Degradation kinetics of Bilastine determined by RP-HPLC method and identification of its degradation product in oxidative condition

Oxidative degradation of Bilastine has been investigated using hydrogen peroxide agent. An RP-HPLC assay method is developed and validated for quantitative determination of Bilastine in tablets. The chromatography is performed using Waters Symmetry C18 (250 mm length × 4.6 mm ID with 5 µm particle size) column, diode array detector (Waters 996) operating at 275 nm. Isocratic elution with mobile phase consisted of a mixture of acetonitrile and phosphate buffer (10 mM Na2HPO4 adjusted to pH with 5.5 with H3PO4) in the proportion 30:70 (v/v). The mobile phase is filtered and degassed in ultrasonic bath prior to use. Flow rate is fixed to 1.0 mL.min−1. LC–ESI–MS/TOF, 1H, and 13C NMR are used to characterize the degradation product resulting from oxidative stress conditions. Degradation kinetic of Bilastine oxidation was established and activation energy calculated. The developed HPLC method was validated after calculation of the current parameters (specificity, linearity, accuracy, precision, robustness, and stability). The proposed method can be used for routine determination of Bilastine in tablets.