Simultaneous estimation of six anti-diabetic drugs—glibenclamide, gliclazide, glipizide, pioglitazone, repaglinide and rosiglitazone: development of a novel HPLC method for use in the analysis of pharmaceutical formulations and its application to human plasma assay

Hydrophilic interaction liquid chromatography-electrospray ionization mass spectrometry combined with fabric phase sorptive extraction for therapeutic drug monitoring of pioglitazone, repaglinide, and nateglinide in human plasma

Polypharmacy in type 2 diabetes is an issue of major concern as the prescription of multiple medi-cations for the management of diabetes-associated comorbidities can lead to drug-to-drug interactions, which can pose serious risks to patients' health. Within this context, the development of bioanalytical methods for monitoring the therapeutic levels of antidiabetic drugs is notably useful to ensure patients' safety. In the present work, a liquid chromatography-mass spectrometry method for the quantitation of pioglitazone, repaglinide, and nateglinide in human plasma is described. Sample preparation was performed by fabric phase sorptive extraction (FPSE), and hydrophilic interaction liquid chromatography (HILIC) was implemented for the chromatographic separation of the analytes, using a ZIC®-cHILIC analytical column (150 × 2.1 mm, 3 µm) under isocratic elution. The mobile phase consisted of 10 mM ammonium formate aqueous solution (pH = 6.5)/ acetonitrile, 10/90 v/v, and was pumped at a flow rate of 0.2 mL min^-1. Design of Experiments was used during the development of the sample preparation method to gain deeper insight into the effect of various experimental parameters on extraction efficiency, their potential interactions and to optimize the recovery rates of the analytes. The linearity of the assay was assessed over the ranges of 25 to 2000, 6.25 to 500, and 125 to 10000 ng mL^-1 for pioglitazone, repaglinide, and nateglinide, respectively. The presented method was fully validated and can be used for the therapeutic monitoring of the targeted analytes in human plasma samples.

Simultaneous HPLC Assay of Gliclazide and Ciprofloxacin in Plasma and its Implementation for Pharmacokinetic Study in Rats

A simple and reliable high-performance liquid chromatography method for simultaneous quantitation of gliclazide and ciprofloxacin in plasma sample has been developed and validated. This method implements protein precipitation, a simple and practical pretreatment method by the addition of acetonitrile that gives a clean supernatant. The separation was carried out in a system consisted of a C18 column with acetonitrile and KH2PO4 (0.01 M, 0.1% v/v of triethylamine, pH 2.7) as the mobile phase in a gradient elution at a total flow-rate of 1 mL/min. Gliclazide and ciprofloxacin were quantitated using an ultraviolet detector set at wavelengths of 229 and 277 nm, respectively, which ensures optimal sensitivity for both compounds. This method possesses an excellent linearity at concentration ranges of 0.5-50 mg/L for gliclazide and 0.1-10 mg/L for ciprofloxacin. High within- and between-run accuracy for both gliclazide (% error of -8.00 to 0.45%) and ciprofloxacin (% error of -10.00 to 7.63%) were demonstrated. The intra- and inter-day precision (expressed as %CV) was <8 and 12% for gliclazide and ciprofloxacin, respectively. Both analytes were stable during storage and sample processing. The method reported in this study can be implemented for pharmacokinetic interaction study in rats.

Development and Validation of a Rapid Analytical Method for the Simultaneous Quantification of Metabolic Syndrome Drugs by HPLC-DAD Chromatography

