32 Page 32-36 © MAT Journals 2019. All Rights Reserved Research & Review: Drugs and Drugs Development Volume 1 Issue 1 Development of a highly sensitive method for quantitative estimation of Hexamine impurity in Febuxostat drug substances using LC-MS Dr. Amit Gosar 1 , Tabrez Shaikh 2 *, Amit Joglekar 3 1 Chief Scientist, Indoco Remedies Limited, Analytical Research & Development Department, Navi mumbai, Maharashtra, India 2,3 Principal Scientist, Indoco Remedies Limited, Analytical Research & Development Department, Navi mumbai, Maharashtra, India Email: tabrezs@indoco.com DOI: http://doi.org/10.5281/zenodo.2588123 Abstract A selective and highly sensitive liquid chromatography-mass spectrometry (LC-MS) method was developed for the determination of Hexamine impurity in Febuxostat drug substance. The method was validated as per International Council for Harmonisation (ICH) guidelines, for which limit of detection and limit of quantitation obtained were 0.75 ppm and 2.26 ppm respectively. The regression coefficient found for the linearity study was 0.9984. The % recovery of the spiked hexamine in drug substance obtained was in the range of 81.9 to 110.5 ensured the accuracy of the method. The method can be adapted to determine hexamine in Febuxostat drug substance (API). Keyword: Febuxostat, Hexamine, development, validation, LCMS INTRODUCTION Febuxostat is a xanthine oxidase inhibitor drug used in the treatment of gout. The chemical name for Febuxostat is 2-(3- cyano-4-isobutoxyphenyl)-4-methyl-1,3- thiazole-5-carboxylic acid [1]. Its molecular formula is C 16 H 16 N 2 O 3 S, which corresponds to a molecular weight of 316.37 (Fig.1). Hexamine is a chemical compound used in the synthesis of Febuxostat as a reagent. Hexamine also is known as Hexamethylenetetramine or methenamine is a heterocyclic organic compound (Fig.1) with the molecular formula C 6 H 12 N 4 . Hexamine molecule has a symmetric tetrahedral cage-like structure of which four corners are having nitrogen atoms and edges are having methylene bridges [2]. Hexamine is considered to be genotoxic as an experimental result shows it to be weak mutagenic. Hexamine structure also shows alert with QSAR software. The hydrolytic degradation product of Hexamine is Formaldehyde which is highly mutagenic [3]. Hence hexamine should be controlled in drug substances to the threshold of toxicological concern (TTC) level 1.5 μg/day in drug substances [4]. A limit for the Hexamine was set based on the maximum daily dose (MDD) of Febuxostat for which its limit comes out to be 12.5 ppm. Figure 1: Structure of Febuxostat and Hexamine