Simultaneous analysis of several antihypertensive drugs in different combinations: Application for determination of drug degradation products and process impurities

Broad-spectrum antibody against thiazides and degraded salamide and immunoassay establishment for simultaneous detection

The illegal additive thiazides and degraded salamide in food supplements poses significant health risks and regulatory challenges. However, the structural differences between thiazides and salamide complicate the hapten design for immunoassay detection. In this study, we first outlined the common skeleton of thiazides and their shared epitopes with salamide through molecular overlap and atomic charge distribution analysis. Several haptens were rationally designed based on the private epitope of salamide and the shared epitopes with thiazides, assisted by computer-aided chemical analysis. Subsequently, the resultant monoclonal antibody exhibited broad specificity for thiazides (IC50 value = 21.43-405.40 ng/mL) and salamide (IC50 value = 0.76 ng/mL). The immunoassay affinities of 5 of these thiazides are reported for the first time. Further elucidation of the intrinsic recognition mechanism was achieved through homology modeling and molecular docking, clarifying the antibody's diverse recognition spectrum. Finally, we established a rapid, reliable colloidal gold-based immunochromatography strip for simultaneous detecting total thiazides and degraded salamide in food supplements and surface water sample for the first time. The cut-off value was as low as 7.5 ng/mL, which was 32 times more sensitive than that of established immunoassays for thiazides.

An eco-friendly separation-based framework for quantitative determination and purity testing of an antihypertensive ternary pharmaceutical formulation

Designing new, verified methodologies with a focus on sustainability, analytical efficiency, simplicity, and the environment has become a major priority for pharmaceutical quality control units. In this way, sustainable and selective separation-based methodologies were designed and validated for the concurrent estimation of amiloride hydrochloride (AML), hydrochlorothiazide (HCT) and timolol maleate (TIM) in their fixed dose formulation (Moducren^® Tablets) along with hydrochlorothiazide potential impurities, salamide (DSA) and chlorothiazide (CT). The first method is a high performance thin layer chromatographic method (HPTLC-densitometry). The first developed method employed silica gel HPTLC F₂₅₄ plates as stationary phase using a chromatographic developing system composed of ethyl acetate-ethanol-water-ammonia (8.5:1:0.5:0.3, by volume). The separated drug bands were densito-metrically measured at 220.0 nm for AML, HCT, DSA and CT and at 295.0 nm for TIM. The linearity was assessed over a wide concentration range, 0.5-10 µg/band, 1.0-16.0 µg/band and 1.0-14 µg/band for AML, HCT and TIM, in order and 0.05-1.0 µg/band for each of DSA and CT. The second method is capillary zone electrophoresis (CZE). The electrophoretic separation was achieved using background electrolyte (BGE), borate buffer 40.0 mM with pH 9.0 ± 0.2, at applied voltage of + 15 kV with on-column diode array detection at 200.0 nm. The method linearity was reached over the concentration range of 20.0-160.0 µg/mL, 10.0-200.0 µg/mL, 10.0-120.0 µg/mL for AML, HCT and TIM, respectively and 10.0-100.0 µg/mL for DSA. The suggested methods were optimized to achieve best performance and validated agreeing with the ICH guidelines. Assessment of methods' sustainability and greenness was performed using different greenness assessment tools.