Worldwide, 25% of the population suffers from metabolic syndrome (MetS). The treatment of patients with MetS regularly includes drugs prescribed simultaneously to treat several disorders that manifest at the same time, such as hypercholesterolemia, arterial hypertension, and diabetes. To the authors’ best knowledge, there is no previous published analytical method for the simultaneous quantification of drugs used in the treatment of these diseases. In the present study, a rapid high-performance liquid chromatography with a diode-array detector HPLC-DAD methodology was developed for simultaneous quantification of carvedilol (CVD), telmisartan (TEL), bezafibrate (BZT), gliclazide (GZD), and glimepiride (GMP) in bulk and pharmaceutical form. The chromatographic separation of the five pharmaceuticals was achieved on a Hypersil GOLD C18 Selectivity (5 µm, 150 × 4.60 mm2) using a mobile phase of acetonitrile (50%) and 0.02 M KH2PO4, pH 3 (50%) at a flow rate of 1 mL/min and at 25 °C. The total separation time was 9 min. The analytical method was validated following the International Conference on Harmonization guidelines. A reproducible method was obtained with acceptable limits of detection (LOD) and quantification (LOQ) for CVD (0.012 and 0.035 μg mL−1), TEL (0.103 and 0.313 μg mL−1), BZT (0.025 and 0.076 μg mL−1), GZD (0.039 and 0.117 μg mL−1), and GMP (0.064 and 0.127 μg mL−1). The validated method allowed the determination of these drugs in commercial pharmaceutical products both individually and simultaneously. The present method was found to be suitable for simultaneous quantification of the five drugs that are most commonly used in the simultaneous treatment of the metabolic syndrome.

The Effect of CYP2C9 Genotype Variants in Type 2 Diabetes on the Pharmacological Effectiveness of Sulfonylureas, Diabetic Retinopathy, and Nephropathy

Aim

Type 2 diabetes (T2D), as a major cause of morbidity and mortality, is predicted to have a prevalence of 629 million by 2045. As diabetic patients show considerable inter-individual variation in response to antidiabetic treatment, this study aimed to investigate the gene polymorphism of cytochrome P450 as well as the effectiveness and safety of glibenclamide and gliclazide for different genotypes of CYP2C9. Besides, the chronic side effects of T2D including retinal microvasculature complications or retinopathy and renal dysfunction due to nephropathy in different genotypes were considered.

Patients and Methods

The participants including 80 T2D patients treated with glibenclamide or gliclazide were recruited from university hospitals of Ahvaz Jundishpur University of Medical Sciences, Ahvaz, in the southwest of Iran. Blood samples were collected from the patients at 2.5h after the morning dose of glibenclamide and 12h after the last dose of gliclazide. Genotyping from the extracted DNA was, then, performed using PCR-RFLP. The plasma level of glibenclamide and gliclazide was, in turn, measured by the reverse-phase high-pressure liquid chromatography.

Results

The results showed that the wild-type allele, i.e., CYP2C9*1, occurred in the highest frequency (0.8), while the frequency rates of the mutant allele, i.e., CYP2C9*2 and CYP2C9*3, were 0.15 and 0.05, respectively. Moreover, no significant association was found between any of the genotypes as well as the clinical and biochemical characteristics of the patients. The findings also showed that the plasma level of sulfonylureas (i.e., glibenclamide and gliclazide) was the highest in the patients with the CYP2C9*3 allele. It was also found that 75.9% of the patients with variant genotypes had experienced hypoglycemia events. Furthermore, in the absence of wild type allele, a significant increase was observed in retinopathy (p=0.039) and nephropathy (p=0.05).

Conclusion

The findings can provide guidelines for the optimal management of the treatment protocols with sulfonylurea intended to control the T2D complications.

Pharmacokinetic Evaluation of Metabolic Drug Interactions between Repaglinide and Celecoxib by a Bioanalytical HPLC Method for Their Simultaneous Determination with Fluorescence Detection

Since diabetes mellitus and osteoarthritis are highly prevalent diseases, combinations of antidiabetic agents like repaglinide (REP) and non-steroidal anti-inflammatory drugs (NSAID) like celecoxib (CEL) could be commonly used in clinical practice. In this study, a simple and sensitive bioanalytical HPLC method combined with fluorescence detector (HPLC-FL) was developed and fully validated for simultaneous quantification of REP and CEL. A simple protein precipitation procedure and reversed C18 column with an isocratic mobile phase (mixture of ACN and pH 6.0 phosphate buffer) were employed for sample preparation and chromatographic separation. The fluorescence detector was set at a single excitation/emission wavelength pair of 240 nm/380 nm. The linearity (10-2000 ng/mL), accuracy, precision, extraction recovery, matrix effect, and stability for this method were validated as per the current FDA guidance. The bioanalytical method was applied to study pharmacokinetic interactions between REP and CEL in vivo, successfully showing that concurrent administration with oral REP significantly altered the pharmacokinetics of oral CEL. Furthermore, an in vitro metabolism and protein binding study using human materials highlighted the possibility of metabolism-based interactions between CEL and REP in clinical settings.

