Simultaneous determination of metformin and vildagliptin in human plasma by a HILIC–MS/MS method

Addressing stability issues of vildagliptin: Method optimization and validation for accurate analysis in human plasma

This research paper introduces novel strategies to address the stability issues arising with vildagliptin, marking the first attempt to tackle this challenge comprehensively. The study incorporates malic acid into the human plasma, a crucial step in stabilizing vildagliptin and preventing its degradation. Additionally, optimization of the elution process on a C18 Asentis Express column, fine-tuned with a combination of acetonitrile and ammonium trifluoroacetate 5mM, ensures optimal chromatographic conditions. For detection and quantification, electrospray ionization (ESI) is employed, monitoring multiple reactions for vildagliptin (304.2 → 154.2) and vildagliptin D7 (311.1 → 161.2). Meticulous validation of the method demonstrates high accuracy (97.30%-104.15%) and precision [(0.32%-3.09% coefficient of variance (CV)] for vildagliptin calibration curve standards (CC STD), establishing its sensitivity and reliability in measuring vildagliptin levels. This refined methodology offers numerous advantages, including the elimination of stability concerns, reduced human plasma sample volume (100 μL), exceptional reproducibility, shortened run time (~2.2 min), and a wide concentration range (1.00 to 851.81 ng/mL). These attributes make it exceptionally well-suited for diverse research applications, spanning from extensive sampling in therapeutic drug monitoring units to bioequivalence and bioavailability studies, as well as pharmacokinetic investigations of vildagliptin.

Effects of Catha edulis (Khat) on the Pharmacokinetics of Metformin in Diabetic Rats Using UPLC/MS/MS Analysis and Its Impact on Hepatic CYP450 Enzymes

Catha edulis Forsk., commonly known as Khat, is a stimulant plant that is chewed in the Horn of Africa and the southern regions of the Arabian Peninsula. It is often used alongside conventional drugs, but there is a lack of research on its interactions with other drugs. In this study, our aim was to investigate the possibility of an herb–drug interaction between KT extract and metformin (MT) by exploring the effect of KT on the in vivo pharmacokinetics of MT in diabetic Wistar albino rats and monitoring blood glucose levels through time intervals, comparing when MT was given alone and co-administered with KT. Rats were given 500 mg/kg of KT extract and 300 mg/kg of MT daily for 7 days. The pharmacokinetic parameters of MT were analyzed using UPLC-MS/MS. The quantification was conducted using multiple reaction monitoring (MRM) in positive ion mode. The transitions used were (m/z) 130.006→59.939 for MT and 260.125→116.018 for propranolol as an internal standard (IS). An Acquity UPLC BEH HSS T3 C18 column was used with isocratic elution, and the mobile phase was formic acid (0.1%): acetonitrile (70:30 v/v) at a flow rate of 0.25 mL/min. In addition, the study delved into the in vitro impact of KT on the CYP3A4 enzyme, seeking to identify any potential disruptions in MT’s metabolism that could alter its pharmacokinetics. The effect of KT extract on CYP3A4 enzyme activity was investigated using fluorescence-based enzyme assays and a CYP3A4 Inhibitor Screening Kit. The results indicated that the combined treatment showed increased systemic exposure to MT, with Cmax and AUC levels increasing by 33.42% and 45.23%, respectively. Additionally, the combination treatment led to significantly lower fasting blood glucose (FBG) levels compared to the groups treated with MT alone. It was found that at a concentration of 500 µg/mL, the CYP3A4 enzyme activity was maximally suppressed by approximately 57%, while at 250 µg/mL, it was inhibited by almost 50%. In comparison, the standard Ketoconazole only inhibited CYP3A4 activity by approximately 58%. Therefore, the in vitro results suggest that KT extract has the potential to affect CYP3A4 activity at high doses. In conclusion, the combination treatment resulted in a significant increase in MT’s blood sugar-lowering effects. Therefore, it is important to be aware of this potential interaction and to monitor blood sugar levels closely when using KT alongside MT.

