Stability-indicating densitometric determination of some antidiabetic drugs in dosage forms, using TLC

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.

Stress degradation study of two oral antidiabetics, gliclazide and glipizide, and chemical analysis by LC and LC/MS methods

Kinetic study of degradation of two oral antidiabetics, gliclazide and glipizide, was performed using new HPLC method which was validated in terms of selectivity, sensitivity, linearity, precision and accuracy. The stress degradation was performed in 0.2 M HCl, 0.2 M NaOH as well as in acetate and phosphate buffers over the pH range 3.8–8.3 at 30 and 70°C. In strong acidic and alkaline media gliclazide was almost fully degraded while glipizide showed much higher stability. Generally, degradation processes of gliclazide and glipizide were observed as the first order reactions while the rates of decomposition for both drugs were smallest at pH 8.3. The samples of gliclazide and glipizide stressed in strong acid and alkali at 70°C were additionally analyzed using an LC/MS method and some products of decomposition were detected and identified. It was concluded that glipizide was more resistant to very high or very low pH and would have higher stability compared to gliclazide. Such comparisons have not been performed so far for these valuable drugs. Additional LC/MS study showed that during decomposition of sulfonylureas, different degradation pathways were possible.

Supramolecular Interaction of Gliclazide with Cucurbit[7]uril and its Analytical Application

Gliclazide (GLZ) is non-fluorescent in aqueous solution. This property makes its determination through direct fluorescent methods impossible. Palmatine (PAL) exhibits very weak fluorescence emissions in aqueous solution. However, in acidic media at room temperature, PAL can react with cucurbit[7]uril (CB[7]) to form a stable complex and the fluorescence intensity of the complex is greatly enhanced. Dramatic quenching of the fluorescence intensity of the CB[7]–PAL complex was observed with the addition of GLZ. The competing reactions and the supramolecular interaction mechanisms between GLZ and PAL as they fight for occupancy of the CB[7] cavity were studied using spectrofluorimetry, 1H NMR spectroscopy, and molecular modelling calculations. The association constants of the complexes formed between the host and the guest were determined. Based on the significant quenching of the supramolecular complex fluorescence intensity, a fluorescent probe method of high sensitivity was developed to determine GLZ in its pharmaceutical dosage forms and in human plasma with good precision and accuracy. The linear range of the method was from 0.003 to 2.100 μg mL–1. The limit of detection was 0.001 μg mL–1. This shows that the proposed method has promising potential for therapeutic monitoring and pharmacokinetics and for clinical application.

Stripping voltammetric quantification of the anti-diabetic drug glipizide in bulk form and pharmaceutical formulation

The electrochemical behavior of glipizide at the hanging mercury drop electrode (HMDE) was studied in B-R universal buffers of pH 1.7-11. The voltammograms exhibited a well-defined 4-electron irreversible cathodic peak which attributed to reduction of the two C=N of the pyrazine ring of glipizide molecule. Glipizide was found to has an interfacial adsorptive character onto the mercury electrode surface. A monolayer surface coverage of 1.02x10(-10)mol cm(-2) was estimated and hence each adsorbed glipizide molecule occupied an area of 1.63 nm(2) onto the mercury electrode surface. A simple and precise square-wave adsorptive cathodic stripping (SWAdCS) voltammetric procedure was described for quantification of bulk glipizide with a limit of detection of 1.5x10(-10)M and a limit of quantitation of 5x10(-10)M. The proposed procedure was successfully applied for quantitation of glipizide in its pharmaceutical formulation (Minidiab tablets) without interference from excipients.

Spectrophotometric determination of gliclazide in pharmaceuticals and biological fluids through ternary complex formation with eosin and palladium (II)

A simple and sensitive spectrophotometric method has been developed for the determination of gliclazide (GLZ) in pharmaceutical formulations and biological fluids. The proposed method is based upon the formation of a ternary complex between palladium (II), eosin and GLZ in the presence of methyl cellulose as a surfactant and acetate buffer of pH 4.5. The ternary complex showed an absorption maximum at 550 nm. The solution of ternary complex obeyed Beer's law over the concentration range of 0.5-4 microg ml(-1) with minimum detectability (S/N = 2) of 0.05 microg ml(-1) (1.545 x 10(-7) M). The different experimental parameters affecting the development and stability of the color were carefully studied and optimized. The proposed method was successfully applied to the analysis of commercial tablets. The results obtained were in good agreement with those obtained using the official or reference spectrophotometric method. The proposed method was further applied to spiked human urine and plasma, the percentage recoveries were 97.84 +/- 0.72 and 97.43 +/- 0.83, respectively, (n = 4). A proposal of the reaction pathway was presented.