Green fluorescence-based approaches for quantitative estimation of the antihistaminic drug meclizine; application to spiked human plasma

Meclizine hydrochloride (MCZ) is a sedating antihistamine having anti-muscarinic properties. It is mainly recognized for its antiemetic properties. Two eco-friendly, facile, and sensitive spectrofluorimetric methods were established for the assay of MCZ in raw material and different pharmaceutical dosage forms. Method I is based on the measurement of MCZ native fluorescence in deionized water at 295 nm after excitation at 265 nm. Method II involves ion-pair complex formation between MCZ and erythrosine B (EB) in aqueous acidic solution of pH 3.0, causing quantitative quenching of the EB native fluorescence. The difference in fluorescence intensity was recorded at λ_ex527/λ_em554 nm. The proposed methods were rectilinear over the concentration ranges of 100–1000 ng/mL for method I and 25–250 ng/mL for method II with excellent correlation coefficient (r = 0.9999) for both methods. Both methods were further applied for determining MCZ in its different dosage forms and spiked human plasma. Method I and method II were successfully applied to spiked human plasma with good recoveries ranging from 95.07 to 102.8 % and 94.01–104.43 %, respectively. Validation of the proposed approaches was performed following the ICH Q2(R1) guidelines. No significant difference was obtained between the proposed methods and the comparison method. The proposed methods’ greenness was affirmed using three recent assessment tools, the Eco-Scale methodology, the Green Analytical Procedure Index (GAPI) metric, and the Analytical GREEnness metric approach. Both developed methods were proven to be eco-friendly, green, and environmentally benign.