A new strategy for the determination of the antidiabetics alogliptin, saxagliptin and vildagliptin using all-solid state potentiometric sensors

Herein, we report on the development of disposable screen printed carbon, nanostructure thin film Au/Pt and Pt/Pt all-solid state potentiometric sensors for some antidiabetic compounds called glibtins. The electrodes showed excellent calibration curves (1 × 10^-5-1 × 10^-2 M) for alogliptin, saxagliptin and vildagliptin. The electrodes were fully characterized with respect to potential stability, dynamic response time, detection limit, effect of pH and interference according to the IUPAC recommendation. The proposed method is rapid and can be applied for the determination of gliptins at low cost with satisfactory precision (RSD ≤ 1%) and accuracy.

Voltammetric quantitative analysis of vildagliptin in bulk form and spiked human serum at a modified electrode

The electrochemical behavior of Vildagliptin (VILD) was studied using the cyclic voltammetric technique in an aqueous Britton–Robinson (BR) universal buffer solution of various pH levels between 4.0 and 10 at a 5% calcium-montmorillonite clay modified with carbon paste electrode surface (5% Ca-MMT/CPE). The results exhibited an irreversible anodic peak at about 1.238 V versus Ag/AgCl, KCl (3 mol L−1). The anodic peak was found to be diffusion–adsorption controlled. The possible reaction mechanism is estimated taking into consideration of the calculated electrons and protons number transferred on the electrode/electrolyte interface using the cyclic voltammetric technique. VILD was found to adsorb onto the surface of 5% Ca-MMT/CPE in a monolayer surface coverage of 3.0 × 10−12 mol cm−2. A validated square wave voltammetry (SWV) technique for VILD determination was performed. The calibration curve of VILD onto the 5% Ca-MMT/CPE surface was linear in the concentration range of 1.0–110 nmol L−1 with the mean limits of detection and quantification was 0.285 and 0.950 nmol L−1, respectively, in the bulk form. The proposed procedure for the assay of VILD in bulk form, dosage form, and spiked human serum has the advantage of being simple, rapid, sensitive, and inexpensive compared to other analytical methods. The described method showed an excellent performance for the trace determination of VILD in its formulation without interference from excipients.

Graphical abstract

Metformin as an emerging concern in wastewater: Occurrence, analysis and treatment methods

Metformin is a wonder drug used as an anti-hypoglycemic medication; it is also used as a cancer suppression medicament. Metformin is a first line of drug choice used by doctors for patients with type 2 diabetes. It is used worldwide where the drug's application varies from an anti-hypoglycemic medication to cancer oppression and as a weight loss treatment drug. Due to its wide range of usage, metformin and its byproducts are found in waste water and receiving aquatic environment. This leads to the accumulation of metformin in living beings and the environment where excess concentration levels can lead to ailments such as lactic acidosis or vitamin B12 deficiency. This drug could become of future water treatment concerns with its tons of production per year and vast usage. As a result of continuous occurrence of metformin has demanded the need of implementing and adopting different strategies to save the aquatic systems and the exposure to metformin. This review discuss the various methods for the elimination of metformin from wastewater. Along with that, the properties, occurrence, and health and environmental impacts of metformin are addressed. The different analytical methods for the detection of metformin are also explained. The main findings are discussed with respect to the management of metformin as an emerging contaminants and the major recommendations are discussed to understand the major research gaps.

LC-MS/MS Method Assay for Simultaneous Determination of the Apixaban and Metformin in Rat Plasma: Assessment of Pharmacokinetic Drug-Drug Interaction Study

A simple, sensitive and accurate LC-MS/MS method was developed and validated for the simultaneous quantification of apixaban (APB) and metformin (MET) in rat plasma using rivaroxaban as internal standard (IS). An Inertsil ODS3 C18 column (150 × 4.6 mm, 5 μm) was used for chromatographic separation with isocratic elution. Multiple reaction monitoring (MRM) using positive-ion ESI mode to monitor ion transitions of m/z 459.8 → 442.8 for APB, m/z 130.2 → 71.2 for MET, m/z 436.8 → 144.9 for IS. The procedure of method validation included selectivity, linearity, precision, accuracy, matrix effect, extraction recovery and stability were conducted according to the guidelines of EMA and FDA. The method was validated over the concentration range of 0.5-250 ng/mL for APB and 8-8000 ng/mL for MET. The intra- and inter-day precision and accuracy of the quality control samples exhibited relative standard deviations (RSD) < 12.5% and the accuracy values ranged from -8.6 to 12.4%. Recovery and matrix effect values variations were all less than 15%. After oral administration APB and MET to rats, the comparison of pharmacokinetic parameters of APB in the single and co-administrated groups showed significant difference in AUC(0-t) from 730.71 ± 121.31 to 573.07 ± 90.13 ng/mL·h, t1/2 from 5.86 ± 3.21 to 4.24 ± 1.15 h and Cmax from113.54 ± 24.04 to 159.42 ± 54.6 ng/mL. The comparison of pharmacokinetic parameters of MET in the single and co-administrated groups showed significant difference in t1/2 from 2.83 ± 1.81 to 3.97 ± 0.57 h and Cmax from 4015.76 ± 873.23 to 3153.6 ± 1012.51 ng/mL. The results indicated that drug-drug interactions (DDI) occurred might be owing to APB affect one or all of OCTs, MATE1, MATE2-K.

