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Objective: The present work represents a reverse-phase high-performance liquid chromatography method in addition to stability studies for sequential estimation of remogliflozin etabonate, vildagliptin, and metformin HCl in tablet formulation., Method: The mentioned method utilizes a Phenomenex Luna C18 column (250×4.6mm, 5μm). It consists of a column oven's temperature of 35°C. Mobile phase includes a mixture of 50% phosphate buffer (pH - 6.8) and 50% acetonitrile along with a flow rate of 0.8mL/min and 20minutes of run time. The injection volume was 20μL; 217nm is a detection wavelength, and a PDA detector is used for detection., Results: The suggested technique was proven and validated per the ICH Q2 (R1) guideline. The combination was put under stress conditions that included acid, base, thermal, photolytic, and oxidative degradation. The combination was considerably degraded under oxidative, acidic, and basic circumstances for deterioration, and the degradation results were accurately identified from the observed peaks, demonstrating the method's effectiveness in detecting stability., Conclusion: The technique was quick, precise, sensitive, and accurate; as a result, it may be used in quality control laboratories and the pharmaceutical industry for routine quality monitoring of tablets containing all three medications., (Copyright © 2024 Académie Nationale de Pharmacie. Published by Elsevier Masson SAS. All rights reserved.)

Metformin is the most commonly used drug for the treatment of type 2 diabetes (T2D), which is dramatically increasing due to factors such as increasing obesity, physical inactivity, and aging of the population. Metformin analysis was carried out in composite wastewater samples seasonally collected from wastewater treatment plants in 10 cities in 2019 and 2020 30 cities in 2021 in Turkiye. Metformin was measured in all wastewater samples, with an average concentration of 97.81 μg/l in 2019, 75.19 μg/l in 2020, and 69.13 μg/l in 2021. This study was utilized to predict metformin usage in different sociodemographic regions in Turkiye using a wastewater-based epidemiology (WBE) approach. As a result of the analysis, the average metformin consumption in Turkiye was estimated to be 22.2 ± 9.6 [1.9-63.8] g/d/1,000 persons (mean ± SD [range]). Furthermore, these estimates were compared with data for time, sociodemographic characteristics, and patient numbers. Assessing the correlation with estimates and the socioeconomic classes of the cities in question revealed that cities with high-income levels had the lowest metformin use rate. Finally, the study provides supporting data aiding the development of public health strategies for decreasing the overall load of T2D across Turkiye., (© 2024 John Wiley & Sons Ltd.)

Due to the increased prevalence of diabetes, the consumption of anti-diabetic drugs for its treatment has likewise increased. Metformin is an anti-diabetic drug that is commonly prescribed for patients with type 2 diabetes and has been frequently detected in surface water and wastewaters, thus representing an emerging contaminant. Metformin can be prescribed in combination with other classes of anti-diabetic drugs; however, these drugs are not sufficiently investigated in environmental samples. Fabric phase sorptive extraction (FPSE) has emerged as a simple and green method for the extraction of analytes in environmental samples. In this study, FPSE coupled with a high-performance liquid chromatography diode array detector (HPLC-DAD) was employed for the simultaneous analysis of different classes of anti-diabetic drugs (metformin, dapagliflozin, liraglutide, pioglitazone, gliclazide, glimepiride, glargine, repaglinide, sitagliptin, and vildagliptin) in environmental water samples. Four different fabric membranes were synthesized but the microfiber glass filter coated with sol-gel polyethylene glycol (PEG 300) was observed to be the best FPSE membrane. The parameters affecting the FPSE process were optimized using a combination of one-factor-at-a-time processes and the design of experiments. The FPSE was evaluated as a green extraction method, based on green sample preparation criteria. The FPSE-HPLC-DAD method achieved acceptable validation results and was applied for the simultaneous analysis of anti-diabetic drugs in surface and wastewater samples. Glimepiride was detected below the quantification limit in both lake and river water samples. Dapagliflozin, liraglutide, and glimepiride were detected at 69.0 ± 1.0 μg·L -1 , 71.9 ± 0.4 μg·L -1 , and 93.9 ± 1.3 μg·L -1 , respectively, in the city wastewater influent. Dapagliflozin and glimepiride were still detected below the quantification limit in city wastewater effluent. For the hospital wastewater influent, metformin and glimepiride were detected at 1158 ± 21 μg·L -1 and 28 ± 0.8 μg·L -1 , respectively, while only metformin (392.6 ± 7.7 μg·L -1 ) was detected in hospital wastewater effluent.

A rapid, green and sensitive technique for the determination of metformin determination was developed based on the direct fluorescence enhancement of carbon dots (CDs) induced by the cited drug. The water-soluble CDs were prepared via a one-pot synthesis from avocado peels using domestic microwave. The prepared CDs exhibited strong fluorescence at 405 nm after excitation at 320 nm with a quantum yield of 51%. The fluorescence of CDs was enhanced linearly by increasing the concentration of metformin within the range 0.5-25 μg/mL with limit of detection 0.087 μg/mL and limit of quantification 0.263 μg/mL. The designed probe was proved to be selective toward metformin in the presence of other drugs such as vildagliptin and alogliptin and also in the presence of excipients in the pharmaceutical dosage form. The suggested and reported methods were compared with the help of the whiteness and greenness tools, specifically the white analytical chemistry and analytical greenness metric tools, for assessing hazardous solvents and reagents used., (© 2024 John Wiley & Sons Ltd.)

In this study, deep UV resonance Raman spectroscopy (DUV-RRS) was coupled with high performance liquid chromatography (HPLC) to be applied in the field of pharmaceutical analysis. Naproxen, Metformin and Epirubicin were employed as active pharmaceutical ingredients (APIs) covering different areas of the pharmacological spectrum. Raman signals were successfully generated and attributed to the test substances, even in the presence of the dominant solvent bands of the mobile phase. To increase sensitivity, a low-flow method was developed to extend the exposure time of the sample. This approach enabled the use of a deep UV pulse laser with a low average power of 0.5 mW. Compared to previous studies, where energy-intensive argon ion lasers were commonly used, we were able to achieve similar detection limits with our setup. Using affordable lasers with low operating costs may facilitate the transfer of the results of this study into practical applications., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Bjoern Fischer reports financial support was provided by Federal Ministry for Economic Affairs and Climate Action. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

