Application of simplex centroid design for the preparation of hydrophilic matrix tablets of diclofenac sodium and statistical optimization of release rate

Abstract

Extended release tablets of Diclofenac sodium (DS) were prepared by applying Simplex Centroid Design (SCD). Eight batches of hydrophilic matrix tablets of DS were prepared according to SCD with average weight of 300.0 mg/tablet. Amount of Methocel E15LV, dibasic calcium phosphate and lactose were chosen as formulation variables. Cumulative % release at 2 h (T_{2 Hr}) and cumulative % release at 8 h (T_{8 Hr}) were dependent variables. Dissolution study of eight batches gave: T_{2 Hr,} 21.59-100.74; and T_{8 Hr,}73.61-101.94%. Target T_{2 Hr} was 37.5 -50% of the total dose and target T_{8 Hr} was above 80% of the total dose. Mathematical models were found by the application of Analysis of Variance using Design Expert Software for cumulative % release at T_{2 Hr} and T_{8 Hr}. Optimized formulation, which met the target, was found out by solving two mathematical models. Finally validation of the suggested formulation was performed.