Development of simultaneous determination of empagliflozin and metformin in human plasma using liquid chromatography-mass spectrometry and application to pharmacokinetics

A Highly Sensitive UPLC-MS/MS Method for the Quantification of the Organic Cation Transporters' Mediated Metformin Uptake and Its Inhibition in Cells

Metformin is the gold standard substrate for evaluating potential inhibitors of the organic cation transporters (OCTs). Here, we established a UPLC-MS/MS assay to quantify metformin in cell pellets with a range of 0.05-50 ng/mL using 6-deuterated metformin as an internal standard. We used an ion-pairing chromatographic approach with heptafluorobutyric acid, making use of a reverse-phase column, and overcame the associated ion-suppression via previously established post-column injection of aqueous ammonia. The assay was validated according to the Food and Drug Administration (FDA) and the European Medicines Agency (EMA) recommendations for bioanalytical methods. The established extraction procedure was simple, very fast and ensured almost 100% recovery of the analyte. The exceptionally sharp peak form and retention of the ion-pairing chromatography are superior to other methods and allow us to measure as sensitively as 0.05 ng/mL. We used the herein established and validated method to develop a cellular OCT inhibition assay by using metformin as a substrate and human embryonic kidney cells (HEK) overexpressing the OCTs 1-3. The method presented may be useful for identifying new OCT inhibitors, but also for drug-drug interactions and other pharmacokinetic studies, where accurate quantification of low metformin amounts in relevant tissues is mandatory.

A Highly Sensitive Inclusion Complex Based Spectrofluorimetric Method for the Determination of Certain Sodium Glucose Cotransporter-2 Inhibitors: Greenness Assessment and Application to Different Biological Fluids

This study introduces a remarkably simple, green, and highly sensitive inclusion complex based spectrofluorimetric method for analyzing two sodium glucose cotransporter-2 (SGLT2) inhibitors: empagliflozin (EGF) and dapagliflozin (DGF). The method utilizes beta-cyclodextrin (β-CD) complexation to enhance the native fluorescence of EGF and DGF in aqueous solutions, resulting in 11.0-fold and 9.0-fold intensity increases, respectively. Fluorescence measurements were conducted at 301 nm emission following 230 nm excitation for both drugs. The method demonstrates excellent linearity (0.9994 for EGF and 0.9993 for DGF) over concentration ranges of 5.0-250.0 ng/mL and 10.0-300.0 ng/mL, with low detection limits of 1.05 and 1.38 ng/mL for EGF and DGF, respectively. The method's versatility was validated through successful application in pharmaceutical formulations, content uniformity testing, and biological fluids. This eco-friendly approach primarily uses water as a solvent and requires minimal reagents. The method's environmental impact was comprehensively evaluated using the analytical eco-scale, green analytical procedure index (GAPI), and analytical greenness metric (AGREE).

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.

Simultaneous estimation of two anti-diabetic drugs; Linagliptin and empagliflozin in their tablet by chemometric spectrophotometry

Four spectrophotometric approaches had been established and optimized for the simultaneous estimation of two anti-diabetic drugs; linagliptin (LIN) and empagliflozin (EMP) in their bulk and tablet dosage form. LIN concentration could be first determined from the zero order spectra at its λmax (293 nm) without interference from EMP as at this wavelength EMP showed zero absorbance. The LIN and EMP zero order absorption spectra displayed considerable overlap which hindered the direct determination of EMP. Thus, four indirect spectrophotometric approaches were established and optimized for the determination and quantification of EMP concentrations in presence of LIN. Method (I) was ratio difference method (RD) which depended on the determination of difference amplitudes in the ratio spectra (ΔP) at 236 nm and 227 nm; ΔP(236-227) was directly proportional to EMP concentration. Method (II) was ratio derivative method (1DD) based on the measuring of the amplitude of first derivative of ratio spectra at 243 nm which was directly proportional to EMP concentration. For determination of EMP concentration using both method (I) and (II); LIN 7 µg/mL was used as the divisor. Method (III) was area under curve method (AUC) which depended on the measurement of area confined between 220 and 230 nm and 273-290 nm. Method (IV) was dual wavelength method (DWL) which based on measurement of absorbance difference (ΔA) in zero order spectra between 239.8 and 282.6 nm which was directly proportional to EMP concentration. The four developed methods were optimized and entirely validated regarding to ICH guidelines. The proposed spectrophotometric approaches were used for the quantification of LIN and EMP simultaneously in their tablet dosage form. F-test and t-test were applied for statistical comparison between the results obtained by the proposed approaches and that obtained by the reported method. There was no significant difference concerning to precision and accuracy.