This study investigated the occurrence, removal rate, and potential risks of 43 organic micropollutants (OMPs) in four municipal wastewater treatment plants (WWTPs) in Korea. Results from two-year intensive monitoring confirmed the presence of various OMPs in the influents, including pharmaceuticals such as acetaminophen (pain relief), caffeine (stimulants), cimetidine (H 2 -blockers), ibuprofen (non-steroidal anti-inflammatory drugs- NSAIDs), metformin (antidiabetics), and naproxen (NSAIDs) with median concentrations of >1 μg/L. Some pharmaceuticals (carbamazepine-anticonvulsants, diclofenac-NSAIDs, propranolol-β-blockers), corrosion inhibitors (1H-benzotriazole-BTR, 4-methyl-1H-benzotriazole-4-TTR), and perfluorinated compounds (PFCs) were negligibly removed during WWTP treatment. The OMP concentrations in the influents and effluents were mostly lower in August than those of other months (p-value <0.05) possibly due to wastewater dilution by high precipitation or enhanced biodegradation under high-temperature conditions. The anaerobic-anoxic-oxic process (A2O) with a membrane bioreactor exhibited higher OMP removal than other processes, such as A2O with sedimentation or the conventional activated sludge process (p-value <0.05). Pesticides (DEET and atrazine), corrosion inhibitors (4-TTR and BTR), and metformin were selected as priority OMPs in toxicity-driven prioritization, whereas PFCs were determined as priority OMPs given their persistence and bioaccumulation properties. Overall, our results contribute to an important database on the occurrence, removal, and potential risks of OMPs in Korean WWTPs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Accurate, sensitive and green HPTLC chromatographic method was proposed for simultaneous determination of metformin, glipizide and sitagliptin in the presence of metformin potential toxic impurities melamine and cyanoguanidine. The separation was completed on silica gel HPTLC F254 plates using a mixture of ethyl acetate: methanol: ammonia: formic acid (7: 2: 0.2: 0.2, by volume) as a developing system with UV scanning for the developed bands at 235 nm. The Rf values for metformin, glipizide, sitagliptin, melamine and cyanoguanidine were 0.17, 0.84, 0.67, 0.47 and 0.75, respectively. Linear responses were observed in the ranges of 0.2-3, 0.07-1.5, 1.5-5, 0.8-4 and 0.4-2 μg/band with correlation coefficients of 0.9999, 0.9998, 0.9997, 0.9996 and 0.9998 for metformin, glipizide, sitagliptin, melamine and cyanoguanidine, respectively. The proposed method was validated as per ICH criteria with respect to linearity, accuracy, precision, specificity and robustness. The validated method was successfully applied for determination of the studied drugs in Janumet® and Engilor® tablets; also, the results were statistically compared to those obtained by the reported spectrophotometric method and no significant difference was found between them. This method permitted the accurate simultaneous determination of the studied drugs, indicating its ability to be used for routine quality control assays of these drugs., (© The Author(s) 2023. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA), group 2A carcinogens, were detected in finished drug products, including metformin, ranitidine, sartans and other drugs which caused multiple recalls in the USA and Europe. Important studies also reported the formation of NDMA when ranitidine and nitrite were added to simulated gastric fluid. Our objective was to screen finished drug products from Europe and USA for nitrosamine impurities and investigate the formation of NDMA in metformin finished drug products when added to simulated gastric fluid. One dosage unit of 30 different commercially available drugs, including metformin, sartans, and ranitidine were tested for NDMA, NDEA, and dimethylformamide (DMF) impurities, using a liquid chromatography-mass spectrometry (LC-MS) method. Then, 6 metformin finished drug products were tested in stomach conditions for 2 h at 37 °C in a 100 mL solution with a pH of 2.5 and different nitrite concentrations (40, 10, 1, 0.1 mM) and tested for NDMA, and DMF using LC-MS. We measured NDMA, NDEA, and DMF in 30 finished drug products. NDMA and DMF were quantified for metformin drug products in simulated gastric fluid with different nitrite concentrations. None of the 30 drugs showed concerning levels of NDMA, NDEA, or DMF when tested as single tablets. However, when metformin tablets are added to simulated gastric fluid solutions with high nitrite concentrations (40 mM and 10 mM), NDMA can reach amounts of thousands of nanograms per tablet. At the closest concentration to physiologic conditions we used, 1 mM, NDMA is still present in the hundreds of nanograms in some metformin products. In this in vitro study, nitrite concentration had a very important effect on NDMA quantification in metformin tablets added to simulated gastric fluid. 1 mM nitrite caused an increase above the acceptable daily intake set by the U.S. Food and Drug Administration (FDA) for some of the metformin drugs. 10 mM, 40 mM nitrite solutions generated NDMA amounts exceeding by more than a hundred times the acceptable daily intake set by the FDA of 96 nanograms. These findings suggest that metformin can react with nitrite in gastric-like conditions and generate NDMA. Thus, patients taking metformin could be exposed to NDMA when high nitrite levels are present in their stomach, and we recommend including a statement within the Patient Package Inserts/Instructions for use., (© 2024. The Author(s).)

Diabetes mellitus, a metabolic disease characterized by hyperglycemia, has been witnessed as a rapidly escalating worldwide health crisis. China currently had 140.9 million diabetic population in 2021, which was the largest globally. DM has witnessed a significant surge in the past few decades, leading to an alarming rise in the overall burden caused by this disease. To monitor the near real-time DM prevalence and the consumption of first-line anti-diabetic drugs, a wastewater-based epidemiology (WBE) approach based on the back-calculation of metformin concentration was implemented in 237 cities in China. The quantitative analysis of metformin in wastewater was conducted by LC-MS/MS with satisfactory results of method validation. The average concentration of metformin in wastewater was 14.07 ± 13.16 μg/L, and the per capita consumption was 5.16 ± 2.08 mg/day/inh, ranging from 0.90 to 10.36 ± 4.63 mg/day/inh. The calculated metformin prevalence was found to be 0.52 % ± 0.28 %, and the final estimated DM prevalence was 11.33 % ± 4.99 %, which was nearly consistent with the result of the International Diabetes Federation survey of 9.98 %. The results suggested that metformin might be one of the suitable WBE biomarkers in DM monitoring and WBE strategy could potentially enable the estimation of DM prevalence in most of Chinese cities after reasonable correction of associated parameters., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

This study introduces an innovative, and rapid HPLC method using reverse phase elution for the simultaneous analysis of Sitagliptin and Metformin HCl in pharmaceutical formulations. This combination was explored in bulk and solid dosage forms using Luna Phenomenex C8 column (4.6 x 250 mm, 5 µm) at ambient temperature in isocratic elution. It was found that the mobile phase comprising of 0.1% ortho-phosphoric acid, potassium dihydrogen phosphate buffer (pH 3.0) and acetonitrile in ratios 35:35:30, showed a symmetrical peak for Sitagliptin and Metformin HCl. The detection was carried out at 210nm, using a flow rate of 1.0mL/min. The method was linear over the concentration range for Sitagliptin 2.5-7.5 ppm and Metformin HCl 25-75 ppm. The assay recoveries of Sitagliptin and Metformin were found to be 100.36% and 100.20%, respectively. The LOD and LOQ for the Sitagliptin were found to be 0.201 ppm and 0.301 ppm and for Metformin HCl 0.101 ppm and 0.303 ppm, respectively. The proposed methods can be implemented for controlling quality in bulk and solid dosage forms. The analytical methods were validated as per the guideline of ICH Q2 (R2). The developed HPLC methods were effectively employed for the determination of combined dosage forms in pharmaceutical formulations.

N-nitrosamine pollutants are probable carcinogens. Regulatory agencies declared their presence in the drugs unsafe for human consumption and demanded their recall. Using ultra-performance liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry (UPLC-APCI-MS/MS) in tablet dosage form based on International Conference on Harmonization (ICH) tripartite guideline criteria, we aim to develop and test a new approach for identifying and validating nitrosamine-contaminants, N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) in irbesartan, olmesartan and metformin. The column was Phenomenex Luna-C18, 100 × 3.0 mm and 3.0 μm. A mobile gradient phase of formic acid in either water or methanol separated the impurities. NDMA and NDEA had retention times of 0.85 and 2.55 min, respectively. The detector's linearity was established at concentrations ranging from 0.6 to 100 ng/mL. R2 for NDMA and NDEA were 0.9996 and 0.9998, respectively, with a linear response function established at 0.6-100 ng/mL. Limit of detection and limit of quantification for NDMA and NDEA were 0.35, 0.29 and 0.55, 0.37 ng/mL, respectively. On average, recovery rates for NDMA and NDEA ranged from 96.0 to 98.4 and 96.2 to 98.0%, respectively. The relative standard deviation for NDMA and NDEA was 3.46 and 2.69, respectively. According to the ICH guidelines, the developed method was quick, sensitive and valid. The pharmaceutical formulations of irbesartan, olmesartan and metformin may be regularly examined using the approach provided here., (© The Author(s) 2023. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

An increasing number of drug research institutions consider genotoxic impurity research a core task in drug research and development. Peroxides in drugs may directly or indirectly attack and damage cell DNA, posing a potential carcinogenic risk to the human body. Currently, the literature only studies hydroperoxide impurities, and benzyl peroxide has not been studied yet. In this study, an effective method for ultra-performance liquid chromatographymass spectrometry (UPLCMS/MS) was established and verified to detect and quantify the potential genotoxic impurity (PGI), empagliflozin benzyl peroxide, in metformin-empagliflozin combination formulations, which has not been reported thus far. A Waters ACQUITY UPLC HSS T3 (3.0 ×100 mm, 1.8 µm) column was used to achieve chromatographic separation with gradient elution. The mass spectrometry conditions were optimized using electrospray ionization in the negative mode. Following the International Conference of Harmonization (ICH) guidelines, this methodology can quantify PGIs at 1.35 ng/mL (5.4 ppm) in samples. This validated method exhibited good linearity over a concentration range of 5.4 to 36 ppm, and the accuracy of this method was in the range of 83.2-95.0% for empagliflozin benzyl peroxide. This approach fills the gap in the detection method for benzyl peroxide impurities in metformin hydrochloride and empagliflozin tablets, providing technical support for the quality control of the drug., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Metformin is considered as type 2 diabetes first line treatment according to American Diabetes Association and European Association. But, in some cases, di- or tri - therapy should be prescribed for glycemic management, prevention of the maximum dose side effects and induced effectiveness. Co-administration of Linagliptin with metformin has many benefits on diabetic patients such as decrease the possibility of hypoglycemia. For the first time, novel and reliable techniques were developed and verified for the concurrent quantification of metformin hydrochloride and linagliptin, while accounting for the existence of metformin toxic impurity 1-cyanoguanidine in their pure and dosage forms. Method (A) utilizes the zero-order spectrophotometric approach to quantitatively determine the concentration of linagliptin. The measurements are performed at a wavelength of 295 nm. The double divisor derivative ratio spectrophotometric method is used in Method (B) to measure the amounts of metformin and cyanoguanidine at 252 nm and 219 nm wavelengths, respectively. The spectrophotometric method (C) for determining metformin and cyanoguanidine at 252 nm and 223 nm, respectively, is based on the single divisor derivative ratio-zero crossing technique. The obtained findings were subjected to statistical comparison with the reported method, revealing no statistically significant differences. The Green Analytical Procedure Index (GAPI) and Analytical GREEnness Metric approach (AGREE) determined that these approaches had a high degree of environmental friendliness. Additionally, the proposed strategy was deemed to be practical according to the Blue Applicability Grade Index (BAGI) assessment tool., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

