Evaluation of tablet punch configuration on mitigating capping by a quality by design approach

Capping is a common problem in the manufacture of some types of tablets and unless resolved, the tableting process cannot proceed. Hence, all factors that can help to lessen the likelihood of capping without unnecessarily reduce turret speed and/or compaction force would be tenable. This study investigated the influence of tablet punch configuration on mitigation of tablet capping. Tablets were prepared from high-dose paracetamol-potato starch granules in a rotary tablet press with flat face plain (FFP), flat face bevel edge (FFBE) and flat face radius edge (FFRE) punch configurations. The directly compressible (DC) fillers tested were microcrystalline cellulose (MCC), pre-gelatinised starch (PGS) and lactose. Design of experiments (DoE), a tool of quality by design (QbD) paradigm, was used and the interaction of input variables (compression force, tablet punch configuration and DC filler) affecting the response factors (tablet hardness and capping rating) were evaluated. FFP punches were able to mitigate capping best. FFRE punches showed more potential than FFBE punches at alleviating capping in a particular compression force range, without the limitations of the FFP punches that produce cylindrical tablets that were more friable. Incorporation of PGS in the tablet formulation was observed to be more efficient at mitigating capping than the other DC fillers when FFBE and FFRE punches were used. Overall, this study serves as a model for prospective product development based on the QbD framework and the optimal use of compaction tools.