A sensitive ultra-performance liquid chromatography-tandem mass spectrometry method for the simultaneous quantification of assay and trace-level genotoxic tosylate analogs (methyl and ethyl) in empagliflozin and its tablet dosage forms

This study performed the simultaneous quantification of assay and two alkyl sulfonate (tosylate) analogs of empagliflozin (EGZ), specifically methyl 4-methyl benzene sulfonate (MMBS) and ethyl 4-methyl benzene sulfonate (EMBS) in EGZ, and its finished dosage form using an accurate and sensitive ultra-performance liquid chromatography-mass spectrometry method. The separation was achieved on a Waters Acquity BEH Shield RP18 (100 × 2.1 mm, 1.7 μm) column in gradient elution mode with 0.1% formic acid and acetonitrile as the mobile phases and a flow rate of 0.5 mL/min. For simultaneous quantification, the multiple reaction monitoring technique was utilized. The procedure was successfully validated in accordance with the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines. The peak areas of both impurities, along with their concentrations, exhibited a good relationship with Pearson's correlation coefficient (R), which was >0.999 in the range of 0.3-6 ppm with an EGZ concentration of 2 mg/mL. The percentage recoveries from the limit of quantitation (LOQ) to 200% to the specification level were in the range of 94.82%-102.92%, whereas the percentage relative standard deviation (%RSD) was <2. Therefore, this method is rapid and accurate to quantify MMBS, EMBS, and EGZ assay simultaneously from the marketed tablet dosage forms of EGZ for commercial release and stability sample testing.

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.

Eco-friendly-assessed micellar-fluorimetric platform for concurrent analysis of empagliflozin and prucalopride succinate in biological fluids: Docking simulation

Fluorescence spectroscopy has an important role in the determination of very small quantities of substances, especially in biological fluids. For this reason, most analysts have adopted the use of this technique in their biological studies and research, which helps them in the determination of any substance found in trace amounts. In addition to the high sensitivity of the fluorimetric technique, it has the advantages of simplicity and being green for the environment. All these reasons encourage the use of fluorimetric spectroscopy for quantifying co-administered therapy in biological fluids, which is considered a crucial step for patients, particularly in emergent cases requiring monitoring of administered therapeutic drugs. In this work, a sensitive, simple, economic, and environmentally friendly fluorimetric analytical technique was developed for the simultaneous determination of prucalopride succinate (a novel anti-constipation agent) and empagliflozin (an anti-diabetic agent) in pharmaceutical forms and spiked plasma depending on third-derivative signal processing at 333 and 314 nm, respectively. Conventional fluorescence spectra of both drugs showed a large overlap that hindered their simultaneous determination. So, third-order derivative fluorescence was adopted to overcome this overlap. The third-derivative corresponding to each spectrum was recorded using data points = 17 and a scaling factor of 10. The greenness of the proposed method was evaluated using an eco-scale scoring system, revealing excellent greenness. Analytical method parameters were validated following ICH guidelines. The method showed high sensitivity, covering a concentration range of 50-1100 ng/mL and 4-500 ng/mL for empagliflozin and prucalopride, respectively, allowing the pharmacokinetic study of both drugs in biological fluids. The LOD values were 14.09 and 0.91 ng/mL, while the LOQ values were 42.72 and 2.77 ng/mL for empagliflozin and prucalopride, respectively.

Ultrafast Measurement of Metformin in the Clinical Setting Using Probe Electrospray Ionization Mass Spectrometry

Metformin (MtF) is a treatment used for type 2 diabetes. Lactic acidosis (LA) is a frequent complication that can be either induced by or associated with elevated MtF plasma concentrations. When coupled with a mass spectrometry (MS) system, the probe electrospray ionization (PESI) method allows direct and rapid analysis of different types of matrices without pretreatment. In this study, we developed a PESI-MS method for the determination of MtF in plasma. We used a tandem mass spectrometer equipped with a PESI source in the reaction monitoring mode for the quantitation of MtF. MtF-d6 was chosen as the internal standard (IS), following an isotope dilution (ID) approach. The method was fully validated with six concentration levels (0.5-50 mg/L). The matrix effect was evaluated for each level, and the specificity was tested with a mix of potential co-medications. Using patient samples, the performance was compared with two classical LC-MS-MS and LC-diode array detector (DAD) methods used in external labs. Sample preparation consisted in mixing 10 µL plasma in 1,000 µL ethanol/ammonium formate buffer including MtF-d6 at a fixed concentration of 5 mg/L. The total run time was 0.31 min. ID gave satisfactory results of accuracy and precision (min-max: -12.1 to 15.8% and 1.0-17.1%, respectively). The matrix effect was fully corrected by the internal standard (bias < 1%). The specificity study also reported satisfactory results. Finally, in a representative group of 29 patients (55% with a concentration <5 mg/L, 38% with a concentration >5 mg/L and 7% not detected), we observed almost identical results when comparing LC-DAD and LC-MS-MS to PESI-MS (r2 > 0.99). We propose a specific, sensitive, accurate and ultrafast solution for the measurement of MtF in patient plasma, with no sample preparation or calibration curve building. This could be helpful in a core lab when rapid diagnosis of LA is needed.

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.

