Trakia Journal of Sciences, Vol. 13, № 1, 2015 1 Trakia Journal of Sciences, No 1, pp 1-11, 2015 Copyright © 2015 Trakia University Available online at: http://www.uni-sz.bg ISSN 1313-7050 (print) doi:10.15547/tjs.2015.01.001 ISSN 1313-3551 (online) Original Contribution STABILITY INDICATING ULTRA PERFORMANCE LIQUID CHROMATOGRAPHIC ASSAY OF LAMOTRIGINE IN PHARMACEUTICALS K. B. Vinay 1 , H. D. Revanasiddappa 1 , M. X. Cijo 1 , P. J. Ramesh 1 , N. Swamy 1 , N. Rajendraprasad 2* 1 Department of Studies in Chemistry, University of Mysore, Manasagangothri, Mysore, Karnataka, India 2 PG Department of Chemistry, J.S.S. College, Karnataka, India ABSTRACT A simple, precise and accurate stability-indicating isocratic reverse phase ultra-performance liquid chromatographic (RP-UPLC) method was developed for the determination of lamotrigine (LMT) in bulk drug and in its tablets. The method was developed using Waters Aquity BEH C 18 (100 mm × 2.1 mm, 1.7 µm) column with mobile phase consisting of a mixture of potassium dihydrogen phosphate buffer of pH 3.5 and an equal ratio of methanol and acetonitrile (50:50 v/v). The eluted compound was detected at 228 nm with a UV detector. The standard curve of mean peak area versus concentration showed an excellent linearity over a concentration range 1.0 – 75 µg/mL. Within-day and between-days RSD were less than 1.3% pronounces precision of the method. The accuracy of the method was further ascertained by recovery studies via standard addition procedure and the recoveries obtained were 98 - 100%. Forced degradation of the bulk sample was conducted in accordance with the ICH guidelines. Acidic, basic, hydrolytic, oxidative, thermal and photolytic degradation were used to assess the stability indicating power of the method. LMT was found to degrade significantly in acidic, basic and oxidative stress conditions and stable in thermal, hydrolytic and photolytic conditions. Key words: Lamotrigine, UPLC, Stability indicating assay, Pharmaceuticals. INTRODUCTION Lamotrigine (LMT), chemically known as [6-(2, 3- dichlorophenyl)-1,2,4-triazine-3,5-diamine] (Figure 1), is a broad spectrum antiepileptic, used as monotherapy and as an adjunct with other antiepileptics for treatment of partial and generalized toxic-clonic seizures. It’s use to treat neurological lesions and as a tranquilizer has also been studied [1, 2]. Owing to its use as an antiepileptic drug, it has attracted the attention of many analysts. LMT is official in United States Pharmacoepia (USP) [3], which describes a chromatographic technique with monobasic potassium phosphate buffer, triethylamine and acetonitrile as mobile ________________________ *Correspondence to: Nagaraju Rajendraprasad b* PG Department of Chemistry, J.S.S. College, Ooty Road, Mysore-570 025, Karnataka, India, email: prasadtnpur@gmail.com phase. The methods for LMT analysis utilized a variety of chromatographic techniques in body- fluids [4-21]. Most of these chromatographic methods describes assay of LMT either in plasma or serum and few are immunoassays. Few methods have been reported for its determination in pharmaceuticals and include titrimetry with acetous perchloric acid in anhydrous acetic acid medium [22], visible spectrophotometry [23-25], UV- spectrophotometry [26, 27], planar chromatography [4], thin layer chromatography and high performance liquid chromatography [28] and adsorptive stripping voltammetry [29]. Simultaneous determination of LMT, oxcarbazepine and zonisamide has been reported by Elizabeth et al [30] using HPLC and gas chromatographic techniques. Recently, Anantha Kumar et al [31] have reported RP-HPLC method in which the assay was carried out on a Luna C 18 column by employing a mixture of KH 2 PO 4 (pH 7.3) and methanol (60:40) as