The present study aims to develop and validate a simple, precise, accurate, stability indicating and isocratic reversephase high-performance liquid chromatography (RP-HPLC) method for estimating Bilastine in bulk and synthetic mixture. Bilastine from its degradation products were well separated and estimated on Discovery C8 column (250 mm x 4.6 mm, 5μm) using methanol: 0.1% ortho-phosphoric acid (55:45 %v/v) as a mobile phase and detection was performed at 276 nm by PDA detector. The degradation of Bilastine was studied under different ICH recommended stress conditions. The developed stability-indicating method was validated for system suitability, linearity, accuracy, precision, robustness, detection limit and quantitation as per ICH guidelines. The method was linear over 25-150 μg/ml. Mathematically computed Limit of Detection and Limit of Quantitation were found to be 0.19μg/ml and 0.57μg/ml, respectively. It was discovered that Bilastine degrades under acid and oxidation conditions. By using LC-MS/MS analysis, the structure of Bilastine breakdown products created amid acidic and oxidative settings was elucidated. A complete fragmentation pathway of Bilastine was established to elucidate the degradation products' structures using LC–MS/MS. The elemental concentrations of oxidation products and their fragmentation products were studied using the acquired mass values. The overall data was utilized to describe the degradation of products and their fragmentation process. The developed method can be used for routine analysis of Bilastine in dosage form as it can estimate of Bilastine in presence of excipients and degradation products.

Condensation of o-phenylene-diamine with formic acid is used in the synthesis of commercially available benzimidazole. N-ribosyldimethyl benzimidazole is the most common benzimidazole compound found in nature, and it functions as an axial ligand for cobalt in vitamin B12. The benzimidazole and its derivatives are important therapeutic agents, such as antiulcer and anthelmintic drugs. Benzimidazole compounds also possess antimicrobial, antiviral, anticancer, anti-inflammatory, analgesic, and other pharmacological properties. The chemistry and pharmacological actions of substituted benzimidazoles are summarised in this article.