Development and validation of the method for the detection of glimepiride via derivatization employing N-methyl-N-(trimethylsilyl) trifluoroacetamide using gas chromatography-mass spectrometry

Background

Recent advances in the diversified anti-diabetic drugs have appeared in the startling increase in the count of poisoning cases. The epidemics of diabetes mellitus are increasing; hence, the no. of anti-diabetic drug users raised by 42.9%. The use of glimepiride raised to 24%. As the toxicity and drug cases are also escalating with increasing epidemics of diabetes mellitus, a novel gas chromatography-mass spectrometry (GC-MS) method for detecting glimepiride in biological matrices is developed.

Results

Liquid-liquid extraction method was employed by using 1-butanol: hexane (50:50, v/v) under an alkaline medium, and then back extraction was done via acetic acid. Distinct derivatization techniques were employed for the sample preparation for GC-MS analysis, i.e., silylation and acylation. Derivatization approaches were optimized under different parameters, i.e., reaction temperature and reaction time. N-Methyl-N-(trimethylsilyl) trifluoroacetamide [MSTFA] was found to be the best sound derivatization reagent for the GC-MS analysis of glimepiride. Total ion current (TIC) mode was selected for the monitoring of ions of trimethylsilyl (TMS) derivative of glimepiride with an m/z ratio of 256. Distinct parameters like specificity, carryover, stability, precision, and accuracy were evaluated for validating the identification method. The GC-MS method is found to be linear and illustrated within the range 500 to 2500 ng/ml with the value of R2 (coefficient of determination) at 0.9924. The stability of the extracted and derivatized glimepiride was accessed with regard to processed/extracted sample conditions and autosampler conditions, respectively. Accuracy at each concentration level was within the + 15% of the nominal concentration. Precision (%) for the interday and intraday analysis was found to be in the respectable spectrum.

Conclusion

Henceforth, the proposed GC-MS method can be employed for the determination of glimepiride in biological matrices.

Optimization of self-nanoemulsifying systems for the enhancement of in vivo hypoglycemic efficacy of glimepiride transdermal patches

OBJECTIVES

To optimize and use of glimepiride (GMD)-loaded self-nanoemulsifying delivery systems (SNEDs) for the preparation of transdermal patches.

METHODS

Mixture design was utilized to optimize GMD-loaded SNEDs in acidic and aqueous pH media. Optimized GMD-loaded SNEDs were used in the preparation of chitosan (acidic) and hydroxypropyl methyl cellulose (HPMC) (aqueous) films. The prepared optimized formulations were investigated for ex vivo skin permeation, for in vivo hypoglycemic activity and for their pharmacokinetic parameters using animal model.

RESULTS

The optimized formulations showed flux value of (2.88 and 4.428 μg/cm(2)/h) through rat skin for chitosan and HPMC films, respectively. The pattern of GMD release from both formulations was in favor of Higuchi and approaching zero order models. The n values for Korsmeyer-Peppas equation were characteristic of anomalous (non-Fickian) release mechanism. Moreover, HPMC patches have shown significant reductions (p < 0.05) in blood glucose levels; (213.33 ± 15.19) mg/100 ml from the base-line measurement after 12 h of application.

CONCLUSIONS

Optimized GMD SNEDs patches were found to improve GMD skin permeability and the essential pharmacokinetic parameters. Further extensive pre/clinical studies are necessary prior to use transdermal GMD as a valuable alternative to peroral dosage forms with improved bioavailability, longer duration of action and more patient convenience.

Development and validation of RP-HPLC method for glimepiride and its application for a novel self-nanoemulsifying powder (SNEP) formulation analysis and dissolution study

Background

There are many analytical methods available for estimation of glimepiride in biological samples and pharmaceutical preparations. To our knowledge, there is no specific reverse-phase high-performance liquid chromatography (RP-HPLC) method for estimation of glimepiride and its dissolution study in self-nanoemulsifying powder (SNEP) formulation.

Methods

A simple method was carried out on a 5-μm particle octadesyl silane (ODS) column (250 × 4.6 mm) with acetonitrile: 0.2 M phosphate buffer (pH = 7.4) 40:60 v/v as a mobile phase at a flow rate of 1 mL/min, and quantification was achieved at 228 nm using PDA detector.

Results

The correlation coefficient (r 2) was found to be 0.999 over the concentration range of 0.2 to 2 μg/mL for glimepiride. The method was validated for linearity, accuracy, and precision. The limit of detection and limit of quantification were found to be 0.38 and 1.17 μg/mL, respectively.

Conclusions

The proposed method was found to be simple, precise, suitable, and accurate for quantification of glimepiride as an alternative to the existing methods for the routine analysis of glimepiride in pharmaceutical formulations and in vitro dissolution studies.