A case study on Sitagliptin drug products and Sitagliptin/Metformin drug products concerning contamination with N-nitrosamines was performed using two newly developed analytical methods for determination of N-nitroso-triazolopyrazine (NTTP; 7-nitroso-3-(trifluoromethyl)-5,6,7,8-tetrahydro-[1,2,4]triazolo[4,3-a]pyrazine) and its precursor triazolopyrazine (3-(trifluoromethyl)-5,6,7,8-tetrahydro-[1,2,4]triazolo[4,3-a]pyrazine). The method for determination of triazolopyrazine was previously unpublished, the method for determination of NTTP was published only for analysis of active pharmaceutical ingredient Sitagliptin and not the drug forms. Solving the N-nitrosamine contamination is requested by regulatory authorities all over the world and thus is vital for all pharmaceutical companies. The solution always requires a sensitive analytical method. Both newly developed methods use liquid chromatography coupled with mass spectrometry (single quadrupole analyzer in case of triazolopyrazine and triple quadrupole analyzer in case of NTTP). Separation of triazolopyrazine was achieved on a column Acquity CSH C18 using a mobile phase consisting of aqueous ammonium formate buffered at pH 4.2 and acetonitrile. Detection was performed using positive electrospray and selected ion monitoring at m/z 193. Separation of NTTP was achieved on a column Acquity HSS T3 using a mobile phase consisting of 0.1 % formic acid in water and methanol. Detection was performed using positive electrospray and multiple reaction monitoring at transitions m/z 222.15→42.05 (collision energy 17 eV) and m/z 222.15→192.15 (collision energy 11 eV). Two issues specific to NTTP and triazolopyrazine previously not described in scientific literature were successfully troubleshooted. Spontaneous degradation of Sitagliptin to triazolopyrazine and methyl (R)-3-amino-4-(2,4,5-trifluorophenyl)butanoate was solved by using N,N-dimethylformamide as sample solvent during development of the method for quantitation of triazolopyrazine. A bad peak shape of NTTP due to the presence of rotamers of NTTP was successfully troubleshooted by increasing column temperature. Both methods were used during an optimization study of manufacturing of Sitagliptin and Sitagliptin/Metformin drug products. The goal of the study was to decrease NTTP content in the final drug product under the strict legislative limit set by Federal Drug Agency. The efficacy of several solutions was proven, but could not be fully disclosed due to Intellectual Property Protection policy of Zentiva. Instead, a brief review of recently published strategies to cope with N-nitrosamine contamination is presented., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Molecular modeling is the science of representing molecular structures numerically and simulating their behavior with the equations of quantum and classical physics. Coupling molecular modeling and simulation with chromatographic resolution for pharmaceutical products constitutes a new technique in pharmaceutical analysis. An innovative high-performance liquid chromatographic (HPLC) methodology was developed for the quantification of metformin hydrochloride (MET), empagliflozin (EMP), and canagliflozin (CAN) in bulk, laboratory-developed combinations, pharmaceutical tablets, and in the presence of melamine. Chromatographic separation was accomplished using a Symmetry column with 0.03 M potassium dihydrogen phosphate buffer and 0.02 M heptane sulphonic acid: acetonitrile as the mobile phase. Molecular modeling using molecular operating environment software was applied to properly select the stationary phase suitable for the developed HPLC method. Additionally, molecular modeling estimates and validates binding between the studied analytes and the stationary phase to clarify and explain the chromatographic separation and elution order. In accordance with the International Conference of Harmonization recommendations, the method was validated in terms of linearity, accuracy, precision, and selectivity. The linearity ranges (μg/ml) were 200-1500 (MET), 2-15 (EMP), and 20-150 (CAN) and the limit of detection values were in the ranges of 0.17-54.58 μg/ml. Analysis of pharmaceutical tablets using the suggested approach yielded satisfactory outcomes. As a result, it might be used in quality control laboratories to analyze the aforementioned medications., (© 2023 Wiley-VCH GmbH.)

Metformin hydrochloride (MH) has recently been repurposed as an anticancer agent, showing antiproliferative activity in vitro and in vivo. In particular, experimental evidence has suggested its potential clinical efficacy in glioblastoma (GBM), a very aggressive tumor frequently characterized by gloomy prognosis. Unfortunately, the published literature concerning experimental applications of MH in glioblastoma animal models report no data on metformin levels reached in the brain, which, considering the high hydrophilicity of the drug, are likely very low. Therefore, new sensitive analytical methods to be applied on biological tissues are necessary to improve our knowledge of MH in vivo biodistribution and biological effects on tumors. In this research work, a GC-MS method for MH quantification in brain tissues is proposed. MH has been derivatized using N-methyl-bis(trifluoroacetamide), as already described in the literature, but the derivatization conditions have been optimized; moreover, deuterated MH has been selected as the best internal standard, after a comparative evaluation including other internal standards employed in published methods. After ascertaining method linearity, its accuracy, precision, specificity, repeatability, LOD and LOQ (0.373 µM and 1.242 µM, respectively, corresponding to 0.887 and 2.958 pmol/mg of wet tissue) have been evaluated on mouse brain tissue samples, obtained through a straightforward preparation procedure involving methanolic extraction from lyophilized brain homogenates and solid phase purification. The method has been validated on brain samples obtained from mice, either healthy or xenografted with GBM cells, receiving metformin dissolved in the drinking water. This analytical method can be usefully applied in preclinical studies aiming at clarifying MH mechanism of action in brain tumors., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Michele Mazzanti reports financial support was provided by AIRC Italian Foundation for Cancer Research., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Canagliflozin is an oral hypoglycemic drug recently formulated in combination with a biguanide, metformin hydrochloride, for improving its hypoglycemic action. Canagliflozin has one reported major degradation product, also metformin hydrochloride has one reported major degradation product, cyanoguanidine, and has a potential toxic impurity, melamine, that is reported to cause crystalluria that causes chronic kidney inflammation and nephrolithiasis leading to a renal failure. As per International Conference of Harmonization guidelines; a drug degradation product is classified as a type of drug impurities. Toxicity profiles of canagliflozin and metformin major degradation products were studied where in silico data disclosed toxicity too; the development of a specific chromatographic thin layer chromatographic assay was a must for quantification of such toxic related components along with the drugs in laboratory-prepared mixtures as a superior study. The proposed method was validated as per the International Conference of Harmonization and applied for the assay of Vokanamet tablets. The separation was achieved using acetone:ethyl acetate:acetic acid (8:2:0.2, by volume) as scanning eluted bands at 205 nm. For minimal environmental impact; greenness profile appraisal of the proposed assay was performed by three greenness assessment approaches; analytical Eco-Scale, Green Analytical Procedure Index, and Greenness metric approaches., (© 2022 Wiley-VCH GmbH.)

