Influence of the punch shape on the core and shell structure of press-coated tablets

July 25, 2022, midnight - by Léo Picart , Vincent Mazel , Aline Moulin , Vanessa Bourgeaux , Pierre Tchoreloff

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Press-coated tablets play a pivotal role in achieving delayed releases in chronotherapeutics, with their drug release properties intricately tied to their distinctive core-shell structure. Therefore, understanding the impact of process parameters on this structure is crucial. Given the various shapes utilized in the industry, our study specifically delved into comprehending the influence of punch shape on the final structure of press-coated tablets. Experimental investigations employed flat, bevel-edged, and concave punches during the coating-compression process to examine the effects of punch shape on both the final properties of the core and the density distribution within the shell. Numerical simulations complemented these experiments, shedding light on the mechanical effects in the powder compression process. The findings highlighted the significant dependence of the radial and axial stress state in both the shell and the core on the punch shape. Notably, the use of concave punches induced a more hydrostatic stress state compared to flat punches. This resulted in a more homogeneous shell and less deformation of the core, underscoring the critical role of tooling shape as a key parameter in the production of press-coated tablets.

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