.0 mm ammonium acetate, pH 6.0-methanol as the mobile phase under gradient program for gemfibrozil; Luna CN (50 × 2.0 mm, 3 μm) column with a mobile phase consisting of acetonitrile-10 mm ammonium acetate, pH 7.0 (90:10, v/v) for rivastigmine; Inertsustain C₁₈ (100 × 2.0 mm, 5 μm) column using methanol-2.0 mm ammonium formate, pH 5.5 (80: 20, v/v) as the mobile phase for isocratic elution of telmisartan; and Acquity BEH C₁₈ (50 × 2.1 mm, 1.7 μm) with methanol-10 mm ammonium acetate, pH 6.0 (95:5, v/v) as mobile phase for tacrolimus. The methods were thoroughly validated as per European Medicines Agency and US Food and Drug Administration guidance and were successfully applied for pharmacokinetic studies in healthy subjects.