Quantitative disintegration profiling using real-time erosion tracking during the standard USP〈701〉 test

For nearly eight decades, the evaluation of disintegration performance has relied on a single disintegration time (DT) value, which serves as the sole pass or fail criterion for drug products. Although practical for regulatory compliance, this endpoint-based metric offers limited scientific insight into the underlying physical breakdown of the tablet matrix. In this study, the dynamic evolution of the gap height between the disk and mesh in the USP〈701〉 disintegration apparatus was monitored using a state-of-the-art non-contact distance sensor, enabling the construction of disintegration profiles that function as a mechanical fingerprint of the dosage form. Simvastatin 20mg tablets from six different brands were investigated, encompassing both originator and generic alternatives, and the resulting gap height profiles clearly discriminate among brands in terms of formulation-dependent disintegration behaviour. Within the measurable range, the erosion interface was found to propagate linearly towards the tablet core at a constant velocity, supporting the interpretation of the process as governed by linear erosion-controlled kinetics, in which the erosion rate and liquid ingress are synchronised. By linking the observed erosion velocity to the rate of surface area generation, this profiling approach provides the physical parameters needed to improve dissolution models within the Noyes-Whitney framework. The results demonstrate the potential of upgrading the conventional USP disintegration setup into an effective Process Analytical Technology tool for formulation development and quality assessment.