The probable carcinogenic nitrosamine impurities, such as N-nitrosodiethylamine (NDEA) and N-nitrosodimethylamine (NDMA), have been detected from various pharmaceuticals in recent years. The sensitive chromatographic methods, including liquid chromatography (LC) and gas chromatography (GC), have been applied for analyzing nitrosamines in the pharmaceutical substrates, such as sartans, ranitidine and metformin. In comparison of LC, the efficacy of GC for analyzing multiple nitrosamines in diverse pharmaceuticals will be limited or attenuated owing to the chemical properties of target analytes or matrix hinderance of pharmaceutical substrates. To extend the applicability of GC analysis for multiple nitrosamines in pharmaceuticals, this study presented a gas chromatograph tandem mass (GC-MS/MS) method for monitoring 14 nitrosamines within 44 pharmaceuticals, whereas the headspace-solid phase microextraction (HS-SPME) sampling mode was introduced. Chromatographic separation was achieved on a DB-heavyWax column (30 m × 0.25 mm; i.d., 0.25 µm), whereas the HS-SPME sampling mode with a 50/30 µm DVB/CAR/PDMS extracting fiber was applied for comparison of the direct injection mode. Meanwhile, the HS-SPME conditions were optimized to evaluate the effects of the parameters on analyzing total nitrosamines in pharmaceuticals by GC-MS/MS. The optimal conditions of HS-SPME were as follows: extracting solution of 90% NaCl, HS incubation time 1 min, SPME adsorbing at 80 ℃ for 30 min, and desorbing at 250 ℃ for 5 min. The limit of quantification (LOQ) for 14 nitrosamines in pharmaceutical matrices under the optimal conditions was 0.05 μg/g for the optimal HS-SPME, whereas the value was 0.05-0.25 μg/g for direct injection., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Metformin is one of the most commonly used drugs in the world for the treatment of type 2 diabetes, while ferulic acid is a molecule that stands out for its antioxidant potential. Recent studies demonstrate hypoglycemic synergy between these molecules. The objective of this study is to develop and validate an analytical methodology by high-performance liquid chromatography for the simultaneous quantification of these drugs in pharmaceutical formulations. The method used an octadecylsilane column and a mobile phase composed of 6 mM sodium lauryl sulfate in 15 mM phosphate buffer:ACN (65:35). Ferulic acid and metformin were monitored at 232 nm, with a mobile phase flow rate of 1 ml/min and oven temperature at 40°C. The method was linear in the range of 5-25 μg/ml for both molecules. In the presence of degradation products, satisfactory selectivity was achieved. Accuracy values were close to 100% and standard deviations in precision were less than 2%. In the robustness evaluation, the proposed variations did not interfere with the quantification. Therefore, it is concluded that the present method can be safely applied to the quality control of ferulic acid and metformin raw materials, as well as when they are combined in pharmaceutical formulations., (© 2022 Wiley-VCH GmbH.)

Metformin is the most widely used drug to treat type 2 diabetes. Monitoring spatial patterns of metformin use could provide new insights into treatment of type 2 diabetes and the distribution among populations. This study applied a wastewater-based epidemiological (WBE) approach to estimate metformin use in different populations across Australia and compared these estimates with traditional approaches of surveys and prescription data. Twenty-four-hour influent samples were collected from 75 wastewater treatment plants (WWTPs) across Australia in 2016 and analysed for metformin. Metformin was detected in all samples ranging in concentration from 8.2 to 191 µg/L (median 58 µg/L). Concentrations were converted to population-weighted average consumption at the national level, resulting in an average consumption of 28.6 g/day/1000 people across Australia, which was within 7% of estimates from national prescription statistics. In addition, results for five out of seven states had an estimated prevalence of type 2 diabetes within 20% compared to the traditional epidemiology surveys. Spatial patterns were also observed between urban and rural settings, with higher consumption rates of metformin found in Major Cities (22.5 ± 10.9 g/d/1000 people) and Inner Regional cities (25.4 ± 13.4 g/d/1000 people) than in Outer Regional (17.0 ± 8.1 g/d/1000 people) and Remote areas (15.1 ± 7.4 g/d/1000 people). Consumption estimates were also correlated against socioeconomic factors of the specific catchment areas. Greater metformin use was correlated with populations of lower education and income levels, while positive correlations were found between metformin consumption and consumption of allopurinol, caffeine and venlafaxine. Our study provides more evidence on the distribution of metformin use across Australia, which can be used to develop public health strategies to reduce the overall burden of type 2 diabetes in specific regions., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Metformin hydrochloride is the first-choice antihyperglycemic agent and its several fixed-dose combinations (FDCs) with pioglitazone hydrochloride, sitagliptin phosphate, and gliclazide are used for the management of type II diabetes. Numerous reversed-phase HPLC (RP-HPLC) and HPTLC methods have been reported for estimation of FDCs of metformin but each FDC needs separate and dedicated chromatographic conditions for analysis. No RP-HPLC method has been reported yet which promotes synchronous estimation of FDC products of metformin to save time, resources, cost, and organic solvent for analysis., Objective: Hence, an economical and eco-friendly RP-HPLC method was developed for the synchronous estimation of FDCs of metformin hydrochloride using an enhanced analytical quality by design (AQbD) approach., Methods: The AQbD approach was implemented using analytical-failure modes critical effects analysis (FMCEA) as per International council for harmonisation (ICH) Q8 and Q9 guidelines. The analytical-FMCEA was applied by identification of potential analytical failure modes followed by their risk assessment by a risk priority number (RPN) ranking and filtering method. Further, the risk of critical failure modes was controlled and mitigated by a design of experiments (DoE)-based Box-Behnken design by navigation of method operable design ranges (MODR)., Results: From the set of control strategies, the RP-HPLC method was developed using a Shim-Pack ODS C18 column and acetonitrile-0.1% triethylamine (40:60, v/v) triethylamine in water (pH 3.2 adjusted by perchloric acid). The method was found to be validated as per ICH Q2 (R1) guideline. The synchronous estimation of different FDCs of metformin hydrochloride was carried out by the developed method., Conclusion: The developed method can be used as a multipurpose chromatography method as an alternative to published chromatography methods for QC of FDCs of metformin hydrochloride in the pharmaceutical industry., Highlights: The multipurpose RP-HPLC method has been developed and validated for the synchronous estimation of multiple combined pharmaceutical dosage forms of metformin hydrochloride. The method was developed by the implementation of the AFMCEA-based AQbD approach as per the regulatory requirements of ICH., (© The Author(s) 2022. Published by Oxford University Press on behalf of AOAC INTERNATIONAL. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

A simple, selective and sensitive ion-pair liquid chromatography method was described for the determination of metformin in human plasma. Plasma samples (200 μL) were deproteinated with 10% ( v/v) perchloric acid followed by LC analysis using a Symmetry C18 column and a mobile phase of 29% acetonitrile—71% 2 mM sodium dodecyl sulfate (with 350 μL 0.1 M HCl) operated at a flow rate of 1.5 mL min−1. Metformin and the internal standard (sodium phenytoin) were detected at 232 nm and eluted at 6.8 and 7.9 min, respectively. Calibration curves were linear ( r > 0.9990) between 9 and 2,000 ng mL−1. The quantitation limit was 9 ng mL−1, intra- and inter-day precision (CV) were 5.26% or less, and accuracy values were found to be within 5.95% of the nominal concentration. [ABSTRACT FROM AUTHOR]

Background: The presented quadruple divisor spectrophotometric method was able to resolve and analyze a complex quintuple drug matrix with severe overlapped spectra without previous separation or extraction steps or need of complicated apparatus like chromatographic methods and had the advantage of being green as the solvent used was water., Method: A simple, sensitive, and precise quadruple devisor spectrophotometric method was developed for simultaneous determination of metformin, glipizide, and sitagliptin in the presence of metformin potential impurities melamine and cyanoguanidine. The proposed method was applied for analysis of metformin, glipizide, and sitagliptin in pure form and pharmaceutical formulation (tablets). The developed method was validated and met the requirements for ICH guidelines with respect to linearity, accuracy, precision, specificity, and robustness., Results: A linear response was observed in the range of 2-27, 2-20, 1-20, 0.5-10, and 1-10 μg/mL for metformin, glipizide, sitagliptin, melamine, and cyanoguanidine, respectively, with a correlation coefficient of 0.9996, 0.9998, 0.9997, 0.9997, and 0.9996 for metformin, glipizide, sitagliptin, melamine, and cyanoguanidine, respectively., Conclusions: The validated method was successfully applied for determination of the studied drugs in Janumet® and Engilor® tablets; moreover, the results were statistically compared to those obtained by the reported RP-HPLC method and no significant difference was found between them, indicating the ability of the proposed method to be used for routine quality-control analysis of these drugs., Highlights: Novel application of quadruple divisor spectrophotometric technique is introduced for resolving mixtures containing five components with severely overlapping spectra. A simple and sensitive spectrophotometric method was developed for simultaneous determination of metformin, glipizide, and sitagliptin in the presence of metformin potential impurities melamine and cyanoguanidine. The validity of the proposed method was revealed as per ICH guidelines., (© The Author(s) 2021. Published by Oxford University Press on behalf of AOAC INTERNATIONAL. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Recalls of some batches of metformin have occurred due to the detection of N-nitrosodimethylamine (NDMA) in amounts above the acceptable intake (AI) of 96 ng per day. Prior to the recalls, an international regulatory laboratory network had been monitoring drugs for nitrosamine impurities with each laboratory independently developing and validating multiple analytical procedures to detect and measure nitrosamines in metformin drugs used in their jurisdictions. Here, we provide an overview of the analysis of metformin active pharmaceutical ingredients (APIs) and drug products with 1090 samples (875 finished dosage forms (FDFs) and 215 API samples) tested beginning in November of 2019 through July of 2020. Samples were obtained internationally by a variety of approaches, including purchased, received from firms via information requests or selected by regional regulatory authorities (either at wholesalers or during GMP inspections). Only one nitrosamine (NDMA) was detected and was only present in some batches of metformin products. For API samples, 213 out of 215 lots tested had no measurable level of NDMA. For FDF samples tested, the number of batches with NDMA above the AI amount for patient safety was 17.8% (156/875). Based on these data, although the presence of NDMA was of concern, 82.2% of the samples of metformin drug products tested met quality and safety standards for patients. Regulatory agencies continue to collaborate extensively and work with marketing authorization holders to understand root causes of nitrosamine formation and agree on corrective actions to mitigate the presence of NDMA in future metformin batches., (© 2022. This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply.)

