This study was oriented toward the disintegration profiling of the diclofenac sodium (DS) immediate-release (IR) tablets and development of its relationship with medium permeability kperm based on Kozeny-Carman equation. Batches (L1-L9) of DS IR tablets with different porosities and specific surface area were prepared at different compression forces and evaluated for porosity, in vitro dissolution and particle-size analysis of the disintegrated mass. The kperm was calculated from porosities and specific surface area, and disintegration profiles were predicted from the dissolution profiles of IR tablets by stripping/residual method. The disintegration profiles were subjected to exponential regression to find out the respective disintegration equations and rate constants kd. Batches L1 and L2 showed the fastest disintegration rates as evident from their bi-exponential equations while the rest of the batches L3-L9 exhibited the first order or mono-exponential disintegration kinetics. The 95% confidence interval (CI95%) revealed significant differences between kd values of different batches except L4 and L6. Similar results were also spotted for dissolution profiles of IR tablets by similarity (f2) test. The final relationship between kd and kperm was found to be hyperbolic, signifying the initial effect of kperm on the disintegration rate. The results showed that disintegration profiling is possible because a relationship exists between kd and kperm. The later being relatable with porosity and specific surface area can be determined by nondestructive tests.
Keywords: Disintegration rate; dissolution; in-vitro models; particle size; permeability; porosity; pre-blend; solid dosage form; tableting.