Analysis Of Metformin Research Articles

Does sildenafil citrate affect the pharmacokinetics of metformin in rats? Screening of mechanism through analytical and molecular docking approach.

In the present study, the effect of sildenafil on the pharmacokinetics of metformin was studied in experimental rats, and we also postulated the molecular mechanism by performing molecular docking studies. Analysis of metformin and sildenafil (SIL) from rat plasma was done by high performance liquid chromatography. Optimum chromatographic separation and quantification of MET, SIL and Cetirizine was achieved on Phenomenex EVO C18 column with triethyl amine (0.3%): Methanol: Acetonitrile (70:05:25 v/v) as mobile phase maintaining flow rate of 1 ml/min, the detector was tuned at 224 nm. The extraction of MET and sildenafil from rat plasma was achieved by solid-phase extraction using Strata-X cartridges. The method was validated as per the ICH guidelines. For docking studies, the crystal structure of organic cation transporter 1 (OCT1) protein and multidrug and toxin extrusion (MATE) protein (5XJJ) were downloaded from the PubChem database. The docking study was performed by PyRx virtual screening software, and the results were analyzed by BIOVIA Discovery Studio. The validation of HPLC method was done, intraday and interday precision study of HPLC method demonstrated %RSD values less than 5%, the extraction recovery for MET and SIL were near to 80 % for low, medium and high QC samples. The plasma stability of MET and SIL showed % RSD values <10% for low, medium, and high QC samples. A sensitivity study for MET and SIL in rat plasma suggested a lower limit of quantification values of 8 and 10 ng/mL, respectively. The pharmacokinetic parameters were recorded, Cmax of experimental and control rats was 611.2 and 913.2 ng/mL; t1/2 1.66 and 1.98, AUC (0-t) 1637.5 and 2727.24, AUC (0-∞) 1832.38 and 2995.24 for MET. The results suggested that the Cmax of MET in experimental rats (MET + SIL) was 33.07% lower than the control (MET only) and also the t1/2 was 0.32 h shorter. Docking analysis suggested a higher binding affinity of sildenafil with MATE protein (5XJJ) compared to OCT1, suggesting possible involvement of MATE family proteins for pharmacokinetic alterations of MET. The HPLC and solid-phase extraction method were developed and applied successfully for the pharmacokinetics of MET and SIL. Intake of SIL altered the pharmacokinetics of MET in rats. Molecular docking studies suggested the involvement of MATE family proteins for alterations of MET pharmacokinetics.

Estimation of anti-diabetes drug metformin in Turkiye using wastewater-based epidemiology.

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.

Analysis of metformin, niacinamide, and niacin as skin cancer preventative medications in solid organ transplant recipients

Analysis of metformin, niacinamide, and niacin as skin cancer preventative medications in solid organ transplant recipients

Abstract 3482: Correlative analysis of metformin and nivolumab combination in treatment-refractory microsatellite stable (MSS) metastatic colorectal cancer (mCRC)