Synthesis and characterization of a new reusable calix[4]arene-bonded silica gel sorbent for antidiabetic drugs

A novel calix[4]arene-bonded silica gel (C4BS) is prepared by covalent attachment of a calix[4]arene derivative to silica gel through a thiol–ene process. The structure and properties of C4BS were studied by Fourier Transform Infra-Red (FTIR) spectroscopy, thermal gravimetric analysis (TGA), elemental analysis (CHN), scanning electron microscopy (SEM), and surface area analysis (BET). In addition, the binding affinity of some antidiabetic drugs towards C4BS was investigated, by quantitative measurement of the drugs in aqueous solution using UV-visible spectroscopy. Results showed that C4BS has higher affinities than plain silica gel for binding to empagliflozin, dapagliflozin and linagliptin at neutral pH, while metformin hydrochloride was not adsorbed efficiently using either C4BS or plain silica gel. Thus, C4BS can be introduced as a promising binder for selective adsorption of the quoted antidiabetic drugs in pharmaceutical effluents, while being reusable by aqueous/acetonitrile (1 : 1) extraction.

C4BS is a new reusable calix[4]arene-bonded silica gel adsorbent for dapagliflozin (DAPA), empagliflozin (EMPA) and linagliptin (LINA) as antidiabetic drugs.

Simple mathematical data processing method for the determination of sever overlapped spectra of linagliptin and empagliflozin in their pure forms and pharmaceutical formulation: Fourier self deconvulated method

A new and simple spectrophotometric method was developed for the simultaneous determination of a new antidiabetic mixture of linagliptin and empagliflozin namely fourier self deconvulated method. The developed method based on minimal mathematical data processing on the zero order spectrum for solving sever overlapping spectra of the mentioned drugs in their pure forms and pharmaceutical dosage form. The zero order spectra of linagliptin and empagliflozin were deconvulated using Fourier transforms function. The peak amplitudes at 232 nm were selected for linagliptin and at 239 nm for empagliflozin. The constructed calibration graphs were linear over the range (5-30 µg/mL) and (2-12 µg/mL) for empagliflozin and linagliptin, respectively. The adopted method was simple, accurate, precise and validated according to the ICH guidelines.

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.

Validation of a novel UPLC-MS/MS method for estimation of metformin and empagliflozin simultaneously in human plasma using freezing lipid precipitation approach and its application to pharmacokinetic study

A fast, sensitive one step UPLC ESI-MS/MS method was successfully applied for the simultaneous estimation of two concurrently administrated antidiabetic drugs, Metformin (MET) and Empagliflozin (EMPA) in human plasma. Metformin-d6 (MET-d6) and Empagliflozin-d4 (EMPA-d4) were utilized as internal standards. Extraction of the analytes from the human plasma was performed through acetonitrile precipitation technique followed by freezing the precipitated plasma proteins and lipids to minimize the matrix effect. Chromatographic analysis was developed on Acquity UPLC BEH C₁₈ column (1.7 μm, 2.1 × 50 mm) using isocratic elution mode. A mobile phase of formic acid (0.01 %): acetonitrile (70:30 v/v) with a flow rate of 0.3 mL/min achieved optimum separation. Multiple reaction monitoring (MRM) in positive ion mode, with transitions at (m/z) 130.14 →71.08 for (MET), 451.72 →71.29 for (EMPA), 136.03 →77.02 for (MET-d6), and 455.43 → 75.05 for (EMPA-d4) was used for quantification. The obtained linearity covered the concentration ranges of 10-1500 ng/mL and 2.0-250.0 ng/mL for MET and EMPA, respectively. The run time of the proposed Method didn't exceed 3.0 min allowing faster analysis and determination of larger number of samples per day without affecting accuracy and sensitivity. The presented chromatographic method could be successfully applied in pharmacokinetics studies and therapeutic monitoring of MET and EMPA in patients' plasma administrating fixed dose combination of both drug with high reproducibility and ruggedness.

Quality-by-Design Approach for Chromatographic Analysis of Metformin, Empagliflozin and Linagliptin

New analytical quality by design-oriented HPLC method with multiple response optimization (Derringer's desirability function) was demonstrated for simultaneous analysis of three antidiabetic drugs (metformin hydrochloride/empagliflozin/linagliptin) in a fixed-dose combination. Central composite design was employed for systematic optimization of critical method parameters, namely, % organic phase (X1), aqueous phase pH (X2) and flow rate (X3) while resolution, capacity factor and theoretical plate number as critical analytical attributes. Effective chromatographic separation of title analytes was accomplished on Std. Discovery C18 column at 30°C with mobile phase comprising acetonitrile: phosphate buffer pH 5 (38:62% v/v), pumped at a flow rate of 1 mL/min by isocratic elution pattern and UV detection at 222 nm. The model is rectilinear in the range of 1.0-200, 0.2-40 and 0.1-20 μg/mL at retention times of 3.04, 3.93 and 5.99 min for metformin, empagliflozin and linagliptin, respectively. The method obeyed all validation parameters of ICH Q2(R1) guidelines. The proposed HPLC method was highly robust for method transfer, regulatory flexibility within design space and can be used for assay of pharmaceutical dosage forms comprising these analytes. The proposed method was applied for stability studies of drugs under various stress conditions.

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.

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.