Simultaneous determination of sitagliptin and simvastatin in human plasma by LC-MS/MS and its application to a human pharmacokinetic study: Simultaneous LC-MS/MS quantification of sitagliptin and simvastatin

Transitioning from Supramolecular Chemistry to Molecularly Imprinted Polymers in Chemical Sensing

This perspective article focuses on the overwhelming significance of molecular recognition in biological processes and its emulation in synthetic molecules and polymers for chemical sensing. The historical journey, from early investigations into enzyme catalysis and antibody-antigen interactions to Nobel Prize-winning breakthroughs in supramolecular chemistry, emphasizes the development of tailored molecular recognition materials. The discovery of supramolecular chemistry and molecular imprinting, as a versatile method for mimicking biological recognition, is discussed. The ability of supramolecular structures to develop selective host-guest interactions and the flexible design of molecularly imprinted polymers (MIPs) are highlighted, discussing their applications in chemical sensing. MIPs, mimicking the selectivity of natural receptors, offer advantages like rapid synthesis and cost-effectiveness. Finally, addressing major challenges in the field, this article summarizes the advancement of molecular recognition-based systems for chemical sensing and their transformative potential.

Determination of sitagliptin in human plasma using a smart electrochemical sensor based on electroactive molecularly imprinted nanoparticles

Sitagliptin is a hypoglycaemic agent used to reduce blood sugar levels in patients with type 2 diabetes mellitus (T2DM). Real time monitoring of sitagliptin levels is crucial to prevent overdose, which might cause liver, kidney and pancreatic diseases. As an alternative solution, a sitagliptin voltammetric sensor was fabricated using artificial receptors called electroactive molecularly imprinted polymer nanoparticles (nanoMIPs). The nanoMIP tagged with a redox probe (ferrocene) combines both the recognition and reporting functions. Traditional electrochemical sensors determine the redox activity of an analyte. Thus, they are influenced by interfering molecules and the nature of the sample. These innovative nanoMIPs allow us to easily design and customise sensors, increase their sensitivity and minimise the cross reactivity in biological samples. The present technology replaces the traditional enzyme-mediator pairs used in traditional biosensors. The polymer composition was optimized "in silico" using docking and screening methods. Nanoparticles were synthesized via free radical polymerization and a solid phase method and then characterized by infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and dynamic light scattering (DLS). The specific sitagliptin nanoparticles were covalently immobilized on platinum electrodes via silane and carbodiimide chemistry. The determination of sitagliptin in human plasma by a nanoMIP sensor was assessed by differential pulse voltammetry (DPV). The sensor current response was directly related to the change in nanoMIP conformation triggered by the analyte. The optimisation of the sensor response was made by adjusting (i) the silane concentration, (ii) nanoMIP concentration, and (iii) immobilization time. The sensor measurements in plasma revealed high selectivity and a sensitivity of 32.5 ± 0.6 nA pM-1 towards sitagliptin, and the limit of detection of the fabricated sensor was found to be 0.06 pM. The sensor displayed a satisfactory performance for the determination of sitagliptin in spiked human plasma, demonstrating the potential of this technology for drug monitoring and clinical diagnosis.

Method development for quantitative determination of seven statins including four active metabolites by means of high-resolution tandem mass spectrometry applicable for adherence testing and therapeutic drug monitoring