Physicochemical Properties and Methods of Analysis of Vildagliptin (Review)

Vildagliptin is an oral agent which is a member of a new class of hypoglycemic drugs, dipeptidylpeptidase-4 (DPP-4) inhibitors. This review presents the physicochemical properties of vildagliptin and assesses analysis methods for its estimation in substances, medicinal formulations, and biological media. These are chromatographic, spectrophotometric, electrochemical and other analysis methods. The material presented may be useful for developing new methods for analysis of medicinal formulations containing vildagliptin. The most widely used method for assay of vildagliptin is HPLC.

Development and Greenness Assessment of HPLC Method for Studying the Pharmacokinetics of Co-Administered Metformin and Papaya Extract

Foods with medical value have been proven to be beneficial, and they are extensively employed since they integrate two essential elements: food and medication. Accordingly, diabetic patients can benefit from papaya because the fruit is low in sugar and high in antioxidants. An RP-HPLC method was designed for studying the pharmacokinetics of metformin (MET) when concurrently administered with papaya extract. A mobile phase of 0.5 mM of KH2PO4 solution and methanol (65:35, v/v), pH = 5 ± 0.2 using aqueous phosphoric acid and NaOH, and guaifenesin (GUF) were used as an internal standard. To perform non-compartmental pharmacokinetic analysis, the Pharmacokinetic program (PK Solver) was used. The method's greenness was analyzed using two tools: the Analytical GREEnness calculator and the RGB additive color model. Taking papaya with MET improved the rate of absorption substantially (time for reaching maximum concentration (Tmax) significantly decreased by 75% while maximum plasma concentration (Cmax) increased by 7.33%). The extent of absorption reduced by 22.90%. Furthermore, the amount of medication distributed increased (30.83 L for MET concurrently used with papaya extract versus 24.25 L for MET used alone) and the clearance rate rose by roughly 13.50%. The results of the greenness assessment indicated that the method is environmentally friendly. Taking papaya with MET changed the pharmacokinetics of the drug dramatically. Hence, this combination will be particularly effective in maintaining quick blood glucose control.

Formulation of Lipid-Based Tableted Spray-Congealed Microparticles for Sustained Release of Vildagliptin: In Vitro and In Vivo Studies

Spray-congealing (SPC) technology was utilized to prepare lipid-based microparticles (MP) capable of sustaining the release of Vildagliptin (VG) for use as a once-daily treatment for type 2 diabetes mellitus. VG microparticles were prepared using Compritol® and Gelucire®50/13 as lipid carriers in the presence of various amounts of Carbomer 934 NF. The lipid carriers were heated to 10 °C above their melting points, and VG was dispersed in the lipid melt and sprayed through the heated two-fluid nozzle of the spray congealer to prepare the VG-loaded MP (VGMP). The microparticles produced were then compressed into tablets and characterized for their morphological and physicochemical characteristics, content analysis, in vitro dissolution, and in vivo bioavailability studies in mixed-breed dogs. The VGMP were spherical with a yield of 76% of the total amount. VG was found to be in its semicrystalline form, with a drug content of 11.11% per tablet and a percentage drug recovery reaching 98.8%. The in vitro dissolution studies showed that VG was released from the tableted particles in a sustained-release fashion for up to 24 h compared with the immediate-release marketed tablets from which VG was completely released within 30 min. The in vivo pharmacokinetics studies reported a Cmax, Tmax, T1/2, and MRT of 118 ng/mL, 3.4 h, 5.27 h, and 9.8 h, respectively, for the SPC formulations, showing a significant difference (p < 0.05)) from the pk parameters of the immediate-release marketed drug (147 ng/mL, 1 h, 2.16 h, and 2.8 h, respectively). The area under the peak (AUC) of both the reference and tested formulations was comparable to indicate similar bioavailabilities. The in vitro-in vivo correlation (IVIVC) studies using multiple level C correlations showed a linear correlation between in vivo pharmacokinetics and dissolution parameters. In conclusion, SPC was successfully utilized to prepare a once-daily sustained-release VG oral drug delivery system.

