İncilay Süslü

Spectrophotometric determination of enoxacin as ion-pairs with bromophenol blue and bromocresol purple in bulk and pharmaceutical dosage form

Three simple, accurate and sensitive spectrophotometric methods were developed for determination of enoxacin. The methods based on extraction of this drug into chloroform as ion pairs with sulphonphthalein dyes as bromophenol blue and bromocresol purple. The optimum conditions of the reactions were studied and optimized. The absorbance of yellow products was measured at 412 nm for enoxacin-bromophenol blue and 410 nm for enoxacin-bromocresol purple. Linearity ranges were found to be 2.0-20.0 microg ml(-1) for enoxacin-bromophenol blue and 0.77-17.62 microg ml(-1) for enoxacin-bromocresol purple. The detection limits were found to be 0.084 microg ml(-1) and 0.193 microg ml(-1) for enoxacin-bromophenol blue and enoxacin-bromocresol purple, respectively. The composition of the ion pairs was found 1:1 by Jobs method. The developed methods were applied successfully for the determination of this drug in pharmaceutical preparation. The data obtained by developed methods were compared with the spectrophotometric method in literature. No differences were found statistically.

Determination of nifedipine in human plasma by square wave adsorptive stripping voltammetry

A simple, sensitive and selective square-wave adsorptive stripping voltammetric method has been developed and validated for the determination of nifedipine (NIF) in plasma. The assay was performed after single extraction of NIF from alkalinised plasma into organic phase. The adsorption behaviour of NIF on a hanging mercury drop electrode (HMDE) was explored by square-wave and cyclic voltammetry. The drug was accumulated at HMDE and a well-defined peak was obtained at -730 mV versus Ag/AgCl in borate buffer of pH 9.0 including 0.01 M KCl. The linear concentration range was 2.89 x 10(-9) M-3.61 x 10(-7) M (1.00-125.01 ng ml(-1)) when using 30 s accumulation time at -300 mV. Limit of detection and limit of quantification were 1.21 x 10(-9) M (0.42 ng ml(-1)) and 2.89 x 10(-9) M (1.00 ng ml(-1)) respectively. The intra-day relative standard deviation (RSD) ranged from 1.93 to 4.12% at three concentrations and the inter-day RSDs varied from 2.53 to 6.68%. The method was applied, to the plasma of pregnant women suffering from pregnancy induced hypertension, for the determination of NIF. The percentage recoveries varied from 96.26 to 99.49%. It has been shown that NIF could be determined in the presence of its main metabolite (dehydronifedipine) by the developed method.

Two derivative spectrophotometric determinations of indapamide in pharmaceutical dosage forms

Simple, fast and reliable derivative spectrophotometric methods were developed for determination of indapamide in bulk and pharmaceutical dosage forms. The solutions of standard and the sample were prepared in methanol. The quantitative determination of the drug was carried out using the first-derivative values measured at 252.8 nm (N=6) and the second-derivative values measured at 260.4 nm (N=9). Calibration graphs constructed at their wavelengths of determination were linear in the concentration range of indapamide using peak to zero 1.00-30.00 microg ml(-1) for first-derivative and 1.00-35.00 microg ml(-1) for second-derivative spectrophotometric method. The developed methods were successfully applied for the assay of pharmaceutical dosage forms which do not require any preliminary separation or treatment of the samples. The details of the statistical treatment of analytical data are also presented. The results obtained from two derivative spectrophotometry were compared with a spectrophotometric method reported in literature and no significant difference was found statistically.

Determination of Pantoprazole in Pharmaceutical Formulations and Human Plasma by Square‐Wave Voltammetry

Abstract A simple, sensitive, and selective square‐wave voltammetric method was developed for the determination of pantoprazole. The influence of the nature of the supporting electrolyte solution, pH, modulation amplitude, frequency, and scan increment was examined by square‐wave voltammetric method for pantoprazole. The best results were obtained in Britton‐Robinson buffer of pH 5.0. The peak currents were measured with hanging mercury drop electrode at −987 mV vs. Ag/AgCI. The calibration curve for pantoprazole was found as linear at a concentration range from 0.15 to 25.23 µg mL−1. The limit of detection and the limit of quantification of pantoprazole were 0.048 µg mL−1 and 0.15 µg mL−1, respectively. The validation parameters of the proposed method were evaluated. The method was applied to the pharmaceutical formulation and to both spiked plasma and the plasma of patients orally administered pantoprazole. A spectrophotometric method reported in the literature was utilized as a comparison method. There were no significant differences between the results obtained by two methods.

