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Accurate and precise TLC-densitometric and HPLC-diode-array detector (DAD) methods have been developed and validated to resolve two binary mixtures containing pyridoxine hydrochloride (PYH) with either cyclizine hydrochloride (CYH) or meclizine hydrochloride (MEH). In the developed TLC-densitometric method, chromatographic separation of the three studied drugs was carried out on silica gel 60 F254 plates using a developing system containing methylene chloride + acetone + methanol (7 + 1 + 0.5, v/v/v) scanning separated bands at 220 nm. Beer-Lambert law was obeyed in the ranges of 0.2-5, 0.2-4, and 0.2-4 µg/band for PYH, CYH, and MEH, respectively. On the other hand, the developed HPLC-DAD method depended on chromatographic separation on a Zorbax Eclipse C18 column using methanol-KH2PO4 (0.05 M; 90 + 10, v/v; pH 5, with H3PO4 and KOH) as the mobile phase, a flow rate of 1 mL/min, and UV scanning at 220 nm. A linear relationship was obtained between the integrated peak area and the concentration in the ranges of 10-50, 10-50, and 7-50 µg/mL for PYH, CYH, and MEH, respectively. The proposed methods were successfully applied for the determination of the cited drugs in their pharmaceutical formulations. Statistical comparison with the reported methods using Student's t- and F-tests found there were no significant differences between the proposed and reported methods for accuracy and precision.

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Background Sulphasalazine as a prodrug, its active metabolite (mesalazine) which also is available in pharmaceutical formulations, and the major active metabolite of mesalazine; N-acetyl-5-aminosalicylic aid are commonly used for treatment of inflammatory bowel diseases. Objectives Two accurate, precise, sensitive and specific spectrophotometric methods were developed and validated for determination of the studied components. Methods The first method was modified ratio difference spectrophotometric method. In this method, SZ was determined by measuring the peak area from 410–500 nm, while MZ and AS were determined by measuring the difference of the selected amplitudes values. The second one was mean centering of ratio spectra spectrophotometric method. Results The developed method were linear over the concentration range of (2-35), (2-30) and (1-25) µg/mL for sulphasalazine, mesalazine, and N-acetyl-5-aminosalicylic acid, respectively. Conclusion The developed methods were validated according to ICH guidelines. They were successfully applied for determination of studied analytes. Greenness assessment was evaluated using three different tools. Highlights Spectrophotometric methods were developed for determination of SZ and its related compounds for the first time. They were designated to be green and ecofriendly ones and their greenness profiles were evaluated using green solvents to keep the environment clean.

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Green TLC‐densitometric and RP‐HPLC methods were developed and validated for the determination of the active prodrug sulfasalazine (SZ), its active metabolite mesalazine (MZ) and the major active metabolite of mesalazine, N‐acetyl‐5‐aminosalicylic acid (AS). In the developed TLC‐densitometric method, chromatographic separation was carried out on TLC silica gel plates 60 F254 using a developing system consisting of ethyl acetate–methanol–ammonia solution 33% (8:2.5:0.3, by volume) and then scanning the separated bands at 215 nm using hydrochlorothiazide as an internal standard with linearity ranges of 0.4–3, 0.4–2.4 and 0.3–2 for SZ, MZ and AS, respectively. The developed RP‐HPLC method depended on chromatographic separation using a C18 column with a solvent mixture of methanol–aqueous acetic acid solution (pH 5) as a mobile phase with gradient elution mode and UV scanning at 243 nm using pyrazinamide as internal standard with linearity ranges of 5–50, 5–40, and 3–20 for SZ, MZ and AS, respectively. US Food and Drug Administration guidelines were followed during validation of the methods. The greenness of the developed methods was estimated using the greenness profile and the Eco‐Scale approach. Both methods passed the four quadrants of the greenness profile and had Eco‐Scale score ˃75, thus they were considered to be green according to these approaches.

Background: Olanzapine (OLZ) is one of most recommended drugs for the treatment of schizophrenia while metformin (MET) is the most commonly used hypoglycemic agent. Aim: Development and validation of two green, sensitive and accurate chromatographic methods for the simultaneous determination of OLZ along with the co-prescribed, MET. Materials & methods: TLC-densitometric method with a developing system consisting of methylene chloride:methanol:ethyl acetate:triethylamine (4:4:5:0.1, by volume) and a reversed-phase (RP)-HPLC method where the chromatographic separation was performed using ethanol:water mixture (50: 50, v/v) as a mobile phase. Results: TLC-densitometric method had linearity over concentration ranges of 160–4000 ng/band for OLZ and 150–4500 ng/band for MET, while RP-HPLC method was linear and validated over concentration range of 300–20000 ng/ml for OLZ and MET. Conclusion: Pharmacokinetic study was successfully performed and suggested the possibility of co-administration of MET with OLZ and their further formulation in one pharmaceutical preparation to enhance patient’s compliance.

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