Effect of Different Polyoxyethylene Matrices on Extended Release Formulation of Cephalexin Trihydrate

The present study was undertaken to evaluate the effect of different viscosity grades of polyoxyethylene, their content level and the method of tablet preparation on the release profile of cephalexin trihydrate from matrix systems. Matrix tablets were prepared using Polyox N-10, Polyox N-80, Polyox N-60 K, Polyox 301 and Polyox 303 as rate-retarding agents by direct compression process. The release of drug from these hydrophillic matrices was studied over 12-hours in buffer media of pH 1.2. Statistically significant difference was found among the drug release profile from different matrices. The release kinetics was found to be governed by the type and content of hydrophillic materials in the matrix. Tablets granulated by PVP K-30 solution have higher hardness than those prepared by direct compression. However, drug release was not influenced by the method of tablet preparation. Formulations containing Polyox N-60K, Polyox 301 and Polyox 303 released 82%, 76% and 70% of the drug respectively, indicating that increasing viscosity can drastically reduce the release rate. Further, a decrease in polymer concentrations resulted a slight increase in thickness and friability, while a increase in polymer level resulted a increase in hardness and decrease in release rate. Numerical fits indicated that the formulations followed the Zero order release pattern which was further confirmed by the domination of super case-II transport in polyox tablets.