Hydrophilic Interaction Liquid Chromatography (HILIC): Latest Applications in the Pharmaceutical Researches

Background:

Significant advances have been occurred in analytical research since the 1970s by Liquid Chromatography (LC) as the separation method. Reverse Phase Liquid Chromatography (RPLC) method, using hydrophobic stationary phases and polar mobile phases, is the most commonly used chromatographic method. However, it is difficult to analyze some polar compounds with this method. Another separation method is the Normal Phase Liquid Chromatography (NPLC), which involves polar stationary phases with organic eluents. NPLC presents low-efficiency separations and asymmetric chromatographic peak shapes when analyzing polar compounds. Hydrophilic Interaction Liquid Chromatography (HILIC) is an interesting and promising alternative method for the analysis of polar compounds. HILIC is defined as a separation method that combines stationary phases used in the NPLC method and mobile phases used in the RPLC method. HILIC can be successfully applied to all types of liquid chromatographic separations such as pharmaceutical compounds, small molecules, metabolites, drugs of abuse, carbohydrates, toxins, oligosaccharides, peptides, amino acids and proteins.

Objective:

This paper provides a general overview of the recent application of HILIC in the pharmaceutical research in the different sample matrices such as pharmaceutical dosage form, plasma, serum, environmental samples, animal origin samples, plant origin samples, etc. Also, this review focuses on the most recent and selected papers in the drug research from 2009 to the submission date in 2020, dealing with the analysis of different components using HILIC.

Results and Conclusion:

The literature survey showed that HILIC applications are increasing every year in pharmaceutical research. It was found that HILIC allows simultaneous analysis of many compounds using different detectors.

Ecological HPLC method for analyzing an antidiabetic drug in real rat plasma samples and studying the effects of concurrently administered fenugreek extract on its pharmacokinetics

Currently, the total number of diabetic people worldwide is constantly increasing. Metformin (MET) is known to be a first-line antidiabetic drug with varied, wide-reaching applications. Concurrent administration of phytomedicines such as fenugreek extract with synthetic drugs is very common. It is reported that concomitant administration of fenugreek extract with metformin maintains lower blood glucose levels than metformin alone. In this work, an ecofriendly RP-HPLC method was established to study and compare the pharmacokinetics of metformin with and without the contemporary administration of fenugreek extract using rat as an animal model. In the developed method, a solvent mixture of 0.5 mM KH₂PO₄ solution : methanol (65 : 35, v/v) was used as a mobile phase and guaiphenesin was used as an internal standard. The plasma concentration–time curve was plotted, and non-compartmental pharmacokinetic analysis was performed using PKSolver. The results of the pharmacokinetic study showed that concurrent administration of fenugreek significantly increased the bioavailability of metformin and doubled the time required to reach the peak plasma concentration (T_max). Moreover, the volume of drug distribution decreased by about 70%, while its rate of clearance decreased by about 55.96%. Accordingly, the administration of fenugreek in combination with metformin significantly affected the pharmacokinetics of metformin, and this combination will be very useful in controlling blood glucose levels in diabetic patients. The greenness of the method was assessed using the Analytical Eco-Scale, Analytical Method Volume Intensity (AMVI), and National Environmental Method Index (NEMI), and all results affirmed that the method can be considered to be ecological.

The combination of fenugreek extract and metformin can be considered as an auspicious treatment for satisfactory diabetes control and minimizing the expected long-term complications of metformin.

