FORMULATION DEVELOPMENT AND EVALUATION OF LAMOTRIGINE SUSTAINED RELEASE TABLETS USING 32 FACTORIAL DESIGN

The main objective of present investigation is to formulate the sustained release tablet of lamotrigine using 3² factorial design. Lamotrigine, a weakly basic and anticonvulsant drug belongs to BCS Class II, having high permeability and poor solubility.  The sustained release tablets of lamotrigine were prepared employing different concentrations of HPMC K4M and HPMC K100M in different combinations as a rate retarding polymer by wet granulation technique using 3² factorial design. The quantity of polymers, HPMC K4M and HPMC K100M required to achieve the desired drug release was selected as independent variables, X₁ and X₂ respectively whereas, time required for 10% of drug dissolution (t_10%) and 50% (t_50%) were selected as dependent variables. Totally nine formulations were designed and are evaluated for hardness, friability, diameter, thickness, % drug content, In-vitro drug release. From the Results it was concluded that all the formulation were found to be within the Pharmacopoeial limits and  the In-vitro dissolution profiles of all formulations were fitted in to different Kinetic models, the statistical parameters like intercept (a), slope (b) & regression coefficient (r)  were calculated. Polynomial equations were developed for t_50%, t_10%, k_1.  According to SUPAC guidelines the formulation (F₅) containing combination of 12.5% HPMC K4M and 12.5% HPMC K100M, is the most similar formulation (similarity factor f₂=85.01 & No significant difference, t=-0.0102) to marketed product (Lamictal). The selected formulation (F₅) follows Higuchi’s kinetics, and the mechanism of drug release was found to be Anomalous type (Non-Fickian, n=0.841).