Background Statins are used to treat and prevent cardiovascular diseases (CVDs) by reducing the total serum cholesterol concentration. Unfortunately, dose-related side effects and sub-optimal response, attributed to non-adherence amongst others, were described. Therefore, a fast and sensitive liquid chromatography-high-resolution tandem mass spectrometry (LC-HRMS/MS) method for adherence testing and therapeutic drug monitoring of all currently marketed statins and their active metabolites in human blood plasma should be developed, validated and tested for applicability. Methods Atorvastatin, fluvastatin, lovastatin, pitavastatin, pravastatin, rosuvastatin, and simvastatin, as well as ortho- and para-hydroxy-atorvastatin, lovastatin hydroxy acid and simvastatin hydroxy acid were included and several internal standards (IS) tested. Validation was performed according to the guideline of the European Medicines Agency including selectivity, carry-over, accuracy, precision, matrix effects, dilution integrity and analyte stability. Finally, applicability was tested using 14 patient samples submitted for regular toxicological analysis. Results Due to an analytical interference of atorvastatin-d5, diazepam-d5 and pentobarbital-d5 were chosen as IS for positive and negative ionization mode, respectively. All statins and metabolites fulfilled the validation acceptance criteria except for fluvastatin, which could not be quantified reliably and reproducibly, most probably due to instability. Analyses of human plasma samples revealed concentrations of statins and metabolites below the reference plasma concentrations in the case of eight patients. However, nothing was known concerning patients' adherence and time between intake and sampling. Conclusions An LC-HRMS/MS method for identification and quantification of atorvastatin, lovastatin, pitavastatin, pravastatin, rosuvastatin, simvastatin and four active metabolites was successfully developed and applicability demonstrated.

Sensitive detection of quinoline-derivatized sitagliptin in small volumes of human plasma by MALDI-TOF mass spectrometry

Dipeptidyl peptidase 4 (DPP-4) inhibitors are incretin-based medications used as oral antidiabetic agents for the treatment of type 2 diabetes. However, DPP-4 inhibitors produce side effects like acute pancreatitis, upper respiratory tract infection, nasopharyngitis, urinary tract infection, serious allergies, cardiovascular diseases, hemolysis, and retinopathy. Hence, the development of a fast and simple method to detect DPP-4 inhibitors in body fluids is important. In this study, we developed a derivatization-assisted microextraction method to enhance the detection sensitivity for trace levels of a DPP-4 inhibitor, sitagliptin, from a small volume (10 μL) of human plasma by using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Subjecting the analyte to 100 W microwave irradiation after derivatization using a quinoline alkylating reagent (8-bromomethyl quinilone, BrMQ) shortened the reaction time to ~120 s and allowed the target analyte to be easily extracted to a small volume of the organic layer (20 μL). The analyte was then detected by MALDI-TOF MS using α-cyano-4-hydroxycinnamic acid as the matrix. The relative standard deviation and relative error were below 10% in intra- and inter-day assays. Using sitagliptin-d4 as an internal standard, the limits of quantitation and detection were found to be 0.03 μg/mL and 0.01 μg/mL, respectively. All the derivatization and extraction procedures described herein were of microliter grade. This method could effectively reduce the use of organic chemicals and solvents, thereby proving to be an eco-friendly strategy that will cause no harm to the environment.

A Rapid and Sensitive Method for the Pharmacokinetic Study of Janumet (Sitagliptin and Metformin) Tablets by LC-MS/MS Coupled with Ion-Pair Solid Phase Extraction

Background:

As first-line treatments for diabetes, sitagliptin and metformin have been widely prescribed as a combination to enhance the therapeutic effect.

Objective:

To establish a methodology to simultaneously monitor the two drugs in vivo by a reversedphase Liquid Chromatography-Tandem Mass Spectrometric (LC-MS/MS) method.

Methods:

The two drugs were extracted from 50 μl human plasma by ion-pair solid phase extraction. The separation of the plasma samples was implemented on an Agilent Zorbax SB-CN column (150×4.6 mm, 5.0 µm). The mobile phase was the mixture (80:20, v/v) of methanol and 5.0 mM ammonium formate in water (pH 4.5). An ion trap spectrometer equipped with an electrospray ionization source was utilized to detect the elution in positive mode. Quantification of the analytes was achieved by Multiple Reaction Monitoring (MRM) using the transitions of m/z 408.3→235.1 for sitagliptin and m/z 130.1→ 60.2 for metformin.

Results:

Sitagliptin and metformin demonstrated good linearity among the range of 1.00-1000 ng/mL and 5.00-4000 ng/mL. The intra-day and inter-day investigations displayed precisions of ≤ 3.6% and an accuracy range of -7.5% to 6.0% for the two drugs. The mean recovery of the two drugs was 96.0% and 98.5%. Under mandatory storage conditions, both the drugs gave an acceptable stability. The throughput of the assay was found to be more than 100 plasma samples per day ascribed to the run time of 3.0 min for each sample.

