Derivatization-free sustainable spectrofluorimetric estimation of antihistamine drug mizolastine in pharmaceutical and biological matrices

Mizolastine is an antihistamine drug that is commonly used for treatment of chronic urticaria and allergic rhinitis. In this study, a facile, rapid, and sustainable fluorimetric method was established for the estimation of mizolastine in pharmaceutical and biological matrices for the first time. The approach methodology relied on the direct assessment of mizolastine's intrinsic fluorescence at 313 nm after excitation at 272 nm. This intrinsic fluorescence, stemming from the benzimidazole fluorophore moiety in mizolastine structure, serves as a distinctive marker for its precise quantification in the spiked human plasma and pharmaceutical formulations with high %recovery. The method exhibits reasonable sensitivity with lower limits of detection and quantification of 5.4 and 16.6 ng mL⁻¹, respectively, across a concentration range of 25.0–2000.0 and 50–1000 ng mL⁻¹ for the standard mizolastine analysis and mizolastine assay in the plasma sample, respectively. Moreover, the established method was applied to assess tablet content uniformity and mizolastine assay in plasma samples with high recoveries (98.50%–100.20%). Such applications underscore the method's potential applicability within quality control laboratories, preventing the need for sample preparation or laborious extraction steps. Finally, the method's sustainability and practicality were confirmed by applying different greenness and whiteness metrics, yielding excellent results.