Formulation and Evaluation of Sustained Release Matrix Tablets of Cephalexin: Effects of Hydrophilic and Hydrophobic Matrix on Drug Release

Sustained release cephalexin tablets were prepared by using different polymers like Hydroxypropyl methylcellulose (HPMC) K4M, HPMC K15M, HPMC K100M, HPMC K 100LV, Ethyl cellulose, Carbopol 971P, Carbopol 974P, Eudragit RS100, Eudragit RL100 and Eudragit L100. Tablets were prepared by wet granulation technique and evaluated for different parameters such as thickness, hardness, weight uniformity, content uniformity, friability, in-vitro drug release, drug release mechanism and stability. Results of the studies indicate that the polymers used have significant release-retarding effect on the formulation. The dissolution profile comparison of the prepared batches and market preparation (Nufex CR Tablet) was done by similarity and difference factor determination. The formulation K4 (5.8% HPMC K100M, 1.0% ethyl cellulose) with a similarity factor of 68.28 was found nearest to the marketed formulation. Formulation K4 shows first order drug release and mechanism of drug release was found to be anomalous. The results of the accelerated stability study of best formulation K4 after two months revealed no significant changes in formulation. It is concluded that carbopol, eudragit and HPMC are suitable as bases for preparing tablet matrices containing cephalexin but only carbopol 971P and HPMC K4M were able to produce release profile similar to that of marketed preparation.