Optimization of a formulation for direct compression using a simplex lattice design

In this paper it is demonstrated how the optimum composition of a mixture for direct compression consisting of alpha-lactose monohydrate, roller-dried beta-lactose and microcrystalline cellulose can be found using a systematic optimization technique. The experiments were chosen according to a simplex lattice design. The results of these experiments were used to fit a mathematical model, which then can predict the properties of all possible mixture compositions and enables a graphic representation of these properties in the form of contour plots. At a level of 4% the effect of three disintegrants (sodium starch glycolate, croscarmellose sodium and crospovidone) on the properties of the tablets compressed from these filler-binders, was evaluated by superimposing the contour plots of the different tablet responses. It was found that all the disintegrants used were effective in this combination of filler-binders. In order to evaluate drug dissolution rate an extra experiment with crospovidone as the disintegrant was performed, in which oxazepam was used as a test drug.