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Journal of Chemistry
Volume 2013 (2013), Article ID 608196, 6 pages
http://dx.doi.org/10.1155/2013/608196
Research Article

Stress Degradation Assessment of Lamotrigine Using a Validated Stability-Indicating HPTLC Method

1Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Alexandria, Khartoum Square 1, Azarita, Alexandria 21521, Egypt
2Dentistry/Pharmacy Centre, Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton AB, Canada T6G 2N8

Received 4 July 2012; Revised 24 August 2012; Accepted 26 August 2012

Academic Editor: Victor David

Copyright © 2013 Karim Michail et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

In this work, a sensitive and stability-indicating HPTLC method for the determination of lamotrigine is presented. According to the International Conference on Harmonization guidelines Q1A, lamotrigine was exposed to a variety of stress conditions; these include heating in acidic, basic and neutral media. Its stability towards oxidative stress, humidity, high temperature and direct sunlight was also examined. Separation of the drug from its forced degradation impurities was achieved using TLC silica gel plates and a mobile phase composed of ethyl acetate: methanol: ammonia. The linear regression analysis of the data obtained for the correlation plots showed good linearity over the concentration range of 10–300 ng/spot. The forced degradation studies showed that lamotrigine is susceptible to degradation under acidic, basic, neutral and oxidative conditions, among which alkaline-induced hydrolysis had the highest degradative potential. Alternatively, the drug was stable under heat, humidity, and daylight stress factors. In order to assess the purity and stability of the drug in tablet formulations, the developed method was applied to the analysis of commercial tablets in brand and generic products. The obtained results showed that the degradation of the drug has not occurred in the marketed formulations that were analyzed by the described methodology.