Application of simplex lattice design for the development of extended release tablets of model drug diclofenac sodium

Simplex lattice design was applied to predict extent of drug release from extended release diclofenac sodium tablets. The effects of composition on dissolution rate were evaluated by varying the levels of hydroxypropyl methylcellulose, dicalcium phosphate and cornstarch via three component design. The rate of drug release was primarily dictated by the proportion of hydroxypropyl methylcellulose and was also affected by the proportion of dicalcium phosphate and the method of processing (direct compression/wet granulation). Polynomial equations constructed for directly compressed and wet-granulated formulations could successfully predict the extent of drug release at an arbitrary time point of 3 h. Simplex lattice design is a viable tool to predict the drug release patterns of extended release formulations.