Determination of Sulphasalazine and Its Related Compounds by Simple, Smart, Validated, Green Spectrophotometric Methods.

BACKGROUND: Sulphasalazine (SZ) is a prodrug. Its active metabolite (mesalazine, MZ), which is also available in pharmaceutical formulations, and the major active metabolite of MZ (N-acetyl-5-aminosalicylic acid, AS) are commonly used for the treatment of inflammatory bowel diseases. OBJECTIVE: Two accurate, precise, sensitive, and specific spectrophotometric methods were developed and validated for determination of the studied components. METHODS: The first method is a 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 amplitude values. The second method is a mean centering of ratio spectra spectrophotometric method. RESULTS: The developed methods were linear over the concentration ranges of 2-35, 2-30 and 1-25 µg/mL for SZ, MZ and AS, respectively. CONCLUSION: The developed methods were validated according to International Conference on Harmonization guidelines. They were successfully applied for determination of studied analytes. A greenness assessment was undertaken 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 eco-friendly and their greenness profiles were evaluated using green solvents to keep the environment clean.

Evaluation of vinburnine in pharmaceuticals by smart spectrophotometric methods; full stability study.

Vinburnine (VNB) is a vinca alkaloid used as a vasodilator to enhance cerebral circulatory insufficiency. It is a cyclic amide containing drug which is expected to be sensitive to hydrolytic degradation. The degradation profile of VNB was studied in this work following ICH recommendations for stability study. The drug was sensitive only to degradation with NaOH with the formation of the carboxylic acid derivative, identified by IR and 1H NMR analyses as 2-((1S,12bS)-1-ethyl-1,2,3,4,6,7,12,12b-octahydroindolo[2,3-a] quinolizin-1-yl) acetic acid, (DEG). In this study five simple, smart and univariate stability indicating spectrophotometric methods were developed and validated for simultaneous determination of VNB and DEG for the first time. The developed methods include; Dual Wavelength Method (DWM), Dual Wavelength Resolution Method (DWRM), Factorized Absorbance Difference Method (FADM), Advanced Absorbance Subtraction Method (AASM), and Derivative Amplitude Factor Method (DAFM). These methods were capable of determination of VNB and DEG over the ranges of 1-30 and 3-50 µg/mL, respectively. The proposed methods were simple, smart, specific, and could be applied for analyzing synthetic mixtures of VNB and DEG and were successfully applied for determination of the drug in commercially available capsules. The obtained results of these methods were statistically compared with the reported HPLC one using student's-t and F- tests, where no significant difference was observed. Validation of the developed methods was applied according to ICH recommendations and all the results were within the acceptable limits.

Ecofriendly chromatographic methods for determination of co-prescribed drugs, olanzapine and metformin, in rat plasma.

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.

Chromatographic determination of sulfasalazine and its active metabolites: greenness assessment and application to spiked human plasma.

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.

Validated Chromatographic Methods for the Analysis of Two Binary Mixtures Containing Pyridoxine Hydrochloride.

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.