Abstract Background: Preclinical results indicate that metformin can modulate immune cell populations in the tumor microenvironment of solid tumors by diminishing exhaustion of CD8+ tumor infiltrating cells and improving T cell responses. Studies also suggest that metformin could complement PD-1 blockade and potentiate its antitumor activity. Previously we reported the results of a phase II trial with metformin and nivolumab and here we report the findings of correlative analysis of the prospectively collected research samples of 18 patients. Methods: We conducted a phase II trial with nivolumab and metformin in treatment-refractory microsatellite stable (MSS) metastatic colorectal cancer (mCRC). Nivolumab 480 mg IV every 4 weeks and metformin 1000 mg orally twice daily was administered in 28-day cycles following a 14-day metformin only lead-in phase. The primary endpoint was overall response rate (ORR). Secondary endpoints were overall survival (OS) and progression free survival (PFS). Pre-treatment and on-treatment research biopsies and correlative peripheral blood specimens were collected. Paired biopsies obtained at baseline and following treatment with metformin only (n=9) or metformin and nivolumab (n=9) and were stained with a panel of 13 markers using ChipCytometry technology by Canopy Biosciences. Sample was assessed prior to establishing the multiplex assay. 30 out of 36 samples were imaged and analyzed up to 30 Fields of View. Single cell recognition and quantitative biomarker analysis were performed to compare immune cell numbers and population distribution in pre- versus post-treatment samples. Results: As previously reported, no patients had objective response based on RECIST version 1.1 and the study was stopped after the first stage for futility. Median OS and PFS was 5.1 months [95% CI (2-11.7)] and 2.3 months [95% CI (1.7-2.4)], respectively. Multiplex analysis of tissues from patients receiving lead in with metformin alone revealed fewer effector CD4 T cells and effector and effector memory CD8 T cells after treatment vs. baseline biopsy. Biopsy tissue from patients treated with metformin and nivolumab had lower pAMPK and decreased PDL-1 expression vs. baseline. The combination also increased percentages of leukocytes, effector CD4 T cells, effector and effector memory CD8 T cells as well as levels of PDL1-Tim3+ cells. Conclusion: In the setting of MSS mCRC, metformin as a single agent did not enhance effector CD4 and CD8 T cell percentages in clinical samples in our patient cohort. Metformin in combination with nivolumab was associated with increased percentages of effector CD4 and CD8 T cells in biopsy specimens, although these improvements did not translate into enhanced clinical endpoints. Analysis of peripheral blood samples are currently underway to corroborate the findings in the tissue samples. Citation Format: Batoul Farran, Jeffrey M. Switchenko, Lana Khalil, Walid L. Shaib, Brian Olson, Amanda Ruggieri, Christina Wu, Olatunji B. Alese, Maria Diab, Gregory B. Lesinski, Bassel El-Rayes, Mehmet Akce. Correlative analysis of metformin and nivolumab combination in treatment-refractory microsatellite stable (MSS) metastatic colorectal cancer (mCRC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3482.

Analysis of Metformin and Five Gliptins in Counterfeit Herbal Products: Designs of Experiment Screening and Optimization.

Drug counterfeiting is a rising problem due to difficulties with identifying counterfeit drugs and the lack of regulations and legislation in developing countries. This study aims to develop a robust and economic reversed phase high performance liquid chromatography (LC) method for simultaneously determining metformin HCl, vildagliptin, saxagliptin, alogliptin benzoate, sitagliptin phosphate monohydrate, and linagliptin to target counterfeiting. Plackett-Burman (PB) and Box-Behnken (BB) designs were used to screen and optimize the mobile phase composition. Chromatographic separation was carried out on an Inertsil® ODS-3 C18 column with isocratic elution mode and the mobile phase was a mixture of acetonitrile-methanol-ammonium formate buffer, pH 3.5 (25:10:65, v/v/v). This method was applied to analyze synthetic drugs in three traditional Chinese and Indian herbal medicines. To identify the adulterants, thin-layer chromatography (TLC), nuclear magnetic resonance (NMR), and mass spectrometry (MS) were used on counterfeit herbal medicines. The developed method is sensitive, simple, rapid, economical, accurate, and highly robust. Student's t-test and variance ratio (F-test at P < 0.05) were used to compare the results statistically with the reference methods. The study found that the analyzed herbal medicines were adulterated with metformin and the quantification of anti-diabetic counterfeits was therefore applied. This study determined counterfeited anti-diabetic drugs in Indian and Chinese traditional herbal medicines(THMs). Design-of-experiment, PB, and BB designs were used. Method validation was also performed in accordance with the International Conference on Harmonization guidelines.

DEVELOPMENT AND VALIDATION OF STABILITY-INDICATING SIMULTANEOUS ESTIMATION OF METFORMIN AND ALOGLIPTIN IN TABLETS BY HIGH-PERFORMANCE THIN LAYER CHROMATOGRAPHY

