In Vitro Comparative Quality Evaluation of Non-Expired and 10 Years-Expired Lamotrigine Immediate-Release Tablet Formulations - Pilot Study

This study aimed to compare the different physical parameters and dissolution profiles of 10 years-expired with non-expired lamotrigine (LTG) immediate-release tablet formulations. Dissolution tests were conducted using a validated high-performance liquid chromatography method. Dissolution characteristics of the tablet formulations were evaluated at three points spanning the physiological pH range (pH 1.2, pH 4.5, pH 6.8). Physical characteristics of LTG tablets were determined according to the European Pharmacopoeia. The dissolution profile comparison was carried out using model-independent (statistical) and model-dependent (kinetic) methods to provide detailed information about dissolution data. The t-test was applied to investigate differences between expired and non-expired tablets, and the differences were considered statistically significant if p <= 0.05. The results demonstrated no statistical differences in physical characteristics between expired and non-expired tablets; however, there were differences in the dissolution profiles, which could cause different pharmacokinetic profiles. The results of this investigation showed that the drug content did not change significantly. Therefore, the lower dissolution rate for expired LTG tablets is due to an interaction of LTG with one or more excipients in the tablet formulation during aging.