Simultaneous Determination of Anti-diabetic Drugs in Their Combined Dosage Forms Using HPLC: An Experimental Design Approach

A liquid chromatographic method has been established for the separation of five presently existing anti-diabetic drugs-metformin, pioglitazone, glibenclamide, glimepiride and repaglinide using design of experiments methodology. The main objective of this method is to identify the suitable conditions for the adequate separation of these five drugs with minimal analysis time. Experiment design is one of the Quality by design approaches, which incorporates multifaceted combinations of independent variables and their interactions during the optimization of analytical methods for the determination of drugs. Phenomenex Luna C8-type column (250 × 4.6 mm; 5 μm particle size) was employed and 0.3% acetic acid in water: acetonitrile mixture was used as mobile phase (0.829 mL min-1 as flow rate) for the separation of analytes (Detection wavelength-230 nm). The chromatographic efficiency was investigated for the combined effects of each of mobile phase composition, buffer strength, flow rate at three levels using Box-Behnken design which is one of experimental design. The optimized method was validated using the above statistical approach and applied for the assay of pharmaceutical formulations.

Rapid, Validated UPLC-MS/MS Method for Determination of Glibenclamide in Rat Plasma

Quick and specific bioanalytical methods are required for analyzing drugs in biological samples. A simple, quick, sensitive, and specific UPLC-MS/MS method was developed and validated for glibenclamide determination in plasma samples. The plasma samples were processed by protein precipitation technique. Glimepiride was used as internal standard (IS). Glibenclamide and glimepiride were eluted on C18 column (Acquity UPLC®BEH). Mobile phase consisting of acetonitrile (0.1% formic acid) and water (0.1% formic acid) was pumped in binary gradient mode at flow rate of 150 μL/min. Glibenclamide and IS elution time was about 1.0 min, and total run time was 2.0 min. The mass spectrometer (triple-quadrupole) was operated in positive electrospray ionization mode. Sodium adducts [M + Na]+ of glibenclamide and IS were monitored in MRM mode. A linear calibration curve was obtained in the range of 10-1280 ng/mL, with regression equation Y = 0.0076 X – 0.0165 and linear regression coefficient r2 = 0.999. Lower limit of quantitation was 10 ng/mL. Accuracy of the method at LQC, MQC, and HQC was 109.7% (± 6.7), 93.6% (± 0.4), and 99.3% (± 1.9), respectively. The coefficient of variation for precision at all QC concentrations was less than 6%. Recovery at LLQC, MQC, and HQC was 104.2% (± 4.9), 100.6% (± 0.9), and 102.9% (± 5.8), respectively. The method was successfully implemented for pharmacokinetic investigations (in-house data).

Liquid chromatography/electrospray ionization tandem mass spectrometry study of repaglinide and its forced degradation products

RATIONALE

Stress stability studies of drugs have been recognized as an essential part of the drug development process. These studies are used to investigate the intrinsic stability of the drugs and for the development of a selective stability indicating assay method (SIAM). Stress testing is also useful for the formulation and packaging development, shelf-life determination and designing of manufacturing processes. As per regulatory guidelines, stress degradation studies and structural characterization should be carried out to establish degradation pathways of the drug, which is essential from both the efficacy and safety point of view. As the stress stability studies of repaglinide have not been reported in the literature, the present study has been undertaken.

METHODS

Repaglinide (RP), an oral anti-diabetic drug, was subjected to hydrolysis (acidic, alkaline and neutral), oxidation, photolysis and thermal stress conditions as per International Conference on Harmonization (ICH) guidelines Q1A (R2). The chromatographic separation of the drug and its degradation products (DPs) was achieved on an Agilent XDB C-18 column using the gradient elution method with a mobile phase consisting of 20 mM ammonium acetate and acetonitrile at flow rate of 1.0 mL min^-1 . The DPs were characterized using liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) in combination with accurate mass measurements.