Objective: A simple and stability-indicating high-performance thin-layer chromatographic method was developed and validated for the simultaneous estimation of metformin and alogliptin in tablets.&#x0D; Methods: The method was developed in TLC aluminum plates pre-coated with silica gel 60F254 as the stationary phase and the solvent system consists of methanol: chloroform: 0.5% ammonium sulphate [4:4:2, v/v/v]. The system was found to conferred a compact spot for metformin [Rf value of 0.44±0.02] and alogliptin [Rf value of 0.66 ± 0.22]. Densitometric analysis of metformin and alogliptin was carried out at the wavelength of 254 nm. Forced degradation studies were conducted to know the stability of the drug samples under various stress conditions like acid, base, peroxide, photolytic degradation according to the ICH guidelines.&#x0D; Results: The developed method was found to be suitable for the excellent separation of the drug samples. Calibration curves were linear in the range of 40-200 ng/spot with a correlation coefficient of 0.996 for metformin and calibration curves were linear in the range of 1-5 ng/spot with a correlation co-efficient of 0.997 for alogliptin, respectively. Stability study shows that the chromatograms of samples degraded with acid, base, hydrogen peroxide, dry heat, and photolytic showed well-separated spots of pure metformin and alogliptin as well as some additional peaks at different Rf values. The method was successively applied to pharmaceutical formulation. No chromatographic interference from the tablet excipients was found.&#x0D; Conclusion: The newly developed method can be applied for the identification and quantitative determination of metformin and alogliptin in the combined dosage form.

Development and validation of rp-hplc method for the simultaneous estimation of linagliptin, empagliflozin and metformin in solid dosage forms

The purpose of the investigation was to develop a simple, rapid and accurate RP-HPLC method to determine assay of Linagliptin, Empagliflozin and Metformin in solid dosage forms. The chromatographic separation was performed on Kromosil 250 x 4.6 mm, 5μm. Eluents were monitored on PDA detector at a wavelength of 233 nm using a Buffer: Acetonitrile (45:55v/v). The column temperature was maintained at 30°C. Validation parameters such as system suitability, linearity, precision, accuracy, specificity, limit of detection (LOD), limit of quantification (LOQ), Stability of sample and standard stock solutions and robustness were studied as reported in the ICH guidelines. The retention time for Linagliptin, Empagliflozin and Metformin was 2.370min, 2.787min and 3.419 min respectively. Assay method further evaluated for Linagliptin, Empagliflozin and Metformin analysis at low concentration of analyte and found limit of detection is 0.02 μg/ml, 0.08 μg/ml and 9.22μg/mlrespectively and limit of Quantitation is 0.05μg/ml, 0.25μg/mland 27.94μg/mlrespectively. The percentage recovery of Linagliptin, Empagliflozin and Metformin was 99.99%, 99.47% and 100.01% respectively. The %RSD for Linagliptin, Empagliflozin and Metformin was 0.5%, 0.7% and 0.2%respectively. Linearity of Linagliptin, Empagliflozin and Metformin performed from 25% to150% and the R2 is 0.999, intercept and slope found to be y = 25605x + 1357, y = 40970x + 3932 and y = 1497.x + 12010 respectively. The method was fast, accurate, precise and sensitive hence it can be employed for routine quality control of Linagliptin, Empagliflozin and Metformin containing drug in quality control laboratories and pharmaceutical industries.

Analysis of Metformin on Endogenous Antioxidants and Oxidative Stress in Mice Brain Tissue of Alloxan-Induced Diabetes

Diabetes has become a serious threat to mankind, as it is found in all parts of the world. Alloxan induced diabetic mice were treated by Metformin to study the impact of oxidative stress and endogenous antioxidants. Due to the establishment of diabetes, the oxidative stress indicators were found to be positively correlated with the elevation in the levels of endogenous antioxidants. Whereas, in Metformin-treated diabetic mice, the data revealed the correction of diabetes by lowering of blood glucose level along with body weight. But the levels of endogenous antioxidants were not recorded to increase except GST. It shows that under in vivo system level of oxidative stress increases due to the Metformin. The data revealed that Metformin treatment of mice, however, manage the glucose level but not effective in controlling oxidative stress.