Simultaneous determination of atorvastatin, metformin and glimepiride in human plasma by LC-MS/MS and its application to a human pharmacokinetic study

A simple, rapid and sensitive liquid chromatography-tandem mass spectrometric (LC–MS/MS) assay method has been developed and fully validated for the simultaneous quantification of atorvastatin, metformin and glimepiride in human plasma. Carbamazepine was used as internal standard (IS). The analytes were extracted from 200 μL aliquots of human plasma via protein precipitation using acetonitrile. The reconstituted samples were chromatographed on a Alltima HP C18 column by using a 60:40 (v/v) mixture of acetonitrile and 10 mM ammonium acetate (pH 3.0) as the mobile phase at a flow rate of 1.1 mL/min. The calibration curves obtained were linear (r²≥0.99) over the concentration range of 0.50–150.03 ng/mL for atorvastatin, 12.14–1207.50 ng/mL for metformin and 4.98–494.29 ng/mL for glimepiride. The API-4000 LC–MS/MS in multiple reaction monitoring (MRM) mode was used for detection. The results of the intra- and inter-day precision and accuracy studies were well within the acceptable limits. All the analytes were found to be stable in a battery of stability studies. The method is precise and sensitive enough for its intended purpose. A run time of 2.5 min for each sample made it possible to analyze more than 300 plasma samples per day. The developed assay method was successfully applied to a pharmacokinetic study in human male volunteers.

Rapid and specific approach for direct measurement of glimepiride in human plasma by LC-ESI-MS-MS employing automated 96 well format: application to a bioequivalence study

A rapid liquid chromatographic method with electrospray ionization tandem mass spectrometric (LC-MS-MS) detection is developed and validated for quantification of glimepiride in heparinized human plasma. Plasma samples, without a drying and reconstitution step, are extracted by solid-phase extraction (SPE) and eluted with 0.9 mL of acetonitrile-methanol (1:1, v/v) containing 0.05% formic acid. The analyte and glimepiride d8 (internal standard, IS) are chromatographed on a C(18) column; the mobile phase is acetonitrile-2 mm ammonium formate (88:12, v/v), with the pH adjusted to 3.5 with formic acid, at a flow rate of 0.5 mL/min. The retention times of glimepiride and the IS are 0.93 min, and the runtime is 1.6 min per sample. Selected reaction monitoring of MH(+) at m/z 491.20 and 499.26 result in stable fragment ions with m/z 351.80 and 359.96 for glimepiride and the IS, respectively. The response was a linear function of the concentration in the range of 2.0-650.0 ng/mL, with r ≥ 0.9994. The recovery of glimepiride and the IS ranged from 81.91 to 83.36%. The assay has excellent characteristics and has been successfully used for the analysis of glimepiride in healthy human subjects in a bioequivalence study. It was well suited to clinical studies of the drug involving large numbers of samples.

Electrochemical study of glimepiride and its complexation with β-cyclodextrin

The electrochemical behavior of a hypoglycemic drug, glimepiride (GM), was studied at glassy carbon (GCE) and carbon paste (CPE) electrodes in phosphate buffer over the pH range of 2.7–11.7 using cyclic and differential pulse voltammetry. Oxidation of the drug was shown to be an irreversible and diffusion-controlled process. Using differential pulse voltammetry (DPV), the drug yielded a well-defined voltammetric peak in phosphate buffer pH 6.4 at +1.16 V and pH 7.0 at +1.07 V (vs Ag|AgCl) on glassy carbon and carbon paste electrodes, respectively. This process could be used to determine glimepiride concentrations in the range from 1.0 × 10–5 to 3.2 × 10–5 mol l–1 with a detection limit of 2.0 × 10–6 mol l–1 in case of the glassy carbon electrode and in the range of 2.0 × 10–6 to 1.5 × 10–5 mol l–1 with a detection limit of 7.5 × 10–7 mol l–1 in case of the carbon paste electrode. The method was successfully applied to the determination of the drug in a tablet dosage form. Next, the formation of an inclusion complex of glimepiride with β-cyclodextrin (β-CD) in phosphate buffer (pH 7.0):methanol (90:10 (v/v)) has been investigated by differential pulse voltammetry as well as UV spectrophotometry and its stability constant was determined by both methods to be 202.0 and 197.9 l mol–1, respectively.

Glimepiride

Glimepiride, which belongs to the sulfonylurea group, has been widely analyzed for its physical chemical properties including its crystallinity. Moreover, methods to quantify glimepiride and its impurities, either in pharmaceutical dosage form or in biological sample, have also been extensively developed and reported. This chapter extracts all information needed to give more perspective regarding to this substance.

