Quantification of tablet sensitivity to a stress concentration: generalization of Hiestand's approach and link with the microstructure

June 1, 2020, midnight - by B. Croquelois , J. Girardot , J.B. Kopp , P. Tchoreloff , V. Mazel

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The sensitivity to stress concentration is a crucial factor in the development of pharmaceutical tablets, given its association with defects such as capping. Hiestand et al. introduced the Brittle Fracture Index (BFI) to assess this sensitivity. Recently, a more comprehensive index, grounded in the average stress criterion, was proposed as a generalized Hiestand approach. In this study, the efficacy of this new approach is evaluated using tablets produced from various products and under different pressure levels, revealing the broad applicability of the novel criterion. Additionally, X-ray micro-computed tomography was employed to establish a connection between the microstructure of the tablets and their sensitivity to stress concentration. A robust correlation emerged, highlighting the relationship between the size of the largest pores in the structure and the value of a0, which quantifies the sensitivity to stress concentration in the generalized Hiestand approach. These findings mark the initial effort to establish a link between the brittle fracture propensity of tablets and their effective microstructure.

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