Conclusion:

The developed method was successfully applied to a pharmacokinetic study for a fixeddose tablet formulation containing 50 mg sitagliptin and 500 mg metformin in 12 healthy volunteers.

UPLC-MS/MS method for the quantification of ertugliflozin and sitagliptin in rat plasma

In the present study, an ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) approach was designed to concurrently measure the levels of ertugliflozin and sitagliptin in rat plasma with diazepam as the internal standard (IS). Acetonitrile-based protein precipitation was applied for sample preparation, then analytes (ertugliflozin and sitagliptin) were subjected to gradient elution chromatography with a mobile phase composed of acetonitrile (A) and 0.1% formic acid in water (B). Ertugliflozin was monitored by m/z 437.2 → 329.0 transition for quantification and m/z 437.2 → 207.5 transition for qualification, and sitagliptin was determined by m/z 408.2 → 235.0 transition for quantification and m/z 408.2 → 174.0 transition for qualification by multiple reaction monitoring (MRM) in positive ion electrospray ionization (ESI) source. When the concentration of ertugliflozin ranged from 1 to 1000 ng/mL and sitagliptin ranged from 2 to 2500 ng/mL, the method exhibited good linearity. For both ertugliflozin and sitagliptin, the intra- and inter-day precision were determined with the values of 1.6-10.9% and 0.8-13.3%, respectively; and the accuracy ranged from -5.7% to 14.6%. Matrix effect, extraction recovery, and stability data were in line with the stipulated FDA guidelines for validating a bioanalytical method. The validity of the designed method was confirmed through the pharmacokinetic experiments.

Comparison of conventional and supported liquid extraction methods for the determination of sitagliptin and simvastatin in rat plasma by LC-ESI-MS/MS

Three extraction methods were compared for their efficiency to analyze sitagliptin and simvastatin in rat plasma by LC–MS/MS, including (1) liquid–liquid extraction (LLE), (2) solid phase extraction (SPE) and (3) supported liquid extraction (SLE). Comparison of recoveries of analytes with different extraction methods revealed that SLE was the best extraction method. The detection was facilitated with ion trap-mass spectrometer by multiple reactions monitoring (MRM) in a positive ion mode with ESI. The transitions monitored were m/z 441.1→325.2 for simvastatin, 408.2→235.1 for sitagliptin and 278.1→260.1 for the IS. The lower limit of quantification (LLOQ) was 0.2 ng/mL for sitagliptin and 0.1 ng/mL for simvastatin. The effective SLE offers enhanced chromatographic selectivity, thus facilitating the potential utility of the method for routine analysis of biological samples along with pharmacokinetic studies.

Microemulsion liquid chromatographic method for simultaneous determination of simvastatin and ezetimibe in their combined dosage forms

A rapid HPLC procedure using a microemulsion as an eluent was developed and validated for analytical quality control of antihyperlipidemic mixture containing simvastatin (SIM) and ezetimibe (EZT) in their pharmaceutical preparations. The separation was performed on a column packed with cyano bonded stationary phase adopting UV detection at 238 nm using a flow rate of 1 mL/min. The optimized microemulsion mobile phase consisted of 0.2 M sodium dodecyl sulphate, 1% octanol, 10% n-propanol, and 0.3% triethylamine in 0.02 M phosphoric acid at pH 5.0. The developed method was validated in terms of specificity, linearity, lower limit of quantification (LOQ), lower limit of detection (LOD), precision, and accuracy. The proposed method is rapid (8.5 min), reproducible (RSD < 2.0%) and achieves satisfactory resolution between SIM and EZT (resolution factor = 2.57). The mean recoveries of the analytes in pharmaceutical preparations were in agreement with those obtained from a reference method, as revealed by statistical analysis of the obtained results using Student's t-test and the variance ratio F-test.