Validation of a green and sensitive spectrofluorimetric method for determination of Bilastine and its application to pharmaceutical preparations, content uniformity test, and spiked human plasma

Bilastine (BIL) is a new second-generation antihistaminic drug used for the management of urticaria and rhino-conjunctivitis symptoms. Herein, a spectrofluorimetric method for determining BIL is described. The method is very sensitive, simple, quick, and green. The suggested method depended on the measurement of the original fluorescence of BIL in 1.0 M sulfuric acid at an emission wavelength of 385 nm after an excitation at 272 nm. The method was evaluated by the International Council on Harmonization (ICH) requirements. The relationship between BIL concentrations and the fluorescence intensities was linear in a range of 10.0-500.0 ng mL^{- 1}, and the correlation coefficient was 0.9999. The detection limit was 2.9 ng mL^{- 1} and the quantitation limit was 8.8 ng mL^{- 1}. The suitable sensitivity and selectivity of the suggested method enabled its application successfully in analyzing BIL in pharmaceutical tablets without any interfering effect from their excipients and in spiked human plasma with appropriate recoveries from 95.72 to 97.24%. Additionally, the suggested method was utilized for content uniformity testing.