Effect of particle size and diluent type on critical parameters for disintegration of tablets containing croscarmellose sodium as a disintegrant

Purpose: The aim of the present work was to determine the effect of particle size and type of diluents on critical concentration for the disintegration of tablet formulations containing a physical binary mixture of a superdisintegrant (croscarmellose sodium, CS) and a diluent.
Methods: The diluents used in this study were microcrystalline cellulose (MCC), dibasic calcium phosphate (DCP) and pregelatinized starch (PGS). Each diluent was divided into 2 different size ranges (small and large size)) and further mixed with 0 - 100 % CS. The binary mixture was compressed at controlled pressure, and the disintegration time and physical characteristic of the tablets were evaluated.
Results: The point of CS concentration that markedly affected the disintegration time of the tablets was recorded as the critical concentration for disintegration. The results showed that the particle size of the diluent did not affect the disintegration time. The critical CS concentrations were 2 % for DCP and MCC tablets and 5 % for PGS tablet. Adding a small amount of CS improved the disintegration of the tablets. However, increasing the amount of CS in the formulation also affected the hardness of the tablets. The particle size of diluents had a significant effect on the critical concentration for tablet disintegration.
Conclusion: Determining the type and appropriate amounts of diluent and disintegrant (percolating component) may be useful in the design of tablet formulations.

Keywords
Disintegration; Percolation threshold; Croscarmellose sodium; Microcrystalline cellulose; Dibasic calcium phosphate; Pre-gelatinized starch