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Identification and synthesis of potential impurities of bilastine drug substance

T. Purendar Reddy, Nageshwar Dussa, Srinivas Mamidi, Mahesh Panasa, Ramadas Chavakula, and M. Padma

Chemical Research Department, APL Research Centre-II, Aurobindo Pharma Ltd, Telangana State, Kandi Mandal, Sangareddy District, India



Received: 5 December 2021  Accepted: 1 March 2022


Bilastine is a new, well-tolerated, nonsedating H1 receptor antihistamine. Herein, we describe the synthesis of four new potential impurities of bilastine, namely 2-[4-(2-(4-(1-(2-methoxyethyl)benzimidazole-2-yl) piperidine-1-yl)ethyl) phenyl]-2-methylpropanoic acid (2) (methoxyethyl bilastine), 2-[4-(2-(4-(1-(2-(2-ethoxyethoxy)ethyl)benzimidazole-2-yl) piperidine-1-yl)ethyl)phenyl]-2-methyl propanoic acid (3) ((2-ethoxyethoxy)ethyl bilastine), 2-amino-2-methylpropyl 2-[4-(2-(4-(1-(2-ethoxyethyl)benzimidazole-2-yl) piperidine-1-yl)ethyl)phenyl]-2-methyl propanoate (4) (2-amino-2-methylpropyl ester of bilastine or bilastine open-ring ester) and 2-[4-(2-(4-(1-(2-ethoxyethyl)benzimidazole-2-yl] piperidine-1-yl) ethyl) phenyl]-N-(1-hydroxy-2-methylpropan-2-yl)-2-methylpropanamide (5) [N-(1-hydroxy-2-methyl-2-propanyl)amide of bilastine or bilastine open-ring amide]. Each (2, 3, 4 and 5) is an observed process-related impurity with a possible significant impact on the quality of the drug product. This work is useful for generic pharmaceutical industry for making impurity reference standards. Pharmacopeia is not available for bilastine; hence, the control of these impurities in the API below the threshold level is essential as per International Conference on Harmonization (ICH) recommendations.

Keywords: Bilastine; Antihistamine; Methoxyethyl bilastine; (2-ethoxyethoxy)ethyl bilastine; 2-amino-2-methylpropyl ester of bilastine or bilastine open-ring ester; N-(1-hydroxy-2-methyl-2-propanyl)amide of bilastine or bilastine open-ring amide

Full paper is available at

DOI: 10.1007/s11696-022-02157-5


Chemical Papers 76 (7) 4137–4145 (2022)

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