Compensate for or Minimize Matrix Effects? Strategies for Overcoming Matrix Effects in Liquid Chromatography-Mass Spectrometry Technique: A Tutorial Review

In recent decades, mass spectrometry techniques, particularly when combined with separation methods such as high-performance liquid chromatography, have become increasingly important in pharmaceutical, bio-analytical, environmental, and food science applications because they afford high selectivity and sensitivity. However, mass spectrometry has limitations due to the matrix effects (ME), which can be particularly marked in complex mixes, when the analyte co-elutes together with other molecules, altering analysis results quantitatively. This may be detrimental during method validation, negatively affecting reproducibility, linearity, selectivity, accuracy, and sensitivity. Starting from literature and own experience, this review intends to provide a simple guideline for selecting the best operative conditions to overcome matrix effects in LC-MS techniques, to obtain the best result in the shortest time. The proposed methodology can be of benefit in different sectors, such as pharmaceutical, bio-analytical, environmental, and food sciences. Depending on the required sensitivity, analysts may minimize or compensate for ME. When sensitivity is crucial, analysis must try to minimize ME by adjusting MS parameters, chromatographic conditions, or optimizing clean-up. On the contrary, to compensate for ME analysts should have recourse to calibration approaches depending on the availability of blank matrix. When blank matrices are available, calibration can occur through isotope labeled internal standards and matrix matched calibration standards; conversely, when blank matrices are not available, calibration can be performed through isotope labeled internal standards, background subtraction, or surrogate matrices. In any case, an adjusting of MS parameters, chromatographic conditions, or a clean-up are necessary.

Stability-indicating RP-HPLC method for simultaneous determination of metformin hydrochloride and vildagliptin in tablet and biological samples

The present work aimed to develop and validate a simple, rapid, sensitive, accurate, and precise method for simultaneous determination of metformin hydrochloride and vildagliptin in tablet and biological samples. Isocratic elution of both the analytes was performed at 35 °C by injecting 20 μL into Thermo Hypersil ODS C18 column (5 μm, 4.6 mm× 250 mm), while the flow rate was set to 0.8 mL/min. The mobile phase comprised of methanol, acetonitrile, and phosphate buffer (5:30:65, v/v, pH 3.5), and wavelength was selected at 212 nm. The overall run time per sample was 7.0 min with a retention time of 3.36 and 5.41 min for metformin hydrochloride and vildagliptin, respectively. The calibration curve was linear from 10–140 μg/mL for metformin and 1–14 μg/mL for vildagliptin with a coefficient of determination (R2) ≤ 0.9919, while repeatability and reproducibility (expressed as relative standard deviation) were lower than 1.13 and 0.97%, respectively. Force degradation studies indicated a complete separation of the analytes in the presence of their degradation products providing a high degree of method specificity. The proposed reversed-phase high-performance liquid chromatography (RP-HPLC) method was demonstrated to be simple and rapid for the determination of metformin hydrochloride and vildagliptin in commercially available tablet and biological samples providing recoveries ranged between 100.13–100.29%.

Liquid chromatography tandem mass spectrometry for the simultaneous determination of metformin and pioglitazone in rat plasma: Application to pharmacokinetic and drug-drug interaction studies

Failure to attain and sustain long term glycemic control is an ongoing challenge in diabetes therapy. The trend to use a combined therapy and the risk of drug-drug interaction (DDI) are elevated and thus the need for sensitive analytical methods is of great significance. Herein, a simple, robust, and sensitive reverse phase high performance liquid chromatography-electrospray ionization-tandem mass spectrometry (ESI-MS/MS) method for simultaneous determination of metformin (MET) and pioglitazone (PGT) in rat plasma using canagliflozin (CAN) as internal standards (IS) was developed and fully validated. Prior Chromatographic separation on an Agilent Eclipse Plus C18 (4.6 × 100 mm, 3.5 μm) using gradient mobile phase system consisting of ammonium formate pH 4.5 and acetonitrile at a flow rate of 0.5 mL min^-1, within a run time of 14 min, the antidiabetic drugs were extracted from rat plasma using acetonitrile-induced protein precipitation technique. Multiple reaction monitoring in positive ion mode was used for quantitation of precursor to production at m/z 130.1 → 71.0 & 60 for MET, 357.2 → 134.2 for PGT, and 462.16 → 191.1 for CAN. Method linearity was obeyed in the range of 1 to 5000 and 1 to 2500 ng mL^-1 for MET and PGT, respectively. The developed method was validated in terms of accuracy, precision, selectivity, recovery, matrix effects, and stability as per US-FDA bioanalytical guidelines and successfully applied to clinical pharmacokinetic and DDI studies with a single oral administration of target compounds. The peak plasma concentrations (C_max) and area under the concentration-time curve (AUC) of MET was significantly influenced by the concomitant administration of PGT at equal concentration and vice versa. PGT affected the absorption and elimination rate of MET via inhibition of organic cationic transporter (OCT). Molecular modeling study revealed the significant interaction of PGT with OCT. A potential DDI in type 2 diabetic patient receiving chronic treatment with MET and PGT deserves further attention and study to improve drug therapy and prevent adverse effects.

