Careful choice of ion-sensing components and substrates is the primary focus when developing ion-selective electrodes to achieve maximum sensitivity, selectivity, stability and accuracy. This study aims to develop and optimize two miniaturized screen-printed solid-contact ion-selective electrodes to quantify Azelastine HCl (AZE) in various pharmaceutical preparations and complex spiked biological samples. The electrodes' optimization involved doping ion-sensing membranes with the most selective ionophore for the studied drug, followed by electro-polymerization of polyaniline (PANI) conducting polymer at screen-printed electrode. Two screen-printed electrodes were developed for AZE determination, and their electrochemical performance was evaluated following IUPAC recommendations. The optimal calix[4]arene-doped PANI-based screen-printed electrode reached a detection limit of 2.50 × 10[-6] M for AZE with a dynamic response of about 3 s. It successfully quantified AZE in its pure form, pharmaceutical dosage forms, spiked aqueous humor and plasma, which demonstrates potential applicability. Its selectivity was assessed in the presence of the induced degradation products of AZE, interfering ions, and the co-formulated drug, fluticasone propionate. A comparison regarding greenness between the developed and two reported methods was established by means of Modified Green Analytical Procedure Index (Mo-GAPI) and Analytical Greenness (AGREE) assessment tools. Sustainability profile was established using NQS index, showing alignment of the study with the UN-17 SDGs.

A green RP-HPLC approach coupled with spectrofluorometric detection was established for the simultaneous estimation of the co-administered drugs Azelastine (AZL) and Losartan (LOS) in spiked human plasma samples. Preliminary trials were carried out for determination of the Critical Method Parameters (CMPs) and Critical Quality Attributes (CQAs). Design of Experiment (DOE) was developed relying on the use of Central Composite Design (CCD) for the optimization of conditions to establish a simple, rapid, cost-effective and environmentally benign approach. The chromatographic separation was based on using a mobile phase composed of methanol: acetonitrile: 0.02M phosphate buffer of pH 3.25 with 0.05% tri-ethylamine (60: 1.5: 38.5, v/v/v) at a flow rate of 1.2 mL/min and injection volume of 10µL. The fluorescence detection was carried out at 245 nm/400 nm and 290 nm/360 nm for estimation of LOS and AZL, respectively. The retention times of AZL and LOS were 8.9 ± 0.2 min and 13.4 ± 0.1 min, respectively. The developed method was validated according to ICH Guidelines with linear relationship in concentration ranges of 0.10–50.0µg/mL for AZL and 0.30–40.0µg/mL for LOS, while in spiked plasma samples the concentration ranges were 0.025–0.07µg/mL for AZL and 0.025–0.10 µg/mL for LOS. The developed approach was successfully applied for the quantitation of both drugs in spiked human plasma samples. Complex MoGAPI and AGREE methodologies were used for greenness assessment.