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Bambuterol HCl (BMT) (bronchodilator) was subjected to stress alkaline hydrolysis. BMT alkaline degradation product (BMT-DP) was prepared, isolated and verified chemically using Fourier transform infrared spectroscopy (FTIR), Proton nuclear magnetic resonance (1H-NMR) as well as mass spectrometry. Na benzoate (BNZ) is commonly co-formulated in oral pharmaceutical preparations as a preservative. Subsequently, a simple, selective and valid stability indicating reversed phase high performance liquid chromatography (RP-HPLC) method was developed for simultaneous estimation of BMT and BNZ in the presence of BMT-DP. Chromatographic separation was achieved using an isocratic mobile phase consisting of a mixture of (20 mM)-KH2PO4(containing 0.2% Triethylamine (TEA)v/v), pH adjusted to 3 with orthophosphoric acid]: acetonitrile (70:30,v/v) with a flow rate 1 mL/min at ambient temperature on a Eurospher II C18 (250 mm × 4.6 mm, 5 μm) column. Analysis was carried out with ultraviolet detection at 215 nm for BMT and BMT-DP, and 225 nm for BNZ. Linearity, accuracy and precision were found to be acceptable over a concentration range of (1-120 μg/mL) and (2-240 μg/mL) for BMT and BNZ, respectively. Limits of detection (LODs) for BMT and BNZ were 0.056 and 0.125 μg/mL, whereas limits of quantitation (LOQs) were 0.169 and 0.378 g/mL, respectively. Moreover, the kinetics of alkaline degradation of BMT was investigated. Arrhenius plot was constructed and the apparent pseudo first-order rate constant, half-life time, shelf-life time, and the activation energy of the degradation process could be calculated. [ABSTRACT FROM AUTHOR]

Aspirin (ASP) (analgesic; anti-inflammatory; anti-platelet), clopidogrel bisulphate (CLP) (anti-platelet) and atorvastatin calcium (ATV) (anti-hyperlipidemia) are co-formulated in several pharmaceutical formulations. Salicylic acid (SAL), clopidogrel carboxylic acid metabolite related impurity A (CLP-RA) and clopidogrel inactiveR-enantiomer related impurity C (CLP-RC) are considered to be the main synthesis impurities and degradation products of ASP and clopidogrel. On the other hand, high efficiency and less elution are the basic requirements of high-speed chromatographic separation. So a comparative study of two simple, precise, and accurate reversed-phase HPLC-UV and UPLC-DAD methods were developed and validated for simultaneous estimation of ASP, CLP and ATV in bulk and capsules and in the presence of SAL, CLP-RA and CLP-RC. An Agilent Eclipse plus C18 (250 mm × 4.6 mm, 5 μm) for HPLC method and an Agilent Eclipse plus C18 (100 × 2.1 mm, 1.7 μm) for UPLC method were used. A gradient mobile phase for HPLC method and an isocratic mobile phase for UPLC, were used. Detection was performed for both methods at 220 nm for ASP, CLP, SAL, CLP-RA and CLP-RC, and at 240 nm for ATV. The propsed UPLC-DAD method had advantages, of being economic on the large scale with relatively much satisfactory results for sensitivity and specificity. [ABSTRACT FROM AUTHOR]

Tioconazole (TCN) (anti fungal) is commonly co-formulated with tinidazole (TND) (antiprotozoal), hydrocortisone acetate (HYD) (anti infalmmatory) and benzyl alcohol (BZL) (preservative) in different pharmaceutical preparations. Tioconazole has three related impurities namely; tioconazole related impurities A, B and C (TCN-RA), (TCN-RB) and (TCN-RC), respectively. As the main purpose of a test for related substances is to control degradation impurities and to limit impurities arising during the synthesis of active ingredients and on the other hand, high efficiency and less elution are the basic requirements of high-speed chromatographic separation. So, two simple, precise, and accurate reversed-phase HPLC-UV and UPLC-DAD methods have been developed and compared for simultaneous estimation of TND, BZL, HYD and TCN in bulk and pharmaceutical formulations in the presence of TCN related impurities. A Eurospher C18 (250 mm × 4.6 mm, 5 μm) for HPLC method and an Eclipse plus C18 (100 × 2.1 mm, 1.7 μm) for UPLC method were used. An isocratic mobile phase consisted of 20 mM anhydrous KH2PO4(containing 0.2% TEAv/v), pH adjusted to 6 with orthophosphoric acid: acetonitrile, (25:75,v/v) for HPLC method and a gradient mobile phase of 20 mM anhydrous KH2PO4(containing 0.2% TEAv/v), pH adjusted to 6 with orthophosphoric acid and acetonitrile mixed in different proportions for UPLC method, were prepared. Flow rate was set at 1.0 mL min-1and 0.3 mL min-1for HPLC and UPLC methods, respectively and the detection was performed for both methods at 295 nm, 210 nm, 245 nm and 225 nm for TND, BZL, HYD and TCN and its related impurities, respectively. The propsed UPLC-DAD method had advantages, of being economic on the large scale with relatively much satisfactory results for linearity, sensitivity and specificity. The two proposed methods are applicable for the purity assessment of TCN in bulk, vaginal tablets and creams. [ABSTRACT FROM PUBLISHER]

Purpose: A new sensitive sensor was fabricated for the determination of ivabradine hydrochloride (IH) based on modification with multiwalled carbon nanotubes using sodium dodecyl sulfate as micellar medium to increase the sensitivity. Methods: The electrochemical behavior of IH was studied in Britton-Robinson buffer (pH: 2.0-11.0) using cyclic and differential pulse voltammetry. Results: The voltammetric response was linear over the range of 3.984 x 10-6-3.475 x 10-5 mol L-1. The limits of detection and quantification were found to be 5.160 x 10-7 and 1.720 x 10-6 mol L-1, respectively. Conclusion: This method is suitable for determination of IH in tablets and plasma. [ABSTRACT FROM AUTHOR]

Aspirin (ASP) and cilostazol (CST) are used as a combination in pharmaceutical formulations for treatment of strokes. Salicylic acid (SAL) is considered to be one of the main synthesis impurities and a degradation product of ASP. On the other hand, the main related impurities of CST are CST related A, B, and C (CST-RA, CST-RB, and CST-RC), respectively. Furthermore, as high efficiency and less elution are the basic requirements of high-speed chromatographic separation, so, a comparative study of two simple, precise, and accurate reversed-phase HPLC and UPLC methods was developed and validated for simultaneous estimation of ASP and CST in bulk and capsules in the presence of SAL, CST-RA, CST-RB, and CST-RC. A Eurospher II C18 (250 × 4.6 mm2, 5 µm) for HPLC method and an Agilent Zorbax Eclipse Plus C18 (50 × 2.1 mm2, 1.8 µm) for UPLC method were used. A gradient mobile phase of 20 mM anhydrous KH2PO4buffer solution (containing 0.2% triethylamine (TEA), v/v) with pH adjusted to 2.9 using orthophosphoric acid (solution A) and acetonitrile (solution B) mixed in different proportions for HPLC and UPLC methods was prepared. Flow rate was set to 1.0 and 0.3 mL min−1for HPLC and UPLC methods, respectively, and the detection was performed for both methods at 210 nm. It worth noting that the proposed UPLC-DAD assay exhibited relatively much more precision, sensitivity, specificity, and economic and chromatographic separation superiority than proposed HPLC-UV assay. Both developed methods were compared with reference methods to prove its applicability and are suitable for purity assessment of ASP and CST in bulk and capsules. [ABSTRACT FROM PUBLISHER]