Applications of Fourier transform infrared spectroscopic method for simultaneous quantitation of some hypoglycemic drugs in their binary mixtures

Cost-effective, green, simple and reliable transmission Fourier-transform infrared (FTIR) spectroscopic method was developed for simultaneous analysis of hypoglycemic drugs in their binary mixtures for the first time. The FTIR method was applied for the determination of vildagliptin (VILD), glimepiride (GLIM) and pioglitazone (PIOG) in binary mixture with metformin (METF). The method was validated according to the International Conference on Harmonization (ICH) guidelines. The obtained results (expressed in peak areas) are linear with concentration in the range of 0.61-20, 0.26-24 and 0.37-4 μg/mg for VILD, PIOG and GLIM, respectively while the linearity ranges for METF were 0.40-200, 0.26-800 and 0.19-1000 μg/mg with VILD, PIOG and GLIM, respectively. The limits of detection (LODs) were 0.20, 0.08 and 0.12 μg/mg for VILD, PIOG and GLIM, respectively while METF LODs were 0.13, 0.08 and 0.06 μg/mg with VILD, PIOG and GLIM, respectively. The FTIR method has been successfully applied for the determination of the cited binary mixtures in its pharmaceutical tablets and the obtained results showed satisfactory % recovery.

The role of mass spectrometry in studies of glycation processes and diabetes management

In the last decade, mass spectrometry has been widely employed in the study of diabetes. This was mainly due to the development of new, highly sensitive, and specific methods representing powerful tools to go deep into the biochemical and pathogenetic processes typical of the disease. The aim of this review is to give a panorama of the scientifically valid results obtained in this contest. The recent studies on glycation processes, in particular those devoted to the mechanism of production and to the reactivity of advanced glycation end products (AGEs, AGE peptides, glyoxal, methylglyoxal, dicarbonyl compounds) allowed to obtain a different view on short and long term complications of diabetes. These results have been employed in the research of effective markers and mass spectrometry represented a precious tool allowing the monitoring of diabetic nephropathy, cardiovascular complications, and gestational diabetes. The same approaches have been employed to monitor the non-insulinic diabetes pharmacological treatments, as well as in the discovery and characterization of antidiabetic agents from natural products. © 2018 Wiley Periodicals, Inc. Mass Spec Rev 38:112-146, 2019.

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.

Mechanistic study for the simultaneous determination of metformin and teneligliptin in human plasma using hydrophilic interaction liquid chromatography–MS/MS

Aim: A simple, selective and sensitive hydrophilic interaction liquid chromatography-MS/MS method is developed for the simultaneous determination of metformin (MET) and teneligliptin (TEN) in human plasma using deuterated internal standards. The mechanism of retention of analytes was studied by varying the proportion of organic diluent, buffer strength, pH of the mobile phase and temperature. Results: The results showed a mixed-mode mechanism comprising of hydrophilic (partition) and electrostatic interaction (ion exchange) for MET and essentially hydrophilic for TEN. The linear calibration curves were established in the concentration range of 1.0–1000 ng/ml for MET and 0.50–750 ng/ml for TEN. Conclusion: The method was applied to determine plasma concentration of MET and TEN in healthy subjects.