Two assay methods for the antidiabetic metformin, one developed and validated in 1990 and one developed and validated in 1996, are compared. The first method, using an octadecyl phase and an ion pairing agent in the eluent, could not be reproduced some five years later, but another method, using a phenyl phase and no ion pairing agent, could be successfully applied. This paper shows that the retention mechanism of the positively charged analyte is not due to ion-pair formation, as originally assumed, but to interaction with free silanol groups in the LC phase. It is suggested that the number of free silanol groups in octadecyl phases was strongly reduced between 1990 and 1996, whereas for phenyl phases this was not the case. For the second method, validation results on linearity, specificity, accuracy, precision, recovery and stability as well as application of the method to samples from a clinical trial are shown. The validated calibration range is from 20.0 to 2000 ng.mL−1, with accuracy (bias) and precision (coefficient of variation) being below 15% at all levels. Using automated solid-phase extraction for sample preparation, a sample throughput of typically 100 per day can be achieved. [ABSTRACT FROM AUTHOR]

A selective and simple salting-out-assisted thin-layer chromatographic methodology was developed for the simultaneous determination of two oral hypoglycemic drugs, dapagliflozin (DAPA) and metformin (MET) in their pure forms, tablets and spiked human plasma samples. Silica gel 60 F 254 plates were used in the separation of the two drugs using a mobile phase consisting of 0.5 m (NH 4 ) 2 SO 4 and methanol (3:7, v/v). The plates were scanned in the reflectance mode at λ max  = 237 nm. The obtained retardation factor (R f ) values for DAPA and MET were 0.77 ± 0.02 and 0.25 ± 0.02, respectively. The thin-layer chromatography method was validated according to International Conference on Harmonization guidelines. The peak areas were linearly increased with the increases in concentrations of 45-1,000 and 50-1,500 ng/band for DAPA and MET, respectively. Moreover, the method was applied to estimate the molecular lipophilicity parameters of DAPA and MET via retention data. The suggested method was efficiently utilized for the analysis of DAPA and MET in pharmaceutical tablets and plasma samples with recoveries 98.4-100.4 and RSDs in the ranges of 1.4-2.6 and 2.2-3.0% for DAPA and MET, respectively., (© 2021 John Wiley & Sons, Ltd.)

Gliflozins and gliptins represent two different pharmacological drug classes that exert different and potentially complementary glucose-lowering effect in patients with type II diabetes mellitus. A novel, selective, and sensitive HPLC method was developed for the determination of canagliflozin, empaglifozin, linagliptin, and metformin in pure form, in laboratory prepared mixtures, and in pharmaceutical dosage form. Experimental design optimization was applied by using Plackett-Burman and face-centered composite designs to achieve the best resolution with minimum experimental trials. Three significant variables affecting optimization, namely buffer pH, percentage of methanol, and percentage of acetonitrile, were studied. Chromatographic separation was achieved using an Agilent Eclipse C 8 column, and column temperature was kept at 45°C. The mobile phase was composed of dipotassium hydrogen phosphate buffer (0.05 M, adjusted to pH 6 using o-phosphoric acid):acetonitrile:methanol (50:25:25, v/v/v) at a flow rate of 1.5 mL/min. Sharp and well-resolved peaks of the cited drugs were obtained. The method was fully validated in terms of linearity, accuracy, precision, selectivity and robustness in agreement with the International Council of Harmonization (ICH) guidelines Q2 (R1). Satisfactory results were obtained by the analysis of tablets through applying the developed method. Therefore, it could be performed for the analysis of the cited drugs in quality control laboratories., (© 2021 John Wiley & Sons, Ltd.)

The aim of this study was to develop an HPLC method for simultaneous quantification of metformin (MET) and methylene blue (MB) in in vitro skin permeation/retention studies, in which retention was evaluated in the different layers of the skin [stratum corneum (SC) and the viable epidermis + dermis (VE + D)]. The method was validated considering the following parameters: specificity, linearity, quantitation limit (LOQ), recovery, precision and accuracy. Calibration curves were obtained using the following six matrices: methanol, water, methanolic extracts from the SC and VE + D spiked with the drugs and drugs extracted from the SC and VE + D. The precision, accuracy and LOQ of the method were evaluated in water and in VE + D and SC, applying the drug extraction process. The results show that the method is selective and linear for both drugs. The precision and accuracy values, independent of matrix and drug, were below the limit of 15%. The LOQ of MB was defined as 0.4 μg/ml in the VE + D and SC and 0.8 μg/ml in water. The LOQ of MET was defined as 0.8 μg/ml in the VE + D and SC and 0.4 μg/ml in the water. The recovery of the method was adequate, consistent and reproducible for the concentration range of 0.4-10 μg/ml for MB (73.3-92.1%) and 0.8-10.0 μg/mL for MET (72.4-94.4%). This method has a potential application in the development of formulation for skin delivery of MB and MET., (© 2021 John Wiley & Sons, Ltd.)

Background: FDA limited N-nitrosodimethylamine (NDMA) - a carcinogenic impurity formed during metformin (MET) tablets manufacturing - level to 96 ng/day; a step which led to recall of MET products. This work aims to investigate the root cause of NDMA formation during MET tablets manufacturing., Research Design and Methods: We focused on three main contributing causes: use of water and heat during intra-granulation, and the nitrite/nitrate quantities in excipients. Thirteen MET tablet formulations (immediate or sustained-release) were manufactured, on batch level. Each batch was manufactured using one excipient and excluding one cause at a time and NDMA level was assayed., Results: NDMA traces were undetectable in MET tablets manufactured using polyvinyl pyrrolidone or hydroxypropyl cellulose SSL, even when water and/or heat were employed during intra-granulation. Levels of NDMA in MET tablets with hydroxypropyl methyl cellulose (HPMC) E5 or carboxymethyl cellulose sodium 4000 were 67.08 ± 2.3 and 66.21 ± 2.5 ng/day, in the presence of water and/or heat. No impact of employing extra-granular Polyox TM , HPMC E5 or HPMC K15 on NDMA formation, despite the high nitrite and nitrate content in these excipients., Conclusions: Water, heat, and excipients' nitrite and nitrate levels are the key players, which should collectively exist, to cause NDMA formation during MET tablets manufacturing.

A rapid stability-indicating reversed phase-ultrapure liquid chromatography (RP-UPLC) was developed and validated for the estimation of metformin (MET), linagliptin (LIN), and empagliflozin (EMP) combination in bulk and tablet dosage form using Kromasil C 18 column (2.1 × 50 mm, 1.8 μm) as a stationary phase and a mixture solution of 40% phosphate buffer (pH = 3) and 60% acetonitrile as mobile phase at a flow rate of 0.6 mL/min. The detection was performed at 248 nm using a photodiode array detector. The linearity, sensitivity, selectivity, robustness, specificity, precision, and accuracy were determined. The peak area response-concentration curve was rectilinear over the range of 50-150 (MET), 5-15 (LIN), and 10-30 μg/mL (EMP) with quantitation limits of 0.042 (MET), 0.023 (LIN), and 0.059 μg/mL (EMP). The proposed method was successfully validated for the determination of MET, LIN, and EMP simultaneously in combined tablet dosage form. The performance of the proposed method was compared with reported RP-UPLC methods and found to be rapid and economical. The developed and validated stability-indicating RP-UPLC method was appropriate for the quality control and drug analysis., (© 2020 John Wiley & Sons, Ltd.)