Novel LC\u2013MS/MS method for analysis of metformin and canagliflozin in human plasma: application to a pharmacokinetic study

Highly sensitive and selective liquid chromatography/tandem mass spectrometry (LC–MS/MS) method was developed and validated for the simultaneous estimation of the recently approved oral hypoglycemic mixture; metformin (MET) and canagliflozin (CFZ) in human plasma using propranolol HCl (PPL) and tadalafil (TDF) as internal standards (IS), respectively. Analytes were extracted using protein precipitation induced by acetonitrile then liquid–liquid extraction was performed using ethyl acetate. Reversed phase HPLC was carried out using C18 analytical column (50 mm × 4.6 mm i.d., 5 µm) with a simple isocratic mobile phase composed of 0.1% formic acid and acetonitrile (60:40, v/v). Detection was performed on a triple quadrupole mass spectrometer employing electrospray ionization technique, operating in multiple reaction monitoring (MRM), with the transitions of m/z 130.2 → 60.1, m/z 462.3 → 191.0, m/z 260.2 → 183.0 and m/z 390.2 → 268.2 for MET, CFZ, PPL and TDF, respectively, in the positive ion mode. The analysis was carried out within 5 min over a linear concentration range of 50–5000 ng/mL for MET and 10–1000 ng/mL for CFZ. The method was validated in accordance with the FDA guidelines for bioanalytical method. All obtained recoveries were higher than 90.0% while the accuracy was in the range of 88.14–113.05% and the relative standard deviation was below 10.0% for all investigated drugs by the proposed method. The achieved promising results has allowed for the successful application of the developed LC–MS/MS method to a pharmacokinetic study of the target drugs after their oral administration to Egyptian healthy volunteers. The pharmacokinetic study was accomplished after the agreement of the ethics committee.

STABILITY INDICATING METHOD DEVELOPMENT AND VALIDATION OF METFORMIN AND ERTUGLIFLOZIN BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY WITH PDA DETECTION AND ITS APPLICATION TO TABLET DOSAGE FORM

Objective: A sensitive, rapid, accurate, and precise stability indicating high-performance liquid chromatography method was developed and validated for the simultaneous estimation of metformin (MET) and ertugliflozin (ERT).&#x0D; Methods: The planned chromatographic method was developed using Kromasil C18 column using 0.1 M sodium dihydrogen phosphate methanol (50:50, by volume, pH 4.0) as mobile phase system followed by peak area response measurement at 238 nm. The developed method was validated by means of ICH guidelines about system suitability, linearity, sensitivity, selectivity, accuracy, precision, robustness, and specificity.&#x0D; Results: Calibration curves of MET and ERT are linear from 250 to 750 μg/ml and 3.75 to 11.25 μg/ml, respectively. Relative standard deviation is &lt;2.0% and recovery is ̴ 100%. Successfully, the developed method was applied for the simultaneous determination of MET and ERT in tablets and to study degradation of MET and ERT in acidic, alkaline, oxidation, thermal, and photolytic degradation conditions. No obstructions from additional common excipients of tablets and degradants were observed.&#x0D; Conclusion: The results recommended method suitability for the analysis of MET and ERT in quality control laboratories.

Dried blood spot testing for estimation of renal function and analysis of metformin and sitagliptin concentrations in diabetic patients: a cross-sectional study.

Dried blot spot (DBS) analysis of drugs or clinical parameters offers many advantages. We investigated the feasibility of using DBS for analysis of anti-diabetic drugs concomitantly with the estimated creatinine clearance (Clcrea). The cross-sectional study involved physicians in an enabling analysis with 70 diabetic patients and community pharmacists in a field investigation with 84 participants. All 154 DBS samples were analyzed for creatinine, metformin, and sitagliptin. The diabetic patients revealed of a wide range of age (32-88years), BMI values (19.8-54.7kg/m2), and extent of polypharmacotherapy (1-21 drugs). A correlation factor to convert capillary blood creatinine from DBS into plasma concentrations was determined. Patients' Clcrea ranged from 21.6-155.9mL/min. The results indicated statistically significant correlations (p< 0.05) between the use of two or three particular drug classes (diuretics, NSAIDs, renin-angiotensin system blockers) and a decreased renal function. DBS concentrations of metformin ranged between 0.23-4.99μg/mL. The estimated elimination half-life (t ½) of metformin was 11.9h in patients with a ClCrea higher than 60mL/min and 18.5h for diabetics with lower ClCrea. Sitagliptin capillary blood concentrations ranged between 11.12-995.6ng/mL. Calculated t ½ of sitagliptin were 8.4h and 13.0h in patients with a ClCrea above and below 60mL/min, respectively. DBS allow for the analysis of concentrations of predominantly renally eliminated drugs and community pharmacists can provide a valuable contribution to DBS sampling.