Pharmacokinetic comparison of a new glimepiride 1-mg + metformin 500-mg combination tablet formulation and a glimepiride 2-mg + metformin 500-mg combination tablet formulation: a single-dose, randomized, open-label, two-period, two-way crossover study in healthy, fasting Korean male volunteers

BACKGROUND

Coadministration of glimepiride and metformin has been used to achieve glucose control. Because compliance with a multiple medication regimen can be difficult for some patients, combination tablets of glimepiride + metformin might be a suitable alternative for these patients.

OBJECTIVE

This study was conducted to compare the pharmacokinetics of test and reference formulations of glimepiride + metformin fixed-dose combination tablets under fasting conditions to meet the regulatory requirements for marketing approval of a new drug in Korea.

METHODS

This was a single-dose, randomized, open-label, 2-period, 2-way crossover study conducted between March 2007 and May 2007. Healthy fasting Korean men were randomized to 1 of 2 dosing sequences: a single oral administration of a fixed-dose glimepiride 1-mg + metformin 500-mg combination tablet (test) followed by single oral administration of a fixed-dose glimepiride 2 mg + metformin 500 mg combination tablet (reference), separated by a 1-week washout period between doses; or a single oral administration of a fixed-dose glimepiride 2-mg + metformin 500-mg combination tablet followed by single oral administration of a fixed-dose glimepiride 1 mg + metformin 500-mg combination tablet, separated by a 1-week washout period between doses. Serial samples of blood were collected up to 24 hours after oral administration, and drug concentrations in plasma were determined by HPLC-MS/MS. Tolerability was assessed based on adverse events and changes in clinical parameters. Serious adverse events included those that resulted in death, a life-threatening condition, congenital anomaly or birth defect, or required hospitalization or prolongation of existing hospitalization.

RESULTS

A total of 30 healthy male subjects (mean age, 25.6 years [range, 20-36 years]; weight, 69.5 kg [range, 58.2-90.7 kg]) participated in the study. After administration of the test and reference formulations, glimepiride was rapidly absorbed, reaching C(max) with a median T(max) of 1.75 and 2.0 hours, respectively, and then declined exponentially with an average t(1/2) of 8.2 and 8.5 hours. The individual C(max) and AUC(last) of glimepiride were observed to be proportionally increased according to the administered glimepiride dose. The mean (SD) dose-normalized Cmax values of glimepiride 1 and 2 mg were 168.2 (54.9) and 149.9 (47.4) ng/mL/mg, respectively; the mean dose-normalized AUC(last) values of glimepiride 1 and 2 mg were 681.5 (190.3) and 635.8 (194.1) ng x h/mL/mg. Individual plots of dose-normalized C(max) and AUC(last) values identified a similarity between the 2 groups but no significant between-group differences. A total of 25 adverse events (12 after the test dose and 13 after the reference dose) were reported by 13 of the 30 subjects. All adverse events were considered mild. Twenty-one adverse events were considered related to the study drug (8 after the test dose and 13 after the reference dose). Adverse events believed to be related to the test formulation were diarrhea (4 cases), dizziness (1), headache (1), tingling sensation (1), and weakness (1). Adverse events believed to be related to the reference formulation were diarrhea (6 cases), headache (3), cold sweats (1), dyspepsia (1), epigastric discomfort (1), and lethargy (1). There were no clinically significant findings in the laboratory test results or vital sign monitoring during the study. There were no serious adverse events reported.

CONCLUSIONS

The C(max) and AUC(last) of glimepiride increased proportionally according to the administered glimepiride dose in this study of healthy, fasting Korean men. The safety profiles of the 2 combination tablets were comparable.

A rapid and highly sensitive method for the determination of glimepiride in human plasma by liquid chromatography–electrospray ionization tandem mass spectrometry: application to a pre-clinical pharmacokinetic study

A sensitive and specific liquid chromatography-positive electrospray ionization-tandem mass spectrometry method has been developed and validated for the determination of glimepiride (GPD) in human plasma. GPD and the internal standard (IS, glibenclamide) were extracted from a small aliquot of human plasma (200 microL) by a simple liquid-liquid extraction technique using ethyl acetate as extraction solvent. The compounds were separated on a YMC Propack, C18, 4.6x50 mm column using a mixture of ammonium acetate buffer, acetonitrile and methanol (30:60:10, v/v) as mobile phase at 0.5 mL/min on an API 4000 Sciex mass spectrometer connected to an Agilent HPLC system. Method validation and pre-clinical sample analysis was performed as per FDA guidelines and the results met the acceptance criteria. GPD and IS were detected without any interference from human plasma matrix. The method was proved to be accurate and precise at linearity range of 0.02-100.00 ng/mL with a correlation coefficient of 0.999. The method was robust with a lower limit of quantitation of 0.02 ng/mL. Intra- and inter-day accuracies for GPD were 88.60-113.50 and 96.82-103.93%, respectively. The inter-day precision was better than 12.21%. This method enabled faster and reliable determination of GPD in a pre-clinical study.