This review discussed the occurrence, ecological impacts, and effects of metformin, a drug used for type 2 diabetes among other diseases. It is one of the most commonly found medicines in aquatic environments owing to its incomplete metabolism in the human body, and is eventually disposed in wastewater. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses were followed as a guide. After searching various databases, 48 eligible studies were selected for the review. Metformin reportedly occurs in different environmental matrices, as measurable concentrations of metformin are found in sewage (urban and hospital), influent/sludge/effluent from wastewater treatment plants, surface water (rivers, lakes, estuaries, oceans, and non-specific sources), tap/drinking water, and sediment (lake and recipient seawaters). Data on metformin detection in aquatic environments in 14 countries were studied, but a consensus on the risk patterns of pharmaceutical products was not determined. Many studies have been conducted on different test organisms, demonstrating that metformin can drive the expression of diverse genes, particularly those responsible for endocrine hormone pathways. Chronic exposure to metformin can be tested using models and other tools to understand this field, which remains largely unexplored. Our results contribute to the current ecotoxicology knowledge related to typically used drugs and provide a basis for further investigations., (Copyright © 2021 Elsevier B.V. All rights reserved.)

We develop a capillary-paper spray (CPS) ion source which allows for sample separation in the capillary and enables rapid and sensitive paper spray (PS) mass spectrometry (MS) analysis of biofluids. The CPS employs a glass capillary to load liquid analytes, vertically standing at the rear of the PS. To further reduce the matrix effect, a nitrocellulose filter membrane is placed between the glass tube and chromatography paper to absorb proteins and other macromolecules, which is beneficial for the detection of the small molecules. Compared with the normal PS method, the CPS method markedly improves spray stability and prolongs analysis duration, and also generates significantly better signal intensities during the analysis of drugs, thus indicating its potential for clinical use. As a proof of concept, quantitative analysis of drugs (metformin hydrochloride and berberine hydrochloride) in serum is performed.

Hair analysis is very useful for toxicological investigations since, by providing a wider detection window, it gives the possibility to perform a retrospective study on the historical consumption of a substance. Unfortunately, there are no data available for hair concentrations in metformin-related deaths. In this study, the authors present 2 cases of fatal metformin intoxication in which, for the first time, hair analysis was performed using a specific GC-MS/MS method. Metformin was tested positive in femoral blood (112.3 mg/L and 64.7 mg/L respectively) and cardiac blood (226.9 and 203.2 mg/L) of the two subjects. For case 1, other samples were also tested positive, including vitreous humor (31.1 mg/L) and gastric contents (773.5 mg/L). In case 2, metformin was measured at 844.9 mg/L in urine. Metformin hair concentrations were 28.3-44.8 and 22.5 ng/mg for both cases, respectively. The concentrations found in the 2 fatal cases are clearly higher than those obtained in a previous study with subjects under treatment (0.3-3.8 ng/mg) or those found in 3 post-mortem cases where metformin death was excluded (0.6-1.4 ng/mg). Excessive sweating during the agonal phase due to fatal hypoglycemia could explain these elevated concentrations as sweat can have contaminated the hair., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Two simple, sensitive, and reproducible methods were developed for the determination of alogliptin and metformin hydrochloride in presence of metformin impurity "melamin" in pure form and in pharmaceutical formulation. Method (A) was a thin layer chromatographic method in which separation was achieved using ethyl acetate-methanol-formic acid (6:3.8:0.2, by volume) as a developing system followed by densitometric scanning at 230 nm. Method (B) was a high-performance liquid chromatography method; separation was achieved on C 18 column, the mobile phase consisted of a mixture of sodium lauryl sulfate buffer 0.1% w/v, pH 3: methanol in the ratio 70:30, v/v and measurement was done at 220 nm. System suitability testing parameters were calculated to ascertain the quality performance of the developed chromatographic methods. The proposed methods have been validated regarding accuracy, precision, and selectivity, moreover they have been successfully applied to Westirizide tablets containing both alogliptin and metformin hydrochloride, results indicate that there was no interference from additives. No significance difference was found when these methods were compared to the reported one., (© 2021 Wiley-VCH GmbH.)

Monitoring the consumption of pharmaceuticals and licit drugs is important for assessing the needs of public health owing to the impact on individuals as well as society. The present work applied wastewater-based epidemiology to profile the spatial patterns of metformin, nicotine, and caffeine use and their correlations. Influent wastewater samples were collected from 27 wastewater treatment plants in 22 typical Chinese cities that covered all geographic regions of the country. The consumption of metformin ranged from 0.02 g/d/1000 inh to 8.92 g/d/1000 inh, whereas caffeine and nicotine consumption ranged from 4.33 g/d/1000 inh to 394 g/d/1000 inh and 0.17 g/d/1000 inh to 1.88 g/d/1000 inh, respectively. There were significant regional differences in the consumption of caffeine, with the highest consumption in East China and the lowest consumption in Northeast China. The consumption and concentration of caffeine were related to the gross domestic product and per capita disposable income of urban residents, respectively. There was a correlation between the concentrations of caffeine and cotinine (a nicotine metabolite), thereby indicating that individuals that use one of these substances are likely to use the other substance. A significant relationship was found between the concentration of metformin and cotinine, thereby implying that the use of tobacco may be correlated with type 2 diabetes. Co-analysis of these substances in wastewater may provide a more accurate picture of substance use situations within different communities and provide more information on human health, human behavior, and the economy. This report describes the newest study related to the consumption of metformin among the general population in China., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

As environment emerging contaminants of anthropogenic origin, antidiabetic drugs are present in the range of high ng/L to ng/mL in the influent and the effluent of the waste water treatment plant (WWTP). The metformin compound is the most used hypoglycemic agent in the world. The aim of this study was to develop a new analytic method, based on solid phase extraction followed by liquid chromatography coupled with mass spectrometric detector (SPE-LC-MS/MS), for identification and quantification of 5 antidiabetic compounds (glibenclamide/glyburide, glimepiride, metformin, glipizide, guanyl urea, gliclazide) and one degradation product (guanyl urea). The investigated environmental samples were the influent and the effluent of four urbans WWTP's. By validating of the analytical method, it was obtained low LOQ's (0.2-4.5 ng/L), satisfactory recovery rates (53.6-116.8%), and corresponding performance parameters: inter-day precision (4.9-8.4%) and reproducibility (11.3-14.6%). The concentrations of antidiabetics were as follow in influent and effluent: metformin 76-2041ng/L and 2-206ng/L, gliclazide (14.1-42.4 ng/L, and 3.3-19.1), glipizide (7.5-11.2 ng/L and 6.5-10ng/L), guanyl urea (6.2-7.3 and 8.3-21.3 ng/L). The efficiency of elimination of the antidiabetics in WWTP's was maximum for metformin (67.6-98.5%), followed, by gliclazide (72.9-78.2%). The lowest elimination efficiency was calculated for glipizide (10.7-13.3%). The guanyl urea undergoes a formation process (74.5-84.2%) in effluent, from the metformin contained in influent.

A GC-MS/MS method with EI ionization was developed and validated to detect and quantify N -nitrosodimethylamine (NDMA) and seven other nitrosamines in 105 samples of metformin tablets from 13 different manufactures. Good linearity for each compound was demonstrated over the calibration range of 0.5-9.5 ng/mL. The assay for all substances was accurate and precise. NDMA was not detected in the acquired active pharmaceutical ingredient (API); however, NDMA was detected in 64 (85.3%) and 22 (91.7%) of the finished product and prolonged finished product samples, respectively. European Medicines Agency recommends the maximum allowed limit of 0.032 ppm in the metformin products. Hence, 28 finished products and 7 pronged dosage products were found to exceed the acceptable limit of daily intake of NDMA contamination. The implications of our findings for the testing of pharmaceutical products are discussed.

