Sensitive, simple and rapid spectrofluorimetric method was developed for simultaneous determination of bisoprolol fumarate (BIS) and rosuvastatin calcium (ROS) in novel formulated tablets and in human spiked plasma depending on measuring their native fluorescence. The fluorescence intensity of BIS and ROS were measured in methanol at emission wavelength of 297 and 485 nm upon excitation at 227 and 242 nm, respectively. The emission spectrum of each drug reveals zero value at the emission wavelength of the other drug, thus allowing their simultaneous determination without any interference and without using any tedious derivatization steps. Excellent linearity was obtained over the range of 10-500 and 20-1000 ng/mL for BIS and ROS, respectively. The developed method was evaluated by applying to laboratory prepared mixtures and pharmaceutical formulation. The high sensitivity of the method was the motivation to its application for analysis of the cited drugs in spiked human plasma. Likewise, analytical and bioanalytical method validation was carried out following International Conference on Harmonisation guidelines and also statistical analysis with the reported methods was carried out and no significant difference was found. The developed method is the first developed spectrofluorimetric method for simultaneous determination of the newly formulated drugs.

Two accurate, selective, and precise chromatographic methods, namely TLC-densitometric and reversed-phase (RP)-HPLC, were developed and validated for the simultaneous determination of nifuroxazide (NIF) and its four synthesized impurities, which are also reported to be its related substances in the range of 10-100 μg/band and 10-100 μg/mL for NIF in the TLC and RP-HPLC methods, respectively. The developed TLC-densitometric method depended on the separation and quantitation of the studied components on silica gel 60 F254 TLC plates. Ethyl acetate-acetone-methanol-ammonia (85 + 25 + 5 + 0.5, v/v/v/v) was used as the developing system, and the separated bands were UV-scanned at 230 nm. On the other hand, the developed RP-HPLC method depended on chromatographic separation using a C8 column at 25°C and an aqueous solution of 0.1% sodium lauryl sulfate-acetonitrile as the mobile phase delivered according to the gradient elution program. Factors affecting the developed methods were studied and optimized. Also, method validation was carried out according to International Conference on Harmonization guidelines. The proposed methods were successfully applied for the determination of the studied drug in its bulk powder and in its pharmaceutical formulation. The developed methods showed no significant difference when compared with the reported RP-HPLC one. Their advantage is being the first stability-indicating methods for NIF and its genotoxic impurities.

A simple, specific, and precise RP-HPLC method was developed and validated for simultaneous determination of Bisoprolol fumarate (BIS) and Rosuvastatin calcium (ROS) in new formulated tablets. The developed RP-HPLC method depended on chromatographic separation using C18 column (150×4.6 mm, 0.5 μm) with mobile phase consisted of acetonitrile and 0.05 aqueous solution of orthophosphoric acid at the ratio of 65:35 % (v:v) with a flow rate of 1 mL/min and UV detection was carried out at 230 nm. Factors affecting the developed methods were studied and optimized and the retention times for BIS and ROS were found to be 2.758 and 4.974 min, respectively. Linearity of the proposed method was observed over a concentration range 0.2-50 μg/mL for each of BIS (r = 0.9999) and ROS (r = 0.9998). The proposed method was successfully applied for the determination of the studied drugs in their bulk powder, laboratory prepared mixtures and in the formulated tablets. The developed method is the first chromatographic method for determination of those drugs and showed no significant difference when compared with the reported methods.

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Two accurate, selective and precise chromatographic methods, namely thin-layer chromatography (TLC)-densitometric method and reversed phase high-performance liquid chromatography (RP-HPLC) method, were developed and validated for the simultaneous determination of tolfenamic acid (TOL) and its two major impurities, 2-chlorobenzoic acid (CBA) and 3-chloro-2-methylaniline (CMA), which are also reported to be its related substances. The developed TLC-densitometric method depended on separation and quantitation of the studied drugs on silica gel 60F254 TLC plates. Hexane:chloroform:acetone:acetic acid (75:25:20:0.1, v/v/v/v) was used as a developing system and the separated bands were UV-scanned at 240 nm. Linear relationships were obtained in the range of 10-100 µg band(-1) for the drug and in the range of 0.1-1 µg band(-1) for the studied impurities. The developed RP-HPLC depended on chromatographic separation of the studied drugs on a C18 column using 0.05 M KH2PO4 buffer (pH 3):acetonitrile (45:55, v/v) as a mobile phase delivered at constant flow rate of 1 mL min(-1) with UV detection at 230 nm. Calibration curves for TOL and the two impurities were constructed over the concentration ranges of 10-100 µg mL(-1) for TOL and 0.01-0.1 µg mL(-1) for both CBA and CMA. Factors affecting the developed methods have been studied and optimized. Further, methods validation has been carried out according to International Conference on Harmonization guidelines. The proposed methods were successfully applied for determination of the studied drug in its bulk powder and in pharmaceutical formulation. The methods showed no significant difference when compared with the reported RP-HPLC one. The developed methods have advantages of being more sensitive and specific than the published methods.