Application of matrix-assisted laser desorption/ionization mass spectrometry imaging in combination with LC–MS in pharmacokinetic study of metformin

Aim: To demonstrate and discuss the pros and cons of various conventional and innovative analytical approaches. Methodology & results: Matrix-assisted laser desorption/ionization mass spectrometry imaging (MSI) of tissue sections as well as the extraction of tissue homogenates, blood plasma and dried blood spots coupled with LC–MS were employed to monitor the pharmacokinetics of metformin in mice. The time profile of metformin measured by matrix-assisted laser desorption/ionization MSI correlated well with the results found by LC–MS. Repeatability of the preparation of tissue sections for MSI was very good. Conclusion: MSI provided valuable information on the spatial distribution and relative concentration of the analyte within tissue sections. The analysis of the extracts of tissue homogenates, blood plasma and blood spots provided quantitative data on metformin. The dried blood spot approach is a progressive method of sampling, especially in studies where the amount of available blood is limited.

Bioanalytical methods for the detection of antidiabetic drugs: a review

Type 2 diabetes mellitus, a disease which prevalence has been progressively increasing worldwide, is characterized by chronic hyperglycemia resulting from the combination of inappropriate insulin secretion and/or resistance to insulin action. If left uncontrolled, diabetes is associated with complications such as dysfunction and failure of various organs, and even premature death. Along with lifestyle-modification strategies, several classes of oral antidiabetic agents can be employed for glycemic control. Thus, therapeutic drug monitoring of these drugs is essential to maintain appropriate treatment. This review discusses the most frequently employed analytical techniques and sample preparation systems to obtain a reliable and trustworthy method to quantify antidiabetic drugs in biological matrices. An adequate choice of internal standard, ideal chromatography conditions and most suitable analytical detector are reported.

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

An ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry method for the simultaneous quantification of chlorpropamide, glibenclamide, gliclazide, glimepiride, metformin, nateglinide, pioglitazone, rosiglitazone, and vildagliptin in human plasma was developed and validated, using isoniazid and sulfaquinoxaline as internal standards. Following plasma protein precipitation using acetonitrile with 1% formic acid, chromatographic separation was performed on a cyano column using gradient elution with water and acetonitrile, both containing 0.1% formic acid. Detection was performed in a quadrupole time-of-flight analyzer, using electrospray ionization operated in the positive mode. Data from validation studies demonstrated that the new method is highly sensitive, selective, precise (RSD < 10%), accurate (RE < 12%), linear (r > 0.99), free of matrix and has no residual effects. The developed method was successfully applied to volunteers' plasma samples. Hence, this method was demonstrated to be appropriate for clinical monitoring of antidiabetic agents.

LC-MS/MS analysis of metformin, saxagliptin and 5-hydroxy saxagliptin in human plasma and its pharmacokinetic study with a fixed-dose formulation in healthy Indian subjects

A specific and rapid liquid chromatography-tandem mass spectrometry method is proposed for the simultaneous determination of metformin (MET), saxagliptin (SAXA) and its active metabolite, 5-hydroxy saxagliptin (5-OH SAXA) in human plasma. Sample preparation was accomplished from 50 μL plasma sample by solid-phase extraction using sodium dodecyl sulfate as an ion-pair reagent. Reversed-phase chromatographic resolution of analytes was possible within 3.5 min on ACE 5CN (150 × 4.6 mm, 5 μm) column using acetonitrile and10.0 mm ammonium formate buffer, pH 5.0 (80:20, v/v) as the mobile phase. Triple quadrupole mass spectrometric detection was performed using electrospray ionization in the positive ionization mode. The calibration curves showed good linearity (r²  ≥ 0.9992) over the established concentration range with limit of quantification of 1.50, 0.10 and 0.20 ng/mL for MET, SAXA and 5-OH SAXA respectively. The extraction recoveries obtained from spiked plasma samples were highly consistent for MET (75.12-77.84%), SAXA (85.90-87.84%) and 5-OH SAXA (80.32-82.69%) across quality controls. The validated method was successfully applied to a bioequivalence study with a fixed-dose formulation consisting of 5 mg SAXA and 500 mg MET in 18 healthy subjects. The reproducibility of the assay was demonstrated by reanalysis of 87 incurred samples.