PHARMACOKINETIC PROFILE OF METFORMIN HYDROCHLORIDE IN DRIED BLOOD SPOT OF HEALTHY SUBJECTS USING HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY–PHOTODIODE ARRAY

Objective: This study aimed to analyze the metformin hydrochloride in dried blood spot (DBS) sample and evaluate a pharmacokinetic profile in sixhealthy subjects who administered 850-mg metformin hydrochloride in tablet using high-performance liquid chromatography–photodiode array(HPLC–PDA).Methods: Metformin analysis was performed on data of six healthy subjects who administered 850 mg of metformin hydrochloride as tablets. Bloodsamples were taken at 12-time points at intervals of up to 12 h, and data were analyzed using HPLC–PDA.Results: A linear calibration curve was obtained in the range of 25–5000 ng/mL, with r=0.9990. Pharmacokinetic profiles of metformin were obtainedusing DBS samples from six healthy participants, with a Cmax of 347.3–416.22 ng/mL. The average tmax and t1/2 were obtained at 3 and 2 h, respectively,and the area under the curve (AUC)0-t/AUC0-∞ ratio was &gt;80% for all subjects.Conclusion: The DBS biosampling technique can be developed for application in pharmacokinetic study of metformin HCl.

A probabilistic threshold analysis of metformin (Met) with enzalutamide (Enza) to determine the cost and added efficacy needed to make such a combination theray cost-effective (CE).

e577 Background: Enza has become known for its' effectiveness in treating patients with metastatic castrate-resistant prostate cancer. However, Enza is expensive (~$3175/month) and unlikely to be CE at any willingness to pay (WTP) threshold from $0-$125 000/quality-adjusted life years (QALYs). Met is inexpensive (~$8.00/month) and recently two large population-based studies of prostate cancer (PCa) demonstrated that diabetics taking Met had improved PCa specific and overall survival compared to those not taking Met. As a result we theorized that there must be a cost of Enza and a specific added effect Met could provide that would make Met a CE adjuvant therapy to Enza even though it is not currently used as such. Methods: We constructed a Markov-based decision analytic model and performed a probabilistic threshold analysis to narrow in on several combinations of costs of Enza and added efficacies needed to make Enza + Met a CE combination therapy at different WTP thresholds. Costs, utilities, and transition probabilities were derived from existing literature. Effectiveness was measured using QALYs. Costs and QALYs were considered over a lifetime horizon and discounted at 5% per annum. Results: At a WTP threshold of $50 000/QALY Enza + Met is unlikely to be CE no matter the cost decrement or added efficacy applied to the model. At a WTP threshold of $75 000/QALY Met is also unlikely to be CE unless the price of Enza could drop to $1934/month and Met could also add 1% to the efficacy of Enza. At Enza's current cost and a WTP threshold of $100 000, Enza + Met could be CE barring Met adds 0.621% to the number of patients still on treatment at 36 months. Conclusions: Enza + Met is unlikely to be CE at WTP thresholds of $50 000/QALY or $75 000/QALY unless there is a significant price drop for Enza; these results make sense because a therapy that is considered not CE at these WTP thresholds by itself is unlikely to be CE with a theoretical adjuvant therapy that would hold a patient on such a treatment for even longer. Our results show that the only way for Enza + Met to be CE is through the theoretical overall survival benefit of Met as the price of Enza is unlikely to drop any time soon.

