Breaking patterns of press-coated tablets during the diametral compression test: Influence of the product, geometry and process parameters
Jan. 25, 2022, midnight
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Press-coated tablets are a highly regarded technology in chronopharmaceutics, particularly for modified release applications. At the industrial level, assessing mechanical resistance is of paramount importance during both the development and production stages. The diametral compression test is a common method used in the industry for evaluating press-coated tablets, similar to its application for single layer tablets. However, the interpretation of test results can be significantly more complex for press-coated tablets compared to single layer tablets.
This study seeks to explore the suitability of the diametral compression test for press-coated tablets. Diametral compression tests were conducted on press-coated tablets produced with different products (shell/core), shell sizes, and compaction pressures. Four distinct breaking profiles were identified: total diametral, shell diametral, around the core, and laminated, depending on the process parameters and products used in tablet formation. Digital image correlation was employed to comprehend breaking patterns, especially concerning failure initiation and propagation.
The breaking pattern obtained is contingent upon the final tablet structure in terms of density distribution and elastic properties. To corroborate these findings, numerical simulations using the finite element method were employed to visualize stress distribution within the tablet and validate the impact of process parameters. The diverse failure profiles obtained suggest that caution should be exercised when interpreting the output value of the diametral compression test applied to press-coated tablets.