RESULTS

The drug degraded under hydrolytic and oxidative stress, while it was stable under thermal and photolytic stress conditions. In total, six DPs were formed and the LC/MS method described here can resolve all DPs from the parent as well as from each other under various stress conditions. To elucidate the structures of DPs, fragmentation of the [M + H]⁺ ions of RP and its DPs was studied by using LC/ESI-MS/MS combined with accurate mass measurements.

CONCLUSIONS

The forced degradation of RP carried out as per ICH guidelines results in the formation of six degradation products which have been characterized using LC/MS/MS in combination with accurate mass measurements.

Simultaneous determination of glipizide and its four hydroxylated metabolites in human urine using LC-MS/MS and its application in urinary phenotype study

Cytochrome P450 (CYP) 2C9 and CYP2C19 genetic mutant could influence the plasma concentration of glipizide in human subjects, which refers to glipizide safety and adverse effects in clinic practice. A further study to investigate the relationship of the concentrations between glipizide and its metabolites in human with different CYP mutants was valuable. We firstly develop a validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for simultaneous quantification of glipizide and its hydroxylated metabolites in human urine. After simple protein precipitation with methanol including 4'-OH-tolbutamide and gliclazide (both are internal standards), the analytes were chromatographed on a reversed-phased column with a mobile phase of 0.1% formic acid in acetonitrile and 0.1% formic acid in water by a gradient elution. The ion transitions of the precursor to the product ion were principally protonated ions [M+H]⁺ at m/z 446.4→m/z 321.1 for glipizide, m/z 462.2→m/z 321.1 for the four hydroxylated forms of glipizide, m/z 287.2→m/z 188.0 for 4'-OH-tolbutamide, and m/z 324.1→m/z 127.1 for gliclazide. The method was linear over a concentration range of 0.02-20.0ng/mL. The intraday and inter-day variances were less than 9.9%, and accuracy was within ±6.8%. The method was successfully applied to the urinary phenotyping study in volunteers after a single oral administration of 5-mg glipizide tablet, and two new hydroxycyclohexyl metabolites of glipizide (OH-gp), 4-cis-OH-gp and 3-trans-OH-gp, were found in this study.

Synthesis and absorption performance of core–shell magnetic polymers for solid phase extraction and detection of glibenclamide in hypoglycemic health products

Synthesis of GO-modified magnetic polymers for fast separation and effective enrichment of trace glibenclamide in hypoglycemic health products.

Separation and Quantification of Eight Antidiabetic Drugs on A High-Performance Liquid Chromatography: Its Application to Human Plasma Assay

An analytical method based on isocratic reverse phase high-performance liquid chromatography was developed and validated for the separation and quantification of eight antidiabetic drugs: rosiglitazone, pioglitazone, glipizide, gliclazide, repaglinide, nateglinide, glibenclamide, and glimepiride for their application in human plasma assay. Metformin is used as internal standard. Analysis was done on Onyx monolithic C18 column (100×4.6 mm, i.d., 5 μm) using a mixture of 0.05% formic acid in water and methanol in the ratio of 42 : 58 (v/v) fixed at a flow rate of 0.5 mL/min, and they were monitored at 234 nm. Separation was achieved in less than 20 min. The calibration curves were linear in the range of 50–2000 ng/mL. The method was validated for its recovery, intra- and interday precision, stability, specificity, and selectivity. Plasma samples were prepared using solid-phase extraction of analytes. Hence, the developed method was found to be suitable for the routine analysis of selected antidiabetic drugs in biological matrices.