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

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

Preconcentration and determination of Metformine Hydrochloride in different samples by cloud point extraction coupling with uv-visible spectrophotometry

This work was influenced the separation and preconcentration steps were carried out to determination of metformin (MET) in pharmaceutical preparations and human serum samples. Complex formation method and cloud-point extraction (CPE) coupling with UV-Visible spectrophotometry were used to investigated of study target.The results has showed the best optical characteristic for calibration curve and statistical data which were obtained under optimum conditions. The first method is based on the reaction of MET with nickel (II) in alkaline medium an absorption maximum ?)max) at 434nm. ''Beer's low'' is obeyed in the concentration range (10-100µg.ml-1) with molar absorptivity of 3.9x103 L.mol-1.cm-1.The limit of detection and quantitation values were 2.37 and7.11 µg.ml-1 respectively. The second method based on extraction of traces amounts of MET using the cloud-point extraction (CPE). This method implicated for using of a nonionic surfactant (Triton x-114) as an extraction medium which was entrap the hydrophobic complex formed between MET and nickel(ii) in basic medium as reaction system for designing the CPE procedure. The optimum conditions were similar the first method expect the amount of surfactant which was 0.5 ml. The concentrations range of calibration curve from 3.5to100 µg.ml-1 and molar absorptivity of 1.2x104 L.mol-1.cm-1. In this method was access to less of concentrations in Limit of detection and quantitation which were 0.74and 2.22 µg.ml-1 respectively. The precise (RSD %) and accuracy (recovery %) of both methods were ranged between 0.24-0.47, 97.86-98.68 respectively. The data of two methods were appeared high acceptable with standered of British Pharmacopoeia through using statistic methods (f-test and t-test), that they may be used in analysis of MET.

Фармакоэкономический анализ использования метформина замедленного высвобождения в терапии сахарного диабета 2 типа

Фармакоэкономический анализ использования метформина замедленного высвобождения в терапии сахарного диабета 2 типа

Preconcentration and determination of Metformine Hydrochloride in different samples by cloud point extraction coupling with uv-visible spectrophotometry

This work was influenced the separation and preconcentration steps were carried out to determination of metformin (MET) in pharmaceutical preparations and human serum samples. Complex formation method and cloud-point extraction (CPE) coupling with UV-Visible spectrophotometry were used to investigated of study target.The results has showed the best optical characteristic for calibration curve and statistical data which were obtained under optimum conditions. The first method is based on the reaction of MET with nickel (II) in alkaline medium an absorption maximum ?)max) at 434nm. ''Beer's low'' is obeyed in the concentration range (10-100µg.ml-1) with molar absorptivity of 3.9x103 L.mol-1.cm-1.The limit of detection and quantitation values were 2.37 and7.11 µg.ml-1 respectively. The second method based on extraction of traces amounts of MET using the cloud-point extraction (CPE). This method implicated for using of a nonionic surfactant (Triton x-114) as an extraction medium which was entrap the hydrophobic complex formed between MET and nickel(ii) in basic medium as reaction system for designing the CPE procedure. The optimum conditions were similar the first method expect the amount of surfactant which was 0.5 ml. The concentrations range of calibration curve from 3.5to100 µg.ml-1 and molar absorptivity of 1.2x104 L.mol-1.cm-1. In this method was access to less of concentrations in Limit of detection and quantitation which were 0.74and 2.22 µg.ml-1 respectively. The precise (RSD %) and accuracy (recovery %) of both methods were ranged between 0.24-0.47, 97.86-98.68 respectively. The data of two methods were appeared high acceptable with standered of British Pharmacopoeia through using statistic methods (f-test and t-test), that they may be used in analysis of MET.

Analysis of metformin, glimepiride and pioglitazone in human serum and its application to pharmacokinetics

A robust method, for the chromatographic separation of three antidiabetic drugs viz metformin, pioglitazone and glimepiride using an isocratic reversed phase high-performance liquid chromatographic (HPLC) system having ultraviolet detection at 254 nm is presented in this paper. The method was developed in human serum and dosage formulation with high-quality chromatographic separation between the drug peaks by using a stainless steel analytical column Nucleosil, C18 (10 micron, 25 × 0.46 cm). The system was operated at room temperature using a mobile phase consisting of acetonitrile, phosphate buffer (pH 4.3) in the ratio of 60 : 40 v/v at a flow rate of 1 mL min−1. The parametric statistics, i.e., correlation coefficient of 0.999 was assessed for all the drugs having linearity over the tested concentration range (10 to 10 000 ng mL−1) in human serum. The accuracy and the relative standard deviations of samples for six replicate measurements were not less than 97% and greater than 2%, respectively. The proposed method was validated for selectivity, linearity, accuracy, and precision according to the International Conference on Harmonization (ICH). The method is applicable for the quality control of the mentioned drugs in raw material, bulk drug, and pharmaceutical formulations as well as in human serum.