Application of Bromophenol Blue and Bromocresol Purple for the Extractive-Spectrophotometric Determination of Ofloxacin

Abstract Simple, rapid, and extractive spectrophotometric methods were developed for the determination of ofloxacin in bulk and pharmaceutical dosage form. These methods are based on the formation of yellow ion-pair complexes between the basic nitrogen of the drug and bromophenol blue and bromocresol purple as sulphonphthalein dyes in phthalate buffer pH 3.0 and pH 3.1, respectively. The formed complexes were extracted with chloroform and measured at 414 nm for ofloxacin–bromophenol blue and 408 nm for ofloxacin–bromocresol purple. The analytical parameters and their effects on the reported systems are investigated. The reactions were extremely rapid at room temperature and the absorbance values remains unchanged at 48 h for ofloxacin–bromophenol blue and 72 h for ofloxacin–bromocresol purple. Beers law was obeyed in the ranges 0.87–17.35 and 0.58–14.46 µg mL−1 for ofloxacin–bromophenol blue and ofloxacin-bromocresol purple, respectively. The composition of the ion pairs was found 1:1 by Jobs method. The proposed methods have been applied successfully for the analysis of the drug bulk form and its dosage form. The results obtained by the proposed methods were compared and statistical analysis showed no significant difference between the proposed methods. †This work was taken from the M.Sc. thesis of İ. Süslü.

Differential Pulse Adsorptive Stripping Voltammetric Determination of Zafirlukast in Pharmaceutical Formulations

Abstract Zafirlukast is a competitive and selective leukotriene receptor antagonist, which is indicated for the prophylaxis and treatment of mild to moderate persistent and chronic asthma. A new, simple, and sensitive adsorptive stripping voltammetric method was developed for the determination of zafirlukast in pharmaceutical formulations. The analysis was performed in pH 8.0 of borate buffer. At a well‐defined cathodic peak currents were measured with a hanging mercury drop electrode at −1232 mV with 20 s of accumulation time vs. Ag/AgCl reference electrode. The influence of several variables including supporting electrolyte, pH, accumulation potential, accumulation time, pulse amplitude, and scan rate on the adsorptive stripping response of zafirlukast were evaluated. The linear calibration range was 38.00–412.00 ng mL−1. The detection and quantification limits were 15.00 ng mL−1 and 38.00 ng mL−1, respectively. The method was validated by evaluating validation parameters and applied for the determination of zafirlukast in its pharmaceutical formulations. The results obtained from developed method were compared with a spectrophotometric method reported in the literature and no significant difference was found statistically.

Application of Micellar Electrokinetic Capillary Chromatography for the Determination of Nifedipine and Its Degradation Product in Pharmaceutical Preparations

Abstract A simple and rapid micellar electrokinetic capillary chromatographic (MEKC) method for the analysis of nifedipine (NIF) and its degradation product was developed and validated. The compounds were separated using a 100 mM borate buffer at pH 9.0 containing 15 mM sodium dodecyl sulphate (SDS) and 25% acetonitrile, applied voltage of 30 kV, at working temperature 30°C and fused silica capillary of 72 cm effective length. Hydrodynamic injection (50 mbar) was applied for 3 s. The detection wavelength was set at 236 nm. Nimodipine was used as internal standard (IS) to compensate for minor fluctuations of migration times. Under the optimum conditions NIF, nitroso analog of dehydronifedipine (NDNIF) (degradation product exposed to sunlight) and IS were well separated with in 9 min. The method was validated with respect to linearity range, limit of detection and quantitation, precision, accuracy, specificity, ruggedness, and robustness. The method exhibited low limit of detection as 0.5 µg mL−1, wide linearity range of 2–100 µg mL−1 and high efficiency 1 × 105 N/m for NIF. The method was applied to the tablet form of NIF containing pharmaceutical preparations. The data were compared with that of the differential pulse polarographic method mentioned in literature. No significant difference was found statistically.

