Effect of the curvature of the punches on the shape of the interface and the delamination tendency of bilayer tablets

May 1, 2017, midnight - by Luca Castrati , Vincent Mazel , Harona Diarra , Virginie Busignies , Pierre Tchoreloff

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Bilayer tablets hold special significance in the pharmaceutical industry, and a primary challenge in their manufacturing is the occurrence of delamination during or after ejection from the die. This study investigates the impact of using punches with curvature on the interfacial strength and, consequently, the tendency for delamination in bilayer tablets. The bilayer tablets were manufactured using a compaction simulator, employing various flat and concave punches with different radii of curvature. While maintaining a constant main compaction pressure, the tamping force was varied. Two bilayer model systems were examined, and the interfacial strength was determined through a previously established indentation test. The factors under scrutiny were statistically analyzed for their significance in relation to the responses. The study revealed that an increased curvature of the punch and tamping force resulted in a higher curvature of the interface. Breaking tests subsequently demonstrated that, for bilayer tablets produced with the same compression parameters, the interfacial strength decreased as the curvature of the interface increased. Consequently, when manufacturing bilayer tablets with concave punches, careful consideration of the tableting parameters is crucial to ensure the interface between the layers is as flat as possible, mitigating delamination issues.

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