A method was established for the determination of N -nitrosodimethylamine (NDMA) in metformin hydrochloride active pharmaceutical ingredient (API) and preparation samples by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Water was used as the extraction solvent for the metformin hydrochloride API and preparation samples. The samples were analyzed by HPLC-MS/MS after vortex mixing, constant temperature shaking, high speed centrifugation and microfiltration. An ACE EXCEL 3 C18-AR column (150 mm×4.6 mm, 3 μm) was used for chromatographic separation. The mobile phases were water and methanol both containing 0.1% formic acid with gradient elution. The flow rate, column temperature, and autosampler temperature were set as 0.8 mL/min, 40℃, and 10℃, respectively. The valve switching technique was used to protect the mass spectrometer, while six-way valve switching was adopted to allow the mobile phase with a retention time of 2.85-7.00 min to enter the mass spectrometer and the mobile phase with other retention times to enter the waste liquid. For the mass spectrometer, an atmospheric pressure chemical ionization (APCI) ion source was used in positive ion MRM scanning mode. The other conditions were as follows:atomizer flow, 3 L/min; heater flow, 10 L/min, interface temperature, 300℃; desolvation line (DL) temperature, 250℃; heating block temperature, 400℃; and dryer flow, 10 L/min. The quantitative transition of NDMA was m/z 75.0→43.1 with a collision energy of-17.0 eV, while the qualitative transition was m/z 75.0→58.2 with a collision energy of-16.0 eV. The external standard method was utilized for quantitative analysis. The established method was validated in detail by investigating the specificity, linear range, limit of detection, limit of quantification, recovery, precision, and stability. This method showed good specificity, since the solvents and excipients did not interfere with the determination of NDMA. A good linear relationship was observed the NDMA peak area and the mass concentrations in the range of 1.00-100.00 ng/mL with an excellent correlation coefficient ( r >0.9999). The limit of detection and limit of quantification in solution were 0.20 ng/mL and 1.00 ng/mL, respectively. The recoveries of NDMA at low, medium, and high spiked levels ranged from 94.55% to 114.67%, and the RSDs ranged from 4.73% to 13.46%, indicating good accuracy and precision for the quantification of NDMA. Stability tests showed that NDMA was stable when placed in the autosampler for 0, 8, 24 h, since the RSD of the peak area was as low as 2.08%. The validated method was then applied to the determination of NDMA in metformin hydrochloride raw materials and preparations (tablets, capsules or enteric tablets). The detected amount of NDMA in the API did not exceed the limit in 113 batches of samples, but NDMA was detected and exceeded the limit in eight batches of preparations. This method is sensitive, accurate, and easy to operate, and it can be used for the determination of NDMA in metformin hydrochloride raw materials and preparation samples.

Metformin, nicotine, caffeine, and methamphetamine are widely used in China. However, the consumption pattern of these substances among the general population during Chinese public holidays may be different. Influent wastewater samples were collected from a municipal wastewater treatment plant in Yingkou, China on public holidays (n = 6) and working days (n = 20) to examine the changes in metformin, nicotine, caffeine, and methamphetamine consumption. The consumption of metformin in the city ranged from 1.94 to 14.4 g d -1 1000 people -1 , while that of nicotine, caffeine, and methamphetamine ranged from 0.46 to 2.18 g d -1 1000 people -1 , 31.8-89.8 g d -1 1000 people -1 , and 87.0-657 mg d -1 1000 people -1 , respectively. The highest consumption of metformin, caffeine, and methamphetamine was observed during the Spring Festival. The results indicated that the consumption of these substances showed almost the same trend and was higher during the Spring Festival, which may be influenced by personal habits and traditional festival reunions. There is a correlation between the consumption of nicotine and caffeine. Moreover, there are correlations between the consumption of metformin and nicotine, caffeine, as well as methamphetamine. The information based on wastewater epidemiology and consumption behavior, suggests that drug use in the region requires more attention or monitoring during holidays., Competing Interests: Declaration of competing interest No conflict declared., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Diabetes mellitus is one of the most important public health challenges. Metformin (1,1-dimethylbiguanide) represents the "gold standard" for the treatment of diabetes mellitus type 2. Despite its important role in reducing mortality and morbidity in the diabetic population, metformin is associated with an increased risk of stroke. To document exposure to a drug, hair is considered to be the specimen of choice to complement blood and urine, since it provides historical detail of a subject's chronic exposure to drug(s). Measuring hair concentration of metformin can be important for forensic toxicologists investigating criminal poisoning or Munchausen's syndrome by proxy. In clinical toxicology, drug monitoring using hair to document metformin observance has not yet been described. To document the interest of hair analysis for metformin, the authors have developed and validated a method using a gas-chromatography tandem mass spectrometry system and applied it to authentic hair obtained from 9 diabetic patients under daily treatment. The validation procedure demonstrated a LOD an LOQ of 1 and 100 pg/mg, respectively and acceptable linearity, repeatability and reproducibility. The hair of the 9 patients tested positive in the low ng/mg range with concentrations ranging from 0.3 to 3.8 ng/mg. It seems obvious, in comparison with other drugs, that metformin is badly incorporated into hair, as the daily dosage varied from 1 to 3 g. Although limited in the number of subjects, the study allowed to postulate a possible correlation between daily dose and concentration in dark hair, while for light hair no correlation was found., (© 2020 John Wiley & Sons, Ltd.)

A novel method for screening and quantification of illegal adulterated antidiabetics in hypoglycemic health products was developed by multi-dimensional fingerprint profiling analysis (MDFPA). By means of aqueous two-phase extraction (ATPE), using aqueous two-phase system (ATPS) of butanol-water as the extractant, 11 common antidiabetics could be effectively extracted to the upper and lower phases, respectively. HPLC separation conditions for the extracts from two phases were investigated by multi-wavelength detection before and after p-nitrobenzoyl chloride (p-NBC) and 2,4-dinitrofluorobenzene (DNBF) derivatizations to establish multi-dimensional fingerprints. For high accuracy and reliability, a hierarchical screening approach to screening illegal adulterated antidiabetics in samples was established by MDFPA and spectral purity examination. Meanwhile, detection limits of identification for illegal adulterants were defined by detection limits of spectra (SLOD). The proposed method exhibited good identification and quantification performances. SLODs, LODs and LOQs of 11 antidiabetics were 1.22-8.37 μg/g, 0.225-4.23 μg/g and 0.755-14.10 μg/g, respectively. They had good linearity ranged from 2.0 μg/g to 300.0 μg/g (R 2  ≥ 0.9978). The recoveries and RSDs were 76.83-109.6% and 0.50-6.5%, respectively. The method was successfully applied to screening of 15 batches of samples in different forms. Among them, four samples were detected to contain 5.47 μg/g of metformin, 6.50 μg/g of phenformin, 3.69 μg/g of glibenclamide and 9.11 μg/g of glimepiride, respectively. The results proved that it was an efficient and feasible alternative to screening and detection of illegal adulterated antidiabetics in hypoglycemic health products., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

A private testing laboratory reported in a Citizen Petition (CP) to FDA that 16 of 38 metformin drug products they tested had N-nitrosodimethyl amine (NDMA) amounts above the allowable intake (AI) of 96 ng/day. Because the FDA had been monitoring drugs for nitrosamines, orthogonal analytical procedures had been developed, validated and applied to detect the following nitrosamines in metformin drug products (if present): (i) NDMA (with a dedicated method) or (ii) NDMA (with a second confirmatory method), N-nitroso-diethylamine (NDEA), N-ethyl-N-nitroso-2-propanamine (NEIPA), N-nitroso-diisopropylamine (NDIPA), N-nitroso-di-n-propylamine (NDPA), N-nitroso-methylphenylamine (NMPA), N-nitroso-di-n-butylamine (NDBA) and N-nitroso-N-methyl-4-aminobutyric acid (NMBA). In contrast to the private laboratory results, FDA testing on the same set of 38 samples with orthogonal procedures observed amounts over the AI in only 8 of the 38 products and generally observed lower values than reported by the private testing laboratory. As described here, the investigation into the cause of the discrepancy revealed that N,N-dimethylformamide (DMF) can interfere with NDMA measurements. The data showed that the use of sufficient mass accuracy in the data acquisition and appropriate mass tolerance setting in the data processing to assure the selectivity of mass spectrometry measurements of NDMA in the presence of co-eluting DMF was necessary to prevent overestimation of the level of NDMA in metformin drug products. Overall, care should be taken to assure the necessary specificity in analytical procedures for adequate assessment of the nitrosamine level in drug products that also contain DMF or other potential interfering substances.

