QUANTIFICATION OF BILASTINE AND MONTELUKAST COMBINATION IN FORMULATIONS UTILIZING LIQUID CHROMATOGRAPHY: STABILITY STUDIES Original Article KANCHARLA VIJAYALAKSHMI 1* , BETHAPUDI SAMUEL ANAND ANDREWS 2 , BOLINENI NAGESWARA RAO 3 1 Quality Control Department, Divis Laboratories Limited, Hyderabad, India 508252, 2 Department of Chemistry, Gitam Institute of Technology, GITAM University, Visakhapatnam, India 530045, 3 Research and Development, Divis Laboratories Limited, Hyderabad, India 500018 Email: vijayalakshmikancharla.msc@gmail.com Received: 27 Apr 2021, Revised and Accepted: 30 Aug 2021 ABSTRACT Objective: We have developed a “stability-indicating RP-HPLC” procedure for the Bilastine (BLS) and montelukast (MTL) analysis of tablets. Methods: The quantification of BLS and MTL combination was implemented utilising a Waters column (C18, 5 μm, 250 mm and 4.6 mm). Isocratic mobile phase had 60% volume KH2PO4 of 0.1M strength with pH 4.2 units and 40% volume methanol at a flow with 1.0 ml/min speed. UV detection at 232 nm was done to examine BLS and MTL. Stability experiments of BLS and MTL under distinctive environments of stress were also performed. Results: The BLS and MTL were eluted at 1.810 min and 2.551 min, respectively. The responses were found to be linear for the concentration ranges of 10-30 µg/ml (BLS) and 5-15 µg/ml (MTL). Percent comparative standard deviance for precision was 0.331% (BLS) and 0.486% (MTL). Percent assay for accuracy was 98.96% (BLS) and 99.00% (MTL). The detection limit and quantitation limit measures for BLS were 0.018 µg/ml and 0.059 µg/ml, respectively, while for MTL it was 0.024 µg/ml and 0.081 µg/ml, respectively. Robustness studies authorized that the method is robust with percent comparative standard deviance of a highest 1.950%. Conclusion: The developed “stability-indicating RP-HPLC” procedure for the BLS and MTL analysis is simple, sensitive, precise, specific and robust, making it appropriate to the assessment of BLS and MTL in a tablet formulation. Keywords: Bilastine, Montelukast, Tablet formulation, Stability indicating, Analysis © 2021 The Authors. Published by Innovare Academic Sciences Pvt Ltd. This is an open access article under the CC BY license (https://creativecommons.org/licenses/by/4.0/) DOI: https://dx.doi.org/10.22159/ijap.2021v13i6.41915. Journal homepage: https://innovareacademics.in/journals/index.php/ijap INTRODUCTION Nonsedating antihistamines are the first treatment option for the allergic rhinoconjunctivitis including urticaria, according to the existing recommendations [1, 2]. Bilastine (BLS) is not structurally relevant to many other antihistamines. BLS, like loratadine, desloratadine, even fexofenadine, falls in the piperidine grouping of antihistamines. BLS, as many other antihistamines, is also an inverse agonist for the H1 receptor. The in vitro tests have revealed that the BLS affinity with the H1 receptor is significant, but the affinity with 30 other checked receptors is very weak, or very little [3]. The in vivo tests have revealed histamine excited smooth muscle relaxation, endothelial permeability, bronchospasms, and microvascular extravasation were all decreased in the rats [4]. The suppression of histamine excited wheal and flare reaction behaviour in the skin, which was marked with BLS, was reported in vivo tests in the human populace. From the findings of both comparative observations of montelukast (MLT) versus placebo and findings of MLT's preventive role on the bronchoconstriction occasioned by exercise or any other nonspecific triggers were reported, the first indications of MLT's efficacy in asthma were recorded [5]. MLT is a cysteinyl leukotriene receptor blocker that is intended to manage asthma as well as alleviate seasonal allergies signs. MLT works via attaching to a cysteinyl leukotriene receptor in the bronchial tubes and lungs and suppressing the operation of leukotriene D4 on it [6]. In mild-to- moderate asthmatics that are not taking inhaled corticosteroids, MLT improves symptoms, relief drug use, and pulmonary functioning as well as lowering the frequency of exacerbation and blood eosinophil quantities. Montelukast also outperformed long- acting beta2-agonists in preventing bronchoconstriction exacerbated by exercise [7]. The BLS and MTL structures were displayed in fig. 1. One publication resulted from a study of BLS and MTL absorbance grounded assays, suggesting BLS and MTL direct quantitative evaluation in the pharmaceutical dosage types [8]. BLS and MTL absorption at 214 nm and 281 nm, respectively, are used in their quantitation. For BLS and MTL analysis of tablets, no liquid chromatography-based approach has been put forward yet. In this investigation project, we developed a “stability-indicating RP-HPLC” method for the BLS and MTL analysis of tablets. We also studied the validated factors of “stability- indicating RP-HPLC” method proposed for the BLS and MTL analysis. Fig. 1: BLS (bilastine) and MTL (montelukast) structures MATERIALS AND METHODS Chemicals The BLS and MTL combination tablet kind used was Bilagio M (BLS 20 mg and MTL 10 mg, “Synokem Pharmaceuticals LTD, India”). “Rainbow Pharma Training Labs, India” provided the BLS and MTL reference samples. Methanol (Merck, India) and water (Milli Q water) utilized in “stability-indicating RP-HPLC” experiments were HPLC rating. NaOH, H2PO4, H2O2, KH2PO4 and HCl were all reagent rating from “Sd Fine Chemicals Ltd, India”. International Journal of Applied Pharmaceutics ISSN- 0975-7058 Vol 13, Issue 6, 2021