Lower plasma pantoprazole level predicts Helicobacter pylori treatment failure in patients with type 2 diabetes mellitus.

We aimed to compare the plasma pantoprazole level (PPL) between patients with type 2 diabetes mellitus and non‐diabetic patients during Helicobacter pylori (H. pylori) eradication treatment and to explore the role of PPL in predicting the treatment success rates.

Electrochemical behaviour investigation and square-wave voltammetric determination of rivaroxaban in pharmaceutical dosage forms

Rivaroxaban, an oral oxazolidinone-based anticoagulant, is a potent, selective direct inhibitor of factor Xa, which is used in the prevention of venous thromboembolism in adult patients after total hip replacement or total knee-replacement surgery. Because there are no reports about the electrochemical behaviour of rivaroxaban and its analytical application, its electrochemical behaviour was investigated at a hanging mercury-drop electrode using square-wave and cyclic voltammetry. For this purpose, the square-wave voltammetric method in electrolytes of different pH and buffers was used. Rivaroxaban showed a reduction peak between pH ranges from 7 to 11. The optimum conditions were obtained using Britton–Robinson buffer at pH 8.0 and a frequency of 80 Hz, a scan increment of 5 mV and pulse amplitude of 25 mV. A well-defined peak current was observed at a hanging mercury-drop electrode of −1770 mV vs. Ag/AgCl reference electrode. The cyclic voltammogram of rivaroxaban exhibited a single peak at the same peak potential as the obtained square-wave voltammogram, and the reduction reaction was irreversible. This response was determined to be related to the electroactive part of the molecule of rivaroxaban. The developed method was validated according to the ICH guideline. Validation parameters, such as linearity, sensitivity, specificity, precision and accuracy, for the developed method were evaluated. The developed method was successfully used for the determination of rivaroxaban in tablets. The results obtained from tablets were compared with the high-performance liquid chromatographic method in the literature to assess active rivaroxaban content, and no statistically significant difference was determined.

Validated voltammetric determination of olmesartan medoxomil: Method development and electrochemical behaviors investigation

In this study, a sensitive, simple and rapid voltammetric method was developed and validated for the determination of olmesartan medoxomil in pharmaceutical formulations. The experimental and instrumental parameters affecting the peak current of olmesartan medoxomil were investigated and optimized. For this purpose, square-wave voltammetry at a hanging mercury drop electrode in electrolytes of different pH and buffers was tried. Olmesartan medoxomil showed a reduction peak between the pH range 5.0 to 8.0, and phosphate buffer at pH 6.5 was selected as the optimum electrolyte condition for analysis, since well-defined peaks were obtained. The following instrumental parameters were employed for analytical application: frequency 50 Hz, scan increment 5 mV and pulse amplitude 25 mV. In these optimum conditions highly sensitive measurements of olmesartan medoxomil were achieved. Validation parameters such as linearity, sensitivity, selectivity, precision, accuracy, ruggedness and robustness for the developed method were evaluated. The square-wave voltammetric peak currents increased linearly with the corresponding olmesartan medoxomil concentration in the range of 1.00–14.56 μg mL−1 (r = 0.9983) with a detection limit of 0.50 μg mL−1 and limit of quantitation of 1.00 μg mL−1. The developed method was successfully used for determination of olmesartan medoxomil in tablets and the data were compared with ones obtained from the capillary electrophoresis method given in the literature. Possible interferences by several substances usually present in the pharmaceutical formulations have been also evaluated. The percentage recoveries varied from 98.20 to 100.26%. It has been shown that olmesartan medoxomil could be directly determined in the presence of excipients from tablets by the developed method without the necessity for prior extraction or interaction with any reagent during the analysis.