Trace analysis of glyclazide in human plasma at microscale level by mass spectrometry

Green (reagents and organic solvents saving) analytical chemistry is a new strategy for pharmaceutical analysis. The principles of this idea include primary elimination or at least reduction of the amounts of organic reagents and solvents. In this study, we have provided two simple methods for the analysis of clinical drugs in human plasma. One is the capillary LC (Cap LC) connected to MS-MS, the other is the matrix-assisted laser desorption ionization (MALDI) connected to TOF MS. Sulfonylurea drugs are usually used in diabetes mellitus patients. Diabetes is a syndrome of disordered metabolism resulting in abnormally high blood sugar levels (hyperglycemia). These microscale methods were successfully applied for the monitoring of drug levels in human plasma using gliclazide (a second-generation sulfonylurea) as the test platform. The sensitivity of these methods is sufficient for detecting the gliclazide within a therapeutic range. All the analytical procedures (including human plasma, sample preparation, and flow rate of the analytical system) were at microscale level. These two methods would lower the consumption of organic solvents further safeguarding our environment.

Liquid chromatography tandem mass spectrometry method for simultaneous determination of antidiabetic drugs metformin and glyburide in human plasma

A simple and rapid liquid chromatography/tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the simultaneous quantitation of antidiabetic drugs metformin and glyburide in human plasma using glimepiride as internal standard (IS). After acidic acetonitrile-induced protein precipitation of the plasma samples, metformin, glyburide and IS were chromatographed on reverse phase C18 (50 mm x 4.6 mm i.d., 5 microm) analytical column. Quantitation was performed on a triple quadrupole mass spectrometer employing electrospray ionization technique and operating in multiple reaction monitoring (MRM) and positive ion mode. The total chromatographic run time was 3.5 min and calibration curves were linear over the concentration range of 20-2500 ng/ml for metformin and 5-500 ng/ml for glyburide. The method was validated for selectivity, sensitivity, recovery, linearity, accuracy and precision, dilution integrity and stability studies. The recoveries obtained for the analytes and IS (>or=69%) were consistent and reproducible. Inter-batch and intra-batch coefficient of variation across four validation runs (LLOQ, LQC, MQC and HQC) was less than 8%. The accuracy determined at these levels was within +/-8% in terms of relative error (RE). The method was applied to a bioequivalence study of 500 mg metformin and 5mg of glyburide tablet after oral administration to 28 healthy human subjects under condition of fasting.

Development of a RP-HPLC method for screening potentially counterfeit anti-diabetic drugs

Pharmaceutical counterfeiting is becoming a serious problem in the world, especially in developing countries including China. Herein an isocratic reversed-phase high performance liquid chromatography (RP-HPLC) method was developed for screening counterfeit medicines and adulterated dietary supplement products. The developed method could be employed to separate and determine simultaneously six anti-diabetic drugs (glipizide, gliclazide, glibenclamide, glimepiride, gliquidone, repaglinide) on an isocratic solvent system using an Alltima C18 column (5 microm, 150 mmx4.6 mm) with an isocratic mobile phase of methanol-phosphate buffer (pH 3.0; 0.01 mol/L) (70:30, v/v), at a flow rate of 1.0 mL/min and at a wavelength of 230 nm. The proposed method was successfully applied to the analysis of medicinal and dietary supplement samples purchased from the local market in China.

Method development and validation of repaglinide in human plasma by HPLC and its application in pharmacokinetic studies

In this study, the development and validation of a high-performance liquid chromatography (HPLC) assay for determination of repaglinide concentration in human plasma for pharmacokinetic studies is described. Plasma samples containing repaglinide and an internal standard, indomethacin were extracted with ethylacetate at pH 7.4. The recovery of repaglinide was 92%+/-55.31. Chromatographic separations were performed on Purospher STAR C-18 analytical column (4.8 mm x 150 mm; 5 microm particle size). The mobile phase composed of acetonitrile-ammonium formate (pH 2.7; 0.01 M) (60:40, v/v). The flow rate was 1 ml/min. The retention time for repaglinide and indomethacin were approximately 6.2 and 5.3 min, respectively. Calibration curves of repaglinide were linear in the concentration range of 20-200 ng/ml in plasma. The limits of detection and quantification were 10 ng/ml and 20 ng/ml, respectively. The inter-day precision was from 5.21 to 11.84% and the intra-day precision ranged from 3.90 to 6.67%. The inter-day accuracy ranged 89.95 to 105.75% and intra-day accuracy ranged from 92.37 to 104.66%. This method was applied to determine repaglinide concentration in human plasma samples for a pharmacokinetic study.