Journal of Pharmaceutical and Biomedical Analysis 48 (2008) 788–795 Contents lists available at ScienceDirect Journal of Pharmaceutical and Biomedical Analysis journal homepage: www.elsevier.com/locate/jpba LC–UV–PDA and LC–MS studies to characterize degradation products of glimepiride Gulshan Bansal a,∗ , Manjeet Singh a , K.C. Jindal b , Saranjit Singh c a Department of Pharmaceutical Sciences and Drug Research, Punjabi University, Patiala 147002, Punjab, India b Panacea Biotec Ltd., Baddi, Himachal Pardesh, India c Department of Pharmaceutical Analysis, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar 160062, Punjab, India article info Article history: Received 23 March 2008 Received in revised form 1 August 2008 Accepted 5 August 2008 Available online 14 August 2008 Keywords: Glimepiride Degradation products Forced degradation LC–MS Mass fragmentation pattern abstract Degradation products of glimepiride formed under different forced conditions have been characterized through LC–UV–PDA and LC–MS studies. Glimepiride was subjected to forced decomposition under the conditions of hydrolysis, oxidation, dry heat and photolysis, in accordance with the ICH guideline Q1A(R2). The reaction solutions were chromatographed on reversed phase C8 (150mm × 4.6 mm i.d., 5 m) ana- lytical column. In total, five degradation products (I–V) were formed under various conditions. The drug degraded to products II and V under acid and neutral hydrolytic conditions while products I, III and IV were formed under the alkaline conditions. The products II and V were also observed on exposure of drug to peroxide. No additional degradation product was shown up under photolytic conditions. All the products, except I, could be characterized through LC–PDA analyses and study of MS fragmentation pattern in both +ESI and -ESI modes. Product I could not be identified, as it did not ionize under MS conditions. The products II, III and V matched, respectively, to impurity B (glimepiride sulfonamide), impurity J and impurity C (glimepiride urethane) listed in European Pharmacopoeia. The product IV was a new degradation product, characterized as [[4-[2-(N-carbamoyl)aminoethyl]phenyl]sulfonyl]-3-trans- (4-methylcyclohexyl) urea. The degradation pathway of the drug to products II–V is proposed, which is yet unreported. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Glimepiride is a third generation sulfonylurea type oral hypo- glycemic agent, which is widely used in treatment of type 2 diabetes [1,2]. Chemically, it is 1-[[4-[2-(3-ethyl-4-methyl-2-oxo- 3-pyrroline-1-carboxamido)-ethyl]phenyl]sulfonyl]-3-trans-(4- mehtylcyclohexyl)urea (Fig. 1). The presence of a sulfonylurea bridge, a carboxamide linkage, a constrained lactam ring and an ,-unsaturated carbonyl system in chemical structure of glimepiride makes the drug susceptible to degradation, due to labiality of these linkages and functional groups to hydrolysis and photolysis [3–10]. As a result, several degradation products are anticipated to be formed during formal stability testing of the drug. The drug substance monograph of glimepiride in European Phar- macopoeia (EP) lists ten impurities (A–J) [11]. Of the list, four are also mentioned as related substances in the drug monograph by the United States Pharmacopeia [12]. Even some studies on the drug are ∗ Corresponding author. Tel.: +91 175 3046255; fax: +91 175 2283073. E-mail address: gulshanbansal@rediffmail.com (G. Bansal). reported in the literature. Khan et al. [13] developed a LC method for the separation of glimepiride and five related impurities. A more relevant publication is by Kov˘ a´ rıková et al. [14], who carried out HPLC study on glimepiride under hydrolytic (acid, neutral and alka- line) and oxidative stress conditions, but no degradation products were identified. Thus, the purpose of the present study was to identify the degradation products of the drug formed under ICH recommended stress conditions of hydrolysis, oxidation, dry heat and photolysis [15–17] taking the help of LC–PDA and LC–MS techniques. Another endeavor was to establish pathway for formation of the identified degradation products. 2. Experimental 2.1. Chemicals and reagents Glimepiride was supplied by Panacea Biotec Ltd. (Lalru, India) as a gift sample. Acetonitrile and methanol (HPLC grade), hydrochlo- ric acid, sodium hydroxide pellets, hydrogen peroxide solution, acetic acid glacial and ammonium acetate (all AR grade) were pur- chased from Ranbaxy Fine Chemicals (Gurgaon, India). HPLC-grade 0731-7085/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jpba.2008.08.003