Urinary metabolomic profiling in mice with diet-induced obesity and type 2 diabetes mellitus after treatment with metformin, vildagliptin and their combination

Metformin, vildagliptin and their combination are widely used for the treatment of diabetes, but little is known about the metabolic responses to these treatments. In the present study, NMR-based metabolomics was applied to detect changes in the urinary metabolomic profile of a mouse model of diet-induced obesity in response to these treatments. Additionally, standard biochemical parameters and the expression of enzymes involved in glucose and fat metabolism were monitored. Significant correlations were observed between several metabolites (e.g., N-carbamoyl-β-alanine, N1-methyl-4-pyridone-3-carboxamide, N1-methyl-2-pyridone-5-carboxamide, glucose, 3-indoxyl sulfate, dimethylglycine and several acylglycines) and the area under the curve of glucose concentrations during the oral glucose tolerance test. The present study is the first to present N-carbamoyl-β-alanine as a potential marker of type 2 diabetes mellitus and consequently to demonstrate the efficacies of the applied antidiabetic interventions. Moreover, the elevated acetate level observed after vildagliptin administration might reflect increased fatty acid oxidation.

LC-tandem mass spectrometry method for the simultaneous determination of metformin and sitagliptin in human plasma after ion-pair solid phase extraction

A reversed-phase liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) method was established for simultaneous determination of two oral hypoglycemic drugs metformin (MET) and sitagliptin (STG) in human plasma. The analytes were extracted from 50μL human plasma by ion-pair solid phase extraction using sodium lauryl sulphate on Phenomenex Strata-X (30mg/1mL) cartridges. The chromatographic separation was accomplished on XSelect HSS CN (150×4.6mm, 5μm) column using mobile phase consisting of methanol-8.0mM ammonium formate in water, pH 4.5 (80:20, v/v) under isocratic condition. Tandem MS detection was performed on a triple quadrupole spectrometer equipped with an electrospray ionization source, operated in the positive mode. Multiple reaction monitoring (MRM) was used to quantify the analytes following transitions, m/z 130.1→60.1 and m/z 408.3→235.1 for MET and STG respectively. The method displayed acceptable linearity in the concentration range of 4.00-3200ng/mL for MET and 1.00-800ng/mL for STG. The intra-batch and inter-batch precisions were ≤5.1% and accuracy ranged from 96.5 to 103.3% for both the drugs. The mean recovery of MET and STG obtained from spiked plasma samples was 82.5% and 90.4% respectively with minimal matrix interference. Both the drugs were found to be stable under all mandatory storage conditions. The validated method was successfully applied to a clinical pharmacokinetic study for a fixed-dose tablet formulation containing 500mg MET and 50mg STG in 16 healthy volunteers.

Development, validation of liquid chromatography-tandem mass spectrometry method for simultaneous determination of rosuvastatin and metformin in human plasma and its application to a pharmacokinetic study

A new, simple and accurate liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for simultaneous determination of rosuvastatin (ROS) and metformin (MET) in human plasma was developed. The assay procedure involved simple protein precipitation with acetonitrile. Following precipitation, fraction of supernatant was decanted and evaporated under gentle stream of nitrogen at 40°C. The residue was reconstituted in mobile phase and injected. The chromatographic separation was achieved with Thermo Hypurity C18 column (50 mm × 4.6 mm, 5 μ) using a mobile phase composition containing 0.1% v/v formic acid in water and acetonitrile (30:70, v/v) at a flow rate of 0.4 mL/min. The total run time was 3.5 min. The method showed good linearity in the range 0.5–200 ng/mL for ROS and 2–2000 ng/mL for MET with correlation coefficient (r) >0.9994 for both the analytes. The intra and inter-day precision values for ROS and MET met the acceptance criteria as per regulatory guidelines. The battery of stability studies viz., bench-top, freeze-thaw and long term stability were performed. The developed method was applied to a pharmacokinetic study.

Hydrophilic interaction chromatography-tandem mass spectrometry based on an amide column for the high-throughput quantification of metformin in rat plasma

A simple, highly sensitive, specific, reproducible, and high-throughput Amide-HILIC-MS/MS assay to quantify metformin in rat plasma was established and successfully applied for sample analysis to support pharmacokinetic studies.

Novel contribution to the simultaneous analysis of certain hypoglycemic drugs in the presence of their impurities and degradation products utilizing UPLC-MS/MS

A novel, sensitive, rapid and selective UPLC-MS/MS method was developed for simultaneous quantification of vildagliptin, sitagliptin and metformin in the presence of their degradation products and impurities.