In this study, a simple and rapid method was investigated for the simultaneous ultra-trace colorimetric determination of Metformin (MET) and Sitagliptin (STG) based on the aggregation of gold nanoparticles (AuNPs). The Morphology and size distribution of synthesized AuNPs before and after adding drug (Zipmet) were monitored using transmission electron microscopy (TEM) and dynamic light scattering (DLS), respectively. By adding a drug, the absorption peak was shifted from 520 to 650 nm. The colorimetric method along with partial least squares (PLS) as a multivariate calibration method, as well as neural network time series were applied to estimate MET and STG simultaneously. The percentage of the mean recovery and root mean square error (RMSE) of the test set of mixtures related to the MET and STG were obtained 99.96, 1.1301 and 99.77, 1.0106, respectively. On the other hand, the regression coefficient (R 2 ) of the training, validation, and test sets corresponding to the artificial neural network (ANN) were close to one for both components. Eventually, the proposed method was compared with a reference technique named high-performance liquid chromatography (HPLC) by analysis of variance (ANOVA) test and there was no significant difference between them., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Based on TLC-IR, the study established an effective method for rapid detection of metformin illegally added in hypoglycemic traditional Chinese medicine and health food products. 12 batches of hypoglycemic traditional Chinese medicine and health products were purchased in the pharmacy, which were produced by different manufacturers. TLC was used to separate metformin and phenformin for preliminary identification from. IR was applied to further identification and HPLC method was used to verify the experimental results of TLC-IR. TLC developing solvents was petroleum ether-methanol-glacial acetic acid (5:12:0.5) and the stationary phase was silica gel prefabricated GF 254 plate. IR used KBr pellet pressing method with a resolution of 4cm -1 and scanned 64 times. The column for HPLC analysis was SinoChrom ODS-BP 5 µm (4.6mm *250mm) and the injection volume was 20μL. The detection wavelength was 234nm. The flow rate was 1ml•min-1. Metformin and phenformin were significantly separated under the TLC condition. Joint identification by TLC-IR, none of metformin and phenformin were identified in the hypoglycemic traditional Chinese medicine. Phenformin was detected in two kinds of health products while metformin was identified in one kind of health food. The result of HPLC was consist with TLC-IR. The established TLC-IR method was simple, rapid and selective, which was suit to apply in the identification of metformin illegally added in hypoglycemic traditional Chinese medicine and health food products.

A sensitive, rapid and cost-effective method based on HPTLC with UV detection was developed for the quantitation of Glibenclamide (GLIBEN), Rosiglitazone maleate (ROSI) and Metformin hydrochloride (MET) from a combined dosage form. Pre-coated RP-18 F254s aluminum sheets were used as the stationary phase. Methanol-tetrahydrofuran-water-glacial acetic acid (16: 3.6: 4: 0.4, v/v) used as the mobile phase, along with chamber saturation of 10 min offered an optimum migration (Rf = 0.54, 0.62 and 0.80 for GLIBEN, ROSI and MET, respectively). TLC Scanner 3 was used for densitometric evaluation of the chromatograms. DigiStore 2 Documentation System with winCATS software version 1.4.10 was used for the quantitation and photodocumentation. The LOD for GLIBEN, ROSI and MET was found to be 80 ng, 80 ng and 48 ng, respectively. Moreover, the LOQ was 200 ng, 200 ng and 120 ng for GLIBEN, ROSI and MET, respectively. The method was linear for GLIBEN (r = 0.9991), ROSI (r = 0.9993) and MET (r = 0.9988) within the tested range (200-1000, 200-1000 and 120-600 ng/band, respectively). The method was found to be precise and accurate for all the three drugs. The method was applied for the analysis of Triglucored tablets, and it proved to be a reliable quality control tool for the routine analysis of GLIBEN, ROSI and MET in a combined dosage form., (© The Author(s) 2020. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Metformin (MET) is the most common drug used to treat type 2 diabetes, but also it is used as an anticancer agent and as a treatment for polycystic ovary syndrome. This drug is not metabolized in the human body, and may enter into the environment through different pathways. In wastewater treatments plants (WWTPs), this contaminant is mainly transformed to guanylurea (GUA). However, three further transformation products (TPs): (a) 2,4- diamino-1,3,5-triazine, 4-DAT; (b) 2-amino-4-methylamino-1,3,5-triazine, 2,4-AMT; and (c) methylbiguanide, MBG; have also been associated with its metabolism. MET, GUA and MBG have been found in WWTPs influents, effluents and surface waters. Furthermore, MET and GUA bioaccumulate in edible plants species, fish and mussels potentially contaminating the human food web. MET is also a potential endocrine disruptor in fish. Phytoremediation, adsorption and biodegradation have shown a high removal efficiency of MET, in laboratory. Nonetheless, these removal methods had less efficiency when tried in WWTPs. Therefore, MET and its TPs are a threat to the human being as well as to our environment. This review comprehensively discuss the (1) pathways of MET to the environment and its life-cycle, (2) occurrence of MET and its transformation products (3) removal, (4) toxic effects and (5) future trends and perspectives of possible methods of elimination in water in order to provide potential options for managing these contaminants., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Novel molecularly imprinted polymer (MIP) for metformin was synthesized on the surface of magnetic multi-walled carbon nanotubes (MMWCNTs) as the support. Metformin was used as the template, methacrylic acid (MAA) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linker and 2,2'-azoisobutyronitrile (AIBN) as the initiator. The synthesized composite was characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and Fourier transform infrared spectroscopy (FTIR). The surface molecularly imprinted composite was used for magnetic solid phase microextraction (MSPME) of metformin before its chemiluminescence (CL) determination and its capability was compared with non-imprinted polymer (NIP). The central composite design was used for optimization as well as consideration of possible interaction of effective variables on extraction. Under the optimized conditions, the developed method exhibited the linear dynamic range of 0.5-50.0 μg L -1 with a detection limit of 0.13 μg L -1 and enhancement factor of 195.3 for the preconcentration of 100 mL of the sample and 500 μL of an eluent. The intra- and inter-day relative standard deviations (RSD%) at 5.0 μg L -1 level of metformin (n = 6) were 3.7 and 4.9%, respectively. The maximum adsorption capacity of the sorbent was found to be 80.0 mg g -1 , the adsorption of metformin was endothermic and spontaneous and followed the Langmuir isotherm model. The adsorption kinetic was also found to be best fitted with the pseudo-second-order model. The designed method was successfully applied to the extraction and determination of metformin in biological fluids and water samples., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A rapid and accurate method for the sensitive detection of illegal drug additives including atenolol (ATN), metformin hydrochloride (MET), and phenformin hydrochloride (PHE) in health products using solvent microextraction (SME) combined with surface-enhanced Raman spectroscopy (SERS) was developed. Various illegal drug additives in different health products were separated via microextraction and then detected in situ using a portable Raman spectrometer with Ag colloids acting as SERS-active substrates. The effects of experimental parameters on the detection sensitivity and producibility were evaluated, and the applications of illegal additives spiked into samples were systematically investigated with SME-SERS. It was demonstrated that the mixture of CH3OH and CHCl3 (v/v = 1 : 4) as the extractant was suitable for the rapid microextraction separation of illegal drug additives and also induced the distribution of the Ag colloids (2 M) on the CHCl3 surface. More importantly, CH3OH can carry the drug molecules to enter into the inter-particles of the Ag colloids in this process, and then significantly improve the detection sensitivity of illegal drug additives. Furthermore, the high-throughput and real-time detection of illegal drug additives spiked into health products with SME-SERS in multi-well 96 plates were achieved with the level of 0.1 μg mg-1. The results reveal that this rapid and convenient method could be used for the effective separation and sensitive detection of illegal additives in complex specimen.

Two ratio derivative spectrophotometric methods were performed for the simultaneous analysis of metformin hydrochloride, empagliflozine, linagliptin, and pioglitazone hydrochloride in their synthetic mixtures without prior chemical separation. The drugs are approved for the treatment of type 2 diabetes. Despite the various advances in the management of diabetes, it remains to be the major cause of disability and morbidity, including blindness, amputation, heart disease, peripheral neuropathy, and kidney disease. These techniques consisted of several steps using ratio and derivative spectra. The absorption spectra of the mentioned drugs were recorded in the range of 200-350 nm, which have the concentration ranges of 1.0-10, 2.5-30, 5.0-40, and 2.5-30 μg mL -1 for metformin hydrochloride, empagliflozine, linagliptin, and pioglitazone hydrochloride, respectively, using zero-order spectra. The mean centring of ratio spectra combined with triple divisor were measured at the amplitude values 242, 256, 272 and 296 nm for metformin hydrochloride, empagliflozine, linagliptin and pioglitazone hydrochloride, respectively; the derivative ratio spectra-zero crossing quantifies the amplitude value of the analytical signal at 234, 244, 260 and 280 nm for metformin hydrochloride, empagliflozine, linagliptin and pioglitazone hydrochloride, respectively. The method was validated according to the ICH guidelines, accuracy, precision and repeatability were found to be within the acceptable limits. Finally, statistical comparisons between the proposed methods and with the reported methods with respect to accuracy and precision show that no significant difference was found by using Student's t-test, the F-test and one-way ANOVA., (Copyright © 2019 Elsevier B.V. All rights reserved.)