Population PK/PD analysis of metformin using the signal transduction model

Metformin, a biguanide glucose lowering agent, is commonly used to manage type 2 diabetes. The molecular mechanisms of metformin have not been fully identified, but turnover of biomarkers such as glucose and signalling pathways or translocation of glucose transporters are closely related to the glucose-lowering effects of metformin. The PK/PD of metformin have been investigated in healthy humans and patients with type 2 diabetes mellitus and modelling has been performed using an indirect response model. The purpose of this investigation was to develop a population PK/PD model for metformin using a signal transduction model in healthy humans and predict the PK/PD profile in patients with type 2 diabetes. The aim was to compare a previous model (a biophase model) with the signal transduction model, and use a more appropriate model to follow the actions of metformin. Additionally, our developed model was appropriate to predict the time course of plasma metformin and fasting plasma glucose (FPG) concentrations in patients with type 2 diabetes. To our knowledge, this is the first published population PK/PD analysis using the signal transduction model for metformin. AIMS To develop a population pharmacokinetic (PK) and pharmacodynamic (PD) model for metformin (500 mg) using the signal transduction model in healthy humans and to predict the PK/PD profile in patients with type 2 diabetes. Following the oral administration of 500 mg metformin to healthy humans, plasma concentrations of metformin were measured using LC-MS/MS. A sequential modelling approach using NONMEM VI was used to facilitate data analysis. Monte Carlo simulation was performed to predict the antihyperglycaemic effect in patients with type 2 diabetes. Forty-two healthy humans were included in the study. Population mean estimates (relative standard error, RSE) of apparent clearance, apparent volume of distribution and the absorption rate constant were 52.6 l h(-1) (4.18%), 113 l (56.6%) and 0.41 h(-1) , respectively. Covariate analyses revealed that creatinine clearance (CL(CR) ) significantly influenced metformin: CL/F= 52.6 × (CL(cr) /106.5)(0.782) . The signal transduction model was applied to describe the antihyperglycaemic effect of metformin. The population means for efficacy, potency, transit time and the Hill coefficient were estimated to be 19.8 (3.17%), 3.68 µg ml(-1) (3.89%), 0.5 h (2.89%) and 0.547 (9.05%), respectively. The developed model was used to predict the antihyperglycaemic effect in patients with type 2 diabetes. The predicted plasma glucose concentration value was similar to previous values. The population signal transduction model was developed and evaluated for metformin use in healthy volunteers. Model evaluation by non-parametric bootstrap analysis suggested that the proposed model was robust and parameter values were estimated with good precision.

Determination of metformin in rat plasma by HILIC‐MS/MS combined with Tecan automation and direct injection

Metformin is a well-known oral antihyperglycemic drug used in treatment of type II diabetes. Analysis of metformin in biological fluids is a challenge owing to its high polarity and small molecular size, which lead to poor retention of metformin on reversed-phase liquid chromatographic columns. A high-throughput method was developed and validated for the determination of metformin in rat plasma in support of preclinical toxicology studies, using hydrophilic interaction liquid chromatography tandem mass spectrometry (HILIC-MS/MS) and Tecan automated sample preparation. Extracted samples were directly injected onto the unbounded silica column with an aqueous-organic mobile phase. This HILIC-MS/MS method was validated for accuracy, precision, sensitivity, stability, matrix effect, recovery and calibration range. Acceptable intra-run and inter-run assay precision (coefficient of variation ≤ 3.9%) and accuracy (99.0-101.8%) were achieved over a linear range of 50-50,000 ng/mL. Metformin is stable in rat plasma for at least 6 h at room temperature, 147 days at -70°C and through three freeze (-70°C) and thaw cycles. Metformin is also stable in rat whole blood for at least 2 h at room temperature and in an ice-water bath. The validated method was successfully used in support of several preclinical studies where metformin is dosed together with an investigational drug substance. The ruggedness of the validated method was demonstrated by the incurred sample reproducibility test.